Posted: October 27th, 2022

lesson 3 psych1300/option 2


Option 2 – Explain how tests are useful.  What type of test question  do you prefer and why?  Complete the “Try It!” 1 “Measure Your  Test-taking Style” (Chapter 5).  Describe two strategies to deal with  test anxiety.

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Power Learning 8e

Chapter 4

Taking Notes



020 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom.

No reproduction or further distribution permitted without the prior written consent of McGraw Hill.

Because learning changes everything.®

Taking Notes in Class 1


Identify your goals for the class.

Complete assignments before coming to class.

Accept the instructor as is.

Skim your notes before class.

Sit where you can take good notes.


© McGraw Hill

LO 4.1 and 4.2

Taking Notes in Class 2
Get the proper tools together.
Find a notebook that fits your notetaking style.
Try the Cornell Method of Notetaking to see how it works for you.
Do you need your textbook for class?
Consider the pros and cons of using a laptop in class.

© McGraw Hill

LO 4.1 and 4.2


Taking Notes in Class 3
Use active listening, rather than just hearing, when taking notes.
Listen for key ideas.
Use short phrases, not complete sentences.
Use abbreviations.
Take notes in an outline form.

© McGraw Hill

LO 4.1 and 4.2


Taking Notes in Class 4
Work, continued:
Write down what your instructor puts on the board and presents on overheads or PowerPoint slides.
Use a different method for class discussions.
Highlight any concluding comments your instructor makes at the end of a discussion.
Ask questions.

© McGraw Hill

LO 4.1 and 4.2


Taking Notes in Class 5
Dealing with difficult instructors:
Remember it’s only temporary.
Ask questions.
Ask politely, and privately, for a change in method.
Work with classmates to get through the class.
Record the lecture and listen to it again.
Communicate with your instructor.

© McGraw Hill

LO 4.1 and 4.2


Taking Notes in Class 6
Before you leave class, determine if your notes are complete.
Do they cover what was presented in class?
Do they emphasize what the instructor emphasized?
Are there key points that are not clear?
Do I need clarification on points my instructor made?
Follow up with your instructor, if needed.

© McGraw Hill

LO 4.1 and 4.2


Taking Notes in Class 7
Use 5 or 10 minutes right after class to review.
This will save you hours of work later.
Promotes transfer of information into long-term memory.
The longer you wait to review your notes, the less effective it will be.
Improve your notes as you review them.
Create concept maps.

© McGraw Hill

LO 4.1 and 4.2


Taking Notes as You Study 1
Taking notes in your text:
Highlight, underline, circle, take notes in the margin.
Transfer your text notes into your class notes.
Transfer your text notes into flash cards for quick review.

© McGraw Hill

LO 4.3

Taking Notes as You Study 2
Taking notes on other materials:
Consider using your laptop.
Approach the material as you would a class lecture – look for the most relevant information.
Use the same notetaking system as you use in lecture notetaking.

© McGraw Hill

LO 4.3

End of Main Content
© 2020 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom.
No reproduction or further distribution permitted without the prior written consent of McGraw Hill.

Because learning changes everything.®



Power Learning 8e

Chapter 5

Taking Tests



020 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom.

No reproduction or further distribution permitted without the prior written consent of McGraw Hill.

Because learning changes everything.®

Getting Ready

Tests cause great anxiety for students and instructors.

Tests are valuable, they help define what you know and what you still need to work on.

Don’t allow tests to define your worth as a person.

Tests measure how well and how much you studied, and your test-taking skills.


© McGraw Hill

LO 5.1

Taking Tests – Prepare 1
Take a long-term view on preparing for tests.
Know what you are preparing for.
What material will be covered?
How many questions will there be?
How much time will you have to take it?
What kinds of questions will be on it?
How much can the test impact your final grade?

© McGraw Hill

LO 5.2

Taking Tests – Prepare 2
Match your preparation to the type of test you are studying for.
How to tackle different types of test questions.
Essay: note specifically what is being asked, write outline if needed, be brief and to the point, move from major points to minor ones, answer every part of question.

© McGraw Hill

LO 5.2

Taking Tests – Prepare 3
Short-answer and fill-in: unlike essays, these require specific information, be brief.
Multiple-choice questions: be sure of the number answers you can choose, answer the question in your head first, look for absolutes as possibilities to discard, break the question apart, use an educated guess strategy.
Short-answer and fill-in: must be able to recall information, study specific and detailed information.
Multiple-choice/True-False/Matching: requires attention to details rather than big-picture, must know a lot of facts, use index cards to study.

© McGraw Hill

LO 5.2

Taking Tests – Prepare 4
Test yourself:
Textbook website.
Write your own questions.
Take practice test questions with your study group.
Deal with test anxiety:
Prepare thoroughly.
Take a realistic view of the test.
Eat right and get enough sleep.
Learn relaxation techniques.
Visualize success.

© McGraw Hill

LO 5.2

Taking Tests – Prepare 5
Organize a study group:
Helps members of the group organize and structure material.
Members can share different perspectives on the material.
Prevents members from overlooking important information.
Forces members to rethink the material by explaining it to other members of the group.
Motivates members to do their best.

© McGraw Hill

LO 5.2

Taking Tests – Prepare 6
When organizing a study group:
Identify motivated members of your class.
Include a variety of people with different strengths.
Identify your group’s purpose.
Keep your group the right size.
Use campus tutoring center.
Try not to cram.

© McGraw Hill

LO 5.2

Taking Tests – Organize
Bring the right tools the day of the test.
Bring notes and text, if permitted.
Avoid comparing study preparation with fellow students on the day of the test.
Listen to what your instructor says before the test is handed out – this is valuable information!

© McGraw Hill

LO 5.2

Taking Tests – Work 1
Take a deep breath.
Tell yourself that you’re going to do your best.
Answer the easy questions first.
Write legibly and only on one side of the paper.
Carefully mark machine-scored tests.
With online exams, be prepared for possible technical difficulties.

© McGraw Hill

LO 5.2

Taking Tests – Work 2
How to tackle different types of test questions:
Essay: note specifically what is being asked, write outline if needed, be brief and to the point, move from major points to minor ones, answer every part of question.
Short-answer and fill-in: unlike essays, these require specific information, be brief.
Multiple-choice questions: be sure of the number answers you can choose, answer the question in your head first, look for absolutes as possibilities to discard, break the question apart, use an educated guess strategy.

© McGraw Hill

LO 5.3

Taking Tests – Work 3
How to tackle different types of test questions.
True – False questions: answer the ones you’re sure about first, consider the absolutes because they will determine the answer, if part of a statement is false then the whole statement is false.
Matching questions: match the ones you know first.
Keep academic honesty a priority.

© McGraw Hill

LO 5.3

Taking Tests – Evaluate
Save time at the end of the test to evaluate your work.
Check for obvious mistakes.
Proof-read your essays and short answers.
Add any additional information and attempt questions you weren’t sure about earlier.
Run out of time?
Stop and plan a quick strategy for the final minutes of the test.
Outline essays, write keywords.
Remember: something is always better than nothing.

© McGraw Hill

LO 5.3

Taking Tests – Rethink
How did you do?
Think beyond just your score.
Examine mistakes for how to do better in the future.
Actively listen to what your instructor says about the test.
Were your errors based on not understanding the material or due to test-taking skills?
Follow up with your instructor, if needed.

© McGraw Hill

LO 5.3

End of Main Content
© 2020 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom.
No reproduction or further distribution permitted without the prior written consent of McGraw Hill.

Because learning changes everything.®





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Table of Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter 1: Introduction to Psychology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 What Is Psychology? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 History of Psychology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3 Contemporary Psychology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.4 Careers in Psychology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Chapter 2: Psychological Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.1 Why Is Research Important? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.2 Approaches to Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.3 Analyzing Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.4 Ethics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Chapter 3: Biopsychology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3.1 Human Genetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
3.2 Cells of the Nervous System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
3.3 Parts of the Nervous System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
3.4 The Brain and Spinal Cord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.5 The Endocrine System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Chapter 4: States of Consciousness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
4.1 What Is Consciousness? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
4.2 Sleep and Why We Sleep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
4.3 Stages of Sleep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
4.4 Sleep Problems and Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
4.5 Substance Use and Abuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
4.6 Other States of Consciousness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Chapter 5: Sensation and Perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
5.1 Sensation versus Perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
5.2 Waves and Wavelengths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
5.3 Vision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
5.4 Hearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
5.5 The Other Senses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
5.6 Gestalt Principles of Perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Chapter 6: Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
6.1 What Is Learning? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
6.2 Classical Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
6.3 Operant Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
6.4 Observational Learning (Modeling) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Chapter 7: Thinking and Intelligence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
7.1 What Is Cognition? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
7.2 Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
7.3 Problem Solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
7.4 What Are Intelligence and Creativity? . . . . . . . . . . . . . . . . . . . . . . . . . . 233
7.5 Measures of Intelligence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
7.6 The Source of Intelligence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
Chapter 8: Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
8.1 How Memory Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
8.2 Parts of the Brain Involved with Memory . . . . . . . . . . . . . . . . . . . . . . . . . 261
8.3 Problems with Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
8.4 Ways to Enhance Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
Chapter 9: Lifespan Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
9.1 What Is Lifespan Development? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286

9.2 Lifespan Theories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290
9.3 Stages of Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
9.4 Death and Dying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318
Chapter 10: Emotion and Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
10.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
10.2 Hunger and Eating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
10.3 Sexual Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342
10.4 Emotion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
Chapter 11: Personality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
11.1 What Is Personality? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366
11.2 Freud and the Psychodynamic Perspective . . . . . . . . . . . . . . . . . . . . . . . 369
11.3 Neo-Freudians: Adler, Erikson, Jung, and Horney . . . . . . . . . . . . . . . . . . . 375
11.4 Learning Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380
11.5 Humanistic Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384
11.6 Biological Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385
11.7 Trait Theorists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387
11.8 Cultural Understandings of Personality . . . . . . . . . . . . . . . . . . . . . . . . . 392
11.9 Personality Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
Chapter 12: Social Psychology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405
12.1 What Is Social Psychology? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406
12.2 Self-presentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411
12.3 Attitudes and Persuasion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
12.4 Conformity, Compliance, and Obedience . . . . . . . . . . . . . . . . . . . . . . . . 421
12.5 Prejudice and Discrimination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 429
12.6 Aggression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435
12.7 Prosocial Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438
Chapter 13: Industrial-Organizational Psychology . . . . . . . . . . . . . . . . . . . . . . . . . 453
13.1 What Is Industrial and Organizational Psychology? . . . . . . . . . . . . . . . . . . . 454
13.2 Industrial Psychology: Selecting and Evaluating Employees . . . . . . . . . . . . . . 460
13.3 Organizational Psychology: The Social Dimension of Work . . . . . . . . . . . . . . 470
13.4 Human Factors Psychology and Workplace Design . . . . . . . . . . . . . . . . . . 479
Chapter 14: Stress, Lifestyle, and Health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 487
14.1 What Is Stress? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 488
14.2 Stressors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498
14.3 Stress and Illness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
14.4 Regulation of Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517
14.5 The Pursuit of Happiness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 524
Chapter 15: Psychological Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 539
15.1 What Are Psychological Disorders? . . . . . . . . . . . . . . . . . . . . . . . . . . . 540
15.2 Diagnosing and Classifying Psychological Disorders . . . . . . . . . . . . . . . . . . 544
15.3 Perspectives on Psychological Disorders . . . . . . . . . . . . . . . . . . . . . . . . 547
15.4 Anxiety Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 550
15.5 Obsessive-Compulsive and Related Disorders . . . . . . . . . . . . . . . . . . . . . 556
15.6 Posttraumatic Stress Disorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560
15.7 Mood Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 562
15.8 Schizophrenia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572
15.9 Dissociative Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 576
15.10 Personality Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 578
15.11 Disorders in Childhood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 584
Chapter 16: Therapy and Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 601
16.1 Mental Health Treatment: Past and Present . . . . . . . . . . . . . . . . . . . . . . 602
16.2 Types of Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608
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16.3 Treatment Modalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 620
16.4 Substance-Related and Addictive Disorders: A Special Case . . . . . . . . . . . . . 624
16.5 The Sociocultural Model and Therapy Utilization . . . . . . . . . . . . . . . . . . . . 627
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 729

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Psychology is designed to meet scope and sequence requirements for the single-semester introduction
to psychology course. The book offers a comprehensive treatment of core concepts, grounded in both
classic studies and current and emerging research. The text also includes coverage of the DSM-5 in
examinations of psychological disorders. Psychology incorporates discussions that reflect the diversity
within the discipline, as well as the diversity of cultures and communities across the globe.
Preface 1

Coverage and Scope
This book is designed to make psychology, as a discipline, interesting and accessible to students research
and examples that represent and include the various sociocultural backgrounds of the many students who
take this course. The result is a book that covers the breadth of psychology topics with variety and depth
that promote student engagement. The organization and pedagogical features were developed and vetted
with feedback from psychology educators dedicated to the project.
Chapter 1: Introduction to Psychology
Chapter 2: Psychological Research
Chapter 3: Biopsychology
Chapter 4: States of Consciousness
Chapter 5: Sensation and Perception
Chapter 6: Learning
Chapter 7: Thinking and Intelligence
Chapter 8: Memory
Chapter 9: Lifespan Development
Chapter 10: Motivation and Emotion
Chapter 11: Personality
Chapter 12: Social Psychology
Chapter 13: Industrial-Organizational Psychology
Chapter 14: Stress, Lifestyle, and Health
Chapter 15: Psychological Disorders
Chapter 16: Therapy and Treatment
Pedagogical Foundation
Throughout Psychology, you will find features that draw the students into psychological inquiry by taking
selected topics a step further.
Everyday Connection features tie psychological topics to everyday issues and behaviors that
students encounter in their lives and the world. Topics include the validity of scores on college
entrance exams, advertising and associative learning, and cognitive mapping.
What Do You Think? features provide research-based information and ask students their views on
controversial issues. Topics include “Brain Dead and on Life Support,” “Hooters and BFOQ Laws,”
and “Intellectually Disabled Criminals and Capital Punishment.”
Dig Deeper features discuss one specific aspect of a topic in greater depth so students can dig more
deeply into the concept. Examples include a discussion on the distinction between evolutionary
psychology and behavioral genetics, an analysis of the increasing prevalence rate of ADHD, and a
presentation of research on strategies for coping with prejudice and discrimination.
Connect the Concepts features revisit a concept learned in another chapter, expanding upon it
within a different context. Features include “Autism Spectrum Disorder and the Expression of
Emotions,” “Tweens, Teens, and Social Norms,” and “Conditioning and OCD.”
Art, Interactives, and Assessments That Engage
Our art program is designed to enhance students’ understanding of psychological concepts through
2 Preface
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simple, effective graphs, diagrams, and photographs. Psychology also incorporates links to relevant
interactive exercises and animations that help bring topics to life. Selected assessment items touch directly
on students’ lives.
Link to Learning features direct students to online interactive exercises and animations that add a
fuller context to core content and provide an opportunity for application.
Personal Application Questions engage students in topics at a personal level to encourage
reflection and promote discussion.
Student and Instructor Resources
We’ve compiled additional resources for both students and instructors, including Getting Started Guides,
an instructor solution guide, a test bank, and PowerPoint slides. Instructor resources require a verified
instructor account, which you can apply for when you log in or create your account on Take
advantage of these resources to supplement your OpenStax book.
Partner Resources
OpenStax Partners are our allies in the mission to make high-quality learning materials affordable and
accessible to students and instructors everywhere. Their tools integrate seamlessly with our OpenStax
titles at a low cost. To access the partner resources for your text, visit your book page on
Senior Contributing Authors
Rose M. Spielman (Content Lead)
Dr. Rose Spielman has been teaching psychology and working as a licensed clinical psychologist for
20 years. Her academic career has included positions at Quinnipiac University, Housatonic Community
College, and Goodwin College. As a licensed clinical psychologist, educator, and volunteer director, Rose
is able to connect with people from diverse backgrounds and facilitate treatment, advocacy, and education.
In her years of work as a teacher, therapist, and administrator, she has helped thousands of students
and clients and taught them to advocate for themselves and move their lives forward to become more
productive citizens and family members.
Kathryn Dumper, Bainbridge State College
William Jenkins, Mercer University
Arlene Lacombe, Saint Joseph’s University
Marilyn Lovett, Livingstone College
Marion Perlmutter, University of Michigan
Daniel Bellack, Trident Technical College
Jerimy Blowers, Cayuga Community College
Salena Brody, Collin College
Bettina Casad, University of Missouri–St. Louis
Sharon Chacon, Northeast Wisconsin Technical College
Barbara Chappell, Walden University
James Corpening
Frank Eyetsemitan, Roger Williams University
Tamara Ferguson, Utah State University
Kathleen Flannery, Saint Anselm College
Johnathan Forbey, Ball State University
Preface 3

Laura Gaudet, Chadron State College
William Goggin, University of Southern Mississippi
Jeffery K. Gray, Charleston Southern University
Heather Griffiths, Fayetteville State University
Mark Holder, University of British Columbia
Rita Houge, Des Moines Area Community College
Colette Jacquot, Strayer University
John Johanson, Winona State University
Andrew Johnson, Park University
Shaila Khan, Tougaloo College
Carol Laman, Houston Community College
Thomas Malloy, Rhode Island College
Jan Mendoza, Golden West College
Christopher Miller, University of Minnesota
Lisa Moeller, Beckfield College
Hugh Riley, Baylor University
Juan Salinas, University of Texas at Austin
Brittney Schrick, Southern Arkansas University
Phoebe Scotland, College of the Rockies
Christine Selby, Husson University
Brian Sexton, Kean University
Nancy Simpson, Trident Technical College
Robert Stennett, University of Georgia
Jennifer Stevenson, Ursinus College
Eric Weiser, Curry College
Valjean Whitlow, American Public University
4 Preface
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Chapter 1
Introduction to Psychology
Figure 1.1 Psychology is the scientific study of mind and behavior. (credit “background”: modification of work by
Nattachai Noogure; credit “top left”: modification of work by U.S. Navy; credit “top middle-left”: modification of work by
Peter Shanks; credit “top middle-right”: modification of work by “devinf”/Flickr; credit “top right”: modification of work
by Alejandra Quintero Sinisterra; credit “bottom left”: modification of work by Gabriel Rocha; credit “bottom middle-
left”: modification of work by Caleb Roenigk; credit “bottom middle-right”: modification of work by Staffan Scherz;
credit “bottom right”: modification of work by Czech Provincial Reconstruction Team)
Chapter Outline
1.1 What Is Psychology?
1.2 History of Psychology
1.3 Contemporary Psychology
1.4 Careers in Psychology
Clive Wearing is an accomplished musician who lost his ability to form new memories when he became
sick at the age of 46. While he can remember how to play the piano perfectly, he cannot remember what
he ate for breakfast just an hour ago (Sacks, 2007). James Wannerton experiences a taste sensation that is
associated with the sound of words. His former girlfriend’s name tastes like rhubarb (Mundasad, 2013).
John Nash is a brilliant mathematician and Nobel Prize winner. However, while he was a professor at MIT,
he would tell people that the New York Times contained coded messages from extraterrestrial beings that
were intended for him. He also began to hear voices and became suspicious of the people around him.
Soon thereafter, Nash was diagnosed with schizophrenia and admitted to a state-run mental institution
(O’Connor & Robertson, 2002). Nash was the subject of the 2001 movie A Beautiful Mind. Why did these
people have these experiences? How does the human brain work? And what is the connection between
the brain’s internal processes and people’s external behaviors? This textbook will introduce you to various
ways that the field of psychology has explored these questions.
Chapter 1 | Introduction to Psychology 5

1.1 What Is Psychology?
Learning Objectives
By the end of this section, you will be able to:
• Understand the etymology of the word “psychology”
• Define psychology
• Understand the merits of an education in psychology
In Greek mythology, Psyche was a mortal woman whose beauty was so great that it rivaled that of the
goddess Aphrodite. Aphrodite became so jealous of Psyche that she sent her son, Eros, to make Psyche fall
in love with the ugliest man in the world. However, Eros accidentally pricked himself with the tip of his
arrow and fell madly in love with Psyche himself. He took Psyche to his palace and showered her with
gifts, yet she could never see his face. While visiting Psyche, her sisters roused suspicion in Psyche about
her mysterious lover, and eventually, Psyche betrayed Eros’ wishes to remain unseen to her (Figure 1.2).
Because of this betrayal, Eros abandoned Psyche. When Psyche appealed to Aphrodite to reunite her with
Eros, Aphrodite gave her a series of impossible tasks to complete. Psyche managed to complete all of these
trials; ultimately, her perseverance paid off as she was reunited with Eros and was ultimately transformed
into a goddess herself (Ashliman, 2001; Greek Myths & Greek Mythology, 2014).
Figure 1.2 Antonio Canova’s sculpture depicts Eros and Psyche.
Psyche comes to represent the human soul’s triumph over the misfortunes of life in the pursuit of true
happiness (Bulfinch, 1855); in fact, the Greek word psyche means soul, and it is often represented as a
butterfly. The word psychology was coined at a time when the concepts of soul and mind were not as
clearly distinguished (Green, 2001). The root ology denotes scientific study of, and psychology refers to the
scientific study of the mind. Since science studies only observable phenomena and the mind is not directly
observable, we expand this definition to the scientific study of mind and behavior.
The scientific study of any aspect of the world uses the scientific method to acquire knowledge. To apply
the scientific method, a researcher with a question about how or why something happens will propose
a tentative explanation, called a hypothesis, to explain the phenomenon. A hypothesis is not just any
explanation; it should fit into the context of a scientific theory. A scientific theory is a broad explanation
or group of explanations for some aspect of the natural world that is consistently supported by evidence
over time. A theory is the best understanding that we have of that part of the natural world. Armed with
the hypothesis, the researcher then makes observations or, better still, carries out an experiment to test
the validity of the hypothesis. That test and its results are then published so that others can check the
results or build on them. It is necessary that any explanation in science be testable, which means that the
phenomenon must be perceivable and measurable. For example, that a bird sings because it is happy is not
6 Chapter 1 | Introduction to Psychology
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a testable hypothesis, since we have no way to measure the happiness of a bird. We must ask a different
question, perhaps about the brain state of the bird, since this can be measured. In general, science deals
only with matter and energy, that is, those things that can be measured, and it cannot arrive at knowledge
about values and morality. This is one reason why our scientific understanding of the mind is so limited,
since thoughts, at least as we experience them, are neither matter nor energy. The scientific method is also a
form of empiricism. An empirical method for acquiring knowledge is one based on observation, including
experimentation, rather than a method based only on forms of logical argument or previous authorities.
It was not until the late 1800s that psychology became accepted as its own academic discipline. Before this
time, the workings of the mind were considered under the auspices of philosophy. Given that any behavior
is, at its roots, biological, some areas of psychology take on aspects of a natural science like biology. No
biological organism exists in isolation, and our behavior is influenced by our interactions with others.
Therefore, psychology is also a social science.
Often, students take their first psychology course because they are interested in helping others and want
to learn more about themselves and why they act the way they do. Sometimes, students take a psychology
course because it either satisfies a general education requirement or is required for a program of study
such as nursing or pre-med. Many of these students develop such an interest in the area that they go
on to declare psychology as their major. As a result, psychology is one of the most popular majors on
college campuses across the United States (Johnson & Lubin, 2011). A number of well-known individuals
were psychology majors. Just a few famous names on this list are Facebook’s creator Mark Zuckerberg,
television personality and political satirist Jon Stewart, actress Natalie Portman, and filmmaker Wes
Craven (Halonen, 2011). About 6 percent of all bachelor degrees granted in the United States are in the
discipline of psychology (U.S. Department of Education, 2013).
An education in psychology is valuable for a number of reasons. Psychology students hone critical
thinking skills and are trained in the use of the scientific method. Critical thinking is the active application
of a set of skills to information for the understanding and evaluation of that information. The evaluation
of information—assessing its reliability and usefulness— is an important skill in a world full of competing
“facts,” many of which are designed to be misleading. For example, critical thinking involves maintaining
an attitude of skepticism, recognizing internal biases, making use of logical thinking, asking appropriate
questions, and making observations. Psychology students also can develop better communication skills
during the course of their undergraduate coursework (American Psychological Association, 2011).
Together, these factors increase students’ scientific literacy and prepare students to critically evaluate the
various sources of information they encounter.
In addition to these broad-based skills, psychology students come to understand the complex factors
that shape one’s behavior. They appreciate the interaction of our biology, our environment, and our
experiences in determining who we are and how we will behave. They learn about basic principles that
guide how we think and behave, and they come to recognize the tremendous diversity that exists across
individuals and across cultural boundaries (American Psychological Association, 2011).
Watch a brief video ( that describes some
of the questions a student should consider before deciding to major in psychology.
Chapter 1 | Introduction to Psychology 7

1.2 History of Psychology
Learning Objectives
By the end of this section, you will be able to:
• Understand the importance of Wundt and James in the development of psychology
• Appreciate Freud’s influence on psychology
• Understand the basic tenets of Gestalt psychology
• Appreciate the important role that behaviorism played in psychology’s history
• Understand basic tenets of humanism
• Understand how the cognitive revolution shifted psychology’s focus back to the mind
Psychology is a relatively young science with its experimental roots in the 19th century, compared, for
example, to human physiology, which dates much earlier. As mentioned, anyone interested in exploring
issues related to the mind generally did so in a philosophical context prior to the 19th century. Two men,
working in the 19th century, are generally credited as being the founders of psychology as a science and
academic discipline that was distinct from philosophy. Their names were Wilhelm Wundt and William
James. This section will provide an overview of the shifts in paradigms that have influenced psychology
from Wundt and James through today.
Wilhelm Wundt (1832–1920) was a German scientist who was the first person to be referred to as a
psychologist. His famous book entitled Principles of Physiological Psychology was published in 1873. Wundt
viewed psychology as a scientific study of conscious experience, and he believed that the goal of
psychology was to identify components of consciousness and how those components combined to result
in our conscious experience. Wundt used introspection (he called it “internal perception”), a process by
which someone examines their own conscious experience as objectively as possible, making the human
mind like any other aspect of nature that a scientist observed. Wundt’s version of introspection used
only very specific experimental conditions in which an external stimulus was designed to produce a
scientifically observable (repeatable) experience of the mind (Danziger, 1980). The first stringent
requirement was the use of “trained” or practiced observers, who could immediately observe and report
a reaction. The second requirement was the use of repeatable stimuli that always produced the same
experience in the subject and allowed the subject to expect and thus be fully attentive to the inner
reaction. These experimental requirements were put in place to eliminate “interpretation” in the reporting
of internal experiences and to counter the argument that there is no way to know that an individual is
observing their mind or consciousness accurately, since it cannot be seen by any other person. This attempt
to understand the structure or characteristics of the mind was known as structuralism. Wundt established
his psychology laboratory at the University at Leipzig in 1879 (Figure 1.3). In this laboratory, Wundt
and his students conducted experiments on, for example, reaction times. A subject, sometimes in a room
isolated from the scientist, would receive a stimulus such as a light, image, or sound. The subject’s reaction
to the stimulus would be to push a button, and an apparatus would record the time to reaction. Wundt
could measure reaction time to one-thousandth of a second (Nicolas & Ferrand, 1999).
8 Chapter 1 | Introduction to Psychology
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Figure 1.3 (a) Wilhelm Wundt is credited as one of the founders of psychology. He created the first laboratory for
psychological research. (b) This photo shows him seated and surrounded by fellow researchers and equipment in his
laboratory in Germany.
However, despite his efforts to train individuals in the process of introspection, this process remained
highly subjective, and there was very little agreement between individuals. As a result, structuralism fell
out of favor with the passing of Wundt’s student, Edward Titchener, in 1927 (Gordon, 1995).
William James (1842–1910) was the first American psychologist who espoused a different perspective on
how psychology should operate (Figure 1.4). James was introduced to Darwin’s theory of evolution by
natural selection and accepted it as an explanation of an organism’s characteristics. Key to that theory is
the idea that natural selection leads to organisms that are adapted to their environment, including their
behavior. Adaptation means that a trait of an organism has a function for the survival and reproduction
of the individual, because it has been naturally selected. As James saw it, psychology’s purpose was to
study the function of behavior in the world, and as such, his perspective was known as functionalism.
Functionalism focused on how mental activities helped an organism fit into its environment.
Functionalism has a second, more subtle meaning in that functionalists were more interested in the
operation of the whole mind rather than of its individual parts, which were the focus of structuralism. Like
Wundt, James believed that introspection could serve as one means by which someone might study mental
activities, but James also relied on more objective measures, including the use of various recording devices,
and examinations of concrete products of mental activities and of anatomy and physiology (Gordon, 1995).
Figure 1.4 William James, shown here in a self-portrait, was the first American psychologist.
Chapter 1 | Introduction to Psychology 9

Perhaps one of the most influential and well-known figures in psychology’s history was Sigmund Freud
(Figure 1.5). Freud (1856–1939) was an Austrian neurologist who was fascinated by patients suffering
from “hysteria” and neurosis. Hysteria was an ancient diagnosis for disorders, primarily of women with
a wide variety of symptoms, including physical symptoms and emotional disturbances, none of which
had an apparent physical cause. Freud theorized that many of his patients’ problems arose from the
unconscious mind. In Freud’s view, the unconscious mind was a repository of feelings and urges of which
we have no awareness. Gaining access to the unconscious, then, was crucial to the successful resolution
of the patient’s problems. According to Freud, the unconscious mind could be accessed through dream
analysis, by examinations of the first words that came to people’s minds, and through seemingly innocent
slips of the tongue. Psychoanalytic theory focuses on the role of a person’s unconscious, as well as early
childhood experiences, and this particular perspective dominated clinical psychology for several decades
(Thorne & Henley, 2005).
Figure 1.5 (a) Sigmund Freud was a highly influential figure in the history of psychology. (b) One of his many books,
A General Introduction to Psychoanalysis, shared his ideas about psychoanalytical therapy; it was published in 1922.
Freud’s ideas were influential, and you will learn more about them when you study lifespan development,
personality, and therapy. For instance, many therapists believe strongly in the unconscious and the
impact of early childhood experiences on the rest of a person’s life. The method of psychoanalysis, which
involves the patient talking about their experiences and selves, while not invented by Freud, was certainly
popularized by him and is still used today. Many of Freud’s other ideas, however, are controversial.
Drew Westen (1998) argues that many of the criticisms of Freud’s ideas are misplaced, in that they
attack his older ideas without taking into account later writings. Westen also argues that critics fail to
consider the success of the broad ideas that Freud introduced or developed, such as the importance
of childhood experiences in adult motivations, the role of unconscious versus conscious motivations in
driving our behavior, the fact that motivations can cause conflicts that affect behavior, the effects of mental
representations of ourselves and others in guiding our interactions, and the development of personality
over time. Westen identifies subsequent research support for all of these ideas.
More modern iterations of Freud’s clinical approach have been empirically demonstrated to be effective
(Knekt et al., 2008; Shedler, 2010). Some current practices in psychotherapy involve examining unconscious
aspects of the self and relationships, often through the relationship between the therapist and the client.
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Freud’s historical significance and contributions to clinical practice merit his inclusion in a discussion of
the historical movements within psychology.
Max Wertheimer (1880–1943), Kurt Koffka (1886–1941), and Wolfgang Köhler (1887–1967) were three
German psychologists who immigrated to the United States in the early 20th century to escape Nazi
Germany. These men are credited with introducing psychologists in the United States to various Gestalt
principles. The word Gestalt roughly translates to “whole;” a major emphasis of Gestalt psychology deals
with the fact that although a sensory experience can be broken down into individual parts, how those parts
relate to each other as a whole is often what the individual responds to in perception. For example, a song
may be made up of individual notes played by different instruments, but the real nature of the song is
perceived in the combinations of these notes as they form the melody, rhythm, and harmony. In many
ways, this particular perspective would have directly contradicted Wundt’s ideas of structuralism (Thorne
& Henley, 2005).
Unfortunately, in moving to the United States, these men were forced to abandon much of their work
and were unable to continue to conduct research on a large scale. These factors along with the rise of
behaviorism (described next) in the United States prevented principles of Gestalt psychology from being as
influential in the United States as they had been in their native Germany (Thorne & Henley, 2005). Despite
these issues, several Gestalt principles are still very influential today. Considering the human individual
as a whole rather than as a sum of individually measured parts became an important foundation in
humanistic theory late in the century. The ideas of Gestalt have continued to influence research on
sensation and perception.
Structuralism, Freud, and the Gestalt psychologists were all concerned in one way or another with
describing and understanding inner experience. But other researchers had concerns that inner experience
could be a legitimate subject of scientific inquiry and chose instead to exclusively study behavior, the
objectively observable outcome of mental processes.
Early work in the field of behavior was conducted by the Russian physiologist Ivan Pavlov (1849–1936).
Pavlov studied a form of learning behavior called a conditioned reflex, in which an animal or human
produced a reflex (unconscious) response to a stimulus and, over time, was conditioned to produce the
response to a different stimulus that the experimenter associated with the original stimulus. The reflex
Pavlov worked with was salivation in response to the presence of food. The salivation reflex could be
elicited using a second stimulus, such as a specific sound, that was presented in association with the
initial food stimulus several times. Once the response to the second stimulus was “learned,” the food
stimulus could be omitted. Pavlov’s “classical conditioning” is only one form of learning behavior studied
by behaviorists.
John B. Watson (1878–1958) was an influential American psychologist whose most famous work occurred
during the early 20th century at Johns Hopkins University (Figure 1.6). While Wundt and James were
concerned with understanding conscious experience, Watson thought that the study of consciousness
was flawed. Because he believed that objective analysis of the mind was impossible, Watson preferred to
focus directly on observable behavior and try to bring that behavior under control. Watson was a major
proponent of shifting the focus of psychology from the mind to behavior, and this approach of observing
and controlling behavior came to be known as behaviorism. A major object of study by behaviorists was
learned behavior and its interaction with inborn qualities of the organism. Behaviorism commonly used
animals in experiments under the assumption that what was learned using animal models could, to some
degree, be applied to human behavior. Indeed, Tolman (1938) stated, “I believe that everything important
in psychology (except … such matters as involve society and words) can be investigated in essence through
the continued experimental and theoretical analysis of the determiners of rat behavior at a choice-point in
Chapter 1 | Introduction to Psychology 11

a maze.”
Figure 1.6 John B. Watson is known as the father of behaviorism within psychology.
Behaviorism dominated experimental psychology for several decades, and its influence can still be felt
today (Thorne & Henley, 2005). Behaviorism is largely responsible for establishing psychology as a
scientific discipline through its objective methods and especially experimentation. In addition, it is used
in behavioral and cognitive-behavioral therapy. Behavior modification is commonly used in classroom
settings. Behaviorism has also led to research on environmental influences on human behavior.
B. F. Skinner (1904–1990) was an American psychologist (Figure 1.7). Like Watson, Skinner was a
behaviorist, and he concentrated on how behavior was affected by its consequences. Therefore, Skinner
spoke of reinforcement and punishment as major factors in driving behavior. As a part of his research,
Skinner developed a chamber that allowed the careful study of the principles of modifying behavior
through reinforcement and punishment. This device, known as an operant conditioning chamber (or more
familiarly, a Skinner box), has remained a crucial resource for researchers studying behavior (Thorne &
Henley, 2005).
Figure 1.7 (a) B. F. Skinner is famous for his research on operant conditioning. (b) Modified versions of the operant
conditioning chamber, or Skinner box, are still widely used in research settings today. (credit a: modification of work
by “Silly rabbit”/Wikimedia Commons)
The Skinner box is a chamber that isolates the subject from the external environment and has a behavior
indicator such as a lever or a button. When the animal pushes the button or lever, the box is able to
deliver a positive reinforcement of the behavior (such as food) or a punishment (such as a noise) or a token
conditioner (such as a light) that is correlated with either the positive reinforcement or punishment.
Skinner’s focus on positive and negative reinforcement of learned behaviors had a lasting influence in
psychology that has waned somewhat since the growth of research in cognitive psychology. Despite
this, conditioned learning is still used in human behavioral modification. Skinner’s two widely read and
controversial popular science books about the value of operant conditioning for creating happier lives
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remain as thought-provoking arguments for his approach (Greengrass, 2004).
During the early 20th century, American psychology was dominated by behaviorism and psychoanalysis.
However, some psychologists were uncomfortable with what they viewed as limited perspectives being
so influential to the field. They objected to the pessimism and determinism (all actions driven by the
unconscious) of Freud. They also disliked the reductionism, or simplifying nature, of behaviorism.
Behaviorism is also deterministic at its core, because it sees human behavior as entirely determined by
a combination of genetics and environment. Some psychologists began to form their own ideas that
emphasized personal control, intentionality, and a true predisposition for “good” as important for our self-
concept and our behavior. Thus, humanism emerged. Humanism is a perspective within psychology that
emphasizes the potential for good that is innate to all humans. Two of the most well-known proponents of
humanistic psychology are Abraham Maslow and Carl Rogers (O’Hara, n.d.).
Abraham Maslow (1908–1970) was an American psychologist who is best known for proposing a hierarchy
of human needs in motivating behavior (Figure 1.8). Although this concept will be discussed in more
detail in a later chapter, a brief overview will be provided here. Maslow asserted that so long as basic needs
necessary for survival were met (e.g., food, water, shelter), higher-level needs (e.g., social needs) would
begin to motivate behavior. According to Maslow, the highest-level needs relate to self-actualization, a
process by which we achieve our full potential. Obviously, the focus on the positive aspects of human
nature that are characteristic of the humanistic perspective is evident (Thorne & Henley, 2005). Humanistic
psychologists rejected, on principle, the research approach based on reductionist experimentation in the
tradition of the physical and biological sciences, because it missed the “whole” human being. Beginning
with Maslow and Rogers, there was an insistence on a humanistic research program. This program
has been largely qualitative (not measurement-based), but there exist a number of quantitative research
strains within humanistic psychology, including research on happiness, self-concept, meditation, and the
outcomes of humanistic psychotherapy (Friedman, 2008).
Figure 1.8 Maslow’s hierarchy of needs is shown.
Carl Rogers (1902–1987) was also an American psychologist who, like Maslow, emphasized the potential
Chapter 1 | Introduction to Psychology 13

for good that exists within all people (Figure 1.9). Rogers used a therapeutic technique known as client-
centered therapy in helping his clients deal with problematic issues that resulted in their seeking
psychotherapy. Unlike a psychoanalytic approach in which the therapist plays an important role in
interpreting what conscious behavior reveals about the unconscious mind, client-centered therapy
involves the patient taking a lead role in the therapy session. Rogers believed that a therapist needed to
display three features to maximize the effectiveness of this particular approach: unconditional positive
regard, genuineness, and empathy. Unconditional positive regard refers to the fact that the therapist
accepts their client for who they are, no matter what he or she might say. Provided these factors, Rogers
believed that people were more than capable of dealing with and working through their own issues
(Thorne & Henley, 2005).
Figure 1.9 Carl Rogers, shown in this portrait, developed a client-centered therapy method that has been influential
in clinical settings. (credit: “Didius”/Wikimedia Commons)
Humanism has been influential to psychology as a whole. Both Maslow and Rogers are well-known names
among students of psychology (you will read more about both men later in this text), and their ideas have
influenced many scholars. Furthermore, Rogers’ client-centered approach to therapy is still commonly
used in psychotherapeutic settings today (O’hara, n.d.)
View a brief video ( of Carl Rogers
describing his therapeutic approach.
Behaviorism’s emphasis on objectivity and focus on external behavior had pulled psychologists’ attention
away from the mind for a prolonged period of time. The early work of the humanistic psychologists
redirected attention to the individual human as a whole, and as a conscious and self-aware being. By the
1950s, new disciplinary perspectives in linguistics, neuroscience, and computer science were emerging,
and these areas revived interest in the mind as a focus of scientific inquiry. This particular perspective
has come to be known as the cognitive revolution (Miller, 2003). By 1967, Ulric Neisser published the first
textbook entitled Cognitive Psychology, which served as a core text in cognitive psychology courses around
the country (Thorne & Henley, 2005).
Although no one person is entirely responsible for starting the cognitive revolution, Noam Chomsky
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was very influential in the early days of this movement (Figure 1.10). Chomsky (1928–), an American
linguist, was dissatisfied with the influence that behaviorism had had on psychology. He believed that
psychology’s focus on behavior was short-sighted and that the field had to re-incorporate mental
functioning into its purview if it were to offer any meaningful contributions to understanding behavior
(Miller, 2003).
Figure 1.10 Noam Chomsky was very influential in beginning the cognitive revolution. In 2010, this mural honoring
him was put up in Philadelphia, Pennsylvania. (credit: Robert Moran)
European psychology had never really been as influenced by behaviorism as had American psychology;
and thus, the cognitive revolution helped reestablish lines of communication between European
psychologists and their American counterparts. Furthermore, psychologists began to cooperate with
scientists in other fields, like anthropology, linguistics, computer science, and neuroscience, among others.
This interdisciplinary approach often was referred to as the cognitive sciences, and the influence and
prominence of this particular perspective resonates in modern-day psychology (Miller, 2003).
Feminist Psychology
The science of psychology has had an impact on human wellbeing, both positive and negative. The dominant
influence of Western, white, and male academics in the early history of psychology meant that psychology
developed with the biases inherent in those individuals, which often had negative consequences for members
of society that were not white or male. Women, members of ethnic minorities in both the United States and
other countries, and individuals with sexual orientations other than heterosexual had difficulties entering the
field of psychology and therefore influencing its development. They also suffered from the attitudes of white,
male psychologists, who were not immune to the nonscientific attitudes prevalent in the society in which they
developed and worked. Until the 1960s, the science of psychology was largely a “womanless” psychology
(Crawford & Marecek, 1989), meaning that few women were able to practice psychology, so they had little
influence on what was studied. In addition, the experimental subjects of psychology were mostly men, which
resulted from underlying assumptions that gender had no influence on psychology and that women were not
of sufficient interest to study.
An article by Naomi Weisstein, first published in 1968 (Weisstein, 1993), stimulated a feminist revolution
in psychology by presenting a critique of psychology as a science. She also specifically criticized male
psychologists for constructing the psychology of women entirely out of their own cultural biases and without
careful experimental tests to verify any of their characterizations of women. Weisstein used, as examples,
statements by prominent psychologists in the 1960s, such as this quote by Bruno Bettleheim: “. . . we must
start with the realization that, as much as women want to be good scientists or engineers, they want first and
foremost to be womanly companions of men and to be mothers.” Weisstein’s critique formed the foundation
for the subsequent development of a feminist psychology that attempted to be free of the influence of male
cultural biases on our knowledge of the psychology of women and, indeed, of both genders.
Crawford & Marecek (1989) identify several feminist approaches to psychology that can be described as
Chapter 1 | Introduction to Psychology 15

feminist psychology. These include re-evaluating and discovering the contributions of women to the history
of psychology, studying psychological gender differences, and questioning the male bias present across the
practice of the scientific approach to knowledge.
Culture has important impacts on individuals and social psychology, yet the effects of culture on
psychology are under-studied. There is a risk that psychological theories and data derived from white,
American settings could be assumed to apply to individuals and social groups from other cultures and this
is unlikely to be true (Betancourt & López, 1993). One weakness in the field of cross-cultural psychology
is that in looking for differences in psychological attributes across cultures, there remains a need to go
beyond simple descriptive statistics (Betancourt & López, 1993). In this sense, it has remained a descriptive
science, rather than one seeking to determine cause and effect. For example, a study of characteristics of
individuals seeking treatment for a binge eating disorder in Hispanic American, African American, and
Caucasian American individuals found significant differences between groups (Franko et al., 2012). The
study concluded that results from studying any one of the groups could not be extended to the other
groups, and yet potential causes of the differences were not measured.
This history of multicultural psychology in the United States is a long one. The role of African American
psychologists in researching the cultural differences between African American individual and social
psychology is but one example. In 1920, Cecil Sumner was the first African American to receive a PhD in
psychology in the United States. Sumner established a psychology degree program at Howard University,
leading to the education of a new generation of African American psychologists (Black, Spence, and
Omari, 2004). Much of the work of early African American psychologists (and a general focus of much
work in first half of the 20th century in psychology in the United States) was dedicated to testing and
intelligence testing in particular (Black et al., 2004). That emphasis has continued, particularly because
of the importance of testing in determining opportunities for children, but other areas of exploration in
African-American psychology research include learning style, sense of community and belonging, and
spiritualism (Black et al., 2004).
The American Psychological Association has several ethnically based organizations for professional
psychologists that facilitate interactions among members. Since psychologists belonging to specific ethnic
groups or cultures have the most interest in studying the psychology of their communities, these
organizations provide an opportunity for the growth of research on the impact of culture on individual
and social psychology.
Read a news story ( about the influence of
an African American’s psychology research on the historic Brown v. Board of
Education civil rights case.
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1.3 Contemporary Psychology
Learning Objectives
By the end of this section, you will be able to:
• Appreciate the diversity of interests and foci within psychology
• Understand basic interests and applications in each of the described areas of psychology
• Demonstrate familiarity with some of the major concepts or important figures in each of the
described areas of psychology
Contemporary psychology is a diverse field that is influenced by all of the historical perspectives described
in the preceding section. Reflective of the discipline’s diversity is the diversity seen within the American
Psychological Association (APA). The APA is a professional organization representing psychologists in
the United States. The APA is the largest organization of psychologists in the world, and its mission is to
advance and disseminate psychological knowledge for the betterment of people. There are 56 divisions
within the APA, representing a wide variety of specialties that range from Societies for the Psychology of
Religion and Spirituality to Exercise and Sport Psychology to Behavioral Neuroscience and Comparative
Psychology. Reflecting the diversity of the field of psychology itself, members, affiliate members, and
associate members span the spectrum from students to doctoral-level psychologists, and come from a
variety of places including educational settings, criminal justice, hospitals, the armed forces, and industry
(American Psychological Association, 2014). The Association for Psychological Science (APS) was founded
in 1988 and seeks to advance the scientific orientation of psychology. Its founding resulted from
disagreements between members of the scientific and clinical branches of psychology within the APA.
The APS publishes five research journals and engages in education and advocacy with funding agencies.
A significant proportion of its members are international, although the majority is located in the United
States. Other organizations provide networking and collaboration opportunities for professionals of
several ethnic or racial groups working in psychology, such as the National Latina/o Psychological
Association (NLPA), the Asian American Psychological Association (AAPA), the Association of Black
Psychologists (ABPsi), and the Society of Indian Psychologists (SIP). Most of these groups are also
dedicated to studying psychological and social issues within their specific communities.
This section will provide an overview of the major subdivisions within psychology today in the order
in which they are introduced throughout the remainder of this textbook. This is not meant to be an
exhaustive listing, but it will provide insight into the major areas of research and practice of modern-day
Please visit this website ( to learn
about the divisions within the APA.
Student resources ( are also
provided by the APA.
As the name suggests, biopsychology explores how our biology influences our behavior. While biological
psychology is a broad field, many biological psychologists want to understand how the structure and
function of the nervous system is related to behavior (Figure 1.11). As such, they often combine the
research strategies of both psychologists and physiologists to accomplish this goal (as discussed in Carlson,
Chapter 1 | Introduction to Psychology 17

Figure 1.11 Biological psychologists study how the structure and function of the nervous system generate behavior.
The research interests of biological psychologists span a number of domains, including but not limited
to, sensory and motor systems, sleep, drug use and abuse, ingestive behavior, reproductive behavior,
neurodevelopment, plasticity of the nervous system, and biological correlates of psychological disorders.
Given the broad areas of interest falling under the purview of biological psychology, it will probably
come as no surprise that individuals from all sorts of backgrounds are involved in this research, including
biologists, medical professionals, physiologists, and chemists. This interdisciplinary approach is often
referred to as neuroscience, of which biological psychology is a component (Carlson, 2013).
While biopsychology typically focuses on the immediate causes of behavior based in the physiology of a
human or other animal, evolutionary psychology seeks to study the ultimate biological causes of behavior.
To the extent that a behavior is impacted by genetics, a behavior, like any anatomical characteristic of a
human or animal, will demonstrate adaption to its surroundings. These surroundings include the physical
environment and, since interactions between organisms can be important to survival and reproduction, the
social environment. The study of behavior in the context of evolution has its origins with Charles Darwin,
the co-discoverer of the theory of evolution by natural selection. Darwin was well aware that behaviors
should be adaptive and wrote books titled, The Descent of Man (1871) and The Expression of the Emotions in
Man and Animals (1872), to explore this field.
Evolutionary psychology, and specifically, the evolutionary psychology of humans, has enjoyed a
resurgence in recent decades. To be subject to evolution by natural selection, a behavior must have a
significant genetic cause. In general, we expect all human cultures to express a behavior if it is caused
genetically, since the genetic differences among human groups are small. The approach taken by most
evolutionary psychologists is to predict the outcome of a behavior in a particular situation based on
evolutionary theory and then to make observations, or conduct experiments, to determine whether the
results match the theory. It is important to recognize that these types of studies are not strong evidence
that a behavior is adaptive, since they lack information that the behavior is in some part genetic and not
entirely cultural (Endler, 1986). Demonstrating that a trait, especially in humans, is naturally selected is
extraordinarily difficult; perhaps for this reason, some evolutionary psychologists are content to assume
the behaviors they study have genetic determinants (Confer et al., 2010).
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One other drawback of evolutionary psychology is that the traits that we possess now evolved under
environmental and social conditions far back in human history, and we have a poor understanding of what
these conditions were. This makes predictions about what is adaptive for a behavior difficult. Behavioral
traits need not be adaptive under current conditions, only under the conditions of the past when they
evolved, about which we can only hypothesize.
There are many areas of human behavior for which evolution can make predictions. Examples include
memory, mate choice, relationships between kin, friendship and cooperation, parenting, social
organization, and status (Confer et al., 2010).
Evolutionary psychologists have had success in finding experimental correspondence between
observations and expectations. In one example, in a study of mate preference differences between men and
women that spanned 37 cultures, Buss (1989) found that women valued earning potential factors greater
than men, and men valued potential reproductive factors (youth and attractiveness) greater than women in
their prospective mates. In general, the predictions were in line with the predictions of evolution, although
there were deviations in some cultures.
Scientists interested in both physiological aspects of sensory systems as well as in the psychological
experience of sensory information work within the area of sensation and perception (Figure 1.12). As
such, sensation and perception research is also quite interdisciplinary. Imagine walking between buildings
as you move from one class to another. You are inundated with sights, sounds, touch sensations, and
smells. You also experience the temperature of the air around you and maintain your balance as you make
your way. These are all factors of interest to someone working in the domain of sensation and perception.
Figure 1.12 When you look at this image, you may see a duck or a rabbit. The sensory information remains the
same, but your perception can vary dramatically.
As described in a later chapter that focuses on the results of studies in sensation and perception, our
experience of our world is not as simple as the sum total of all of the sensory information (or sensations)
together. Rather, our experience (or perception) is complex and is influenced by where we focus our
attention, our previous experiences, and even our cultural backgrounds.
As mentioned in the previous section, the cognitive revolution created an impetus for psychologists to
focus their attention on better understanding the mind and mental processes that underlie behavior. Thus,
cognitive psychology is the area of psychology that focuses on studying cognitions, or thoughts, and
their relationship to our experiences and our actions. Like biological psychology, cognitive psychology is
broad in its scope and often involves collaborations among people from a diverse range of disciplinary
backgrounds. This has led some to coin the term cognitive science to describe the interdisciplinary nature
of this area of research (Miller, 2003).
Cognitive psychologists have research interests that span a spectrum of topics, ranging from attention to
problem solving to language to memory. The approaches used in studying these topics are equally diverse.
Chapter 1 | Introduction to Psychology 19

Given such diversity, cognitive psychology is not captured in one chapter of this text per se; rather, various
concepts related to cognitive psychology will be covered in relevant portions of the chapters in this text
on sensation and perception, thinking and intelligence, memory, lifespan development, social psychology,
and therapy.
View a brief video ( recapping some of the
major concepts explored by cognitive psychologists.
Developmental psychology is the scientific study of development across a lifespan. Developmental
psychologists are interested in processes related to physical maturation. However, their focus is not limited
to the physical changes associated with aging, as they also focus on changes in cognitive skills, moral
reasoning, social behavior, and other psychological attributes.
Early developmental psychologists focused primarily on changes that occurred through reaching
adulthood, providing enormous insight into the differences in physical, cognitive, and social capacities
that exist between very young children and adults. For instance, research by Jean Piaget (Figure 1.13)
demonstrated that very young children do not demonstrate object permanence. Object permanence refers
to the understanding that physical things continue to exist, even if they are hidden from us. If you were to
show an adult a toy, and then hide it behind a curtain, the adult knows that the toy still exists. However,
very young infants act as if a hidden object no longer exists. The age at which object permanence is
achieved is somewhat controversial (Munakata, McClelland, Johnson, and Siegler, 1997).
Figure 1.13 Jean Piaget is famous for his theories regarding changes in cognitive ability that occur as we move from
infancy to adulthood.
While Piaget was focused on cognitive changes during infancy and childhood as we move to adulthood,
there is an increasing interest in extending research into the changes that occur much later in life. This
may be reflective of changing population demographics of developed nations as a whole. As more and
more people live longer lives, the number of people of advanced age will continue to increase. Indeed,
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it is estimated that there were just over 40 million people aged 65 or older living in the United States
in 2010. However, by 2020, this number is expected to increase to about 55 million. By the year 2050, it
is estimated that nearly 90 million people in this country will be 65 or older (Department of Health and
Human Services, n.d.).
Personality psychology focuses on patterns of thoughts and behaviors that make each individual unique.
Several individuals (e.g., Freud and Maslow) that we have already discussed in our historical overview of
psychology, and the American psychologist Gordon Allport, contributed to early theories of personality.
These early theorists attempted to explain how an individual’s personality develops from his or her
given perspective. For example, Freud proposed that personality arose as conflicts between the conscious
and unconscious parts of the mind were carried out over the lifespan. Specifically, Freud theorized that
an individual went through various psychosexual stages of development. According to Freud, adult
personality would result from the resolution of various conflicts that centered on the migration of
erogenous (or sexual pleasure-producing) zones from the oral (mouth) to the anus to the phallus to the
genitals. Like many of Freud’s theories, this particular idea was controversial and did not lend itself to
experimental tests (Person, 1980).
More recently, the study of personality has taken on a more quantitative approach. Rather than explaining
how personality arises, research is focused on identifying personality traits, measuring these traits, and
determining how these traits interact in a particular context to determine how a person will behave in
any given situation. Personality traits are relatively consistent patterns of thought and behavior, and
many have proposed that five trait dimensions are sufficient to capture the variations in personality seen
across individuals. These five dimensions are known as the “Big Five” or the Five Factor model, and
include dimensions of conscientiousness, agreeableness, neuroticism, openness, and extraversion (Figure
1.14). Each of these traits has been demonstrated to be relatively stable over the lifespan (e.g., Rantanen,
Metsäpelto, Feldt, Pulkinnen, and Kokko, 2007; Soldz & Vaillant, 1999; McCrae & Costa, 2008) and is
influenced by genetics (e.g., Jang, Livesly, and Vernon, 1996).
Chapter 1 | Introduction to Psychology 21

Figure 1.14 Each of the dimensions of the Five Factor model is shown in this figure. The provided description would
describe someone who scored highly on that given dimension. Someone with a lower score on a given dimension
could be described in opposite terms.
Social psychology focuses on how we interact with and relate to others. Social psychologists conduct
research on a wide variety of topics that include differences in how we explain our own behavior versus
how we explain the behaviors of others, prejudice, and attraction, and how we resolve interpersonal
conflicts. Social psychologists have also sought to determine how being among other people changes our
own behavior and patterns of thinking.
There are many interesting examples of social psychological research, and you will read about many of
these in a later chapter of this textbook. Until then, you will be introduced to one of the most controversial
psychological studies ever conducted. Stanley Milgram was an American social psychologist who is
most famous for research that he conducted on obedience. After the holocaust, in 1961, a Nazi war
criminal, Adolf Eichmann, who was accused of committing mass atrocities, was put on trial. Many people
wondered how German soldiers were capable of torturing prisoners in concentration camps, and they
were unsatisfied with the excuses given by soldiers that they were simply following orders. At the
time, most psychologists agreed that few people would be willing to inflict such extraordinary pain and
suffering, simply because they were obeying orders. Milgram decided to conduct research to determine
whether or not this was true (Figure 1.15). As you will read later in the text, Milgram found that nearly
two-thirds of his participants were willing to deliver what they believed to be lethal shocks to another
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person, simply because they were instructed to do so by an authority figure (in this case, a man dressed in
a lab coat). This was in spite of the fact that participants received payment for simply showing up for the
research study and could have chosen not to inflict pain or more serious consequences on another person
by withdrawing from the study. No one was actually hurt or harmed in any way, Milgram’s experiment
was a clever ruse that took advantage of research confederates, those who pretend to be participants in
a research study who are actually working for the researcher and have clear, specific directions on how
to behave during the research study (Hock, 2009). Milgram’s and others’ studies that involved deception
and potential emotional harm to study participants catalyzed the development of ethical guidelines for
conducting psychological research that discourage the use of deception of research subjects, unless it can
be argued not to cause harm and, in general, requiring informed consent of participants.
Figure 1.15 Stanley Milgram’s research demonstrated just how far people will go in obeying orders from an authority
figure. This advertisement was used to recruit subjects for his research.
Industrial-Organizational psychology (I-O psychology) is a subfield of psychology that applies
psychological theories, principles, and research findings in industrial and organizational settings. I-O
psychologists are often involved in issues related to personnel management, organizational structure,
and workplace environment. Businesses often seek the aid of I-O psychologists to make the best hiring
decisions as well as to create an environment that results in high levels of employee productivity and
efficiency. In addition to its applied nature, I-O psychology also involves conducting scientific research on
behavior within I-O settings (Riggio, 2013).
Chapter 1 | Introduction to Psychology 23

Health psychology focuses on how health is affected by the interaction of biological, psychological, and
sociocultural factors. This particular approach is known as the biopsychosocial model (Figure 1.16).
Health psychologists are interested in helping individuals achieve better health through public policy,
education, intervention, and research. Health psychologists might conduct research that explores the
relationship between one’s genetic makeup, patterns of behavior, relationships, psychological stress,
and health. They may research effective ways to motivate people to address patterns of behavior that
contribute to poorer health (MacDonald, 2013).
Figure 1.16 The biopsychosocial model suggests that health/illness is determined by an interaction of these three
Researchers in sport and exercise psychology study the psychological aspects of sport performance,
including motivation and performance anxiety, and the effects of sport on mental and emotional
wellbeing. Research is also conducted on similar topics as they relate to physical exercise in general. The
discipline also includes topics that are broader than sport and exercise but that are related to interactions
between mental and physical performance under demanding conditions, such as fire fighting, military
operations, artistic performance, and surgery.
Clinical psychology is the area of psychology that focuses on the diagnosis and treatment of psychological
disorders and other problematic patterns of behavior. As such, it is generally considered to be a more
applied area within psychology; however, some clinicians are also actively engaged in scientific research.
Counseling psychology is a similar discipline that focuses on emotional, social, vocational, and health-
related outcomes in individuals who are considered psychologically healthy.
As mentioned earlier, both Freud and Rogers provided perspectives that have been influential in shaping
how clinicians interact with people seeking psychotherapy. While aspects of the psychoanalytic theory are
still found among some of today’s therapists who are trained from a psychodynamic perspective, Roger’s
ideas about client-centered therapy have been especially influential in shaping how many clinicians
operate. Furthermore, both behaviorism and the cognitive revolution have shaped clinical practice in the
forms of behavioral therapy, cognitive therapy, and cognitive-behavioral therapy (Figure 1.17). Issues
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related to the diagnosis and treatment of psychological disorders and problematic patterns of behavior will
be discussed in detail in later chapters of this textbook.
Figure 1.17 Cognitive-behavioral therapists take cognitive processes and behaviors into account when providing
psychotherapy. This is one of several strategies that may be used by practicing clinical psychologists.
By far, this is the area of psychology that receives the most attention in popular media, and many people
mistakenly assume that all psychology is clinical psychology.
Forensic psychology is a branch of psychology that deals questions of psychology as they arise in the
context of the justice system. For example, forensic psychologists (and forensic psychiatrists) will assess
a person’s competency to stand trial, assess the state of mind of a defendant, act as consultants on
child custody cases, consult on sentencing and treatment recommendations, and advise on issues such as
eyewitness testimony and children’s testimony (American Board of Forensic Psychology, 2014). In these
capacities, they will typically act as expert witnesses, called by either side in a court case to provide their
research- or experience-based opinions. As expert witnesses, forensic psychologists must have a good
understanding of the law and provide information in the context of the legal system rather than just within
the realm of psychology. Forensic psychologists are also used in the jury selection process and witness
preparation. They may also be involved in providing psychological treatment within the criminal justice
system. Criminal profilers are a relatively small proportion of psychologists that act as consultants to law
The APA provides career information (
about various areas of psychology.
Chapter 1 | Introduction to Psychology 25

1.4 Careers in Psychology
Learning Objectives
By the end of this section, you will be able to:
• Understand educational requirements for careers in academic settings
• Understand the demands of a career in an academic setting
• Understand career options outside of academic settings
Psychologists can work in many different places doing many different things. In general, anyone wishing
to continue a career in psychology at a 4-year institution of higher education will have to earn a doctoral
degree in psychology for some specialties and at least a master’s degree for others. In most areas of
psychology, this means earning a PhD in a relevant area of psychology. Literally, PhD refers to a doctor
of philosophy degree, but here, philosophy does not refer to the field of philosophy per se. Rather,
philosophy in this context refers to many different disciplinary perspectives that would be housed in a
traditional college of liberal arts and sciences.
The requirements to earn a PhD vary from country to country and even from school to school, but usually,
individuals earning this degree must complete a dissertation. A dissertation is essentially a long research
paper or bundled published articles describing research that was conducted as a part of the candidate’s
doctoral training. In the United States, a dissertation generally has to be defended before a committee of
expert reviewers before the degree is conferred (Figure 1.18).
Figure 1.18 Doctoral degrees are generally conferred in formal ceremonies involving special attire and rites. (credit:
Public Affairs Office Fort Wainwright)
Once someone earns her PhD, she may seek a faculty appointment at a college or university. Being on the
faculty of a college or university often involves dividing time between teaching, research, and service to
the institution and profession. The amount of time spent on each of these primary responsibilities varies
dramatically from school to school, and it is not uncommon for faculty to move from place to place in
search of the best personal fit among various academic environments. The previous section detailed some
of the major areas that are commonly represented in psychology departments around the country; thus,
depending on the training received, an individual could be anything from a biological psychologist to a
clinical psychologist in an academic setting (Figure 1.19).
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Figure 1.19 Individuals earning a PhD in psychology have a range of employment options.
Often times, schools offer more courses in psychology than their full-time faculty can teach. In these cases,
it is not uncommon to bring in an adjunct faculty member or instructor. Adjunct faculty members and
instructors usually have an advanced degree in psychology, but they often have primary careers outside
of academia and serve in this role as a secondary job. Alternatively, they may not hold the doctoral
degree required by most 4-year institutions and use these opportunities to gain experience in teaching.
Furthermore, many 2-year colleges and schools need faculty to teach their courses in psychology. In
general, many of the people who pursue careers at these institutions have master’s degrees in psychology,
although some PhDs make careers at these institutions as well.
Some people earning PhDs may enjoy research in an academic setting. However, they may not be
interested in teaching. These individuals might take on faculty positions that are exclusively devoted
to conducting research. This type of position would be more likely an option at large, research-focused
In some areas in psychology, it is common for individuals who have recently earned their PhD to seek out
positions in postdoctoral training programs that are available before going on to serve as faculty. In most
cases, young scientists will complete one or two postdoctoral programs before applying for a full-time
faculty position. Postdoctoral training programs allow young scientists to further develop their research
programs and broaden their research skills under the supervision of other professionals in the field.
Individuals who wish to become practicing clinical psychologists have another option for earning a
doctoral degree, which is known as a PsyD. A PsyD is a doctor of psychology degree that is increasingly
popular among individuals interested in pursuing careers in clinical psychology. PsyD programs generally
place less emphasis on research-oriented skills and focus more on application of psychological principles
in the clinical context (Norcorss & Castle, 2002).
Regardless of whether earning a PhD or PsyD, in most states, an individual wishing to practice as a
licensed clinical or counseling psychologist may complete postdoctoral work under the supervision of
a licensed psychologist. Within the last few years, however, several states have begun to remove this
requirement, which would allow someone to get an earlier start in his career (Munsey, 2009). After an
Chapter 1 | Introduction to Psychology 27

individual has met the state requirements, his credentials are evaluated to determine whether he can sit for
the licensure exam. Only individuals that pass this exam can call themselves licensed clinical or counseling
psychologists (Norcross, n.d.). Licensed clinical or counseling psychologists can then work in a number
of settings, ranging from private clinical practice to hospital settings. It should be noted that clinical
psychologists and psychiatrists do different things and receive different types of education. While both can
conduct therapy and counseling, clinical psychologists have a PhD or a PsyD, whereas psychiatrists have
a doctor of medicine degree (MD). As such, licensed clinical psychologists can administer and interpret
psychological tests, while psychiatrists can prescribe medications.
Individuals earning a PhD can work in a variety of settings, depending on their areas of specialization.
For example, someone trained as a biopsychologist might work in a pharmaceutical company to help test
the efficacy of a new drug. Someone with a clinical background might become a forensic psychologist and
work within the legal system to make recommendations during criminal trials and parole hearings, or
serve as an expert in a court case.
While earning a doctoral degree in psychology is a lengthy process, usually taking between 5–6 years of
graduate study (DeAngelis, 2010), there are a number of careers that can be attained with a master’s degree
in psychology. People who wish to provide psychotherapy can become licensed to serve as various types
of professional counselors (Hoffman, 2012). Relevant master’s degrees are also sufficient for individuals
seeking careers as school psychologists (National Association of School Psychologists, n.d.), in some
capacities related to sport psychology (American Psychological Association, 2014), or as consultants in
various industrial settings (Landers, 2011, June 14). Undergraduate coursework in psychology may be
applicable to other careers such as psychiatric social work or psychiatric nursing, where assessments and
therapy may be a part of the job.
As mentioned in the opening section of this chapter, an undergraduate education in psychology is
associated with a knowledge base and skill set that many employers find quite attractive. It should come as
no surprise, then, that individuals earning bachelor’s degrees in psychology find themselves in a number
of different careers, as shown in Table 1.1. Examples of a few such careers can involve serving as case
managers, working in sales, working in human resource departments, and teaching in high schools. The
rapidly growing realm of healthcare professions is another field in which an education in psychology is
helpful and sometimes required. For example, the Medical College Admission Test (MCAT) exam that
people must take to be admitted to medical school now includes a section on the psychological foundations
of behavior.
Table 1.1 Top Occupations Employing Graduates with a BA in
Psychology (Fogg, Harrington, Harrington, & Shatkin, 2012)
Ranking Occupation
1 Mid- and top-level management (executive, administrator)
2 Sales
3 Social work
4 Other management positions
5 Human resources (personnel, training)
6 Other administrative positions
7 Insurance, real estate, business
8 Marketing and sales
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Table 1.1 Top Occupations Employing Graduates with a BA in
Psychology (Fogg, Harrington, Harrington, & Shatkin, 2012)
Ranking Occupation
9 Healthcare (nurse, pharmacist, therapist)
10 Finance (accountant, auditor)
Watch a brief video ( describing some
of the career options available to people earning bachelor’s degrees in psychology.
Chapter 1 | Introduction to Psychology 29

American Psychological Association
biopsychosocial model
clinical psychology
cognitive psychology
counseling psychology
developmental psychology
empirical method
forensic psychology
personality psychology
personality trait
postdoctoral training program
psychoanalytic theory
Key Terms
professional organization representing psychologists in the United
focus on observing and controlling behavior
study of how biology influences behavior
perspective that asserts that biology, psychology, and social factors interact to
determine an individual’s health
area of psychology that focuses on the diagnosis and treatment of psychological
disorders and other problematic patterns of behavior
study of cognitions, or thoughts, and their relationship to experiences and actions
area of psychology that focuses on improving emotional, social, vocational, and
other aspects of the lives of psychologically healthy individuals
scientific study of development across a lifespan
long research paper about research that was conducted as a part of the candidate’s doctoral
method for acquiring knowledge based on observation, including experimentation,
rather than a method based only on forms of logical argument or previous authorities
area of psychology that applies the science and practice of psychology to issues
within and related to the justice system
focused on how mental activities helped an organism adapt to its environment
perspective within psychology that emphasizes the potential for good that is innate to all
process by which someone examines their own conscious experience in an attempt to
break it into its component parts
suffix that denotes “scientific study of”
study of patterns of thoughts and behaviors that make each individual unique
consistent pattern of thought and behavior
(doctor of philosophy) doctoral degree conferred in many disciplinary perspectives housed in a
traditional college of liberal arts and sciences
allows young scientists to further develop their research programs and
broaden their research skills under the supervision of other professionals in the field
Greek word for soul
focus on the role of the unconscious in affecting conscious behavior
scientific study of the mind and behavior
30 Chapter 1 | Introduction to Psychology
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sport and exercise psychology
(doctor of psychology) doctoral degree that places less emphasis on research-oriented skills and
focuses more on application of psychological principles in the clinical context
area of psychology that focuses on the interactions between mental and
emotional factors and physical performance in sports, exercise, and other activities
understanding the conscious experience through introspection
1.1 What Is Psychology?
Psychology derives from the roots psyche (meaning soul) and –ology (meaning scientific study of). Thus,
psychology is defined as the scientific study of mind and behavior. Students of psychology develop critical
thinking skills, become familiar with the scientific method, and recognize the complexity of behavior.
1.2 History of Psychology
Before the time of Wundt and James, questions about the mind were considered by philosophers.
However, both Wundt and James helped create psychology as a distinct scientific discipline. Wundt was a
structuralist, which meant he believed that our cognitive experience was best understood by breaking that
experience into its component parts. He thought this was best accomplished by introspection.
William James was the first American psychologist, and he was a proponent of functionalism. This
particular perspective focused on how mental activities served as adaptive responses to an organism’s
environment. Like Wundt, James also relied on introspection; however, his research approach also
incorporated more objective measures as well.
Sigmund Freud believed that understanding the unconscious mind was absolutely critical to understand
conscious behavior. This was especially true for individuals that he saw who suffered from various
hysterias and neuroses. Freud relied on dream analysis, slips of the tongue, and free association as means
to access the unconscious. Psychoanalytic theory remained a dominant force in clinical psychology for
several decades.
Gestalt psychology was very influential in Europe. Gestalt psychology takes a holistic view of an
individual and his experiences. As the Nazis came to power in Germany, Wertheimer, Koffka, and Köhler
immigrated to the United States. Although they left their laboratories and their research behind, they did
introduce America to Gestalt ideas. Some of the principles of Gestalt psychology are still very influential
in the study of sensation and perception.
One of the most influential schools of thought within psychology’s history was behaviorism. Behaviorism
focused on making psychology an objective science by studying overt behavior and deemphasizing the
importance of unobservable mental processes. John Watson is often considered the father of behaviorism,
and B. F. Skinner’s contributions to our understanding of principles of operant conditioning cannot be
As behaviorism and psychoanalytic theory took hold of so many aspects of psychology, some began to
become dissatisfied with psychology’s picture of human nature. Thus, a humanistic movement within
psychology began to take hold. Humanism focuses on the potential of all people for good. Both Maslow
and Rogers were influential in shaping humanistic psychology.
During the 1950s, the landscape of psychology began to change. A science of behavior began to shift back
to its roots of focus on mental processes. The emergence of neuroscience and computer science aided this
transition. Ultimately, the cognitive revolution took hold, and people came to realize that cognition was
crucial to a true appreciation and understanding of behavior.
1.3 Contemporary Psychology
Psychology is a diverse discipline that is made up of several major subdivisions with unique perspectives.
Chapter 1 | Introduction to Psychology 31

Biological psychology involves the study of the biological bases of behavior. Sensation and perception
refer to the area of psychology that is focused on how information from our sensory modalities is
received, and how this information is transformed into our perceptual experiences of the world around
us. Cognitive psychology is concerned with the relationship that exists between thought and behavior,
and developmental psychologists study the physical and cognitive changes that occur throughout one’s
lifespan. Personality psychology focuses on individuals’ unique patterns of behavior, thought, and
emotion. Industrial and organizational psychology, health psychology, sport and exercise psychology,
forensic psychology, and clinical psychology are all considered applied areas of psychology. Industrial
and organizational psychologists apply psychological concepts to I-O settings. Health psychologists look
for ways to help people live healthier lives, and clinical psychology involves the diagnosis and treatment
of psychological disorders and other problematic behavioral patterns. Sport and exercise psychologists
study the interactions between thoughts, emotions, and physical performance in sports, exercise, and other
activities. Forensic psychologists carry out activities related to psychology in association with the justice
1.4 Careers in Psychology
Generally, academic careers in psychology require doctoral degrees. However, there are a number of
nonacademic career options for people who have master’s degrees in psychology. While people with
bachelor’s degrees in psychology have more limited psychology-related career options, the skills acquired
as a function of an undergraduate education in psychology are useful in a variety of work contexts.
Review Questions
1. Which of the following was mentioned as a
skill to which psychology students would be
a. critical thinking
b. use of the scientific method
c. critical evaluation of sources of information
d. all of the above
2. Psyche is a Greek word meaning ________.
a. essence
b. soul
c. behavior
d. love
3. Before psychology became a recognized
academic discipline, matters of the mind were
undertaken by those in ________.
a. biology
b. chemistry
c. philosophy
d. physics
4. In the scientific method, a hypothesis is a(n)
a. observation
b. measurement
c. test
d. proposed explanation
5. Based on your reading, which theorist would
have been most likely to agree with this statement:
Perceptual phenomena are best understood as a
combination of their components.
a. William James
b. Max Wertheimer
c. Carl Rogers
d. Noam Chomsky
6. ________ is most well-known for proposing his
hierarchy of needs.
a. Noam Chomsky
b. Carl Rogers
c. Abraham Maslow
d. Sigmund Freud
7. Rogers believed that providing genuineness,
empathy, and ________ in the therapeutic
environment for his clients was critical to their
being able to deal with their problems.
a. structuralism
b. functionalism
c. Gestalt
d. unconditional positive regard
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8. The operant conditioning chamber (aka
________ box) is a device used to study the
principles of operant conditioning.
a. Skinner
b. Watson
c. James
d. Koffka
9. A researcher interested in how changes in the
cells of the hippocampus (a structure in the brain
related to learning and memory) are related to
memory formation would be most likely to
identify as a(n) ________ psychologist.
a. biological
b. health
c. clinical
d. social
10. An individual’s consistent pattern of thought
and behavior is known as a(n) ________.
a. psychosexual stage
b. object permanence
c. personality
d. perception
11. In Milgram’s controversial study on
obedience, nearly ________ of the participants
were willing to administer what appeared to be
lethal electrical shocks to another person because
they were told to do so by an authority figure.
a. 1/3
b. 2/3
c. 3/4
d. 4/5
12. A researcher interested in what factors make
an employee best suited for a given job would
most likely identify as a(n) ________ psychologist.
a. personality
b. clinical
c. social
d. I-O
13. If someone wanted to become a psychology
professor at a 4-year college, then s/he would
probably need a ________ degree in psychology.
a. bachelor of science
b. bachelor of art
c. master’s
d. PhD
14. The ________ places less emphasis on
research and more emphasis on application of
therapeutic skills.
a. PhD
b. PsyD
c. postdoctoral training program
d. dissertation
15. Which of the following degrees would be the
minimum required to teach psychology courses in
high school?
a. PhD
b. PsyD
c. master’s degree
d. bachelor’s degree
16. One would need at least a(n) ________ degree
to serve as a school psychologist.
a. associate’s
b. bachelor’s
c. master’s
d. doctoral
Critical Thinking Questions
17. Why do you think psychology courses like this one are often requirements of so many different
programs of study?
18. Why do you think many people might be skeptical about psychology being a science?
19. How did the object of study in psychology change over the history of the field since the 19th century?
20. In part, what aspect of psychology was the behaviorist approach to psychology a reaction to?
Chapter 1 | Introduction to Psychology 33

21. Given the incredible diversity among the various areas of psychology that were described in this
section, how do they all fit together?
22. What are the potential ethical concerns associated with Milgram’s research on obedience?
23. Why is an undergraduate education in psychology so helpful in a number of different lines of work?
24. Other than a potentially greater salary, what would be the reasons an individual would continue on
to get a graduate degree in psychology?
Personal Application Questions
25. Why are you taking this course? What do you hope to learn about during this course?
26. Freud is probably one of the most well-known historical figures in psychology. Where have you
encountered references to Freud or his ideas about the role that the unconscious mind plays in determining
conscious behavior?
27. Now that you’ve been briefly introduced to some of the major areas within psychology, which are you
most interested in learning more about? Why?
28. Which of the career options described in this section is most appealing to you?
34 Chapter 1 | Introduction to Psychology
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Chapter 2
Psychological Research
Figure 2.1 How does television content impact children’s behavior? (credit: modification of work by
Chapter Outline
2.1 Why Is Research Important?
2.2 Approaches to Research
2.3 Analyzing Findings
2.4 Ethics
Have you ever wondered whether the violence you see on television affects your behavior? Are you more
likely to behave aggressively in real life after watching people behave violently in dramatic situations on
the screen? Or, could seeing fictional violence actually get aggression out of your system, causing you to be
more peaceful? How are children influenced by the media they are exposed to? A psychologist interested
in the relationship between behavior and exposure to violent images might ask these very questions.
The topic of violence in the media today is contentious. Since ancient times, humans have been concerned
about the effects of new technologies on our behaviors and thinking processes. The Greek philosopher
Socrates, for example, worried that writing—a new technology at that time—would diminish people’s
ability to remember because they could rely on written records rather than committing information to
memory. In our world of quickly changing technologies, questions about the effects of media continue to
emerge. Many of us find ourselves with a strong opinion on these issues, only to find the person next to us
bristling with the opposite view.
How can we go about finding answers that are supported not by mere opinion, but by evidence that we
can all agree on? The findings of psychological research can help us navigate issues like this.
Chapter 2 | Psychological Research 35

2.1 Why Is Research Important?
Learning Objectives
By the end of this section, you will be able to:
• Explain how scientific research addresses questions about behavior
• Discuss how scientific research guides public policy
• Appreciate how scientific research can be important in making personal decisions
Scientific research is a critical tool for successfully navigating our complex world. Without it, we would be
forced to rely solely on intuition, other people’s authority, and blind luck. While many of us feel confident
in our abilities to decipher and interact with the world around us, history is filled with examples of how
very wrong we can be when we fail to recognize the need for evidence in supporting claims. At various
times in history, we would have been certain that the sun revolved around a flat earth, that the earth’s
continents did not move, and that mental illness was caused by possession (Figure 2.2). It is through
systematic scientific research that we divest ourselves of our preconceived notions and superstitions and
gain an objective understanding of ourselves and our world.
Figure 2.2 Some of our ancestors, across the world and over the centuries, believed that trephination—the practice
of making a hole in the skull, as shown here—allowed evil spirits to leave the body, thus curing mental illness and
other disorders. (credit: “taiproject”/Flickr)
The goal of all scientists is to better understand the world around them. Psychologists focus their attention
on understanding behavior, as well as the cognitive (mental) and physiological (body) processes that
underlie behavior. In contrast to other methods that people use to understand the behavior of others,
such as intuition and personal experience, the hallmark of scientific research is that there is evidence to
support a claim. Scientific knowledge is empirical: It is grounded in objective, tangible evidence that can
be observed time and time again, regardless of who is observing.
While behavior is observable, the mind is not. If someone is crying, we can see behavior. However, the
reason for the behavior is more difficult to determine. Is the person crying due to being sad, in pain,
or happy? Sometimes we can learn the reason for someone’s behavior by simply asking a question, like
“Why are you crying?” However, there are situations in which an individual is either uncomfortable or
unwilling to answer the question honestly, or is incapable of answering. For example, infants would not
be able to explain why they are crying. In such circumstances, the psychologist must be creative in finding
ways to better understand behavior. This chapter explores how scientific knowledge is generated, and how
important that knowledge is in forming decisions in our personal lives and in the public domain.
36 Chapter 2 | Psychological Research
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Trying to determine which theories are and are not accepted by the scientific community can be difficult,
especially in an area of research as broad as psychology. More than ever before, we have an incredible
amount of information at our fingertips, and a simple internet search on any given research topic might
result in a number of contradictory studies. In these cases, we are witnessing the scientific community
going through the process of reaching a consensus, and it could be quite some time before a consensus
emerges. For example, the hypothesized link between exposure to media violence and subsequent
aggression has been debated in the scientific community for roughly 60 years. Even today, we will find
detractors, but a consensus is building. Several professional organizations view media violence exposure
as a risk factor for actual violence, including the American Medical Association, the American Psychiatric
Association, and the American Psychological Association (American Academy of Pediatrics, American
Academy of Child & Adolescent Psychiatry, American Psychological Association, American Medical
Association, American Academy of Family Physicians, American Psychiatric Association, 2000).
In the meantime, we should strive to think critically about the information we encounter by exercising a
degree of healthy skepticism. When someone makes a claim, we should examine the claim from a number
of different perspectives: what is the expertise of the person making the claim, what might they gain if the
claim is valid, does the claim seem justified given the evidence, and what do other researchers think of
the claim? This is especially important when we consider how much information in advertising campaigns
and on the internet claims to be based on “scientific evidence” when in actuality it is a belief or perspective
of just a few individuals trying to sell a product or draw attention to their perspectives.
We should be informed consumers of the information made available to us because decisions based on
this information have significant consequences. One such consequence can be seen in politics and public
policy. Imagine that you have been elected as the governor of your state. One of your responsibilities
is to manage the state budget and determine how to best spend your constituents’ tax dollars. As the
new governor, you need to decide whether to continue funding the D.A.R.E. (Drug Abuse Resistance
Education) program in public schools (Figure 2.3). This program typically involves police officers coming
into the classroom to educate students about the dangers of becoming involved with alcohol and other
drugs. According to the D.A.R.E. website (, this program has been very popular since its
inception in 1983, and it is currently operating in 75% of school districts in the United States and in more
than 40 countries worldwide. Sounds like an easy decision, right? However, on closer review, you discover
that the vast majority of research into this program consistently suggests that participation has little, if
any, effect on whether or not someone uses alcohol or other drugs (Clayton, Cattarello, & Johnstone, 1996;
Ennett, Tobler, Ringwalt, & Flewelling, 1994; Lynam et al., 1999; Ringwalt, Ennett, & Holt, 1991). If you are
committed to being a good steward of taxpayer money, will you fund this particular program, or will you
try to find other programs that research has consistently demonstrated to be effective?
Figure 2.3 The D.A.R.E. program continues to be popular in schools around the world despite research suggesting
that it is ineffective.
Chapter 2 | Psychological Research 37

Watch this news report ( to learn more about some
of the controversial issues surrounding the D.A.R.E. program.
Ultimately, it is not just politicians who can benefit from using research in guiding their decisions. We all
might look to research from time to time when making decisions in our lives. Imagine you just found out
that a close friend has breast cancer or that one of your young relatives has recently been diagnosed with
autism. In either case, you want to know which treatment options are most successful with the fewest side
effects. How would you find that out? You would probably talk with your doctor and personally review
the research that has been done on various treatment options—always with a critical eye to ensure that
you are as informed as possible.
In the end, research is what makes the difference between facts and opinions. Facts are observable realities,
and opinions are personal judgments, conclusions, or attitudes that may or may not be accurate. In the
scientific community, facts can be established only using evidence collected through empirical research.
Scientific knowledge is advanced through a process known as the scientific method. Basically, ideas (in the
form of theories and hypotheses) are tested against the real world (in the form of empirical observations),
and those empirical observations lead to more ideas that are tested against the real world, and so on. In this
sense, the scientific process is circular. The types of reasoning within the circle are called deductive and
inductive. In deductive reasoning, ideas are tested against the empirical world; in inductive reasoning,
empirical observations lead to new ideas (Figure 2.4). These processes are inseparable, like inhaling
and exhaling, but different research approaches place different emphasis on the deductive and inductive
Figure 2.4 Psychological research relies on both inductive and deductive reasoning.
In the scientific context, deductive reasoning begins with a generalization—one hypothesis—that is then
used to reach logical conclusions about the real world. If the hypothesis is correct, then the logical
conclusions reached through deductive reasoning should also be correct. A deductive reasoning argument
might go something like this: All living things require energy to survive (this would be your hypothesis).
Ducks are living things. Therefore, ducks require energy to survive (logical conclusion). In this example,
38 Chapter 2 | Psychological Research
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the hypothesis is correct; therefore, the conclusion is correct as well. Sometimes, however, an incorrect
hypothesis may lead to a logical but incorrect conclusion. Consider this argument: all ducks are born with
the ability to see. Quackers is a duck. Therefore, Quackers was born with the ability to see. Scientists
use deductive reasoning to empirically test their hypotheses. Returning to the example of the ducks,
researchers might design a study to test the hypothesis that if all living things require energy to survive,
then ducks will be found to require energy to survive.
Deductive reasoning starts with a generalization that is tested against real-world observations; however,
inductive reasoning moves in the opposite direction. Inductive reasoning uses empirical observations to
construct broad generalizations. Unlike deductive reasoning, conclusions drawn from inductive reasoning
may or may not be correct, regardless of the observations on which they are based. For instance, you may
notice that your favorite fruits—apples, bananas, and oranges—all grow on trees; therefore, you assume
that all fruit must grow on trees. This would be an example of inductive reasoning, and, clearly, the
existence of strawberries, blueberries, and kiwi demonstrate that this generalization is not correct despite
it being based on a number of direct observations. Scientists use inductive reasoning to formulate theories,
which in turn generate hypotheses that are tested with deductive reasoning. In the end, science involves
both deductive and inductive processes.
For example, case studies, which you will read about in the next section, are heavily weighted on the
side of empirical observations. Thus, case studies are closely associated with inductive processes as
researchers gather massive amounts of observations and seek interesting patterns (new ideas) in the data.
Experimental research, on the other hand, puts great emphasis on deductive reasoning.
Play this “Deal Me In” interactive card game (
dealmein) to practice using inductive reasoning.
We’ve stated that theories and hypotheses are ideas, but what sort of ideas are they, exactly? A theory is a
well-developed set of ideas that propose an explanation for observed phenomena. Theories are repeatedly
checked against the world, but they tend to be too complex to be tested all at once; instead, researchers
create hypotheses to test specific aspects of a theory.
A hypothesis is a testable prediction about how the world will behave if our idea is correct, and it is
often worded as an if-then statement (e.g., if I study all night, I will get a passing grade on the test). The
hypothesis is extremely important because it bridges the gap between the realm of ideas and the real
world. As specific hypotheses are tested, theories are modified and refined to reflect and incorporate the
result of these tests Figure 2.5.
Chapter 2 | Psychological Research 39

Figure 2.5 The scientific method of research includes proposing hypotheses, conducting research, and creating or
modifying theories based on results.
To see how this process works, let’s consider a specific theory and a hypothesis that might be generated
from that theory. As you’ll learn in a later chapter, the James-Lange theory of emotion asserts that
emotional experience relies on the physiological arousal associated with the emotional state. If you walked
out of your home and discovered a very aggressive snake waiting on your doorstep, your heart would
begin to race and your stomach churn. According to the James-Lange theory, these physiological changes
would result in your feeling of fear. A hypothesis that could be derived from this theory might be that a
person who is unaware of the physiological arousal that the sight of the snake elicits will not feel fear.
A scientific hypothesis is also falsifiable, or capable of being shown to be incorrect. Recall from the
introductory chapter that Sigmund Freud had lots of interesting ideas to explain various human behaviors
(Figure 2.6). However, a major criticism of Freud’s theories is that many of his ideas are not falsifiable;
for example, it is impossible to imagine empirical observations that would disprove the existence of the id,
the ego, and the superego—the three elements of personality described in Freud’s theories. Despite this,
Freud’s theories are widely taught in introductory psychology texts because of their historical significance
for personality psychology and psychotherapy, and these remain the root of all modern forms of therapy.
40 Chapter 2 | Psychological Research
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Figure 2.6 Many of the specifics of (a) Freud’s theories, such as (b) his division of the mind into id, ego, and
superego, have fallen out of favor in recent decades because they are not falsifiable. In broader strokes, his views set
the stage for much of psychological thinking today, such as the unconscious nature of the majority of psychological
In contrast, the James-Lange theory does generate falsifiable hypotheses, such as the one described
above. Some individuals who suffer significant injuries to their spinal columns are unable to feel the
bodily changes that often accompany emotional experiences. Therefore, we could test the hypothesis by
determining how emotional experiences differ between individuals who have the ability to detect these
changes in their physiological arousal and those who do not. In fact, this research has been conducted and
while the emotional experiences of people deprived of an awareness of their physiological arousal may be
less intense, they still experience emotion (Chwalisz, Diener, & Gallagher, 1988).
Scientific research’s dependence on falsifiability allows for great confidence in the information that it
produces. Typically, by the time information is accepted by the scientific community, it has been tested
Visit this website ( to apply the scientific
method and practice its steps by using them to solve a murder mystery, determine
why a student is in trouble, and design an experiment to test house paint.
Chapter 2 | Psychological Research 41

2.2 Approaches to Research
Learning Objectives
By the end of this section, you will be able to:
• Describe the different research methods used by psychologists
• Discuss the strengths and weaknesses of case studies, naturalistic observation, surveys, and
archival research
• Compare longitudinal and cross-sectional approaches to research
There are many research methods available to psychologists in their efforts to understand, describe,
and explain behavior and the cognitive and biological processes that underlie it. Some methods rely
on observational techniques. Other approaches involve interactions between the researcher and the
individuals who are being studied—ranging from a series of simple questions to extensive, in-depth
interviews—to well-controlled experiments.
Each of these research methods has unique strengths and weaknesses, and each method may only be
appropriate for certain types of research questions. For example, studies that rely primarily on observation
produce incredible amounts of information, but the ability to apply this information to the larger
population is somewhat limited because of small sample sizes. Survey research, on the other hand,
allows researchers to easily collect data from relatively large samples. While this allows for results to
be generalized to the larger population more easily, the information that can be collected on any given
survey is somewhat limited and subject to problems associated with any type of self-reported data. Some
researchers conduct archival research by using existing records. While this can be a fairly inexpensive
way to collect data that can provide insight into a number of research questions, researchers using this
approach have no control on how or what kind of data was collected. All of the methods described thus
far are correlational in nature. This means that researchers can speak to important relationships that might
exist between two or more variables of interest. However, correlational data cannot be used to make claims
about cause-and-effect relationships.
Correlational research can find a relationship between two variables, but the only way a researcher can
claim that the relationship between the variables is cause and effect is to perform an experiment. In
experimental research, which will be discussed later in this chapter, there is a tremendous amount of
control over variables of interest. While this is a powerful approach, experiments are often conducted in
very artificial settings. This calls into question the validity of experimental findings with regard to how
they would apply in real-world settings. In addition, many of the questions that psychologists would like
to answer cannot be pursued through experimental research because of ethical concerns.
In 2011, the New York Times published a feature story on Krista and Tatiana Hogan, Canadian twin girls.
These particular twins are unique because Krista and Tatiana are conjoined twins, connected at the head.
There is evidence that the two girls are connected in a part of the brain called the thalamus, which is
a major sensory relay center. Most incoming sensory information is sent through the thalamus before
reaching higher regions of the cerebral cortex for processing.
42 Chapter 2 | Psychological Research
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To learn more about Krista and Tatiana, watch this New York Times video
( about their lives.
The implications of this potential connection mean that it might be possible for one twin to experience the
sensations of the other twin. For instance, if Krista is watching a particularly funny television program,
Tatiana might smile or laugh even if she is not watching the program. This particular possibility has
piqued the interest of many neuroscientists who seek to understand how the brain uses sensory
These twins represent an enormous resource in the study of the brain, and since their condition is very
rare, it is likely that as long as their family agrees, scientists will follow these girls very closely throughout
their lives to gain as much information as possible (Dominus, 2011).
In observational research, scientists are conducting a clinical or case study when they focus on one person
or just a few individuals. Indeed, some scientists spend their entire careers studying just 10–20 individuals.
Why would they do this? Obviously, when they focus their attention on a very small number of people,
they can gain a tremendous amount of insight into those cases. The richness of information that is collected
in clinical or case studies is unmatched by any other single research method. This allows the researcher to
have a very deep understanding of the individuals and the particular phenomenon being studied.
If clinical or case studies provide so much information, why are they not more frequent among
researchers? As it turns out, the major benefit of this particular approach is also a weakness. As mentioned
earlier, this approach is often used when studying individuals who are interesting to researchers because
they have a rare characteristic. Therefore, the individuals who serve as the focus of case studies are not like
most other people. If scientists ultimately want to explain all behavior, focusing attention on such a special
group of people can make it difficult to generalize any observations to the larger population as a whole.
Generalizing refers to the ability to apply the findings of a particular research project to larger segments of
society. Again, case studies provide enormous amounts of information, but since the cases are so specific,
the potential to apply what’s learned to the average person may be very limited.
If you want to understand how behavior occurs, one of the best ways to gain information is to simply
observe the behavior in its natural context. However, people might change their behavior in unexpected
ways if they know they are being observed. How do researchers obtain accurate information when people
tend to hide their natural behavior? As an example, imagine that your professor asks everyone in your
class to raise their hand if they always wash their hands after using the restroom. Chances are that almost
everyone in the classroom will raise their hand, but do you think hand washing after every trip to the
restroom is really that universal?
This is very similar to the phenomenon mentioned earlier in this chapter: many individuals do not feel
comfortable answering a question honestly. But if we are committed to finding out the facts about hand
washing, we have other options available to us.
Suppose we send a classmate into the restroom to actually watch whether everyone washes their hands
after using the restroom. Will our observer blend into the restroom environment by wearing a white
lab coat, sitting with a clipboard, and staring at the sinks? We want our researcher to be
inconspicuous—perhaps standing at one of the sinks pretending to put in contact lenses while secretly
Chapter 2 | Psychological Research 43

recording the relevant information. This type of observational study is called naturalistic observation:
observing behavior in its natural setting. To better understand peer exclusion, Suzanne Fanger
collaborated with colleagues at the University of Texas to observe the behavior of preschool children
on a playground. How did the observers remain inconspicuous over the duration of the study? They
equipped a few of the children with wireless microphones (which the children quickly forgot about) and
observed while taking notes from a distance. Also, the children in that particular preschool (a “laboratory
preschool”) were accustomed to having observers on the playground (Fanger, Frankel, & Hazen, 2012).
It is critical that the observer be as unobtrusive and as inconspicuous as possible: when people know they
are being watched, they are less likely to behave naturally. If you have any doubt about this, ask yourself
how your driving behavior might differ in two situations: In the first situation, you are driving down a
deserted highway during the middle of the day; in the second situation, you are being followed by a police
car down the same deserted highway (Figure 2.7).
Figure 2.7 Seeing a police car behind you would probably affect your driving behavior. (credit: Michael Gil)
It should be pointed out that naturalistic observation is not limited to research involving humans. Indeed,
some of the best-known examples of naturalistic observation involve researchers going into the field to
observe various kinds of animals in their own environments. As with human studies, the researchers
maintain their distance and avoid interfering with the animal subjects so as not to influence their natural
behaviors. Scientists have used this technique to study social hierarchies and interactions among animals
ranging from ground squirrels to gorillas. The information provided by these studies is invaluable in
understanding how those animals organize socially and communicate with one another. The
anthropologist Jane Goodall, for example, spent nearly five decades observing the behavior of
chimpanzees in Africa (Figure 2.8). As an illustration of the types of concerns that a researcher might
encounter in naturalistic observation, some scientists criticized Goodall for giving the chimps names
instead of referring to them by numbers—using names was thought to undermine the emotional
detachment required for the objectivity of the study (McKie, 2010).
Figure 2.8 (a) Jane Goodall made a career of conducting naturalistic observations of (b) chimpanzee behavior.
(credit “Jane Goodall”: modification of work by Erik Hersman; “chimpanzee”: modification of work by “Afrika
The greatest benefit of naturalistic observation is the validity, or accuracy, of information collected
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unobtrusively in a natural setting. Having individuals behave as they normally would in a given situation
means that we have a higher degree of ecological validity, or realism, than we might achieve with
other research approaches. Therefore, our ability to generalize the findings of the research to real-world
situations is enhanced. If done correctly, we need not worry about people or animals modifying their
behavior simply because they are being observed. Sometimes, people may assume that reality programs
give us a glimpse into authentic human behavior. However, the principle of inconspicuous observation
is violated as reality stars are followed by camera crews and are interviewed on camera for personal
confessionals. Given that environment, we must doubt how natural and realistic their behaviors are.
The major downside of naturalistic observation is that they are often difficult to set up and control. In
our restroom study, what if you stood in the restroom all day prepared to record people’s hand washing
behavior and no one came in? Or, what if you have been closely observing a troop of gorillas for weeks
only to find that they migrated to a new place while you were sleeping in your tent? The benefit of realistic
data comes at a cost. As a researcher you have no control of when (or if) you have behavior to observe. In
addition, this type of observational research often requires significant investments of time, money, and a
good dose of luck.
Sometimes studies involve structured observation. In these cases, people are observed while engaging in
set, specific tasks. An excellent example of structured observation comes from Strange Situation by Mary
Ainsworth (you will read more about this in the chapter on lifespan development). The Strange Situation is
a procedure used to evaluate attachment styles that exist between an infant and caregiver. In this scenario,
caregivers bring their infants into a room filled with toys. The Strange Situation involves a number of
phases, including a stranger coming into the room, the caregiver leaving the room, and the caregiver’s
return to the room. The infant’s behavior is closely monitored at each phase, but it is the behavior of the
infant upon being reunited with the caregiver that is most telling in terms of characterizing the infant’s
attachment style with the caregiver.
Another potential problem in observational research is observer bias. Generally, people who act as
observers are closely involved in the research project and may unconsciously skew their observations to
fit their research goals or expectations. To protect against this type of bias, researchers should have clear
criteria established for the types of behaviors recorded and how those behaviors should be classified. In
addition, researchers often compare observations of the same event by multiple observers, in order to test
inter-rater reliability: a measure of reliability that assesses the consistency of observations by different
Often, psychologists develop surveys as a means of gathering data. Surveys are lists of questions to be
answered by research participants, and can be delivered as paper-and-pencil questionnaires, administered
electronically, or conducted verbally (Figure 2.9). Generally, the survey itself can be completed in a short
time, and the ease of administering a survey makes it easy to collect data from a large number of people.
Surveys allow researchers to gather data from larger samples than may be afforded by other research
methods. A sample is a subset of individuals selected from a population, which is the overall group of
individuals that the researchers are interested in. Researchers study the sample and seek to generalize their
findings to the population.
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Figure 2.9 Surveys can be administered in a number of ways, including electronically administered research, like
the survey shown here. (credit: Robert Nyman)
There is both strength and weakness of the survey in comparison to case studies. By using surveys, we
can collect information from a larger sample of people. A larger sample is better able to reflect the actual
diversity of the population, thus allowing better generalizability. Therefore, if our sample is sufficiently
large and diverse, we can assume that the data we collect from the survey can be generalized to the larger
population with more certainty than the information collected through a case study. However, given the
greater number of people involved, we are not able to collect the same depth of information on each person
that would be collected in a case study.
Another potential weakness of surveys is something we touched on earlier in this chapter: People don’t
always give accurate responses. They may lie, misremember, or answer questions in a way that they think
makes them look good. For example, people may report drinking less alcohol than is actually the case.
Any number of research questions can be answered through the use of surveys. One real-world example
is the research conducted by Jenkins, Ruppel, Kizer, Yehl, and Griffin (2012) about the backlash against
the US Arab-American community following the terrorist attacks of September 11, 2001. Jenkins and
colleagues wanted to determine to what extent these negative attitudes toward Arab-Americans still
existed nearly a decade after the attacks occurred. In one study, 140 research participants filled out a
survey with 10 questions, including questions asking directly about the participant’s overt prejudicial
attitudes toward people of various ethnicities. The survey also asked indirect questions about how likely
the participant would be to interact with a person of a given ethnicity in a variety of settings (such as,
“How likely do you think it is that you would introduce yourself to a person of Arab-American descent?”).
The results of the research suggested that participants were unwilling to report prejudicial attitudes
toward any ethnic group. However, there were significant differences between their pattern of responses
to questions about social interaction with Arab-Americans compared to other ethnic groups: they indicated
less willingness for social interaction with Arab-Americans compared to the other ethnic groups. This
suggested that the participants harbored subtle forms of prejudice against Arab-Americans, despite their
assertions that this was not the case (Jenkins et al., 2012).
Some researchers gain access to large amounts of data without interacting with a single research
participant. Instead, they use existing records to answer various research questions. This type of research
approach is known as archival research. Archival research relies on looking at past records or data sets to
look for interesting patterns or relationships.
For example, a researcher might access the academic records of all individuals who enrolled in college
within the past ten years and calculate how long it took them to complete their degrees, as well as course
loads, grades, and extracurricular involvement. Archival research could provide important information
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about who is most likely to complete their education, and it could help identify important risk factors for
struggling students (Figure 2.10).
Figure 2.10 A researcher doing archival research examines records, whether archived as a (a) hardcopy or (b)
electronically. (credit “paper files”: modification of work by “Newtown graffiti”/Flickr; “computer”: modification of work
by INPIVIC Family/Flickr)
In comparing archival research to other research methods, there are several important distinctions. For
one, the researcher employing archival research never directly interacts with research participants.
Therefore, the investment of time and money to collect data is considerably less with archival research.
Additionally, researchers have no control over what information was originally collected. Therefore,
research questions have to be tailored so they can be answered within the structure of the existing data sets.
There is also no guarantee of consistency between the records from one source to another, which might
make comparing and contrasting different data sets problematic.
Sometimes we want to see how people change over time, as in studies of human development and
lifespan. When we test the same group of individuals repeatedly over an extended period of time, we
are conducting longitudinal research. Longitudinal research is a research design in which data-gathering
is administered repeatedly over an extended period of time. For example, we may survey a group of
individuals about their dietary habits at age 20, retest them a decade later at age 30, and then again at age
Another approach is cross-sectional research. In cross-sectional research, a researcher compares multiple
segments of the population at the same time. Using the dietary habits example above, the researcher
might directly compare different groups of people by age. Instead a group of people for 20 years to
see how their dietary habits changed from decade to decade, the researcher would study a group of
20-year-old individuals and compare them to a group of 30-year-old individuals and a group of 40-year-
old individuals. While cross-sectional research requires a shorter-term investment, it is also limited by
differences that exist between the different generations (or cohorts) that have nothing to do with age per
se, but rather reflect the social and cultural experiences of different generations of individuals make them
different from one another.
To illustrate this concept, consider the following survey findings. In recent years there has been significant
growth in the popular support of same-sex marriage. Many studies on this topic break down survey
participants into different age groups. In general, younger people are more supportive of same-sex
marriage than are those who are older (Jones, 2013). Does this mean that as we age we become less open to
the idea of same-sex marriage, or does this mean that older individuals have different perspectives because
of the social climates in which they grew up? Longitudinal research is a powerful approach because the
same individuals are involved in the research project over time, which means that the researchers need to
be less concerned with differences among cohorts affecting the results of their study.
Often longitudinal studies are employed when researching various diseases in an effort to understand
Chapter 2 | Psychological Research 47

particular risk factors. Such studies often involve tens of thousands of individuals who are followed
for several decades. Given the enormous number of people involved in these studies, researchers can
feel confident that their findings can be generalized to the larger population. The Cancer Prevention
Study-3 (CPS-3) is one of a series of longitudinal studies sponsored by the American Cancer Society aimed
at determining predictive risk factors associated with cancer. When participants enter the study, they
complete a survey about their lives and family histories, providing information on factors that might cause
or prevent the development of cancer. Then every few years the participants receive additional surveys
to complete. In the end, hundreds of thousands of participants will be tracked over 20 years to determine
which of them develop cancer and which do not.
Clearly, this type of research is important and potentially very informative. For instance, earlier
longitudinal studies sponsored by the American Cancer Society provided some of the first scientific
demonstrations of the now well-established links between increased rates of cancer and smoking
(American Cancer Society, n.d.) (Figure 2.11).
Figure 2.11 Longitudinal research like the CPS-3 help us to better understand how smoking is associated with
cancer and other diseases. (credit: CDC/Debora Cartagena)
As with any research strategy, longitudinal research is not without limitations. For one, these studies
require an incredible time investment by the researcher and research participants. Given that some
longitudinal studies take years, if not decades, to complete, the results will not be known for a considerable
period of time. In addition to the time demands, these studies also require a substantial financial
investment. Many researchers are unable to commit the resources necessary to see a longitudinal project
through to the end.
Research participants must also be willing to continue their participation for an extended period of time,
and this can be problematic. People move, get married and take new names, get ill, and eventually die.
Even without significant life changes, some people may simply choose to discontinue their participation
in the project. As a result, the attrition rates, or reduction in the number of research participants due to
dropouts, in longitudinal studies are quite high and increases over the course of a project. For this reason,
researchers using this approach typically recruit many participants fully expecting that a substantial
number will drop out before the end. As the study progresses, they continually check whether the sample
still represents the larger population, and make adjustments as necessary.
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2.3 Analyzing Findings
Learning Objectives
By the end of this section, you will be able to:
• Explain what a correlation coefficient tells us about the relationship between variables
• Recognize that correlation does not indicate a cause-and-effect relationship between
• Discuss our tendency to look for relationships between variables that do not really exist
• Explain random sampling and assignment of participants into experimental and control
• Discuss how experimenter or participant bias could affect the results of an experiment
• Identify independent and dependent variables
Did you know that as sales in ice cream increase, so does the overall rate of crime? Is it possible that
indulging in your favorite flavor of ice cream could send you on a crime spree? Or, after committing crime
do you think you might decide to treat yourself to a cone? There is no question that a relationship exists
between ice cream and crime (e.g., Harper, 2013), but it would be pretty foolish to decide that one thing
actually caused the other to occur.
It is much more likely that both ice cream sales and crime rates are related to the temperature outside.
When the temperature is warm, there are lots of people out of their houses, interacting with each other,
getting annoyed with one another, and sometimes committing crimes. Also, when it is warm outside, we
are more likely to seek a cool treat like ice cream. How do we determine if there is indeed a relationship
between two things? And when there is a relationship, how can we discern whether it is attributable to
coincidence or causation?
Correlation means that there is a relationship between two or more variables (such as ice cream
consumption and crime), but this relationship does not necessarily imply cause and effect. When two
variables are correlated, it simply means that as one variable changes, so does the other. We can measure
correlation by calculating a statistic known as a correlation coefficient. A correlation coefficient is a
number from -1 to +1 that indicates the strength and direction of the relationship between variables. The
correlation coefficient is usually represented by the letter r.
The number portion of the correlation coefficient indicates the strength of the relationship. The closer
the number is to 1 (be it negative or positive), the more strongly related the variables are, and the more
predictable changes in one variable will be as the other variable changes. The closer the number is to zero,
the weaker the relationship, and the less predictable the relationships between the variables becomes. For
instance, a correlation coefficient of 0.9 indicates a far stronger relationship than a correlation coefficient of
0.3. If the variables are not related to one another at all, the correlation coefficient is 0. The example above
about ice cream and crime is an example of two variables that we might expect to have no relationship to
each other.
The sign—positive or negative—of the correlation coefficient indicates the direction of the relationship
(Figure 2.12). A positive correlation means that the variables move in the same direction. Put another
way, it means that as one variable increases so does the other, and conversely, when one variable decreases
so does the other. A negative correlation means that the variables move in opposite directions. If two
variables are negatively correlated, a decrease in one variable is associated with an increase in the other
and vice versa.
The example of ice cream and crime rates is a positive correlation because both variables increase when
Chapter 2 | Psychological Research 49

temperatures are warmer. Other examples of positive correlations are the relationship between an
individual’s height and weight or the relationship between a person’s age and number of wrinkles. One
might expect a negative correlation to exist between someone’s tiredness during the day and the number
of hours they slept the previous night: the amount of sleep decreases as the feelings of tiredness increase.
In a real-world example of negative correlation, student researchers at the University of Minnesota found
a weak negative correlation (r = -0.29) between the average number of days per week that students got
fewer than 5 hours of sleep and their GPA (Lowry, Dean, & Manders, 2010). Keep in mind that a negative
correlation is not the same as no correlation. For example, we would probably find no correlation between
hours of sleep and shoe size.
As mentioned earlier, correlations have predictive value. Imagine that you are on the admissions
committee of a major university. You are faced with a huge number of applications, but you are able
to accommodate only a small percentage of the applicant pool. How might you decide who should be
admitted? You might try to correlate your current students’ college GPA with their scores on standardized
tests like the SAT or ACT. By observing which correlations were strongest for your current students, you
could use this information to predict relative success of those students who have applied for admission
into the university.
Figure 2.12 Scatterplots are a graphical view of the strength and direction of correlations. The stronger the
correlation, the closer the data points are to a straight line. In these examples, we see that there is (a) a positive
correlation between weight and height, (b) a negative correlation between tiredness and hours of sleep, and (c) no
correlation between shoe size and hours of sleep.
Manipulate this interactive scatterplot ( to
practice your understanding of positive and negative correlation.
Correlation Does Not Indicate Causation
Correlational research is useful because it allows us to discover the strength and direction of relationships
that exist between two variables. However, correlation is limited because establishing the existence of a
relationship tells us little about cause and effect. While variables are sometimes correlated because one
does cause the other, it could also be that some other factor, a confounding variable, is actually causing the
systematic movement in our variables of interest. In the ice cream/crime rate example mentioned earlier,
temperature is a confounding variable that could account for the relationship between the two variables.
Even when we cannot point to clear confounding variables, we should not assume that a correlation
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between two variables implies that one variable causes changes in another. This can be frustrating when a
cause-and-effect relationship seems clear and intuitive. Think back to our discussion of the research done
by the American Cancer Society and how their research projects were some of the first demonstrations of
the link between smoking and cancer. It seems reasonable to assume that smoking causes cancer, but if we
were limited to correlational research, we would be overstepping our bounds by making this assumption.
Unfortunately, people mistakenly make claims of causation as a function of correlations all the time. Such
claims are especially common in advertisements and news stories. For example, recent research found
that people who eat cereal on a regular basis achieve healthier weights than those who rarely eat cereal
(Frantzen, Treviño, Echon, Garcia-Dominic, & DiMarco, 2013; Barton et al., 2005). Guess how the cereal
companies report this finding. Does eating cereal really cause an individual to maintain a healthy weight,
or are there other possible explanations, such as, someone at a healthy weight is more likely to regularly
eat a healthy breakfast than someone who is obese or someone who avoids meals in an attempt to diet
(Figure 2.13)? While correlational research is invaluable in identifying relationships among variables, a
major limitation is the inability to establish causality. Psychologists want to make statements about cause
and effect, but the only way to do that is to conduct an experiment to answer a research question. The next
section describes how scientific experiments incorporate methods that eliminate, or control for, alternative
explanations, which allow researchers to explore how changes in one variable cause changes in another
Figure 2.13 Does eating cereal really cause someone to be a healthy weight? (credit: Tim Skillern)
Illusory Correlations
The temptation to make erroneous cause-and-effect statements based on correlational research is not
the only way we tend to misinterpret data. We also tend to make the mistake of illusory correlations,
especially with unsystematic observations. Illusory correlations, or false correlations, occur when people
believe that relationships exist between two things when no such relationship exists. One well-known
illusory correlation is the supposed effect that the moon’s phases have on human behavior. Many people
passionately assert that human behavior is affected by the phase of the moon, and specifically, that people
act strangely when the moon is full (Figure 2.14).
Figure 2.14 Many people believe that a full moon makes people behave oddly. (credit: Cory Zanker)
There is no denying that the moon exerts a powerful influence on our planet. The ebb and flow of the
Chapter 2 | Psychological Research 51

ocean’s tides are tightly tied to the gravitational forces of the moon. Many people believe, therefore, that
it is logical that we are affected by the moon as well. After all, our bodies are largely made up of water.
A meta-analysis of nearly 40 studies consistently demonstrated, however, that the relationship between
the moon and our behavior does not exist (Rotton & Kelly, 1985). While we may pay more attention to
odd behavior during the full phase of the moon, the rates of odd behavior remain constant throughout the
lunar cycle.
Why are we so apt to believe in illusory correlations like this? Often we read or hear about them and
simply accept the information as valid. Or, we have a hunch about how something works and then look
for evidence to support that hunch, ignoring evidence that would tell us our hunch is false; this is known
as confirmation bias. Other times, we find illusory correlations based on the information that comes most
easily to mind, even if that information is severely limited. And while we may feel confident that we can
use these relationships to better understand and predict the world around us, illusory correlations can
have significant drawbacks. For example, research suggests that illusory correlations—in which certain
behaviors are inaccurately attributed to certain groups—are involved in the formation of prejudicial
attitudes that can ultimately lead to discriminatory behavior (Fiedler, 2004).
As you’ve learned, the only way to establish that there is a cause-and-effect relationship between two
variables is to conduct a scientific experiment. Experiment has a different meaning in the scientific context
than in everyday life. In everyday conversation, we often use it to describe trying something for the first
time, such as experimenting with a new hair style or a new food. However, in the scientific context, an
experiment has precise requirements for design and implementation.
The Experimental Hypothesis
In order to conduct an experiment, a researcher must have a specific hypothesis to be tested. As you’ve
learned, hypotheses can be formulated either through direct observation of the real world or after careful
review of previous research. For example, if you think that children should not be allowed to watch violent
programming on television because doing so would cause them to behave more violently, then you have
basically formulated a hypothesis—namely, that watching violent television programs causes children to
behave more violently. How might you have arrived at this particular hypothesis? You may have younger
relatives who watch cartoons featuring characters using martial arts to save the world from evildoers, with
an impressive array of punching, kicking, and defensive postures. You notice that after watching these
programs for a while, your young relatives mimic the fighting behavior of the characters portrayed in the
cartoon (Figure 2.15).
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Figure 2.15 Seeing behavior like this right after a child watches violent television programming might lead you to
hypothesize that viewing violent television programming leads to an increase in the display of violent behaviors.
(credit: Emran Kassim)
These sorts of personal observations are what often lead us to formulate a specific hypothesis, but
we cannot use limited personal observations and anecdotal evidence to rigorously test our hypothesis.
Instead, to find out if real-world data supports our hypothesis, we have to conduct an experiment.
Designing an Experiment
The most basic experimental design involves two groups: the experimental group and the control group.
The two groups are designed to be the same except for one difference— experimental manipulation. The
experimental group gets the experimental manipulation—that is, the treatment or variable being tested
(in this case, violent TV images)—and the control group does not. Since experimental manipulation is the
only difference between the experimental and control groups, we can be sure that any differences between
the two are due to experimental manipulation rather than chance.
In our example of how violent television programming might affect violent behavior in children, we
have the experimental group view violent television programming for a specified time and then measure
their violent behavior. We measure the violent behavior in our control group after they watch nonviolent
television programming for the same amount of time. It is important for the control group to be treated
similarly to the experimental group, with the exception that the control group does not receive the
experimental manipulation. Therefore, we have the control group watch non-violent television
programming for the same amount of time as the experimental group.
We also need to precisely define, or operationalize, what is considered violent and nonviolent. An
operational definition is a description of how we will measure our variables, and it is important in
allowing others understand exactly how and what a researcher measures in a particular experiment. In
operationalizing violent behavior, we might choose to count only physical acts like kicking or punching
as instances of this behavior, or we also may choose to include angry verbal exchanges. Whatever we
determine, it is important that we operationalize violent behavior in such a way that anyone who hears
about our study for the first time knows exactly what we mean by violence. This aids peoples’ ability to
interpret our data as well as their capacity to repeat our experiment should they choose to do so.
Once we have operationalized what is considered violent television programming and what is considered
violent behavior from our experiment participants, we need to establish how we will run our experiment.
In this case, we might have participants watch a 30-minute television program (either violent or
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nonviolent, depending on their group membership) before sending them out to a playground for an hour
where their behavior is observed and the number and type of violent acts is recorded.
Ideally, the people who observe and record the children’s behavior are unaware of who was assigned to
the experimental or control group, in order to control for experimenter bias. Experimenter bias refers to
the possibility that a researcher’s expectations might skew the results of the study. Remember, conducting
an experiment requires a lot of planning, and the people involved in the research project have a vested
interest in supporting their hypotheses. If the observers knew which child was in which group, it might
influence how much attention they paid to each child’s behavior as well as how they interpreted that
behavior. By being blind to which child is in which group, we protect against those biases. This situation
is a single-blind study, meaning that one of the groups (participants) are unaware as to which group they
are in (experiment or control group) while the researcher who developed the experiment knows which
participants are in each group.
In a double-blind study, both the researchers and the participants are blind to group assignments. Why
would a researcher want to run a study where no one knows who is in which group? Because by doing
so, we can control for both experimenter and participant expectations. If you are familiar with the phrase
placebo effect, you already have some idea as to why this is an important consideration. The placebo effect
occurs when people’s expectations or beliefs influence or determine their experience in a given situation.
In other words, simply expecting something to happen can actually make it happen.
The placebo effect is commonly described in terms of testing the effectiveness of a new medication.
Imagine that you work in a pharmaceutical company, and you think you have a new drug that is effective
in treating depression. To demonstrate that your medication is effective, you run an experiment with two
groups: The experimental group receives the medication, and the control group does not. But you don’t
want participants to know whether they received the drug or not.
Why is that? Imagine that you are a participant in this study, and you have just taken a pill that you
think will improve your mood. Because you expect the pill to have an effect, you might feel better simply
because you took the pill and not because of any drug actually contained in the pill—this is the placebo
To make sure that any effects on mood are due to the drug and not due to expectations, the control group
receives a placebo (in this case a sugar pill). Now everyone gets a pill, and once again neither the researcher
nor the experimental participants know who got the drug and who got the sugar pill. Any differences in
mood between the experimental and control groups can now be attributed to the drug itself rather than to
experimenter bias or participant expectations (Figure 2.16).
Figure 2.16 Providing the control group with a placebo treatment protects against bias caused by expectancy.
(credit: Elaine and Arthur Shapiro)
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Independent and Dependent Variables
In a research experiment, we strive to study whether changes in one thing cause changes in another. To
achieve this, we must pay attention to two important variables, or things that can be changed, in any
experimental study: the independent variable and the dependent variable. An independent variable is
manipulated or controlled by the experimenter. In a well-designed experimental study, the independent
variable is the only important difference between the experimental and control groups. In our example
of how violent television programs affect children’s display of violent behavior, the independent variable
is the type of program—violent or nonviolent—viewed by participants in the study (Figure 2.17). A
dependent variable is what the researcher measures to see how much effect the independent variable
had. In our example, the dependent variable is the number of violent acts displayed by the experimental
Figure 2.17 In an experiment, manipulations of the independent variable are expected to result in changes in the
dependent variable. (credit “automatic weapon”: modification of work by Daniel Oines; credit “toy gun”: modification of
work by Emran Kassim)
We expect that the dependent variable will change as a function of the independent variable. In other
words, the dependent variable depends on the independent variable. A good way to think about the
relationship between the independent and dependent variables is with this question: What effect does
the independent variable have on the dependent variable? Returning to our example, what effect does
watching a half hour of violent television programming or nonviolent television programming have on the
number of incidents of physical aggression displayed on the playground?
Selecting and Assigning Experimental Participants
Now that our study is designed, we need to obtain a sample of individuals to include in our experiment.
Our study involves human participants so we need to determine who to include. Participants are the
subjects of psychological research, and as the name implies, individuals who are involved in psychological
research actively participate in the process. Often, psychological research projects rely on college students
to serve as participants. In fact, the vast majority of research in psychology subfields has historically
involved students as research participants (Sears, 1986; Arnett, 2008). But are college students truly
Chapter 2 | Psychological Research 55

representative of the general population? College students tend to be younger, more educated, more
liberal, and less diverse than the general population. Although using students as test subjects is an
accepted practice, relying on such a limited pool of research participants can be problematic because it is
difficult to generalize findings to the larger population.
Our hypothetical experiment involves children, and we must first generate a sample of child participants.
Samples are used because populations are usually too large to reasonably involve every member in
our particular experiment (Figure 2.18). If possible, we should use a random sample (there are other
types of samples, but for the purposes of this chapter, we will focus on random samples). A random
sample is a subset of a larger population in which every member of the population has an equal chance
of being selected. Random samples are preferred because if the sample is large enough we can be
reasonably sure that the participating individuals are representative of the larger population. This means
that the percentages of characteristics in the sample—sex, ethnicity, socioeconomic level, and any other
characteristics that might affect the results—are close to those percentages in the larger population.
In our example, let’s say we decide our population of interest is fourth graders. But all fourth graders
is a very large population, so we need to be more specific; instead we might say our population of
interest is all fourth graders in a particular city. We should include students from various income brackets,
family situations, races, ethnicities, religions, and geographic areas of town. With this more manageable
population, we can work with the local schools in selecting a random sample of around 200 fourth graders
who we want to participate in our experiment.
In summary, because we cannot test all of the fourth graders in a city, we want to find a group of about
200 that reflects the composition of that city. With a representative group, we can generalize our findings
to the larger population without fear of our sample being biased in some way.
Figure 2.18 Researchers may work with (a) a large population or (b) a sample group that is a subset of the larger
population. (credit “crowd”: modification of work by James Cridland; credit “students”: modification of work by Laurie
Now that we have a sample, the next step of the experimental process is to split the participants into
experimental and control groups through random assignment. With random assignment, all participants
have an equal chance of being assigned to either group. There is statistical software that will randomly
assign each of the fourth graders in the sample to either the experimental or the control group.
Random assignment is critical for sound experimental design. With sufficiently large samples, random
assignment makes it unlikely that there are systematic differences between the groups. So, for instance, it
would be very unlikely that we would get one group composed entirely of males, a given ethnic identity,
or a given religious ideology. This is important because if the groups were systematically different before
the experiment began, we would not know the origin of any differences we find between the groups: Were
the differences preexisting, or were they caused by manipulation of the independent variable? Random
assignment allows us to assume that any differences observed between experimental and control groups
result from the manipulation of the independent variable.
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Use this online tool ( to instantly generate
randomized numbers and to learn more about random sampling and assignments.
Issues to Consider
While experiments allow scientists to make cause-and-effect claims, they are not without problems. True
experiments require the experimenter to manipulate an independent variable, and that can complicate
many questions that psychologists might want to address. For instance, imagine that you want to know
what effect sex (the independent variable) has on spatial memory (the dependent variable). Although you
can certainly look for differences between males and females on a task that taps into spatial memory, you
cannot directly control a person’s sex. We categorize this type of research approach as quasi-experimental
and recognize that we cannot make cause-and-effect claims in these circumstances.
Experimenters are also limited by ethical constraints. For instance, you would not be able to conduct an
experiment designed to determine if experiencing abuse as a child leads to lower levels of self-esteem
among adults. To conduct such an experiment, you would need to randomly assign some experimental
participants to a group that receives abuse, and that experiment would be unethical.
Interpreting Experimental Findings
Once data is collected from both the experimental and the control groups, a statistical analysis is
conducted to find out if there are meaningful differences between the two groups. A statistical analysis
determines how likely any difference found is due to chance (and thus not meaningful). In psychology,
group differences are considered meaningful, or significant, if the odds that these differences occurred by
chance alone are 5 percent or less. Stated another way, if we repeated this experiment 100 times, we would
expect to find the same results at least 95 times out of 100.
The greatest strength of experiments is the ability to assert that any significant differences in the findings
are caused by the independent variable. This occurs because random selection, random assignment, and
a design that limits the effects of both experimenter bias and participant expectancy should create groups
that are similar in composition and treatment. Therefore, any difference between the groups is attributable
to the independent variable, and now we can finally make a causal statement. If we find that watching a
violent television program results in more violent behavior than watching a nonviolent program, we can
safely say that watching violent television programs causes an increase in the display of violent behavior.
Reporting Research
When psychologists complete a research project, they generally want to share their findings with other
scientists. The American Psychological Association (APA) publishes a manual detailing how to write
a paper for submission to scientific journals. Unlike an article that might be published in a magazine
like Psychology Today, which targets a general audience with an interest in psychology, scientific journals
generally publish peer-reviewed journal articles aimed at an audience of professionals and scholars who
are actively involved in research themselves.
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The Online Writing Lab (OWL) ( at Purdue
University can walk you through the APA writing guidelines.
A peer-reviewed journal article is read by several other scientists (generally anonymously) with expertise
in the subject matter. These peer reviewers provide feedback—to both the author and the journal
editor—regarding the quality of the draft. Peer reviewers look for a strong rationale for the research being
described, a clear description of how the research was conducted, and evidence that the research was
conducted in an ethical manner. They also look for flaws in the study’s design, methods, and statistical
analyses. They check that the conclusions drawn by the authors seem reasonable given the observations
made during the research. Peer reviewers also comment on how valuable the research is in advancing the
discipline’s knowledge. This helps prevent unnecessary duplication of research findings in the scientific
literature and, to some extent, ensures that each research article provides new information. Ultimately, the
journal editor will compile all of the peer reviewer feedback and determine whether the article will be
published in its current state (a rare occurrence), published with revisions, or not accepted for publication.
Peer review provides some degree of quality control for psychological research. Poorly conceived or
executed studies can be weeded out, and even well-designed research can be improved by the revisions
suggested. Peer review also ensures that the research is described clearly enough to allow other scientists
to replicate it, meaning they can repeat the experiment using different samples to determine reliability.
Sometimes replications involve additional measures that expand on the original finding. In any case,
each replication serves to provide more evidence to support the original research findings. Successful
replications of published research make scientists more apt to adopt those findings, while repeated failures
tend to cast doubt on the legitimacy of the original article and lead scientists to look elsewhere. For
example, it would be a major advancement in the medical field if a published study indicated that taking
a new drug helped individuals achieve a healthy weight without changing their diet. But if other scientists
could not replicate the results, the original study’s claims would be questioned.
The Vaccine-Autism Myth and Retraction of Published Studies
Some scientists have claimed that routine childhood vaccines cause some children to develop autism, and,
in fact, several peer-reviewed publications published research making these claims. Since the initial reports,
large-scale epidemiological research has suggested that vaccinations are not responsible for causing autism
and that it is much safer to have your child vaccinated than not. Furthermore, several of the original studies
making this claim have since been retracted.
A published piece of work can be rescinded when data is called into question because of falsification,
fabrication, or serious research design problems. Once rescinded, the scientific community is informed that
there are serious problems with the original publication. Retractions can be initiated by the researcher who
led the study, by research collaborators, by the institution that employed the researcher, or by the editorial
board of the journal in which the article was originally published. In the vaccine-autism case, the retraction
was made because of a significant conflict of interest in which the leading researcher had a financial interest
in establishing a link between childhood vaccines and autism (Offit, 2008). Unfortunately, the initial studies
received so much media attention that many parents around the world became hesitant to have their children
vaccinated (Figure 2.19). For more information about how the vaccine/autism story unfolded, as well as the
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repercussions of this story, take a look at Paul Offit’s book, Autism’s False Prophets: Bad Science, Risky
Medicine, and the Search for a Cure.
Figure 2.19 Some people still think vaccinations cause autism. (credit: modification of work by UNICEF
Reliability and validity are two important considerations that must be made with any type of data
collection. Reliability refers to the ability to consistently produce a given result. In the context of
psychological research, this would mean that any instruments or tools used to collect data do so in
consistent, reproducible ways.
Unfortunately, being consistent in measurement does not necessarily mean that you have measured
something correctly. To illustrate this concept, consider a kitchen scale that would be used to measure the
weight of cereal that you eat in the morning. If the scale is not properly calibrated, it may consistently
under- or overestimate the amount of cereal that’s being measured. While the scale is highly reliable in
producing consistent results (e.g., the same amount of cereal poured onto the scale produces the same
reading each time), those results are incorrect. This is where validity comes into play. Validity refers to
the extent to which a given instrument or tool accurately measures what it’s supposed to measure. While
any valid measure is by necessity reliable, the reverse is not necessarily true. Researchers strive to use
instruments that are both highly reliable and valid.
How Valid Is the SAT?
Standardized tests like the SAT are supposed to measure an individual’s aptitude for a college education, but
how reliable and valid are such tests? Research conducted by the College Board suggests that scores on
the SAT have high predictive validity for first-year college students’ GPA (Kobrin, Patterson, Shaw, Mattern,
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& Barbuti, 2008). In this context, predictive validity refers to the test’s ability to effectively predict the GPA of
college freshmen. Given that many institutions of higher education require the SAT for admission, this high
degree of predictive validity might be comforting.
However, the emphasis placed on SAT scores in college admissions has generated some controversy on a
number of fronts. For one, some researchers assert that the SAT is a biased test that places minority students
at a disadvantage and unfairly reduces the likelihood of being admitted into a college (Santelices & Wilson,
2010). Additionally, some research has suggested that the predictive validity of the SAT is grossly exaggerated
in how well it is able to predict the GPA of first-year college students. In fact, it has been suggested that
the SAT’s predictive validity may be overestimated by as much as 150% (Rothstein, 2004). Many institutions
of higher education are beginning to consider de-emphasizing the significance of SAT scores in making
admission decisions (Rimer, 2008).
In 2014, College Board president David Coleman expressed his awareness of these problems, recognizing
that college success is more accurately predicted by high school grades than by SAT scores. To address these
concerns, he has called for significant changes to the SAT exam (Lewin, 2014).
2.4 Ethics
Learning Objectives
By the end of this section, you will be able to:
• Discuss how research involving human subjects is regulated
• Summarize the processes of informed consent and debriefing
• Explain how research involving animal subjects is regulated
Today, scientists agree that good research is ethical in nature and is guided by a basic respect for human
dignity and safety. However, as you will read in the feature box, this has not always been the case. Modern
researchers must demonstrate that the research they perform is ethically sound. This section presents how
ethical considerations affect the design and implementation of research conducted today.
Any experiment involving the participation of human subjects is governed by extensive, strict guidelines
designed to ensure that the experiment does not result in harm. Any research institution that receives
federal support for research involving human participants must have access to an institutional review
board (IRB). The IRB is a committee of individuals often made up of members of the institution’s
administration, scientists, and community members (Figure 2.20). The purpose of the IRB is to review
proposals for research that involves human participants. The IRB reviews these proposals with the
principles mentioned above in mind, and generally, approval from the IRB is required in order for the
experiment to proceed.
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Figure 2.20 An institution’s IRB meets regularly to review experimental proposals that involve human participants.
(credit: modification of work by Lowndes Area Knowledge Exchange (LAKE)/Flickr)
An institution’s IRB requires several components in any experiment it approves. For one, each participant
must sign an informed consent form before they can participate in the experiment. An informed consent
form provides a written description of what participants can expect during the experiment, including
potential risks and implications of the research. It also lets participants know that their involvement is
completely voluntary and can be discontinued without penalty at any time. Furthermore, the informed
consent guarantees that any data collected in the experiment will remain completely confidential. In cases
where research participants are under the age of 18, the parents or legal guardians are required to sign the
informed consent form.
Visit this website ( to see an example of
a consent form.
While the informed consent form should be as honest as possible in describing exactly what participants
will be doing, sometimes deception is necessary to prevent participants’ knowledge of the exact research
question from affecting the results of the study. Deception involves purposely misleading experiment
participants in order to maintain the integrity of the experiment, but not to the point where the deception
could be considered harmful. For example, if we are interested in how our opinion of someone is affected
by their attire, we might use deception in describing the experiment to prevent that knowledge from
affecting participants’ responses. In cases where deception is involved, participants must receive a full
debriefing upon conclusion of the study—complete, honest information about the purpose of the
experiment, how the data collected will be used, the reasons why deception was necessary, and
information about how to obtain additional information about the study.
Ethics and the Tuskegee Syphilis Study
Unfortunately, the ethical guidelines that exist for research today were not always applied in the past. In 1932,
poor, rural, black, male sharecroppers from Tuskegee, Alabama, were recruited to participate in an experiment
conducted by the U.S. Public Health Service, with the aim of studying syphilis in black men (Figure 2.21). In
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exchange for free medical care, meals, and burial insurance, 600 men agreed to participate in the study. A little
more than half of the men tested positive for syphilis, and they served as the experimental group (given that
the researchers could not randomly assign participants to groups, this represents a quasi-experiment). The
remaining syphilis-free individuals served as the control group. However, those individuals that tested positive
for syphilis were never informed that they had the disease.
While there was no treatment for syphilis when the study began, by 1947 penicillin was recognized as an
effective treatment for the disease. Despite this, no penicillin was administered to the participants in this
study, and the participants were not allowed to seek treatment at any other facilities if they continued in the
study. Over the course of 40 years, many of the participants unknowingly spread syphilis to their wives (and
subsequently their children born from their wives) and eventually died because they never received treatment
for the disease. This study was discontinued in 1972 when the experiment was discovered by the national
press (Tuskegee University, n.d.). The resulting outrage over the experiment led directly to the National
Research Act of 1974 and the strict ethical guidelines for research on humans described in this chapter. Why
is this study unethical? How were the men who participated and their families harmed as a function of this
Figure 2.21 A participant in the Tuskegee Syphilis Study receives an injection.
Visit this website ( to learn more about the
Tuskegee Syphilis Study.
Many psychologists conduct research involving animal subjects. Often, these researchers use rodents
(Figure 2.22) or birds as the subjects of their experiments—the APA estimates that 90% of all animal
research in psychology uses these species (American Psychological Association, n.d.). Because many basic
processes in animals are sufficiently similar to those in humans, these animals are acceptable substitutes
for research that would be considered unethical in human participants.
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Figure 2.22 Rats, like the one shown here, often serve as the subjects of animal research.
This does not mean that animal researchers are immune to ethical concerns. Indeed, the humane and
ethical treatment of animal research subjects is a critical aspect of this type of research. Researchers must
design their experiments to minimize any pain or distress experienced by animals serving as research
Whereas IRBs review research proposals that involve human participants, animal experimental proposals
are reviewed by an Institutional Animal Care and Use Committee (IACUC). An IACUC consists of
institutional administrators, scientists, veterinarians, and community members. This committee is charged
with ensuring that all experimental proposals require the humane treatment of animal research subjects. It
also conducts semi-annual inspections of all animal facilities to ensure that the research protocols are being
followed. No animal research project can proceed without the committee’s approval.
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archival research
cause-and-effect relationship
clinical or case study
confirmation bias
confounding variable
control group
correlation coefficient
cross-sectional research
deductive reasoning
dependent variable
double-blind study
experimental group
experimenter bias
Key Terms
method of research using past records or data sets to answer various research
questions, or to search for interesting patterns or relationships
reduction in number of research participants as some drop out of the study over time
changes in one variable cause the changes in the other variable; can be
determined only through an experimental research design
observational research study focusing on one or a few people
tendency to ignore evidence that disproves ideas or beliefs
unanticipated outside factor that affects both variables of interest, often giving the
false impression that changes in one variable causes changes in the other variable, when, in actuality, the
outside factor causes changes in both variables
serves as a basis for comparison and controls for chance factors that might influence the
results of the study—by holding such factors constant across groups so that the experimental
manipulation is the only difference between groups
relationship between two or more variables; when two variables are correlated, one variable
changes as the other does
number from -1 to +1, indicating the strength and direction of the relationship
between variables, and usually represented by r
compares multiple segments of a population at a single time
when an experiment involved deception, participants are told complete and truthful
information about the experiment at its conclusion
purposely misleading experiment participants in order to maintain the integrity of the
results are predicted based on a general premise
variable that the researcher measures to see how much effect the independent
variable had
experiment in which both the researchers and the participants are blind to group
grounded in objective, tangible evidence that can be observed time and time again, regardless
of who is observing
group designed to answer the research question; experimental manipulation is the
only difference between the experimental and control groups, so any differences between the two are due
to experimental manipulation rather than chance
researcher expectations skew the results of the study
objective and verifiable observation, established using evidence collected through empirical research
able to be disproven by experimental results
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illusory correlation
independent variable
inductive reasoning
informed consent
Institutional Animal Care and Use Committee (IACUC)
Institutional Review Board (IRB)
inter-rater reliability
longitudinal research
naturalistic observation
negative correlation
observer bias
operational definition
peer-reviewed journal article
placebo effect
positive correlation
random assignment
inferring that the results for a sample apply to the larger population
(plural: hypotheses) tentative and testable statement about the relationship between two or
more variables
seeing relationships between two things when in reality no such relationship exists
variable that is influenced or controlled by the experimenter; in a sound
experimental study, the independent variable is the only important difference between the experimental
and control group
conclusions are drawn from observations
process of informing a research participant about what to expect during an
experiment, any risks involved, and the implications of the research, and then obtaining the person’s
consent to participate
committee of administrators, scientists,
veterinarians, and community members that reviews proposals for research involving non-human
committee of administrators, scientists, and community members that
reviews proposals for research involving human participants
measure of agreement among observers on how they record and classify a
particular event
studies in which the same group of individuals is surveyed or measured
repeatedly over an extended period of time
observation of behavior in its natural setting
two variables change in different directions, with one becoming larger as the other
becomes smaller; a negative correlation is not the same thing as no correlation
when observations may be skewed to align with observer expectations
description of what actions and operations will be used to measure the dependent
variables and manipulate the independent variables
personal judgments, conclusions, or attitudes that may or may not be accurate
subjects of psychological research
article read by several other scientists (usually anonymously) with
expertise in the subject matter, who provide feedback regarding the quality of the manuscript before it is
accepted for publication
people’s expectations or beliefs influencing or determining their experience in a given
overall group of individuals that the researchers are interested in
two variables change in the same direction, both becoming either larger or smaller
method of experimental group assignment in which all participants have an equal
chance of being assigned to either group
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random sample
single-blind study
statistical analysis
subset of a larger population in which every member of the population has an equal
chance of being selected
consistency and reproducibility of a given result
repeating an experiment using different samples to determine the research’s reliability
subset of individuals selected from the larger population
experiment in which the researcher knows which participants are in the experimental
group and which are in the control group
determines how likely any difference between experimental groups is due to chance
list of questions to be answered by research participants—given as paper-and-pencil
questionnaires, administered electronically, or conducted verbally—allowing researchers to collect data
from a large number of people
well-developed set of ideas that propose an explanation for observed phenomena
accuracy of a given result in measuring what it is designed to measure
2.1 Why Is Research Important?
Scientists are engaged in explaining and understanding how the world around them works, and they are
able to do so by coming up with theories that generate hypotheses that are testable and falsifiable. Theories
that stand up to their tests are retained and refined, while those that do not are discarded or modified.
In this way, research enables scientists to separate fact from simple opinion. Having good information
generated from research aids in making wise decisions both in public policy and in our personal lives.
2.2 Approaches to Research
The clinical or case study involves studying just a few individuals for an extended period of time. While
this approach provides an incredible depth of information, the ability to generalize these observations to
the larger population is problematic. Naturalistic observation involves observing behavior in a natural
setting and allows for the collection of valid, true-to-life information from realistic situations. However,
naturalistic observation does not allow for much control and often requires quite a bit of time and money
to perform. Researchers strive to ensure that their tools for collecting data are both reliable (consistent and
replicable) and valid (accurate).
Surveys can be administered in a number of ways and make it possible to collect large amounts of data
quickly. However, the depth of information that can be collected through surveys is somewhat limited
compared to a clinical or case study.
Archival research involves studying existing data sets to answer research questions.
Longitudinal research has been incredibly helpful to researchers who need to collect data on how people
change over time. Cross-sectional research compares multiple segments of a population at a single time.
2.3 Analyzing Findings
A correlation is described with a correlation coefficient, r, which ranges from -1 to 1. The correlation
coefficient tells us about the nature (positive or negative) and the strength of the relationship between
two or more variables. Correlations do not tell us anything about causation—regardless of how strong
the relationship is between variables. In fact, the only way to demonstrate causation is by conducting an
experiment. People often make the mistake of claiming that correlations exist when they really do not.
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Researchers can test cause-and-effect hypotheses by conducting experiments. Ideally, experimental
participants are randomly selected from the population of interest. Then, the participants are randomly
assigned to their respective groups. Sometimes, the researcher and the participants are blind to group
membership to prevent their expectations from influencing the results.
In ideal experimental design, the only difference between the experimental and control groups is whether
participants are exposed to the experimental manipulation. Each group goes through all phases of the
experiment, but each group will experience a different level of the independent variable: the experimental
group is exposed to the experimental manipulation, and the control group is not exposed to the
experimental manipulation. The researcher then measures the changes that are produced in the dependent
variable in each group. Once data is collected from both groups, it is analyzed statistically to determine if
there are meaningful differences between the groups.
Psychologists report their research findings in peer-reviewed journal articles. Research published in this
format is checked by several other psychologists who serve as a filter separating ideas that are supported
by evidence from ideas that are not. Replication has an important role in ensuring the legitimacy of
published research. In the long run, only those findings that are capable of being replicated consistently
will achieve consensus in the scientific community.
2.4 Ethics
Ethics in research is an evolving field, and some practices that were accepted or tolerated in the past
would be considered unethical today. Researchers are expected to adhere to basic ethical guidelines when
conducting experiments that involve human participants. Any experiment involving human participants
must be approved by an IRB. Participation in experiments is voluntary and requires informed consent of
the participants. If any deception is involved in the experiment, each participant must be fully debriefed
upon the conclusion of the study.
Animal research is also held to a high ethical standard. Researchers who use animals as experimental
subjects must design their projects so that pain and distress are minimized. Animal research requires the
approval of an IACUC, and all animal facilities are subject to regular inspections to ensure that animals are
being treated humanely.
Review Questions
1. Scientific hypotheses are ________ and
a. observable
b. original
c. provable
d. testable
2. ________ are defined as observable realities.
a. behaviors
b. facts
c. opinions
d. theories
3. Scientific knowledge is ________.
a. intuitive
b. empirical
c. permanent
d. subjective
4. A major criticism of Freud’s early theories
involves the fact that his theories ________.
a. were too limited in scope
b. were too outrageous
c. were too broad
d. were not testable
5. Sigmund Freud developed his theory of
human personality by conducting in-depth
interviews over an extended period of time with a
few clients. This type of research approach is
known as a(n): ________.
a. archival research
b. case study
c. naturalistic observation
d. survey
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6. ________ involves observing behavior in
individuals in their natural environments.
a. archival research
b. case study
c. naturalistic observation
d. survey
7. The major limitation of case studies is
a. the superficial nature of the information
collected in this approach
b. the lack of control that the researcher has in
this approach
c. the inability to generalize the findings from
this approach to the larger population
d. the absence of inter-rater reliability
8. The benefit of naturalistic observation studies
is ________.
a. the honesty of the data that is collected in a
realistic setting
b. how quick and easy these studies are to
c. the researcher’s capacity to make sure that
data is collected as efficiently as possible
d. the ability to determine cause and effect in
this particular approach
9. Using existing records to try to answer a
research question is known as ________.
a. naturalistic observation
b. survey research
c. longitudinal research
d. archival research
10. ________ involves following a group of
research participants for an extended period of
a. archival research
b. longitudinal research
c. naturalistic observation
d. cross-sectional research
11. A(n) ________ is a list of questions developed
by a researcher that can be administered in paper
a. archive
b. case Study
c. naturalistic observation
d. survey
12. Longitudinal research is complicated by high
rates of ________.
a. deception
b. observation
c. attrition
d. generalization
13. Height and weight are positively correlated.
This means that:
a. There is no relationship between height and
b. Usually, the taller someone is, the thinner
they are.
c. Usually, the shorter someone is, the heavier
they are.
d. As height increases, typically weight
14. Which of the following correlation coefficients
indicates the strongest relationship between two
a. -.90
b. -.50
c. +.80
d. +.25
15. Which statement best illustrates a negative
correlation between the number of hours spent
watching TV the week before an exam and the
grade on that exam?
a. Watching too much television leads to poor
exam performance.
b. Smart students watch less television.
c. Viewing television interferes with a
student’s ability to prepare for the
upcoming exam.
d. Students who watch more television
perform more poorly on their exams.
16. The correlation coefficient indicates the
weakest relationship when ________.
a. it is closest to 0
b. it is closest to -1
c. it is positive
d. it is negative
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17. ________ means that everyone in the
population has the same likelihood of being asked
to participate in the study.
a. operationalizing
b. placebo effect
c. random assignment
d. random sampling
18. The ________ is controlled by the
experimenter, while the ________ represents the
information collected and statistically analyzed by
the experimenter.
a. dependent variable; independent variable
b. independent variable; dependent variable
c. placebo effect; experimenter bias
d. experiment bias; placebo effect
19. Researchers must ________ important
concepts in their studies so others would have a
clear understanding of exactly how those concepts
were defined.
a. randomly assign
b. randomly select
c. operationalize
d. generalize
20. Sometimes, researchers will administer a(n)
________ to participants in the control group to
control for the effects that participant expectation
might have on the experiment.
a. dependent variable
b. independent variable
c. statistical analysis
d. placebo
21. ________ is to animal research as ________ is
to human research.
a. informed consent; deception
d. deception; debriefing
22. Researchers might use ________ when
providing participants with the full details of the
experiment could skew their responses.
a. informed consent
b. deception
c. ethics
d. debriefing
23. A person’s participation in a research project
must be ________.
a. confidential
b. rewarded
c. voluntary
d. public
24. Before participating in an experiment,
individuals should read and sign the ________
a. informed consent
b. debriefing
c. IRB
d. ethics
Critical Thinking Questions
25. In this section, the D.A.R.E. program was described as an incredibly popular program in schools
across the United States despite the fact that research consistently suggests that this program is largely
ineffective. How might one explain this discrepancy?
26. The scientific method is often described as self-correcting and cyclical. Briefly describe your
understanding of the scientific method with regard to these concepts.
27. In this section, conjoined twins, Krista and Tatiana, were described as being potential participants in a
case study. In what other circumstances would you think that this particular research approach would be
especially helpful and why?
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28. Presumably, reality television programs aim to provide a realistic portrayal of the behavior displayed
by the characters featured in such programs. This section pointed out why this is not really the case. What
changes could be made in the way that these programs are produced that would result in more honest
portrayals of realistic behavior?
29. Which of the research methods discussed in this section would be best suited to research the
effectiveness of the D.A.R.E. program in preventing the use of alcohol and other drugs? Why?
30. Aside from biomedical research, what other areas of research could greatly benefit by both
longitudinal and archival research?
31. Earlier in this section, we read about research suggesting that there is a correlation between eating
cereal and weight. Cereal companies that present this information in their advertisements could lead
someone to believe that eating more cereal causes healthy weight. Why would they make such a claim and
what arguments could you make to counter this cause-and-effect claim?
32. Recently a study was published in the journal, Nutrition and Cancer, which established a negative
correlation between coffee consumption and breast cancer. Specifically, it was found that women
consuming more than 5 cups of coffee a day were less likely to develop breast cancer than women who
never consumed coffee (Lowcock, Cotterchio, Anderson, Boucher, & El-Sohemy, 2013). Imagine you see
a newspaper story about this research that says, “Coffee Protects Against Cancer.” Why is this headline
misleading and why would a more accurate headline draw less interest?
33. Sometimes, true random sampling can be very difficult to obtain. Many researchers make use of
convenience samples as an alternative. For example, one popular convenience sample would involve
students enrolled in Introduction to Psychology courses. What are the implications of using this sampling
34. Peer review is an important part of publishing research findings in many scientific disciplines. This
process is normally conducted anonymously; in other words, the author of the article being reviewed does
not know who is reviewing the article, and the reviewers are unaware of the author’s identity. Why would
this be an important part of this process?
35. Some argue that animal research is inherently flawed in terms of being ethical because unlike human
participants, animals do not consent to be involved in research. Do you agree with this perspective? Given
that animals do not consent to be involved in research projects, what sorts of extra precautions should be
taken to ensure that they receive the most humane treatment possible?
36. At the end of the last section, you were asked to design a basic experiment to answer some question
of interest. What ethical considerations should be made with the study you proposed to ensure that your
experiment would conform to the scientific community’s expectations of ethical research?
Personal Application Questions
37. Healthcare professionals cite an enormous number of health problems related to obesity, and many
people have an understandable desire to attain a healthy weight. There are many diet programs, services,
and products on the market to aid those who wish to lose weight. If a close friend was considering
purchasing or participating in one of these products, programs, or services, how would you make sure
your friend was fully aware of the potential consequences of this decision? What sort of information would
you want to review before making such an investment or lifestyle change yourself?
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38. A friend of yours is working part-time in a local pet store. Your friend has become increasingly
interested in how dogs normally communicate and interact with each other, and is thinking of visiting a
local veterinary clinic to see how dogs interact in the waiting room. After reading this section, do you think
this is the best way to better understand such interactions? Do you have any suggestions that might result
in more valid data?
39. As a college student, you are no doubt concerned about the grades that you earn while completing
your coursework. If you wanted to know how overall GPA is related to success in life after college, how
would you choose to approach this question and what kind of resources would you need to conduct this
40. We all have a tendency to make illusory correlations from time to time. Try to think of an illusory
correlation that is held by you, a family member, or a close friend. How do you think this illusory
correlation came about and what can be done in the future to combat them?
41. Are there any questions about human or animal behavior that you would really like to answer?
Generate a hypothesis and briefly describe how you would conduct an experiment to answer your
42. Take a few minutes to think about all of the advancements that our society has achieved as a function
of research involving animal subjects. How have you, a friend, or a family member benefited directly from
this kind of research?
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Chapter 3
Figure 3.1 Different brain imaging techniques provide scientists with insight into different aspects of how the human
brain functions. Left to right, PET scan (positron emission tomography), CT scan (computed tomography), and fMRI
(functional magnetic resonance imaging) are three types of scans. (credit “left”: modification of work by Health and
Human Services Department, National Institutes of Health; credit “center”: modification of work by
“Aceofhearts1968″/Wikimedia Commons; credit “right”: modification of work by Kim J, Matthews NL, Park S.)
Chapter Outline
3.1 Human Genetics
3.2 Cells of the Nervous System
3.3 Parts of the Nervous System
3.4 The Brain and Spinal Cord
3.5 The Endocrine System
Have you ever taken a device apart to find out how it works? Many of us have done so, whether to attempt
a repair or simply to satisfy our curiosity. A device’s internal workings are often distinct from its user
interface on the outside. For example, we don’t think about microchips and circuits when we turn up
the volume on a mobile phone; instead, we think about getting the volume just right. Similarly, the inner
workings of the human body are often distinct from the external expression of those workings. It is the
job of psychologists to find the connection between these—for example, to figure out how the firings of
millions of neurons become a thought.
This chapter strives to explain the biological mechanisms that underlie behavior. These physiological and
anatomical foundations are the basis for many areas of psychology. In this chapter, you will learn how
genetics influence both physiological and psychological traits. You will become familiar with the structure
and function of the nervous system. And, finally, you will learn how the nervous system interacts with the
endocrine system.
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3.1 Human Genetics
Learning Objectives
By the end of this section, you will be able to:
• Explain the basic principles of the theory of evolution by natural selection
• Describe the differences between genotype and phenotype
• Discuss how gene-environment interactions are critical for expression of physical and
psychological characteristics
Psychological researchers study genetics in order to better understand the biological basis that contributes
to certain behaviors. While all humans share certain biological mechanisms, we are each unique. And
while our bodies have many of the same parts—brains and hormones and cells with genetic codes—these
are expressed in a wide variety of behaviors, thoughts, and reactions.
Why do two people infected by the same disease have different outcomes: one surviving and one
succumbing to the ailment? How are genetic diseases passed through family lines? Are there genetic
components to psychological disorders, such as depression or schizophrenia? To what extent might there
be a psychological basis to health conditions such as childhood obesity?
To explore these questions, let’s start by focusing on a specific disease, sickle-cell anemia, and how it might
affect two infected sisters. Sickle-cell anemia is a genetic condition in which red blood cells, which are
normally round, take on a crescent-like shape (Figure 3.2). The changed shape of these cells affects how
they function: sickle-shaped cells can clog blood vessels and block blood flow, leading to high fever, severe
pain, swelling, and tissue damage.
Figure 3.2 Normal blood cells travel freely through the blood vessels, while sickle-shaped cells form blockages
preventing blood flow.
Many people with sickle-cell anemia—and the particular genetic mutation that causes it—die at an early
age. While the notion of “survival of the fittest” may suggest that people suffering from this disease have
a low survival rate and therefore the disease will become less common, this is not the case. Despite the
negative evolutionary effects associated with this genetic mutation, the sickle-cell gene remains relatively
common among people of African descent. Why is this? The explanation is illustrated with the following
Imagine two young women—Luwi and Sena—sisters in rural Zambia, Africa. Luwi carries the gene for
sickle-cell anemia; Sena does not carry the gene. Sickle-cell carriers have one copy of the sickle-cell gene but
do not have full-blown sickle-cell anemia. They experience symptoms only if they are severely dehydrated
or are deprived of oxygen (as in mountain climbing). Carriers are thought to be immune from malaria
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(an often deadly disease that is widespread in tropical climates) because changes in their blood chemistry
and immune functioning prevent the malaria parasite from having its effects (Gong, Parikh, Rosenthal, &
Greenhouse, 2013). However, full-blown sickle-cell anemia, with two copies of the sickle-cell gene, does
not provide immunity to malaria.
While walking home from school, both sisters are bitten by mosquitos carrying the malaria parasite. Luwi
does not get malaria because she carries the sickle-cell mutation. Sena, on the other hand, develops malaria
and dies just two weeks later. Luwi survives and eventually has children, to whom she may pass on the
sickle-cell mutation.
Visit this website ( to learn more about how a
mutation in DNA leads to sickle-cell anemia.
Malaria is rare in the United States, so the sickle-cell gene benefits nobody: the gene manifests primarily in
health problems—minor in carriers, severe in the full-blown disease—with no health benefits for carriers.
However, the situation is quite different in other parts of the world. In parts of Africa where malaria
is prevalent, having the sickle-cell mutation does provide health benefits for carriers (protection from
This is precisely the situation that Charles Darwin describes in the theory of evolution by natural
selection (Figure 3.3). In simple terms, the theory states that organisms that are better suited for their
environment will survive and reproduce, while those that are poorly suited for their environment will
die off. In our example, we can see that as a carrier, Luwi’s mutation is highly adaptive in her African
homeland; however, if she resided in the United States (where malaria is much less common), her mutation
could prove costly—with a high probability of the disease in her descendants and minor health problems
of her own.
Figure 3.3 (a) In 1859, Charles Darwin proposed his theory of evolution by natural selection in his book, On the
Origin of Species. (b) The book contains just one illustration: this diagram that shows how species evolve over time
through natural selection.
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Two Perspectives on Genetics and Behavior
It’s easy to get confused about two fields that study the interaction of genes and the environment, such as the
fields of evolutionary psychology and behavioral genetics. How can we tell them apart?
In both fields, it is understood that genes not only code for particular traits, but also contribute to certain
patterns of cognition and behavior. Evolutionary psychology focuses on how universal patterns of behavior
and cognitive processes have evolved over time. Therefore, variations in cognition and behavior would make
individuals more or less successful in reproducing and passing those genes to their offspring. Evolutionary
psychologists study a variety of psychological phenomena that may have evolved as adaptations, including
fear response, food preferences, mate selection, and cooperative behaviors (Confer et al., 2010).
Whereas evolutionary psychologists focus on universal patterns that evolved over millions of years, behavioral
geneticists study how individual differences arise, in the present, through the interaction of genes and the
environment. When studying human behavior, behavioral geneticists often employ twin and adoption studies
to research questions of interest. Twin studies compare the rates that a given behavioral trait is shared
among identical and fraternal twins; adoption studies compare those rates among biologically related relatives
and adopted relatives. Both approaches provide some insight into the relative importance of genes and
environment for the expression of a given trait.
Watch this interview ( with renowned
evolutionary psychologist Davis Buss for an explanation of how a psychologist
approaches evolution and how this approach fits within the field of social science.
Genetic variation, the genetic difference between individuals, is what contributes to a species’ adaptation
to its environment. In humans, genetic variation begins with an egg, about 100 million sperm, and
fertilization. Fertile women ovulate roughly once per month, releasing an egg from follicles in the ovary.
During the egg’s journey from the ovary through the fallopian tubes, to the uterus, a sperm may fertilize
an egg.
The egg and the sperm each contain 23 chromosomes. Chromosomes are long strings of genetic material
known as deoxyribonucleic acid (DNA). DNA is a helix-shaped molecule made up of nucleotide base
pairs. In each chromosome, sequences of DNA make up genes that control or partially control a number
of visible characteristics, known as traits, such as eye color, hair color, and so on. A single gene may have
multiple possible variations, or alleles. An allele is a specific version of a gene. So, a given gene may code
for the trait of hair color, and the different alleles of that gene affect which hair color an individual has.
When a sperm and egg fuse, their 23 chromosomes pair up and create a zygote with 23 pairs of
chromosomes. Therefore, each parent contributes half the genetic information carried by the offspring; the
resulting physical characteristics of the offspring (called the phenotype) are determined by the interaction
of genetic material supplied by the parents (called the genotype). A person’s genotype is the genetic
makeup of that individual. Phenotype, on the other hand, refers to the individual’s inherited physical
characteristics, which are a combination of genetic and environmental influences (Figure 3.4).
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Figure 3.4 (a) Genotype refers to the genetic makeup of an individual based on the genetic material (DNA) inherited
from one’s parents. (b) Phenotype describes an individual’s observable characteristics, such as hair color, skin color,
height, and build. (credit a: modification of work by Caroline Davis; credit b: modification of work by Cory Zanker)
Most traits are controlled by multiple genes, but some traits are controlled by one gene. A characteristic
like cleft chin, for example, is influenced by a single gene from each parent. In this example, we will call
the gene for cleft chin “B,” and the gene for smooth chin “b.” Cleft chin is a dominant trait, which means
that having the dominant allele either from one parent (Bb) or both parents (BB) will always result in the
phenotype associated with the dominant allele. When someone has two copies of the same allele, they are
said to be homozygous for that allele. When someone has a combination of alleles for a given gene, they
are said to be heterozygous. For example, smooth chin is a recessive trait, which means that an individual
will only display the smooth chin phenotype if they are homozygous for that recessive allele (bb).
Imagine that a woman with a cleft chin mates with a man with a smooth chin. What type of chin will their
child have? The answer to that depends on which alleles each parent carries. If the woman is homozygous
for cleft chin (BB), her offspring will always have cleft chin. It gets a little more complicated, however, if
the mother is heterozygous for this gene (Bb). Since the father has a smooth chin—therefore homozygous
for the recessive allele (bb)—we can expect the offspring to have a 50% chance of having a cleft chin and a
50% chance of having a smooth chin (Figure 3.5).
Figure 3.5 (a) A Punnett square is a tool used to predict how genes will interact in the production of offspring. The
capital B represents the dominant allele, and the lowercase b represents the recessive allele. In the example of the
cleft chin, where B is cleft chin (dominant allele), wherever a pair contains the dominant allele, B, you can expect a
cleft chin phenotype. You can expect a smooth chin phenotype only when there are two copies of the recessive allele,
bb. (b) A cleft chin, shown here, is an inherited trait.
Sickle-cell anemia is just one of many genetic disorders caused by the pairing of two recessive genes.
For example, phenylketonuria (PKU) is a condition in which individuals lack an enzyme that normally
converts harmful amino acids into harmless byproducts. If someone with this condition goes untreated,
he or she will experience significant deficits in cognitive function, seizures, and increased risk of various
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psychiatric disorders. Because PKU is a recessive trait, each parent must have at least one copy of the
recessive allele in order to produce a child with the condition (Figure 3.6).
So far, we have discussed traits that involve just one gene, but few human characteristics are controlled
by a single gene. Most traits are polygenic: controlled by more than one gene. Height is one example of a
polygenic trait, as are skin color and weight.
Figure 3.6 In this Punnett square, N represents the normal allele, and p represents the recessive allele that is
associated with PKU. If two individuals mate who are both heterozygous for the allele associated with PKU, their
offspring have a 25% chance of expressing the PKU phenotype.
Where do harmful genes that contribute to diseases like PKU come from? Gene mutations provide one
source of harmful genes. A mutation is a sudden, permanent change in a gene. While many mutations can
be harmful or lethal, once in a while, a mutation benefits an individual by giving that person an advantage
over those who do not have the mutation. Recall that the theory of evolution asserts that individuals best
adapted to their particular environments are more likely to reproduce and pass on their genes to future
generations. In order for this process to occur, there must be competition—more technically, there must
be variability in genes (and resultant traits) that allow for variation in adaptability to the environment.
If a population consisted of identical individuals, then any dramatic changes in the environment would
affect everyone in the same way, and there would be no variation in selection. In contrast, diversity in
genes and associated traits allows some individuals to perform slightly better than others when faced with
environmental change. This creates a distinct advantage for individuals best suited for their environments
in terms of successful reproduction and genetic transmission.
Genes do not exist in a vacuum. Although we are all biological organisms, we also exist in an environment
that is incredibly important in determining not only when and how our genes express themselves, but
also in what combination. Each of us represents a unique interaction between our genetic makeup and our
environment; range of reaction is one way to describe this interaction. Range of reaction asserts that our
genes set the boundaries within which we can operate, and our environment interacts with the genes to
determine where in that range we will fall. For example, if an individual’s genetic makeup predisposes her
to high levels of intellectual potential and she is reared in a rich, stimulating environment, then she will be
more likely to achieve her full potential than if she were raised under conditions of significant deprivation.
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According to the concept of range of reaction, genes set definite limits on potential, and environment
determines how much of that potential is achieved. Some disagree with this theory and argue that genes
do not set a limit on a person’s potential.
Another perspective on the interaction between genes and the environment is the concept of genetic
environmental correlation. Stated simply, our genes influence our environment, and our environment
influences the expression of our genes (Figure 3.7). Not only do our genes and environment interact,
as in range of reaction, but they also influence one another bidirectionally. For example, the child of an
NBA player would probably be exposed to basketball from an early age. Such exposure might allow the
child to realize his or her full genetic, athletic potential. Thus, the parents’ genes, which the child shares,
influence the child’s environment, and that environment, in turn, is well suited to support the child’s
genetic potential.
Figure 3.7 Nature and nurture work together like complex pieces of a human puzzle. The interaction of our
environment and genes makes us the individuals we are. (credit “puzzle”: modification of work by Cory Zanker; credit
“houses”: modification of work by Ben Salter; credit “DNA”: modification of work by NHGRI)
In another approach to gene-environment interactions, the field of epigenetics looks beyond the genotype
itself and studies how the same genotype can be expressed in different ways. In other words, researchers
study how the same genotype can lead to very different phenotypes. As mentioned earlier, gene
expression is often influenced by environmental context in ways that are not entirely obvious. For instance,
identical twins share the same genetic information (identical twins develop from a single fertilized egg
that split, so the genetic material is exactly the same in each; in contrast, fraternal twins develop from two
different eggs fertilized by different sperm, so the genetic material varies as with non-twin siblings). But
even with identical genes, there remains an incredible amount of variability in how gene expression can
unfold over the course of each twin’s life. Sometimes, one twin will develop a disease and the other will
not. In one example, Tiffany, an identical twin, died from cancer at age 7, but her twin, now 19 years old,
has never had cancer. Although these individuals share an identical genotype, their phenotypes differ as a
result of how that genetic information is expressed over time. The epigenetic perspective is very different
from range of reaction, because here the genotype is not fixed and limited.
Visit this site ( for an engaging video
primer on the epigenetics of twin studies.
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Genes affect more than our physical characteristics. Indeed, scientists have found genetic linkages to
a number of behavioral characteristics, ranging from basic personality traits to sexual orientation to
spirituality (for examples, see Mustanski et al., 2005; Comings, Gonzales, Saucier, Johnson, & MacMurray,
2000). Genes are also associated with temperament and a number of psychological disorders, such as
depression and schizophrenia. So while it is true that genes provide the biological blueprints for our cells,
tissues, organs, and body, they also have significant impact on our experiences and our behaviors.
Let’s look at the following findings regarding schizophrenia in light of our three views of gene-
environment interactions. Which view do you think best explains this evidence?
In a study of people who were given up for adoption, adoptees whose biological mothers had
schizophrenia and who had been raised in a disturbed family environment were much more likely to
develop schizophrenia or another psychotic disorder than were any of the other groups in the study:
• Of adoptees whose biological mothers had schizophrenia (high genetic risk) and who were raised
in disturbed family environments, 36.8% were likely to develop schizophrenia.
• Of adoptees whose biological mothers had schizophrenia (high genetic risk) and who were raised
in healthy family environments, 5.8% were likely to develop schizophrenia.
• Of adoptees with a low genetic risk (whose mothers did not have schizophrenia) and who were
raised in disturbed family environments, 5.3% were likely to develop schizophrenia.
• Of adoptees with a low genetic risk (whose mothers did not have schizophrenia) and who were
raised in healthy family environments, 4.8% were likely to develop schizophrenia (Tienari et al.,
The study shows that adoptees with high genetic risk were especially likely to develop schizophrenia only
if they were raised in disturbed home environments. This research lends credibility to the notion that both
genetic vulnerability and environmental stress are necessary for schizophrenia to develop, and that genes
alone do not tell the full tale.
3.2 Cells of the Nervous System
Learning Objectives
By the end of this section, you will be able to:
• Identify the basic parts of a neuron
• Describe how neurons communicate with each other
• Explain how drugs act as agonists or antagonists for a given neurotransmitter system
Psychologists striving to understand the human mind may study the nervous system. Learning how
the cells and organs (like the brain) function, help us understand the biological basis behind human
psychology. The nervous system is composed of two basic cell types: glial cells (also known as glia) and
neurons. Glial cells, which outnumber neurons ten to one, are traditionally thought to play a supportive
role to neurons, both physically and metabolically. Glial cells provide scaffolding on which the nervous
system is built, help neurons line up closely with each other to allow neuronal communication, provide
insulation to neurons, transport nutrients and waste products, and mediate immune responses. Neurons,
on the other hand, serve as interconnected information processors that are essential for all of the tasks of
the nervous system. This section briefly describes the structure and function of neurons.
Neurons are the central building blocks of the nervous system, 100 billion strong at birth. Like all cells,
neurons consist of several different parts, each serving a specialized function (Figure 3.8). A neuron’s
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outer surface is made up of a semipermeable membrane. This membrane allows smaller molecules
and molecules without an electrical charge to pass through it, while stopping larger or highly charged
Figure 3.8 This illustration shows a prototypical neuron, which is being myelinated.
The nucleus of the neuron is located in the soma, or cell body. The soma has branching extensions known
as dendrites. The neuron is a small information processor, and dendrites serve as input sites where signals
are received from other neurons. These signals are transmitted electrically across the soma and down a
major extension from the soma known as the axon, which ends at multiple terminal buttons. The terminal
buttons contain synaptic vesicles that house neurotransmitters, the chemical messengers of the nervous
Axons range in length from a fraction of an inch to several feet. In some axons, glial cells form a fatty
substance known as the myelin sheath, which coats the axon and acts as an insulator, increasing the
speed at which the signal travels. The myelin sheath is crucial for the normal operation of the neurons
within the nervous system: the loss of the insulation it provides can be detrimental to normal function. To
understand how this works, let’s consider an example. Multiple sclerosis (MS), an autoimmune disorder,
involves a large-scale loss of the myelin sheath on axons throughout the nervous system. The resulting
interference in the electrical signal prevents the quick transmittal of information by neurons and can lead
to a number of symptoms, such as dizziness, fatigue, loss of motor control, and sexual dysfunction. While
some treatments may help to modify the course of the disease and manage certain symptoms, there is
currently no known cure for multiple sclerosis.
In healthy individuals, the neuronal signal moves rapidly down the axon to the terminal buttons, where
synaptic vesicles release neurotransmitters into the synapse (Figure 3.9). The synapse is a very small
space between two neurons and is an important site where communication between neurons occurs.
Once neurotransmitters are released into the synapse, they travel across the small space and bind with
corresponding receptors on the dendrite of an adjacent neuron. Receptors, proteins on the cell surface
where neurotransmitters attach, vary in shape, with different shapes “matching” different
How does a neurotransmitter “know” which receptor to bind to? The neurotransmitter and the receptor
have what is referred to as a lock-and-key relationship—specific neurotransmitters fit specific receptors
similar to how a key fits a lock. The neurotransmitter binds to any receptor that it fits.
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Figure 3.9 (a) The synapse is the space between the terminal button of one neuron and the dendrite of another
neuron. (b) In this pseudo-colored image from a scanning electron microscope, a terminal button (green) has been
opened to reveal the synaptic vesicles (orange and blue) inside. Each vesicle contains about 10,000 neurotransmitter
molecules. (credit b: modification of work by Tina Carvalho, NIH-NIGMS; scale-bar data from Matt Russell)
Now that we have learned about the basic structures of the neuron and the role that these structures play
in neuronal communication, let’s take a closer look at the signal itself—how it moves through the neuron
and then jumps to the next neuron, where the process is repeated.
We begin at the neuronal membrane. The neuron exists in a fluid environment—it is surrounded by
extracellular fluid and contains intracellular fluid (i.e., cytoplasm). The neuronal membrane keeps these
two fluids separate—a critical role because the electrical signal that passes through the neuron depends
on the intra- and extracellular fluids being electrically different. This difference in charge across the
membrane, called the membrane potential, provides energy for the signal.
The electrical charge of the fluids is caused by charged molecules (ions) dissolved in the fluid. The
semipermeable nature of the neuronal membrane somewhat restricts the movement of these charged
molecules, and, as a result, some of the charged particles tend to become more concentrated either inside
or outside the cell.
Between signals, the neuron membrane’s potential is held in a state of readiness, called the resting
potential. Like a rubber band stretched out and waiting to spring into action, ions line up on either side
of the cell membrane, ready to rush across the membrane when the neuron goes active and the membrane
opens its gates (i.e., a sodium-potassium pump that allows movement of ions across the membrane). Ions
in high-concentration areas are ready to move to low-concentration areas, and positive ions are ready to
move to areas with a negative charge.
In the resting state, sodium (Na+) is at higher concentrations outside the cell, so it will tend to move into
the cell. Potassium (K+), on the other hand, is more concentrated inside the cell, and will tend to move out
of the cell (Figure 3.10). In addition, the inside of the cell is slightly negatively charged compared to the
outside. This provides an additional force on sodium, causing it to move into the cell.
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Figure 3.10 At resting potential, Na+ (blue pentagons) is more highly concentrated outside the cell in the
extracellular fluid (shown in blue), whereas K+ (purple squares) is more highly concentrated near the membrane in
the cytoplasm or intracellular fluid. Other molecules, such as chloride ions (yellow circles) and negatively charged
proteins (brown squares), help contribute to a positive net charge in the extracellular fluid and a negative net charge
in the intracellular fluid.
From this resting potential state, the neuron receives a signal and its state changes abruptly (Figure
3.11). When a neuron receives signals at the dendrites—due to neurotransmitters from an adjacent neuron
binding to its receptors—small pores, or gates, open on the neuronal membrane, allowing Na+ ions,
propelled by both charge and concentration differences, to move into the cell. With this influx of positive
ions, the internal charge of the cell becomes more positive. If that charge reaches a certain level, called the
threshold of excitation, the neuron becomes active and the action potential begins.
Many additional pores open, causing a massive influx of Na+ ions and a huge positive spike in the
membrane potential, the peak action potential. At the peak of the spike, the sodium gates close and the
potassium gates open. As positively charged potassium ions leave, the cell quickly begins repolarization.
At first, it hyperpolarizes, becoming slightly more negative than the resting potential, and then it levels
off, returning to the resting potential.
Figure 3.11 During the action potential, the electrical charge across the membrane changes dramatically.
This positive spike constitutes the action potential: the electrical signal that typically moves from the cell
body down the axon to the axon terminals. The electrical signal moves down the axon like a wave; at each
point, some of the sodium ions that enter the cell diffuse to the next section of the axon, raising the charge
past the threshold of excitation and triggering a new influx of sodium ions. The action potential moves all
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the way down the axon to the terminal buttons.
The action potential is an all-or-none phenomenon. In simple terms, this means that an incoming signal
from another neuron is either sufficient or insufficient to reach the threshold of excitation. There is no in-
between, and there is no turning off an action potential once it starts. Think of it like sending an email or
a text message. You can think about sending it all you want, but the message is not sent until you hit the
send button. Furthermore, once you send the message, there is no stopping it.
Because it is all or none, the action potential is recreated, or propagated, at its full strength at every point
along the axon. Much like the lit fuse of a firecracker, it does not fade away as it travels down the axon. It
is this all-or-none property that explains the fact that your brain perceives an injury to a distant body part
like your toe as equally painful as one to your nose.
As noted earlier, when the action potential arrives at the terminal button, the synaptic vesicles release
their neurotransmitters into the synapse. The neurotransmitters travel across the synapse and bind to
receptors on the dendrites of the adjacent neuron, and the process repeats itself in the new neuron
(assuming the signal is sufficiently strong to trigger an action potential). Once the signal is delivered,
excess neurotransmitters in the synapse drift away, are broken down into inactive fragments, or are
reabsorbed in a process known as reuptake. Reuptake involves the neurotransmitter being pumped
back into the neuron that released it, in order to clear the synapse (Figure 3.12). Clearing the synapse
serves both to provide a clear “on” and “off” state between signals and to regulate the production of
neurotransmitter (full synaptic vesicles provide signals that no additional neurotransmitters need to be
Figure 3.12 Reuptake involves moving a neurotransmitter from the synapse back into the axon terminal from which
it was released.
Neuronal communication is often referred to as an electrochemical event. The movement of the action
potential down the length of the axon is an electrical event, and movement of the neurotransmitter across
the synaptic space represents the chemical portion of the process.
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Click through this interactive simulation (
for a closer look at neuronal communication.
There are several different types of neurotransmitters released by different neurons, and we can speak in
broad terms about the kinds of functions associated with different neurotransmitters (Table 3.1). Much
of what psychologists know about the functions of neurotransmitters comes from research on the effects
of drugs in psychological disorders. Psychologists who take a biological perspective and focus on the
physiological causes of behavior assert that psychological disorders like depression and schizophrenia are
associated with imbalances in one or more neurotransmitter systems. In this perspective, psychotropic
medications can help improve the symptoms associated with these disorders. Psychotropic medications
are drugs that treat psychiatric symptoms by restoring neurotransmitter balance.
Table 3.1 Major Neurotransmitters and How They Affect Behavior
Neurotransmitter Involved in Potential Effect on Behavior
Acetylcholine Muscle action, memory Increased arousal, enhanced
Beta-endorphin Pain, pleasure Decreased anxiety, decreased
Dopamine Mood, sleep, learning Increased pleasure, suppressed
Gamma-aminobutyric acid
Brain function, sleep Decreased anxiety, decreased
Glutamate Memory, learning Increased learning, enhanced
Norepinephrine Heart, intestines,
Increased arousal, suppressed
Serotonin Mood, sleep Modulated mood, suppressed
Psychoactive drugs can act as agonists or antagonists for a given neurotransmitter system. Agonists are
chemicals that mimic a neurotransmitter at the receptor site and, thus, strengthen its effects. An antagonist,
on the other hand, blocks or impedes the normal activity of a neurotransmitter at the receptor. Agonist and
antagonist drugs are prescribed to correct the specific neurotransmitter imbalances underlying a person’s
condition. For example, Parkinson’s disease, a progressive nervous system disorder, is associated with
low levels of dopamine. Therefore dopamine agonists, which mimic the effects of dopamine by binding to
dopamine receptors, are one treatment strategy.
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Certain symptoms of schizophrenia are associated with overactive dopamine neurotransmission. The
antipsychotics used to treat these symptoms are antagonists for dopamine—they block dopamine’s effects
by binding its receptors without activating them. Thus, they prevent dopamine released by one neuron
from signaling information to adjacent neurons.
In contrast to agonists and antagonists, which both operate by binding to receptor sites, reuptake inhibitors
prevent unused neurotransmitters from being transported back to the neuron. This leaves more
neurotransmitters in the synapse for a longer time, increasing its effects. Depression, which has been
consistently linked with reduced serotonin levels, is commonly treated with selective serotonin reuptake
inhibitors (SSRIs). By preventing reuptake, SSRIs strengthen the effect of serotonin, giving it more time
to interact with serotonin receptors on dendrites. Common SSRIs on the market today include Prozac,
Paxil, and Zoloft. The drug LSD is structurally very similar to serotonin, and it affects the same neurons
and receptors as serotonin. Psychotropic drugs are not instant solutions for people suffering from
psychological disorders. Often, an individual must take a drug for several weeks before seeing
improvement, and many psychoactive drugs have significant negative side effects. Furthermore,
individuals vary dramatically in how they respond to the drugs. To improve chances for success, it is not
uncommon for people receiving pharmacotherapy to undergo psychological and/or behavioral therapies
as well. Some research suggests that combining drug therapy with other forms of therapy tends to be more
effective than any one treatment alone (for one such example, see March et al., 2007).
3.3 Parts of the Nervous System
Learning Objectives
By the end of this section, you will be able to:
• Describe the difference between the central and peripheral nervous systems
• Explain the difference between the somatic and autonomic nervous systems
• Differentiate between the sympathetic and parasympathetic divisions of the autonomic
nervous system
The nervous system can be divided into two major subdivisions: the central nervous system (CNS) and
the peripheral nervous system (PNS), shown in Figure 3.13. The CNS is comprised of the brain and spinal
cord; the PNS connects the CNS to the rest of the body. In this section, we focus on the peripheral nervous
system; later, we look at the brain and spinal cord.
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Figure 3.13 The nervous system is divided into two major parts: (a) the Central Nervous System and (b) the
Peripheral Nervous System.
The peripheral nervous system is made up of thick bundles of axons, called nerves, carrying messages
back and forth between the CNS and the muscles, organs, and senses in the periphery of the body (i.e.,
everything outside the CNS). The PNS has two major subdivisions: the somatic nervous system and the
autonomic nervous system.
The somatic nervous system is associated with activities traditionally thought of as conscious or
voluntary. It is involved in the relay of sensory and motor information to and from the CNS; therefore,
it consists of motor neurons and sensory neurons. Motor neurons, carrying instructions from the CNS to
the muscles, are efferent fibers (efferent means “moving away from”). Sensory neurons, carrying sensory
information to the CNS, are afferent fibers (afferent means “moving toward”). Each nerve is basically a
two-way superhighway, containing thousands of axons, both efferent and afferent.
The autonomic nervous system controls our internal organs and glands and is generally considered
to be outside the realm of voluntary control. It can be further subdivided into the sympathetic and
parasympathetic divisions (Figure 3.14). The sympathetic nervous system is involved in preparing the
body for stress-related activities; the parasympathetic nervous system is associated with returning the
body to routine, day-to-day operations. The two systems have complementary functions, operating in
tandem to maintain the body’s homeostasis. Homeostasis is a state of equilibrium, in which biological
conditions (such as body temperature) are maintained at optimal levels.
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Figure 3.14 The sympathetic and parasympathetic divisions of the autonomic nervous system have the opposite
effects on various systems.
The sympathetic nervous system is activated when we are faced with stressful or high-arousal situations.
The activity of this system was adaptive for our ancestors, increasing their chances of survival. Imagine,
for example, that one of our early ancestors, out hunting small game, suddenly disturbs a large bear
with her cubs. At that moment, his body undergoes a series of changes—a direct function of sympathetic
activation—preparing him to face the threat. His pupils dilate, his heart rate and blood pressure increase,
his bladder relaxes, his liver releases glucose, and adrenaline surges into his bloodstream. This
constellation of physiological changes, known as the fight or flight response, allows the body access to
energy reserves and heightened sensory capacity so that it might fight off a threat or run away to safety.
Reinforce what you’ve learned about the nervous system by playing this BBC-
produced interactive game ( about the
nervous system.
While it is clear that such a response would be critical for survival for our ancestors, who lived in a world
full of real physical threats, many of the high-arousal situations we face in the modern world are more
psychological in nature. For example, think about how you feel when you have to stand up and give a
presentation in front of a roomful of people, or right before taking a big test. You are in no real physical
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danger in those situations, and yet you have evolved to respond to any perceived threat with the fight
or flight response. This kind of response is not nearly as adaptive in the modern world; in fact, we suffer
negative health consequences when faced constantly with psychological threats that we can neither fight
nor flee. Recent research suggests that an increase in susceptibility to heart disease (Chandola, Brunner, &
Marmot, 2006) and impaired function of the immune system (Glaser & Kiecolt-Glaser, 2005) are among the
many negative consequences of persistent and repeated exposure to stressful situations.
Once the threat has been resolved, the parasympathetic nervous system takes over and returns bodily
functions to a relaxed state. Our hunter’s heart rate and blood pressure return to normal, his pupils
constrict, he regains control of his bladder, and the liver begins to store glucose in the form of glycogen for
future use. These processes are associated with activation of the parasympathetic nervous system.
3.4 The Brain and Spinal Cord
Learning Objectives
By the end of this section, you will be able to:
• Explain the functions of the spinal cord
• Identify the hemispheres and lobes of the brain
• Describe the types of techniques available to clinicians and researchers to image or scan the
The brain is a remarkably complex organ comprised of billions of interconnected neurons and glia. It is
a bilateral, or two-sided, structure that can be separated into distinct lobes. Each lobe is associated with
certain types of functions, but, ultimately, all of the areas of the brain interact with one another to provide
the foundation for our thoughts and behaviors. In this section, we discuss the overall organization of
the brain and the functions associated with different brain areas, beginning with what can be seen as an
extension of the brain, the spinal cord.
It can be said that the spinal cord is what connects the brain to the outside world. Because of it, the brain
can act. The spinal cord is like a relay station, but a very smart one. It not only routes messages to and from
the brain, but it also has its own system of automatic processes, called reflexes.
The top of the spinal cord merges with the brain stem, where the basic processes of life are controlled, such
as breathing and digestion. In the opposite direction, the spinal cord ends just below the ribs—contrary to
what we might expect, it does not extend all the way to the base of the spine.
The spinal cord is functionally organized in 30 segments, corresponding with the vertebrae. Each segment
is connected to a specific part of the body through the peripheral nervous system. Nerves branch out
from the spine at each vertebra. Sensory nerves bring messages in; motor nerves send messages out to the
muscles and organs. Messages travel to and from the brain through every segment.
Some sensory messages are immediately acted on by the spinal cord, without any input from the brain.
Withdrawal from heat and knee jerk are two examples. When a sensory message meets certain parameters,
the spinal cord initiates an automatic reflex. The signal passes from the sensory nerve to a simple
processing center, which initiates a motor command. Seconds are saved, because messages don’t have to
go the brain, be processed, and get sent back. In matters of survival, the spinal reflexes allow the body to
react extraordinarily fast.
The spinal cord is protected by bony vertebrae and cushioned in cerebrospinal fluid, but injuries still occur.
When the spinal cord is damaged in a particular segment, all lower segments are cut off from the brain,
causing paralysis. Therefore, the lower on the spine damage is, the fewer functions an injured individual
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The surface of the brain, known as the cerebral cortex, is very uneven, characterized by a distinctive
pattern of folds or bumps, known as gyri (singular: gyrus), and grooves, known as sulci (singular: sulcus),
shown in Figure 3.15. These gyri and sulci form important landmarks that allow us to separate the brain
into functional centers. The most prominent sulcus, known as the longitudinal fissure, is the deep groove
that separates the brain into two halves or hemispheres: the left hemisphere and the right hemisphere.
Figure 3.15 The surface of the brain is covered with gyri and sulci. A deep sulcus is called a fissure, such as the
longitudinal fissure that divides the brain into left and right hemispheres. (credit: modification of work by Bruce Blaus)
There is evidence of some specialization of function—referred to as lateralization—in each hemisphere,
mainly regarding differences in language ability. Beyond that, however, the differences that have been
found have been minor. What we do know is that the left hemisphere controls the right half of the body,
and the right hemisphere controls the left half of the body.
The two hemispheres are connected by a thick band of neural fibers known as the corpus callosum,
consisting of about 200 million axons. The corpus callosum allows the two hemispheres to communicate
with each other and allows for information being processed on one side of the brain to be shared with the
other side.
Normally, we are not aware of the different roles that our two hemispheres play in day-to-day functions,
but there are people who come to know the capabilities and functions of their two hemispheres quite
well. In some cases of severe epilepsy, doctors elect to sever the corpus callosum as a means of controlling
the spread of seizures (Figure 3.16). While this is an effective treatment option, it results in individuals
who have split brains. After surgery, these split-brain patients show a variety of interesting behaviors. For
instance, a split-brain patient is unable to name a picture that is shown in the patient’s left visual field
because the information is only available in the largely nonverbal right hemisphere. However, they are
able to recreate the picture with their left hand, which is also controlled by the right hemisphere. When the
more verbal left hemisphere sees the picture that the hand drew, the patient is able to name it (assuming
the left hemisphere can interpret what was drawn by the left hand).
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Figure 3.16 (a, b) The corpus callosum connects the left and right hemispheres of the brain. (c) A scientist spreads
this dissected sheep brain apart to show the corpus callosum between the hemispheres. (credit c: modification of
work by Aaron Bornstein)
This interactive animation ( on the
Nobel Prize website walks users through the hemispheres of the brain.
Much of what we know about the functions of different areas of the brain comes from studying changes in
the behavior and ability of individuals who have suffered damage to the brain. For example, researchers
study the behavioral changes caused by strokes to learn about the functions of specific brain areas. A
stroke, caused by an interruption of blood flow to a region in the brain, causes a loss of brain function in
the affected region. The damage can be in a small area, and, if it is, this gives researchers the opportunity
to link any resulting behavioral changes to a specific area. The types of deficits displayed after a stroke will
be largely dependent on where in the brain the damage occurred.
Consider Theona, an intelligent, self-sufficient woman, who is 62 years old. Recently, she suffered a stroke
in the front portion of her right hemisphere. As a result, she has great difficulty moving her left leg. (As you
learned earlier, the right hemisphere controls the left side of the body; also, the brain’s main motor centers
are located at the front of the head, in the frontal lobe.) Theona has also experienced behavioral changes.
For example, while in the produce section of the grocery store, she sometimes eats grapes, strawberries,
and apples directly from their bins before paying for them. This behavior—which would have been very
embarrassing to her before the stroke—is consistent with damage in another region in the frontal lobe—the
prefrontal cortex, which is associated with judgment, reasoning, and impulse control.
The two hemispheres of the cerebral cortex are part of the forebrain (Figure 3.17), which is the largest part
of the brain. The forebrain contains the cerebral cortex and a number of other structures that lie beneath
the cortex (called subcortical structures): thalamus, hypothalamus, pituitary gland, and the limbic system
(collection of structures). The cerebral cortex, which is the outer surface of the brain, is associated with
higher level processes such as consciousness, thought, emotion, reasoning, language, and memory. Each
cerebral hemisphere can be subdivided into four lobes, each associated with different functions.
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Figure 3.17 The brain and its parts can be divided into three main categories: the forebrain, midbrain, and hindbrain.
Lobes of the Brain
The four lobes of the brain are the frontal, parietal, temporal, and occipital lobes (Figure 3.18). The frontal
lobe is located in the forward part of the brain, extending back to a fissure known as the central sulcus. The
frontal lobe is involved in reasoning, motor control, emotion, and language. It contains the motor cortex,
which is involved in planning and coordinating movement; the prefrontal cortex, which is responsible for
higher-level cognitive functioning; and Broca’s area, which is essential for language production.
Figure 3.18 The lobes of the brain are shown.
People who suffer damage to Broca’s area have great difficulty producing language of any form (Figure
3.18). For example, Padma was an electrical engineer who was socially active and a caring, involved
mother. About twenty years ago, she was in a car accident and suffered damage to her Broca’s area. She
completely lost the ability to speak and form any kind of meaningful language. There is nothing wrong
with her mouth or her vocal cords, but she is unable to produce words. She can follow directions but can’t
respond verbally, and she can read but no longer write. She can do routine tasks like running to the market
to buy milk, but she could not communicate verbally if a situation called for it.
Probably the most famous case of frontal lobe damage is that of a man by the name of Phineas Gage. On
September 13, 1848, Gage (age 25) was working as a railroad foreman in Vermont. He and his crew were
using an iron rod to tamp explosives down into a blasting hole to remove rock along the railway’s path.
Unfortunately, the iron rod created a spark and caused the rod to explode out of the blasting hole, into
Gage’s face, and through his skull (Figure 3.19). Although lying in a pool of his own blood with brain
matter emerging from his head, Gage was conscious and able to get up, walk, and speak. But in the months
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following his accident, people noticed that his personality had changed. Many of his friends described him
as no longer being himself. Before the accident, it was said that Gage was a well-mannered, soft-spoken
man, but he began to behave in odd and inappropriate ways after the accident. Such changes in personality
would be consistent with loss of impulse control—a frontal lobe function.
Beyond the damage to the frontal lobe itself, subsequent investigations into the rod’s path also identified
probable damage to pathways between the frontal lobe and other brain structures, including the limbic
system. With connections between the planning functions of the frontal lobe and the emotional processes
of the limbic system severed, Gage had difficulty controlling his emotional impulses.
However, there is some evidence suggesting that the dramatic changes in Gage’s personality were
exaggerated and embellished. Gage’s case occurred in the midst of a 19th century debate over
localization—regarding whether certain areas of the brain are associated with particular functions. On the
basis of extremely limited information about Gage, the extent of his injury, and his life before and after the
accident, scientists tended to find support for their own views, on whichever side of the debate they fell
(Macmillan, 1999).
Figure 3.19 (a) Phineas Gage holds the iron rod that penetrated his skull in an 1848 railroad construction accident.
(b) Gage’s prefrontal cortex was severely damaged in the left hemisphere. The rod entered Gage’s face on the left
side, passed behind his eye, and exited through the top of his skull, before landing about 80 feet away. (credit a:
modification of work by Jack and Beverly Wilgus)
The brain’s parietal lobe is located immediately behind the frontal lobe, and is involved in processing
information from the body’s senses. It contains the somatosensory cortex, which is essential for processing
sensory information from across the body, such as touch, temperature, and pain. The somatosensory cortex
is organized topographically, which means that spatial relationships that exist in the body are maintained
on the surface of the somatosensory cortex (Figure 3.20). For example, the portion of the cortex that
processes sensory information from the hand is adjacent to the portion that processes information from the
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Figure 3.20 Spatial relationships in the body are mirrored in the organization of the somatosensory cortex.
The temporal lobe is located on the side of the head (temporal means “near the temples”), and is associated
with hearing, memory, emotion, and some aspects of language. The auditory cortex, the main area
responsible for processing auditory information, is located within the temporal lobe. Wernicke’s area,
important for speech comprehension, is also located here. Whereas individuals with damage to Broca’s
area have difficulty producing language, those with damage to Wernicke’s area can produce sensible
language, but they are unable to understand it (Figure 3.21).
Figure 3.21 Damage to either Broca’s area or Wernicke’s area can result in language deficits. The types of deficits
are very different, however, depending on which area is affected.
The occipital lobe is located at the very back of the brain, and contains the primary visual cortex, which is
responsible for interpreting incoming visual information. The occipital cortex is organized retinotopically,
which means there is a close relationship between the position of an object in a person’s visual field and
the position of that object’s representation on the cortex. You will learn much more about how visual
information is processed in the occipital lobe when you study sensation and perception.
Other Areas of the Forebrain
Other areas of the forebrain, located beneath the cerebral cortex, include the thalamus and the limbic
system. The thalamus is a sensory relay for the brain. All of our senses, with the exception of smell, are
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routed through the thalamus before being directed to other areas of the brain for processing (Figure 3.22).
Figure 3.22 The thalamus serves as the relay center of the brain where most senses are routed for processing.
The limbic system is involved in processing both emotion and memory. Interestingly, the sense of smell
projects directly to the limbic system; therefore, not surprisingly, smell can evoke emotional responses
in ways that other sensory modalities cannot. The limbic system is made up of a number of different
structures, but three of the most important are the hippocampus, the amygdala, and the hypothalamus
(Figure 3.23). The hippocampus is an essential structure for learning and memory. The amygdala is
involved in our experience of emotion and in tying emotional meaning to our memories. The
hypothalamus regulates a number of homeostatic processes, including the regulation of body
temperature, appetite, and blood pressure. The hypothalamus also serves as an interface between the
nervous system and the endocrine system and in the regulation of sexual motivation and behavior.
Figure 3.23 The limbic system is involved in mediating emotional response and memory.
The Case of Henry Molaison (H.M.)
In 1953, Henry Gustav Molaison (H. M.) was a 27-year-old man who experienced severe seizures. In
an attempt to control his seizures, H. M. underwent brain surgery to remove his hippocampus and
amygdala. Following the surgery, H.M’s seizures became much less severe, but he also suffered some
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unexpected—and devastating—consequences of the surgery: he lost his ability to form many types of new
memories. For example, he was unable to learn new facts, such as who was president of the United States.
He was able to learn new skills, but afterward he had no recollection of learning them. For example, while
he might learn to use a computer, he would have no conscious memory of ever having used one. He could
not remember new faces, and he was unable to remember events, even immediately after they occurred.
Researchers were fascinated by his experience, and he is considered one of the most studied cases in
medical and psychological history (Hardt, Einarsson, & Nader, 2010; Squire, 2009). Indeed, his case has
provided tremendous insight into the role that the hippocampus plays in the consolidation of new learning
into explicit memory.
Clive Wearing, an accomplished musician, lost the ability to form new memories
when his hippocampus was damaged through illness. Check out the first few
minutes of this documentary video ( for an
introduction to this man and his condition.
The midbrain is comprised of structures located deep within the brain, between the forebrain and the
hindbrain. The reticular formation is centered in the midbrain, but it actually extends up into the forebrain
and down into the hindbrain. The reticular formation is important in regulating the sleep/wake cycle,
arousal, alertness, and motor activity.
The substantia nigra (Latin for “black substance”) and the ventral tegmental area (VTA) are also located
in the midbrain (Figure 3.24). Both regions contain cell bodies that produce the neurotransmitter
dopamine, and both are critical for movement. Degeneration of the substantia nigra and VTA is involved
in Parkinson’s disease. In addition, these structures are involved in mood, reward, and addiction (Berridge
& Robinson, 1998; Gardner, 2011; George, Le Moal, & Koob, 2012).
Figure 3.24 The substantia nigra and ventral tegmental area (VTA) are located in the midbrain.
The hindbrain is located at the back of the head and looks like an extension of the spinal cord. It contains
the medulla, pons, and cerebellum (Figure 3.25). The medulla controls the automatic processes of the
autonomic nervous system, such as breathing, blood pressure, and heart rate. The word pons literally
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means “bridge,” and as the name suggests, the pons serves to connect the brain and spinal cord. It also is
involved in regulating brain activity during sleep. The medulla, pons, and midbrain together are known
as the brainstem.
Figure 3.25 The pons, medulla, and cerebellum make up the hindbrain.
The cerebellum (Latin for “little brain”) receives messages from muscles, tendons, joints, and structures
in our ear to control balance, coordination, movement, and motor skills. The cerebellum is also thought
to be an important area for processing some types of memories. In particular, procedural memory, or
memory involved in learning and remembering how to perform tasks, is thought to be associated with the
cerebellum. Recall that H. M. was unable to form new explicit memories, but he could learn new tasks.
This is likely due to the fact that H. M.’s cerebellum remained intact.
Brain Dead and on Life Support
What would you do if your spouse or loved one was declared brain dead but his or her body was being kept
alive by medical equipment? Whose decision should it be to remove a feeding tube? Should medical care
costs be a factor?
On February 25, 1990, a Florida woman named Terri Schiavo went into cardiac arrest, apparently triggered by
a bulimic episode. She was eventually revived, but her brain had been deprived of oxygen for a long time. Brain
scans indicated that there was no activity in her cerebral cortex, and she suffered from severe and permanent
cerebral atrophy. Basically, Schiavo was in a vegetative state. Medical professionals determined that she would
never again be able to move, talk, or respond in any way. To remain alive, she required a feeding tube, and
there was no chance that her situation would ever improve.
On occasion, Schiavo’s eyes would move, and sometimes she would groan. Despite the doctors’ insistence to
the contrary, her parents believed that these were signs that she was trying to communicate with them.
After 12 years, Schiavo’s husband argued that his wife would not have wanted to be kept alive with no
feelings, sensations, or brain activity. Her parents, however, were very much against removing her feeding
tube. Eventually, the case made its way to the courts, both in the state of Florida and at the federal level. By
2005, the courts found in favor of Schiavo’s husband, and the feeding tube was removed on March 18, 2005.
Schiavo died 13 days later.
Why did Schiavo’s eyes sometimes move, and why did she groan? Although the parts of her brain that
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control thought, voluntary movement, and feeling were completely damaged, her brainstem was still intact. Her
medulla and pons maintained her breathing and caused involuntary movements of her eyes and the occasional
groans. Over the 15-year period that she was on a feeding tube, Schiavo’s medical costs may have topped $7
million (Arnst, 2003).
These questions were brought to popular conscience 25 years ago in the case of Terri Schiavo, and they
persist today. In 2013, a 13-year-old girl who suffered complications after tonsil surgery was declared brain
dead. There was a battle between her family, who wanted her to remain on life support, and the hospital’s
policies regarding persons declared brain dead. In another complicated 2013–14 case in Texas, a pregnant
EMT professional declared brain dead was kept alive for weeks, despite her spouse’s directives, which were
based on her wishes should this situation arise. In this case, state laws designed to protect an unborn fetus
came into consideration until doctors determined the fetus unviable.
Decisions surrounding the medical response to patients declared brain dead are complex. What do you think
about these issues?
You have learned how brain injury can provide information about the functions of different parts of the
brain. Increasingly, however, we are able to obtain that information using brain imaging techniques on
individuals who have not suffered brain injury. In this section, we take a more in-depth look at some of the
techniques that are available for imaging the brain, including techniques that rely on radiation, magnetic
fields, or electrical activity within the brain.
Techniques Involving Radiation
A computerized tomography (CT) scan involves taking a number of x-rays of a particular section of a
person’s body or brain (Figure 3.26). The x-rays pass through tissues of different densities at different
rates, allowing a computer to construct an overall image of the area of the body being scanned. A CT scan
is often used to determine whether someone has a tumor, or significant brain atrophy.
Figure 3.26 A CT scan can be used to show brain tumors. (a) The image on the left shows a healthy brain, whereas
(b) the image on the right indicates a brain tumor in the left frontal lobe. (credit a: modification of work by
“Aceofhearts1968″/Wikimedia Commons; credit b: modification of work by Roland Schmitt et al)
Positron emission tomography (PET) scans create pictures of the living, active brain (Figure 3.27). An
individual receiving a PET scan drinks or is injected with a mildly radioactive substance, called a tracer.
Once in the bloodstream, the amount of tracer in any given region of the brain can be monitored. As brain
areas become more active, more blood flows to that area. A computer monitors the movement of the tracer
and creates a rough map of active and inactive areas of the brain during a given behavior. PET scans
show little detail, are unable to pinpoint events precisely in time, and require that the brain be exposed
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to radiation; therefore, this technique has been replaced by the fMRI as an alternative diagnostic tool.
However, combined with CT, PET technology is still being used in certain contexts. For example, CT/
PET scans allow better imaging of the activity of neurotransmitter receptors and open new avenues in
schizophrenia research. In this hybrid CT/PET technology, CT contributes clear images of brain structures,
while PET shows the brain’s activity.
Figure 3.27 A PET scan is helpful for showing activity in different parts of the brain. (credit: Health and Human
Services Department, National Institutes of Health)
Techniques Involving Magnetic Fields
In magnetic resonance imaging (MRI), a person is placed inside a machine that generates a strong
magnetic field. The magnetic field causes the hydrogen atoms in the body’s cells to move. When the
magnetic field is turned off, the hydrogen atoms emit electromagnetic signals as they return to their
original positions. Tissues of different densities give off different signals, which a computer interprets and
displays on a monitor. Functional magnetic resonance imaging (fMRI) operates on the same principles,
but it shows changes in brain activity over time by tracking blood flow and oxygen levels. The fMRI
provides more detailed images of the brain’s structure, as well as better accuracy in time, than is possible
in PET scans (Figure 3.28). With their high level of detail, MRI and fMRI are often used to compare the
brains of healthy individuals to the brains of individuals diagnosed with psychological disorders. This
comparison helps determine what structural and functional differences exist between these populations.
Figure 3.28 An fMRI shows activity in the brain over time. This image represents a single frame from an fMRI.
(credit: modification of work by Kim J, Matthews NL, Park S.)
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Visit this virtual lab ( to learn more about MRI and
Techniques Involving Electrical Activity
In some situations, it is helpful to gain an understanding of the overall activity of a person’s brain, without
needing information on the actual location of the activity. Electroencephalography (EEG) serves this
purpose by providing a measure of a brain’s electrical activity. An array of electrodes is placed around
a person’s head (Figure 3.29). The signals received by the electrodes result in a printout of the electrical
activity of his or her brain, or brainwaves, showing both the frequency (number of waves per second) and
amplitude (height) of the recorded brainwaves, with an accuracy within milliseconds. Such information is
especially helpful to researchers studying sleep patterns among individuals with sleep disorders.
Figure 3.29 Using caps with electrodes, modern EEG research can study the precise timing of overall brain
activities. (credit: SMI Eye Tracking)
3.5 The Endocrine System
Learning Objectives
By the end of this section, you will be able to:
• Identify the major glands of the endocrine system
• Identify the hormones secreted by each gland
• Describe each hormone’s role in regulating bodily functions
The endocrine system consists of a series of glands that produce chemical substances known as hormones
(Figure 3.30). Like neurotransmitters, hormones are chemical messengers that must bind to a receptor in
order to send their signal. However, unlike neurotransmitters, which are released in close proximity to
cells with their receptors, hormones are secreted into the bloodstream and travel throughout the body,
affecting any cells that contain receptors for them. Thus, whereas neurotransmitters’ effects are localized,
the effects of hormones are widespread. Also, hormones are slower to take effect, and tend to be longer
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Figure 3.30 The major glands of the endocrine system are shown.
Hormones are involved in regulating all sorts of bodily functions, and they are ultimately controlled
through interactions between the hypothalamus (in the central nervous system) and the pituitary gland (in
the endocrine system). Imbalances in hormones are related to a number of disorders. This section explores
some of the major glands that make up the endocrine system and the hormones secreted by these glands.
The pituitary gland descends from the hypothalamus at the base of the brain, and acts in close association
with it. The pituitary is often referred to as the “master gland” because its messenger hormones control
all the other glands in the endocrine system, although it mostly carries out instructions from the
hypothalamus. In addition to messenger hormones, the pituitary also secretes growth hormone,
endorphins for pain relief, and a number of key hormones that regulate fluid levels in the body.
Located in the neck, the thyroid gland releases hormones that regulate growth, metabolism, and appetite.
In hyperthyroidism, or Grave’s disease, the thyroid secretes too much of the hormone thyroxine, causing
agitation, bulging eyes, and weight loss. In hypothyroidism, reduced hormone levels cause sufferers to
experience tiredness, and they often complain of feeling cold. Fortunately, thyroid disorders are often
treatable with medications that help reestablish a balance in the hormones secreted by the thyroid.
The adrenal glands sit atop our kidneys and secrete hormones involved in the stress response, such
as epinephrine (adrenaline) and norepinephrine (noradrenaline). The pancreas is an internal organ that
secretes hormones that regulate blood sugar levels: insulin and glucagon. These pancreatic hormones are
essential for maintaining stable levels of blood sugar throughout the day by lowering blood glucose levels
(insulin) or raising them (glucagon). People who suffer from diabetes do not produce enough insulin;
therefore, they must take medications that stimulate or replace insulin production, and they must closely
control the amount of sugars and carbohydrates they consume.
The gonads secrete sexual hormones, which are important in reproduction, and mediate both sexual
motivation and behavior. The female gonads are the ovaries; the male gonads are the testes. Ovaries
Chapter 3 | Biopsychology 101

secrete estrogens and progesterone, and the testes secrete androgens, such as testosterone.
Athletes and Anabolic Steroids
Although it is against Federal laws and many professional athletic associations (The National Football League,
for example) have banned their use, anabolic steroid drugs continue to be used by amateur and professional
athletes. The drugs are believed to enhance athletic performance. Anabolic steroid drugs mimic the effects
of the body’s own steroid hormones, like testosterone and its derivatives. These drugs have the potential to
provide a competitive edge by increasing muscle mass, strength, and endurance, although not all users may
experience these results. Moreover, use of performance-enhancing drugs (PEDs) does not come without risks.
Anabolic steroid use has been linked with a wide variety of potentially negative outcomes, ranging in severity
from largely cosmetic (acne) to life threatening (heart attack). Furthermore, use of these substances can result
in profound changes in mood and can increase aggressive behavior (National Institute on Drug Abuse, 2001).
Baseball player Alex Rodriguez (A-Rod) has been at the center of a media storm regarding his use of illegal
PEDs. Rodriguez’s performance on the field was unparalleled while using the drugs; his success played a
large role in negotiating a contract that made him the highest paid player in professional baseball. Although
Rodriguez maintains that he has not used PEDs for the several years, he received a substantial suspension
in 2013 that, if upheld, will cost him more than 20 million dollars in earnings (Gaines, 2013). What are your
thoughts on athletes and doping? Why or why not should the use of PEDs be banned? What advice would you
give an athlete who was considering using PEDs?
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action potential
adrenal gland
auditory cortex
autonomic nervous system
biological perspective
Broca’s area
central nervous system (CNS)
cerebral cortex
computerized tomography (CT) scan
corpus callosum
deoxyribonucleic acid (DNA)
dominant allele
electroencephalography (EEG)
endocrine system
Key Terms
electrical signal that moves down the neuron’s axon
sits atop our kidneys and secretes hormones involved in the stress response
drug that mimics or strengthens the effects of a neurotransmitter
phenomenon that incoming signal from another neuron is either sufficient or insufficient to
reach the threshold of excitation
specific version of a gene
structure in the limbic system involved in our experience of emotion and tying emotional
meaning to our memories
drug that blocks or impedes the normal activity of a given neurotransmitter
strip of cortex in the temporal lobe that is responsible for processing auditory
controls our internal organs and glands
major extension of the soma
view that psychological disorders like depression and schizophrenia are
associated with imbalances in one or more neurotransmitter systems
region in the left hemisphere that is essential for language production
brain and spinal cord
hindbrain structure that controls our balance, coordination, movement, and motor skills, and
it is thought to be important in processing some types of memory
surface of the brain that is associated with our highest mental capabilities
long strand of genetic information
imaging technique in which a computer coordinates and integrates
multiple x-rays of a given area
thick band of neural fibers connecting the brain’s two hemispheres
branch-like extension of the soma that receives incoming signals from other neurons
helix-shaped molecule made of nucleotide base pairs
disease related to insufficient insulin production
allele whose phenotype will be expressed in an individual that possesses that allele
recording the electrical activity of the brain via electrodes on the scalp
series of glands that produce chemical substances known as hormones
study of gene-environment interactions, such as how the same genotype leads to different
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fight or flight response
fraternal twins
frontal lobe
functional magnetic resonance imaging (fMRI)
genetic environmental correlation
glial cell
identical twins
limbic system
longitudinal fissure
magnetic resonance imaging (MRI)
activation of the sympathetic division of the autonomic nervous system,
allowing access to energy reserves and heightened sensory capacity so that we might fight off a given
threat or run away to safety
largest part of the brain, containing the cerebral cortex, the thalamus, and the limbic system,
among other structures
twins who develop from two different eggs fertilized by different sperm, so their genetic
material varies the same as in non-twin siblings
part of the cerebral cortex involved in reasoning, motor control, emotion, and language;
contains motor cortex
MRI that shows changes in metabolic activity over time
sequence of DNA that controls or partially controls physical characteristics
view of gene-environment interaction that asserts our genes affect
our environment, and our environment influences the expression of our genes
genetic makeup of an individual
nervous system cell that provides physical and metabolic support to neurons, including
neuronal insulation and communication, and nutrient and waste transport
secretes sexual hormones, which are important for successful reproduction, and mediate both
sexual motivation and behavior
(plural: gyri) bump or ridge on the cerebral cortex
left or right half of the brain
consisting of two different alleles
division of the brain containing the medulla, pons, and cerebellum
structure in the temporal lobe associated with learning and memory
state of equilibrium—biological conditions, such as body temperature, are maintained at
optimal levels
consisting of two identical alleles
chemical messenger released by endocrine glands
forebrain structure that regulates sexual motivation and behavior and a number of
homeostatic processes; serves as an interface between the nervous system and the endocrine system
twins that develop from the same sperm and egg
concept that each hemisphere of the brain is associated with specialized functions
collection of structures involved in processing emotion and memory
deep groove in the brain’s cortex
magnetic fields used to produce a picture of the tissue being imaged
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membrane potential
motor cortex
myelin sheath
occipital lobe
parasympathetic nervous system
parietal lobe
peripheral nervous system (PNS)
pituitary gland
positron emission tomography (PET) scan
prefrontal cortex
psychotropic medication
range of reaction
recessive allele
resting potential
hindbrain structure that controls automated processes like breathing, blood pressure, and heart
difference in charge across the neuronal membrane
division of the brain located between the forebrain and the hindbrain; contains the reticular
strip of cortex involved in planning and coordinating movement
sudden, permanent change in a gene
fatty substance that insulates axons
cells in the nervous system that act as interconnected information processors, which are essential
for all of the tasks of the nervous system
chemical messenger of the nervous system
part of the cerebral cortex associated with visual processing; contains the primary visual
secretes hormones that regulate blood sugar
associated with routine, day-to-day operations of the body
part of the cerebral cortex involved in processing various sensory and perceptual
information; contains the primary somatosensory cortex
connects the brain and spinal cord to the muscles, organs and senses
in the periphery of the body
individual’s inheritable physical characteristics
secretes a number of key hormones, which regulate fluid levels in the body, and a
number of messenger hormones, which direct the activity of other glands in the endocrine system
multiple genes affecting a given trait
hindbrain structure that connects the brain and spinal cord; involved in regulating brain activity
during sleep
involves injecting individuals with a mildly radioactive
substance and monitoring changes in blood flow to different regions of the brain
area in the frontal lobe responsible for higher-level cognitive functioning
drugs that treat psychiatric symptoms by restoring neurotransmitter balance
asserts our genes set the boundaries within which we can operate, and our
environment interacts with the genes to determine where in that range we will fall
protein on the cell surface where neurotransmitters attach
allele whose phenotype will be expressed only if an individual is homozygous for that
the state of readiness of a neuron membrane’s potential between signals
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reticular formation
semipermeable membrane
somatic nervous system
somatosensory cortex
substantia nigra
sympathetic nervous system
synaptic vesicle
temporal lobe
terminal button
theory of evolution by natural selection
threshold of excitation
ventral tegmental area (VTA)
Wernicke’s area
midbrain structure important in regulating the sleep/wake cycle, arousal, alertness,
and motor activity
neurotransmitter is pumped back into the neuron that released it
cell membrane that allows smaller molecules or molecules without an
electrical charge to pass through it, while stopping larger or highly charged molecules
cell body
relays sensory and motor information to and from the CNS
essential for processing sensory information from across the body, such as touch,
temperature, and pain
midbrain structure where dopamine is produced; involved in control of movement
(plural: sulci) depressions or grooves in the cerebral cortex
involved in stress-related activities and functions
small gap between two neurons where communication occurs
storage site for neurotransmitters
part of cerebral cortex associated with hearing, memory, emotion, and some aspects of
language; contains primary auditory cortex
axon terminal containing synaptic vesicles
sensory relay for the brain
states that organisms that are better suited for their
environments will survive and reproduce compared to those that are poorly suited for their
level of charge in the membrane that causes the neuron to become active
secretes hormones that regulate growth, metabolism, and appetite
midbrain structure where dopamine is produced: associated with mood,
reward, and addiction
important for speech comprehension
3.1 Human Genetics
Genes are sequences of DNA that code for a particular trait. Different versions of a gene are called
alleles—sometimes alleles can be classified as dominant or recessive. A dominant allele always results in
the dominant phenotype. In order to exhibit a recessive phenotype, an individual must be homozygous
for the recessive allele. Genes affect both physical and psychological characteristics. Ultimately, how and
when a gene is expressed, and what the outcome will be—in terms of both physical and psychological
characteristics—is a function of the interaction between our genes and our environments.
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3.2 Cells of the Nervous System
Glia and neurons are the two cell types that make up the nervous system. While glia generally play
supporting roles, the communication between neurons is fundamental to all of the functions associated
with the nervous system. Neuronal communication is made possible by the neuron’s specialized
structures. The soma contains the cell nucleus, and the dendrites extend from the soma in tree-like
branches. The axon is another major extension of the cell body; axons are often covered by a myelin sheath,
which increases the speed of transmission of neural impulses. At the end of the axon are terminal buttons
that contain synaptic vesicles filled with neurotransmitters.
Neuronal communication is an electrochemical event. The dendrites contain receptors for
neurotransmitters released by nearby neurons. If the signals received from other neurons are sufficiently
strong, an action potential will travel down the length of the axon to the terminal buttons, resulting in the
release of neurotransmitters into the synapse. Action potentials operate on the all-or-none principle and
involve the movement of Na+ and K+ across the neuronal membrane.
Different neurotransmitters are associated with different functions. Often, psychological disorders involve
imbalances in a given neurotransmitter system. Therefore, psychotropic drugs are prescribed in an attempt
to bring the neurotransmitters back into balance. Drugs can act either as agonists or as antagonists for a
given neurotransmitter system.
3.3 Parts of the Nervous System
The brain and spinal cord make up the central nervous system. The peripheral nervous system is
comprised of the somatic and autonomic nervous systems. The somatic nervous system transmits sensory
and motor signals to and from the central nervous system. The autonomic nervous system controls the
function of our organs and glands, and can be divided into the sympathetic and parasympathetic divisions.
Sympathetic activation prepares us for fight or flight, while parasympathetic activation is associated with
normal functioning under relaxed conditions.
3.4 The Brain and Spinal Cord
The brain consists of two hemispheres, each controlling the opposite side of the body. Each hemisphere
can be subdivided into different lobes: frontal, parietal, temporal, and occipital. In addition to the lobes
of the cerebral cortex, the forebrain includes the thalamus (sensory relay) and limbic system (emotion and
memory circuit). The midbrain contains the reticular formation, which is important for sleep and arousal,
as well as the substantia nigra and ventral tegmental area. These structures are important for movement,
reward, and addictive processes. The hindbrain contains the structures of the brainstem (medulla, pons,
and midbrain), which control automatic functions like breathing and blood pressure. The hindbrain also
contains the cerebellum, which helps coordinate movement and certain types of memories.
Individuals with brain damage have been studied extensively to provide information about the role of
different areas of the brain, and recent advances in technology allow us to glean similar information by
imaging brain structure and function. These techniques include CT, PET, MRI, fMRI, and EEG.
3.5 The Endocrine System
The glands of the endocrine system secrete hormones to regulate normal body functions. The
hypothalamus serves as the interface between the nervous system and the endocrine system, and it
controls the secretions of the pituitary. The pituitary serves as the master gland, controlling the secretions
of all other glands. The thyroid secretes thyroxine, which is important for basic metabolic processes
and growth; the adrenal glands secrete hormones involved in the stress response; the pancreas secretes
hormones that regulate blood sugar levels; and the ovaries and testes produce sex hormones that regulate
sexual motivation and behavior.
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Review Questions
1. A(n) ________ is a sudden, permanent change
in a sequence of DNA.
a. allele
b. chromosome
c. epigenetic
d. mutation
2. ________ refers to a person’s genetic makeup,
while ________ refers to a person’s physical
a. Phenotype; genotype
b. Genotype; phenotype
c. DNA; gene
d. Gene; DNA
3. ________ is the field of study that focuses on
genes and their expression.
a. Social psychology
b. Evolutionary psychology
c. Epigenetics
d. Behavioral neuroscience
4. Humans have ________ pairs of chromosomes.
a. 15
b. 23
c. 46
d. 78
5. The ________ receive(s) incoming signals from
other neurons.
a. soma
b. terminal buttons
c. myelin sheath
d. dendrites
6. A(n) ________ facilitates or mimics the activity
of a given neurotransmitter system.
a. axon
c. agonist
d. antagonist
7. Multiple sclerosis involves a breakdown of the
a. soma
b. myelin sheath
c. synaptic vesicles
d. dendrites
8. An action potential involves Na+ moving
________ the cell and K+ moving ________ the cell.
a. inside; outside
b. outside; inside
c. inside; inside
d. outside; outside
9. Our ability to make our legs move as we walk
across the room is controlled by the ________
nervous system.
a. autonomic
b. somatic
c. sympathetic
d. parasympathetic
10. If your ________ is activated, you will feel
relatively at ease.
a. somatic nervous system
b. sympathetic nervous system
c. parasympathetic nervous system
d. spinal cord
11. The central nervous system is comprised of
a. sympathetic and parasympathetic nervous
b. organs and glands
c. somatic and autonomic nervous systems
d. brain and spinal cord
12. Sympathetic activation is associated with
a. pupil dilation
b. storage of glucose in the liver
c. increased heart rate
d. both A and C
13. The ________ is a sensory relay station where
all sensory information, except for smell, goes
before being sent to other areas of the brain for
further processing.
a. amygdala
b. hippocampus
c. hypothalamus
d. thalamus
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14. Damage to the ________ disrupts one’s ability
to comprehend language, but it leaves one’s ability
to produce words intact.
a. amygdala
b. Broca’s Area
c. Wernicke’s Area
d. occipital lobe
15. A(n) ________ uses magnetic fields to create
pictures of a given tissue.
a. EEG
b. MRI
c. PET scan
d. CT scan
16. Which of the following is not a structure of
the forebrain?
a. thalamus
b. hippocampus
c. amygdala
d. substantia nigra
17. The two major hormones secreted from the
pancreas are:
a. estrogen and progesterone
b. norepinephrine and epinephrine
c. thyroxine and oxytocin
d. glucagon and insulin
18. The ________ secretes messenger hormones
that direct the function of the rest of the endocrine
a. ovary
b. thyroid
c. pituitary
d. pancreas
19. The ________ gland secretes epinephrine.
a. adrenal
b. thyroid
c. pituitary
d. master
20. The ________ secretes hormones that regulate
the body’s fluid levels.
a. adrenal
b. pituitary
c. testes
d. thyroid
Critical Thinking Questions
21. The theory of evolution by natural selection requires variability of a given trait. Why is variability
necessary and where does it come from?
22. Cocaine has two effects on synaptic transmission: it impairs reuptake of dopamine and it causes more
dopamine to be released into the synapse. Would cocaine be classified as an agonist or antagonist? Why?
23. Drugs such as lidocaine and novocaine act as Na+ channel blockers. In other words, they prevent
sodium from moving across the neuronal membrane. Why would this particular effect make these drugs
such effective local anesthetics?
24. What are the implications of compromised immune function as a result of exposure to chronic stress?
25. Examine Figure 3.14, illustrating the effects of sympathetic nervous system activation. How would
all of these things play into the fight or flight response?
26. Before the advent of modern imaging techniques, scientists and clinicians relied on autopsies of
people who suffered brain injury with resultant change in behavior to determine how different areas of
the brain were affected. What are some of the limitations associated with this kind of approach?
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27. Which of the techniques discussed would be viable options for you to determine how activity in the
reticular formation is related to sleep and wakefulness? Why?
28. Hormone secretion is often regulated through a negative feedback mechanism, which means that once
a hormone is secreted it will cause the hypothalamus and pituitary to shut down the production of signals
necessary to secrete the hormone in the first place. Most oral contraceptives are made of small doses of
estrogen and/or progesterone. Why would this be an effective means of contraception?
29. Chemical messengers are used in both the nervous system and the endocrine system. What properties
do these two systems share? What properties are different? Which one would be faster? Which one would
result in long-lasting changes?
Personal Application Questions
30. You share half of your genetic makeup with each of your parents, but you are no doubt very different
from both of them. Spend a few minutes jotting down the similarities and differences between you and
your parents. How do you think your unique environment and experiences have contributed to some of
the differences you see?
31. Have you or someone you know ever been prescribed a psychotropic medication? If so, what side
effects were associated with the treatment?
32. Hopefully, you do not face real physical threats from potential predators on a daily basis. However,
you probably have your fair share of stress. What situations are your most common sources of stress? What
can you do to try to minimize the negative consequences of these particular stressors in your life?
33. You read about H. M.’s memory deficits following the bilateral removal of his hippocampus and
amygdala. Have you encountered a character in a book, television program, or movie that suffered
memory deficits? How was that character similar to and different from H. M.?
34. Given the negative health consequences associated with the use of anabolic steroids, what kinds of
considerations might be involved in a person’s decision to use them?
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Chapter 4
States of Consciousness
Figure 4.1 Sleep, which we all experience, is a quiet and mysterious pause in our daily lives. Two sleeping children
are depicted in this 1895 oil painting titled Zwei schlafende Mädchen auf der Ofenbank, which translates as “two
sleeping girls on the stove,” by Swiss painter Albert Anker.
Chapter Outline
4.1 What Is Consciousness?
4.2 Sleep and Why We Sleep
4.3 Stages of Sleep
4.4 Sleep Problems and Disorders
4.5 Substance Use and Abuse
4.6 Other States of Consciousness
Our lives involve regular, dramatic changes in the degree to which we are aware of our surroundings and
our internal states. While awake, we feel alert and aware of the many important things going on around us.
Our experiences change dramatically while we are in deep sleep and once again when we are dreaming.
This chapter will discuss states of consciousness with a particular emphasis on sleep. The different stages
of sleep will be identified, and sleep disorders will be described. The chapter will close with discussions of
altered states of consciousness produced by psychoactive drugs, hypnosis, and meditation.
Chapter 4 | States of Consciousness 111

4.1 What Is Consciousness?
Learning Objectives
By the end of this section, you will be able to:
• Understand what is meant by consciousness
• Explain how circadian rhythms are involved in regulating the sleep-wake cycle, and how
circadian cycles can be disrupted
• Discuss the concept of sleep debt
Consciousness describes our awareness of internal and external stimuli. Awareness of internal stimuli
includes feeling pain, hunger, thirst, sleepiness, and being aware of our thoughts and emotions. Awareness
of external stimuli includes seeing the light from the sun, feeling the warmth of a room, and hearing the
voice of a friend.
We experience different states of consciousness and different levels of awareness on a regular basis. We
might even describe consciousness as a continuum that ranges from full awareness to a deep sleep. Sleep
is a state marked by relatively low levels of physical activity and reduced sensory awareness that is
distinct from periods of rest that occur during wakefulness. Wakefulness is characterized by high levels of
sensory awareness, thought, and behavior. In between these extremes are states of consciousness related
to daydreaming, intoxication as a result of alcohol or other drug use, meditative states, hypnotic states,
and altered states of consciousness following sleep deprivation. We might also experience unconscious
states of being via drug-induced anesthesia for medical purposes. Often, we are not completely aware of
our surroundings, even when we are fully awake. For instance, have you ever daydreamed while driving
home from work or school without really thinking about the drive itself? You were capable of engaging in
the all of the complex tasks involved with operating a motor vehicle even though you were not aware of
doing so. Many of these processes, like much of psychological behavior, are rooted in our biology.
Biological rhythms are internal rhythms of biological activity. A woman’s menstrual cycle is an example
of a biological rhythm—a recurring, cyclical pattern of bodily changes. One complete menstrual cycle
takes about 28 days—a lunar month—but many biological cycles are much shorter. For example, body
temperature fluctuates cyclically over a 24-hour period (Figure 4.2). Alertness is associated with higher
body temperatures, and sleepiness with lower body temperatures.
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Figure 4.2 This chart illustrates the circadian change in body temperature over 28 hours in a group of eight young
men. Body temperature rises throughout the waking day, peaking in the afternoon, and falls during sleep with the
lowest point occurring during the very early morning hours.
This pattern of temperature fluctuation, which repeats every day, is one example of a circadian rhythm. A
circadian rhythm is a biological rhythm that takes place over a period of about 24 hours. Our sleep-wake
cycle, which is linked to our environment’s natural light-dark cycle, is perhaps the most obvious example
of a circadian rhythm, but we also have daily fluctuations in heart rate, blood pressure, blood sugar, and
body temperature. Some circadian rhythms play a role in changes in our state of consciousness.
If we have biological rhythms, then is there some sort of biological clock? In the brain, the hypothalamus,
which lies above the pituitary gland, is a main center of homeostasis. Homeostasis is the tendency to
maintain a balance, or optimal level, within a biological system.
The brain’s clock mechanism is located in an area of the hypothalamus known as the suprachiasmatic
nucleus (SCN). The axons of light-sensitive neurons in the retina provide information to the SCN based on
the amount of light present, allowing this internal clock to be synchronized with the outside world (Klein,
Moore, & Reppert, 1991; Welsh, Takahashi, & Kay, 2010) (Figure 4.3).
Chapter 4 | States of Consciousness 113

Figure 4.3 The suprachiasmatic nucleus (SCN) serves as the brain’s clock mechanism. The clock sets itself with
light information received through projections from the retina.
Generally, and for most people, our circadian cycles are aligned with the outside world. For example, most
people sleep during the night and are awake during the day. One important regulator of sleep-wake cycles
is the hormone melatonin. The pineal gland, an endocrine structure located inside the brain that releases
melatonin, is thought to be involved in the regulation of various biological rhythms and of the immune
system during sleep (Hardeland, Pandi-Perumal, & Cardinali, 2006). Melatonin release is stimulated by
darkness and inhibited by light.
There are individual differences with regards to our sleep-wake cycle. For instance, some people would
say they are morning people, while others would consider themselves to be night owls. These individual
differences in circadian patterns of activity are known as a person’s chronotype, and research
demonstrates that morning larks and night owls differ with regard to sleep regulation (Taillard, Philip,
Coste, Sagaspe, & Bioulac, 2003). Sleep regulation refers to the brain’s control of switching between sleep
and wakefulness as well as coordinating this cycle with the outside world.
Watch this brief video ( describing circadian
rhythms and how they affect sleep.
Disruptions of Normal Sleep
Whether lark, owl, or somewhere in between, there are situations in which a person’s circadian clock gets
out of synchrony with the external environment. One way that this happens involves traveling across
multiple time zones. When we do this, we often experience jet lag. Jet lag is a collection of symptoms that
results from the mismatch between our internal circadian cycles and our environment. These symptoms
include fatigue, sluggishness, irritability, and insomnia (i.e., a consistent difficulty in falling or staying
asleep for at least three nights a week over a month’s time) (Roth, 2007).
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Individuals who do rotating shift work are also likely to experience disruptions in circadian cycles.
Rotating shift work refers to a work schedule that changes from early to late on a daily or weekly
basis. For example, a person may work from 7:00 a.m. to 3:00 p.m. on Monday, 3:00 a.m. to 11:00 a.m.
on Tuesday, and 11:00 a.m. to 7:00 p.m. on Wednesday. In such instances, the individual’s schedule
changes so frequently that it becomes difficult for a normal circadian rhythm to be maintained. This
often results in sleeping problems, and it can lead to signs of depression and anxiety. These kinds of
schedules are common for individuals working in health care professions and service industries, and they
are associated with persistent feelings of exhaustion and agitation that can make someone more prone to
making mistakes on the job (Gold et al., 1992; Presser, 1995).
Rotating shift work has pervasive effects on the lives and experiences of individuals engaged in that
kind of work, which is clearly illustrated in stories reported in a qualitative study that researched the
experiences of middle-aged nurses who worked rotating shifts (West, Boughton & Byrnes, 2009). Several of
the nurses interviewed commented that their work schedules affected their relationships with their family.
One of the nurses said,
If you’ve had a partner who does work regular job 9 to 5 office hours . . . the ability to spend
time, good time with them when you’re not feeling absolutely exhausted . . . that would be one
of the problems that I’ve encountered. (West et al., 2009, p. 114)
While disruptions in circadian rhythms can have negative consequences, there are things we can do to help
us realign our biological clocks with the external environment. Some of these approaches, such as using
a bright light as shown in Figure 4.4, have been shown to alleviate some of the problems experienced by
individuals suffering from jet lag or from the consequences of rotating shift work. Because the biological
clock is driven by light, exposure to bright light during working shifts and dark exposure when not
working can help combat insomnia and symptoms of anxiety and depression (Huang, Tsai, Chen, & Hsu,
Figure 4.4 Devices like this are designed to provide exposure to bright light to help people maintain a regular
circadian cycle. They can be helpful for people working night shifts or for people affected by seasonal variations in
Watch this video ( to hear tips on how to
overcome jet lag.
Insufficient Sleep
When people have difficulty getting sleep due to their work or the demands of day-to-day life, they
Chapter 4 | States of Consciousness 115

accumulate a sleep debt. A person with a sleep debt does not get sufficient sleep on a chronic basis. The
consequences of sleep debt include decreased levels of alertness and mental efficiency. Interestingly, since
the advent of electric light, the amount of sleep that people get has declined. While we certainly welcome
the convenience of having the darkness lit up, we also suffer the consequences of reduced amounts of sleep
because we are more active during the nighttime hours than our ancestors were. As a result, many of us
sleep less than 7–8 hours a night and accrue a sleep debt. While there is tremendous variation in any given
individual’s sleep needs, the National Sleep Foundation (n.d.) cites research to estimate that newborns
require the most sleep (between 12 and 18 hours a night) and that this amount declines to just 7–9 hours
by the time we are adults.
If you lie down to take a nap and fall asleep very easily, chances are you may have sleep debt. Given that
college students are notorious for suffering from significant sleep debt (Hicks, Fernandez, & Pelligrini,
2001; Hicks, Johnson, & Pelligrini, 1992; Miller, Shattuck, & Matsangas, 2010), chances are you and your
classmates deal with sleep debt-related issues on a regular basis. Table 4.1 shows recommended amounts
of sleep at different ages.
Table 4.1 Sleep Needs at Different Ages
Age Nightly Sleep Needs
0–3 months 12–18 hours
3 months–1 year 14–15 hours
1–3 years 12–14 hours
3–5 years 11–13 hours
5–10 years 10–11 hours
10–18 years 8–10 hours
18 and older 7–9 hours
Sleep debt and sleep deprivation have significant negative psychological and physiological consequences
Figure 4.5. As mentioned earlier, lack of sleep can result in decreased mental alertness and cognitive
function. In addition, sleep deprivation often results in depression-like symptoms. These effects can occur
as a function of accumulated sleep debt or in response to more acute periods of sleep deprivation. It may
surprise you to know that sleep deprivation is associated with obesity, increased blood pressure, increased
levels of stress hormones, and reduced immune functioning (Banks & Dinges, 2007). A sleep deprived
individual generally will fall asleep more quickly than if she were not sleep deprived. Some sleep-deprived
individuals have difficulty staying awake when they stop moving (example sitting and watching television
or driving a car). That is why individuals suffering from sleep deprivation can also put themselves and
others at risk when they put themselves behind the wheel of a car or work with dangerous machinery.
Some research suggests that sleep deprivation affects cognitive and motor function as much as, if not more
than, alcohol intoxication (Williamson & Feyer, 2000).
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Figure 4.5 This figure illustrates some of the negative consequences of sleep deprivation. While cognitive deficits
may be the most obvious, many body systems are negatively impacted by lack of sleep. (credit: modification of work
by Mikael Häggström)
To assess your own sleeping habits, read this article (
sleephabits) about sleep needs.
The amount of sleep we get varies across the lifespan. When we are very young, we spend up to 16 hours
a day sleeping. As we grow older, we sleep less. In fact, a meta-analysis, which is a study that combines
the results of many related studies, conducted within the last decade indicates that by the time we are 65
years old, we average fewer than 7 hours of sleep per day (Ohayon, Carskadon, Guilleminault, & Vitiello,
2004). As the amount of time we sleep varies over our lifespan, presumably the sleep debt would adjust
4.2 Sleep and Why We Sleep
Learning Objectives
By the end of this section, you will be able to:
• Describe areas of the brain involved in sleep
• Understand hormone secretions associated with sleep
• Describe several theories aimed at explaining the function of sleep
We spend approximately one-third of our lives sleeping. Given the average life expectancy for U.S. citizens
Chapter 4 | States of Consciousness 117

falls between 73 and 79 years old (Singh & Siahpush, 2006), we can expect to spend approximately 25
years of our lives sleeping. Some animals never sleep (e.g., several fish and amphibian species); other
animals can go extended periods of time without sleep and without apparent negative consequences (e.g.,
dolphins); yet some animals (e.g., rats) die after two weeks of sleep deprivation (Siegel, 2008). Why do we
devote so much time to sleeping? Is it absolutely essential that we sleep? This section will consider these
questions and explore various explanations for why we sleep.
You have read that sleep is distinguished by low levels of physical activity and reduced sensory
awareness. As discussed by Siegel (2008), a definition of sleep must also include mention of the interplay
of the circadian and homeostatic mechanisms that regulate sleep. Homeostatic regulation of sleep is
evidenced by sleep rebound following sleep deprivation. Sleep rebound refers to the fact that a sleep-
deprived individual will tend to take a shorter time to fall asleep during subsequent opportunities for
sleep. Sleep is characterized by certain patterns of activity of the brain that can be visualized using
electroencephalography (EEG), and different phases of sleep can be differentiated using EEG as well
(Figure 4.6).
Figure 4.6 This is a segment of a polysonograph (PSG), a recording of several physical variables during sleep. The
x-axis shows passage of time in seconds; this record includes 30 seconds of data. The location of the sets of
electrode that produced each signal is labeled on the y-axis. The red box encompasses EEG output, and the
waveforms are characteristic of a specific stage of sleep. Other curves show other sleep-related data, such as body
temperature, muscle activity, and heartbeat.
Sleep-wake cycles seem to be controlled by multiple brain areas acting in conjunction with one another.
Some of these areas include the thalamus, the hypothalamus, and the pons. As already mentioned, the
hypothalamus contains the SCN—the biological clock of the body—in addition to other nuclei that, in
conjunction with the thalamus, regulate slow-wave sleep. The pons is important for regulating rapid eye
movement (REM) sleep (National Institutes of Health, n.d.).
Sleep is also associated with the secretion and regulation of a number of hormones from several endocrine
glands including: melatonin, follicle stimulating hormone (FSH), luteinizing hormone (LH), and growth
hormone (National Institutes of Health, n.d.). You have read that the pineal gland releases melatonin
during sleep (Figure 4.7). Melatonin is thought to be involved in the regulation of various biological
rhythms and the immune system (Hardeland et al., 2006). During sleep, the pituitary gland secretes both
FSH and LH which are important in regulating the reproductive system (Christensen et al., 2012; Sofikitis
et al., 2008). The pituitary gland also secretes growth hormone, during sleep, which plays a role in physical
growth and maturation as well as other metabolic processes (Bartke, Sun, & Longo, 2013).
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Figure 4.7 The pineal and pituitary glands secrete a number of hormones during sleep.
Given the central role that sleep plays in our lives and the number of adverse consequences that have been
associated with sleep deprivation, one would think that we would have a clear understanding of why it
is that we sleep. Unfortunately, this is not the case; however, several hypotheses have been proposed to
explain the function of sleep.
Adaptive Function of Sleep
One popular hypothesis of sleep incorporates the perspective of evolutionary psychology. Evolutionary
psychology is a discipline that studies how universal patterns of behavior and cognitive processes have
evolved over time as a result of natural selection. Variations and adaptations in cognition and behavior
make individuals more or less successful in reproducing and passing their genes to their offspring. One
hypothesis from this perspective might argue that sleep is essential to restore resources that are expended
during the day. Just as bears hibernate in the winter when resources are scarce, perhaps people sleep at
night to reduce their energy expenditures. While this is an intuitive explanation of sleep, there is little
research that supports this explanation. In fact, it has been suggested that there is no reason to think that
energetic demands could not be addressed with periods of rest and inactivity (Frank, 2006; Rial et al., 2007),
and some research has actually found a negative correlation between energetic demands and the amount
of time spent sleeping (Capellini, Barton, McNamara, Preston, & Nunn, 2008).
Another evolutionary hypothesis of sleep holds that our sleep patterns evolved as an adaptive response
to predatory risks, which increase in darkness. Thus we sleep in safe areas to reduce the chance of harm.
Again, this is an intuitive and appealing explanation for why we sleep. Perhaps our ancestors spent
extended periods of time asleep to reduce attention to themselves from potential predators. Comparative
research indicates, however, that the relationship that exists between predatory risk and sleep is very
complex and equivocal. Some research suggests that species that face higher predatory risks sleep fewer
hours than other species (Capellini et al., 2008), while other researchers suggest there is no relationship
between the amount of time a given species spends in deep sleep and its predation risk (Lesku, Roth,
Amlaner, & Lima, 2006).
It is quite possible that sleep serves no single universally adaptive function, and different species have
evolved different patterns of sleep in response to their unique evolutionary pressures. While we have
discussed the negative outcomes associated with sleep deprivation, it should be pointed out that there
are many benefits that are associated with adequate amounts of sleep. A few such benefits listed by the
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National Sleep Foundation (n.d.) include maintaining healthy weight, lowering stress levels, improving
mood, and increasing motor coordination, as well as a number of benefits related to cognition and memory
Cognitive Function of Sleep
Another theory regarding why we sleep involves sleep’s importance for cognitive function and memory
formation (Rattenborg, Lesku, Martinez-Gonzalez, & Lima, 2007). Indeed, we know sleep deprivation
results in disruptions in cognition and memory deficits (Brown, 2012), leading to impairments in our
abilities to maintain attention, make decisions, and recall long-term memories. Moreover, these
impairments become more severe as the amount of sleep deprivation increases (Alhola & Polo-Kantola,
2007). Furthermore, slow-wave sleep after learning a new task can improve resultant performance on that
task (Huber, Ghilardi, Massimini, & Tononi, 2004) and seems essential for effective memory formation
(Stickgold, 2005). Understanding the impact of sleep on cognitive function should help you understand
that cramming all night for a test may be not effective and can even prove counterproductive.
Watch this brief video ( describing
sleep deprivation in college students.
Here’s another brief video ( describing
sleep tips for college students.
Sleep has also been associated with other cognitive benefits. Research indicates that included among
these possible benefits are increased capacities for creative thinking (Cai, Mednick, Harrison, Kanady,
& Mednick, 2009; Wagner, Gais, Haider, Verleger, & Born, 2004), language learning (Fenn, Nusbaum, &
Margoliash, 2003; Gómez, Bootzin, & Nadel, 2006), and inferential judgments (Ellenbogen, Hu, Payne,
Titone, & Walker, 2007). It is possible that even the processing of emotional information is influenced by
certain aspects of sleep (Walker, 2009).
Watch this brief video ( describing the
relationship between sleep and memory.
4.3 Stages of Sleep
Learning Objectives
By the end of this section, you will be able to:
• Differentiate between REM and non-REM sleep
• Describe the differences between the four stages of non-REM sleep
• Understand the role that REM and non-REM sleep play in learning and memory
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Sleep is not a uniform state of being. Instead, sleep is composed of several different stages that can
be differentiated from one another by the patterns of brain wave activity that occur during each stage.
These changes in brain wave activity can be visualized using EEG and are distinguished from one
another by both the frequency and amplitude of brain waves (Figure 4.8). Sleep can be divided into
two different general phases: REM sleep and non-REM (NREM) sleep. Rapid eye movement (REM)
sleep is characterized by darting movements of the eyes under closed eyelids. Brain waves during REM
sleep appear very similar to brain waves during wakefulness. In contrast, non-REM (NREM) sleep is
subdivided into four stages distinguished from each other and from wakefulness by characteristic patterns
of brain waves. The first four stages of sleep are NREM sleep, while the fifth and final stage of sleep is REM
sleep. In this section, we will discuss each of these stages of sleep and their associated patterns of brain
wave activity.
Figure 4.8 Brainwave activity changes dramatically across the different stages of sleep. (credit “sleeping”:
modification of work by Ryan Vaarsi)
The first stage of NREM sleep is known as stage 1 sleep. Stage 1 sleep is a transitional phase that occurs
between wakefulness and sleep, the period during which we drift off to sleep. During this time, there is
a slowdown in both the rates of respiration and heartbeat. In addition, stage 1 sleep involves a marked
decrease in both overall muscle tension and core body temperature.
In terms of brain wave activity, stage 1 sleep is associated with both alpha and theta waves. The early
portion of stage 1 sleep produces alpha waves, which are relatively low frequency (8–13Hz), high
amplitude patterns of electrical activity (waves) that become synchronized (Figure 4.9). This pattern of
brain wave activity resembles that of someone who is very relaxed, yet awake. As an individual continues
through stage 1 sleep, there is an increase in theta wave activity. Theta waves are even lower frequency
(4–7 Hz), higher amplitude brain waves than alpha waves. It is relatively easy to wake someone from stage
1 sleep; in fact, people often report that they have not been asleep if they are awoken during stage 1 sleep.
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Figure 4.9 Brainwave activity changes dramatically across the different stages of sleep.
As we move into stage 2 sleep, the body goes into a state of deep relaxation. Theta waves still dominate
the activity of the brain, but they are interrupted by brief bursts of activity known as sleep spindles
(Figure 4.10). A sleep spindle is a rapid burst of higher frequency brain waves that may be important for
learning and memory (Fogel & Smith, 2011; Poe, Walsh, & Bjorness, 2010). In addition, the appearance of
K-complexes is often associated with stage 2 sleep. A K-complex is a very high amplitude pattern of brain
activity that may in some cases occur in response to environmental stimuli. Thus, K-complexes might serve
as a bridge to higher levels of arousal in response to what is going on in our environments (Halász, 1993;
Steriade & Amzica, 1998).
Figure 4.10 Stage 2 sleep is characterized by the appearance of both sleep spindles and K-complexes.
Stage 3 and stage 4 of sleep are often referred to as deep sleep or slow-wave sleep because these stages
are characterized by low frequency (up to 4 Hz), high amplitude delta waves (Figure 4.11). During this
time, an individual’s heart rate and respiration slow dramatically. It is much more difficult to awaken
someone from sleep during stage 3 and stage 4 than during earlier stages. Interestingly, individuals who
have increased levels of alpha brain wave activity (more often associated with wakefulness and transition
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into stage 1 sleep) during stage 3 and stage 4 often report that they do not feel refreshed upon waking,
regardless of how long they slept (Stone, Taylor, McCrae, Kalsekar, & Lichstein, 2008).
Figure 4.11 (a) Delta waves, which are low frequency and high amplitude, characterize (b) slow-wave stage 3 and
stage 4 sleep.
As mentioned earlier, REM sleep is marked by rapid movements of the eyes. The brain waves associated
with this stage of sleep are very similar to those observed when a person is awake, as shown in Figure
4.12, and this is the period of sleep in which dreaming occurs. It is also associated with paralysis of muscle
systems in the body with the exception of those that make circulation and respiration possible. Therefore,
no movement of voluntary muscles occurs during REM sleep in a normal individual; REM sleep is often
referred to as paradoxical sleep because of this combination of high brain activity and lack of muscle tone.
Like NREM sleep, REM has been implicated in various aspects of learning and memory (Wagner, Gais,
& Born, 2001), although there is disagreement within the scientific community about how important both
NREM and REM sleep are for normal learning and memory (Siegel, 2001).
Figure 4.12 (a) A period of rapid eye movement is marked by the short red line segment. The brain waves
associated with REM sleep, outlined in the red box in (a), look very similar to those seen (b) during wakefulness.
If people are deprived of REM sleep and then allowed to sleep without disturbance, they will spend more
time in REM sleep in what would appear to be an effort to recoup the lost time in REM. This is known as
the REM rebound, and it suggests that REM sleep is also homeostatically regulated. Aside from the role
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that REM sleep may play in processes related to learning and memory, REM sleep may also be involved in
emotional processing and regulation. In such instances, REM rebound may actually represent an adaptive
response to stress in nondepressed individuals by suppressing the emotional salience of aversive events
that occurred in wakefulness (Suchecki, Tiba, & Machado, 2012).
While sleep deprivation in general is associated with a number of negative consequences (Brown, 2012),
the consequences of REM deprivation appear to be less profound (as discussed in Siegel, 2001). In fact,
some have suggested that REM deprivation can actually be beneficial in some circumstances. For instance,
REM sleep deprivation has been demonstrated to improve symptoms of people suffering from major
depression, and many effective antidepressant medications suppress REM sleep (Riemann, Berger, &
Volderholzer, 2001; Vogel, 1975).
It should be pointed out that some reviews of the literature challenge this finding, suggesting that sleep
deprivation that is not limited to REM sleep is just as effective or more effective at alleviating depressive
symptoms among some patients suffering from depression. In either case, why sleep deprivation improves
the mood of some patients is not entirely understood (Giedke & Schwärzler, 2002). Recently, however,
some have suggested that sleep deprivation might change emotional processing so that various stimuli are
more likely to be perceived as positive in nature (Gujar, Yoo, Hu, & Walker, 2011). The hypnogram below
(Figure 4.13) shows a person’s passage through the stages of sleep.
Figure 4.13 A hypnogram is a diagram of the stages of sleep as they occur during a period of sleep. This
hypnogram illustrates how an individual moves through the various stages of sleep.
View this video ( that describes the
various stages of sleep.
The meaning of dreams varies across different cultures and periods of time. By the late 19th century,
German psychiatrist Sigmund Freud had become convinced that dreams represented an opportunity to
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gain access to the unconscious. By analyzing dreams, Freud thought people could increase self-awareness
and gain valuable insight to help them deal with the problems they faced in their lives. Freud made
distinctions between the manifest content and the latent content of dreams. Manifest content is the actual
content, or storyline, of a dream. Latent content, on the other hand, refers to the hidden meaning of a
dream. For instance, if a woman dreams about being chased by a snake, Freud might have argued that this
represents the woman’s fear of sexual intimacy, with the snake serving as a symbol of a man’s penis.
Freud was not the only theorist to focus on the content of dreams. The 20th century Swiss psychiatrist Carl
Jung believed that dreams allowed us to tap into the collective unconscious. The collective unconscious,
as described by Jung, is a theoretical repository of information he believed to be shared by everyone.
According to Jung, certain symbols in dreams reflected universal archetypes with meanings that are
similar for all people regardless of culture or location.
The sleep and dreaming researcher Rosalind Cartwright, however, believes that dreams simply reflect life
events that are important to the dreamer. Unlike Freud and Jung, Cartwright’s ideas about dreaming have
found empirical support. For example, she and her colleagues published a study in which women going
through divorce were asked several times over a five month period to report the degree to which their
former spouses were on their minds. These same women were awakened during REM sleep in order to
provide a detailed account of their dream content. There was a significant positive correlation between the
degree to which women thought about their former spouses during waking hours and the number of times
their former spouses appeared as characters in their dreams (Cartwright, Agargun, Kirkby, & Friedman,
2006). Recent research (Horikawa, Tamaki, Miyawaki, & Kamitani, 2013) has uncovered new techniques
by which researchers may effectively detect and classify the visual images that occur during dreaming by
using fMRI for neural measurement of brain activity patterns, opening the way for additional research in
this area.
Recently, neuroscientists have also become interested in understanding why we dream. For example,
Hobson (2009) suggests that dreaming may represent a state of protoconsciousness. In other words,
dreaming involves constructing a virtual reality in our heads that we might use to help us during
wakefulness. Among a variety of neurobiological evidence, John Hobson cites research on lucid dreams
as an opportunity to better understand dreaming in general. Lucid dreams are dreams in which certain
aspects of wakefulness are maintained during a dream state. In a lucid dream, a person becomes aware of
the fact that they are dreaming, and as such, they can control the dream’s content (LaBerge, 1990).
4.4 Sleep Problems and Disorders
Learning Objectives
By the end of this section, you will be able to:
• Describe the symptoms and treatments of insomnia
• Recognize the symptoms of several parasomnias
• Describe the symptoms and treatments for sleep apnea
• Recognize risk factors associated with sudden infant death syndrome (SIDS) and steps to
prevent it
• Describe the symptoms and treatments for narcolepsy
Many people experience disturbances in their sleep at some point in their lives. Depending on the
population and sleep disorder being studied, between 30% and 50% of the population suffers from a sleep
disorder at some point in their lives (Bixler, Kales, Soldatos, Kaels, & Healey, 1979; Hossain & Shapiro,
2002; Ohayon, 1997, 2002; Ohayon & Roth, 2002). This section will describe several sleep disorders as well
as some of their treatment options.
Chapter 4 | States of Consciousness 125

Insomnia, a consistent difficulty in falling or staying asleep, is the most common of the sleep disorders.
Individuals with insomnia often experience long delays between the times that they go to bed and actually
fall asleep. In addition, these individuals may wake up several times during the night only to find that
they have difficulty getting back to sleep. As mentioned earlier, one of the criteria for insomnia involves
experiencing these symptoms for at least three nights a week for at least one month’s time (Roth, 2007).
It is not uncommon for people suffering from insomnia to experience increased levels of anxiety about
their inability to fall asleep. This becomes a self-perpetuating cycle because increased anxiety leads to
increased arousal, and higher levels of arousal make the prospect of falling asleep even more unlikely.
Chronic insomnia is almost always associated with feeling overtired and may be associated with
symptoms of depression.
There may be many factors that contribute to insomnia, including age, drug use, exercise, mental status,
and bedtime routines. Not surprisingly, insomnia treatment may take one of several different approaches.
People who suffer from insomnia might limit their use of stimulant drugs (such as caffeine) or increase
their amount of physical exercise during the day. Some people might turn to over-the-counter (OTC) or
prescribed sleep medications to help them sleep, but this should be done sparingly because many sleep
medications result in dependence and alter the nature of the sleep cycle, and they can increase insomnia
over time. Those who continue to have insomnia, particularly if it affects their quality of life, should seek
professional treatment.
Some forms of psychotherapy, such as cognitive-behavioral therapy, can help sufferers of insomnia.
Cognitive-behavioral therapy is a type of psychotherapy that focuses on cognitive processes and problem
behaviors. The treatment of insomnia likely would include stress management techniques and changes
in problematic behaviors that could contribute to insomnia (e.g., spending more waking time in bed).
Cognitive-behavioral therapy has been demonstrated to be quite effective in treating insomnia (Savard,
Simard, Ivers, & Morin, 2005; Williams, Roth, Vatthauer, & McCrae, 2013).
A parasomnia is one of a group of sleep disorders in which unwanted, disruptive motor activity and/
or experiences during sleep play a role. Parasomnias can occur in either REM or NREM phases of sleep.
Sleepwalking, restless leg syndrome, and night terrors are all examples of parasomnias (Mahowald &
Schenck, 2000).
In sleepwalking, or somnambulism, the sleeper engages in relatively complex behaviors ranging from
wandering about to driving an automobile. During periods of sleepwalking, sleepers often have their eyes
open, but they are not responsive to attempts to communicate with them. Sleepwalking most often occurs
during slow-wave sleep, but it can occur at any time during a sleep period in some affected individuals
(Mahowald & Schenck, 2000).
Historically, somnambulism has been treated with a variety of pharmacotherapies ranging from
benzodiazepines to antidepressants. However, the success rate of such treatments is questionable.
Guilleminault et al. (2005) found that sleepwalking was not alleviated with the use of benzodiazepines.
However, all of their somnambulistic patients who also suffered from sleep-related breathing problems
showed a marked decrease in sleepwalking when their breathing problems were effectively treated.
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A Sleepwalking Defense?
On January 16, 1997, Scott Falater sat down to dinner with his wife and children and told them about difficulties
he was experiencing on a project at work. After dinner, he prepared some materials to use in leading a church
youth group the following morning, and then he attempted repair the family’s swimming pool pump before
retiring to bed. The following morning, he awoke to barking dogs and unfamiliar voices from downstairs. As
he went to investigate what was going on, he was met by a group of police officers who arrested him for the
murder of his wife (Cartwright, 2004; CNN, 1999).
Yarmila Falater’s body was found in the family’s pool with 44 stab wounds. A neighbor called the police after
witnessing Falater standing over his wife’s body before dragging her into the pool. Upon a search of the
premises, police found blood-stained clothes and a bloody knife in the trunk of Falater’s car, and he had blood
stains on his neck.
Remarkably, Falater insisted that he had no recollection of hurting his wife in any way. His children and his
wife’s parents all agreed that Falater had an excellent relationship with his wife and they couldn’t think of a
reason that would provide any sort of motive to murder her (Cartwright, 2004).
Scott Falater had a history of regular episodes of sleepwalking as a child, and he had even behaved violently
toward his sister once when she tried to prevent him from leaving their home in his pajamas during a
sleepwalking episode. He suffered from no apparent anatomical brain anomalies or psychological disorders. It
appeared that Scott Falater had killed his wife in his sleep, or at least, that is the defense he used when he
was tried for his wife’s murder (Cartwright, 2004; CNN, 1999). In Falater’s case, a jury found him guilty of first
degree murder in June of 1999 (CNN, 1999); however, there are other murder cases where the sleepwalking
defense has been used successfully. As scary as it sounds, many sleep researchers believe that homicidal
sleepwalking is possible in individuals suffering from the types of sleep disorders described below (Broughton
et al., 1994; Cartwright, 2004; Mahowald, Schenck, & Cramer Bornemann, 2005; Pressman, 2007).
REM Sleep Behavior Disorder (RBD)
REM sleep behavior disorder (RBD) occurs when the muscle paralysis associated with the REM sleep
phase does not occur. Individuals who suffer from RBD have high levels of physical activity during REM
sleep, especially during disturbing dreams. These behaviors vary widely, but they can include kicking,
punching, scratching, yelling, and behaving like an animal that has been frightened or attacked. People
who suffer from this disorder can injure themselves or their sleeping partners when engaging in these
behaviors. Furthermore, these types of behaviors ultimately disrupt sleep, although affected individuals
have no memories that these behaviors have occurred (Arnulf, 2012).
This disorder is associated with a number of neurodegenerative diseases such as Parkinson’s disease. In
fact, this relationship is so robust that some view the presence of RBD as a potential aid in the diagnosis
and treatment of a number of neurodegenerative diseases (Ferini-Strambi, 2011). Clonazepam, an anti-
anxiety medication with sedative properties, is most often used to treat RBD. It is administered alone or
in conjunction with doses of melatonin (the hormone secreted by the pineal gland). As part of treatment,
the sleeping environment is often modified to make it a safer place for those suffering from RBD (Zangini,
Calandra-Buonaura, Grimaldi, & Cortelli, 2011).
Other Parasomnias
A person with restless leg syndrome has uncomfortable sensations in the legs during periods of inactivity
or when trying to fall asleep. This discomfort is relieved by deliberately moving the legs, which, not
surprisingly, contributes to difficulty in falling or staying asleep. Restless leg syndrome is quite common
and has been associated with a number of other medical diagnoses, such as chronic kidney disease and
diabetes (Mahowald & Schenck, 2000). There are a variety of drugs that treat restless leg syndrome:
Chapter 4 | States of Consciousness 127

benzodiazepines, opiates, and anticonvulsants (Restless Legs Syndrome Foundation, n.d.).
Night terrors result in a sense of panic in the sufferer and are often accompanied by screams and attempts
to escape from the immediate environment (Mahowald & Schenck, 2000). Although individuals suffering
from night terrors appear to be awake, they generally have no memories of the events that occurred, and
attempts to console them are ineffective. Typically, individuals suffering from night terrors will fall back
asleep again within a short time. Night terrors apparently occur during the NREM phase of sleep (Provini,
Tinuper, Bisulli, & Lagaresi, 2011). Generally, treatment for night terrors is unnecessary unless there is
some underlying medical or psychological condition that is contributing to the night terrors (Mayo Clinic,
Sleep apnea is defined by episodes during which a sleeper’s breathing stops. These episodes can last 10–20
seconds or longer and often are associated with brief periods of arousal. While individuals suffering from
sleep apnea may not be aware of these repeated disruptions in sleep, they do experience increased levels of
fatigue. Many individuals diagnosed with sleep apnea first seek treatment because their sleeping partners
indicate that they snore loudly and/or stop breathing for extended periods of time while sleeping (Henry
& Rosenthal, 2013). Sleep apnea is much more common in overweight people and is often associated
with loud snoring. Surprisingly, sleep apnea may exacerbate cardiovascular disease (Sánchez-de-la-Torre,
Campos-Rodriguez, & Barbé, 2012). While sleep apnea is less common in thin people, anyone, regardless
of their weight, who snores loudly or gasps for air while sleeping, should be checked for sleep apnea.
While people are often unaware of their sleep apnea, they are keenly aware of some of the adverse
consequences of insufficient sleep. Consider a patient who believed that as a result of his sleep apnea he
“had three car accidents in six weeks. They were ALL my fault. Two of them I didn’t even know I was
involved in until afterwards” (Henry & Rosenthal, 2013, p. 52). It is not uncommon for people suffering
from undiagnosed or untreated sleep apnea to fear that their careers will be affected by the lack of sleep,
illustrated by this statement from another patient, “I’m in a job where there’s a premium on being mentally
alert. I was really sleepy… and having trouble concentrating…. It was getting to the point where it was
kind of scary” (Henry & Rosenthal, 2013, p. 52).
There are two types of sleep apnea: obstructive sleep apnea and central sleep apnea. Obstructive sleep
apnea occurs when an individual’s airway becomes blocked during sleep, and air is prevented from
entering the lungs. In central sleep apnea, disruption in signals sent from the brain that regulate breathing
cause periods of interrupted breathing (White, 2005).
One of the most common treatments for sleep apnea involves the use of a special device during sleep.
A continuous positive airway pressure (CPAP) device includes a mask that fits over the sleeper’s nose
and mouth, which is connected to a pump that pumps air into the person’s airways, forcing them to
remain open, as shown in Figure 4.14. Some newer CPAP masks are smaller and cover only the nose.
This treatment option has proven to be effective for people suffering from mild to severe cases of sleep
apnea (McDaid et al., 2009). However, alternative treatment options are being explored because consistent
compliance by users of CPAP devices is a problem. Recently, a new EPAP (expiratory positive air pressure)
device has shown promise in double-blind trials as one such alternative (Berry, Kryger, & Massie, 2011).
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Figure 4.14 (a) A typical CPAP device used in the treatment of sleep apnea is (b) affixed to the head with straps,
and a mask that covers the nose and mouth.
In sudden infant death syndrome (SIDS) an infant stops breathing during sleep and dies. Infants younger
than 12 months appear to be at the highest risk for SIDS, and boys have a greater risk than girls. A number
of risk factors have been associated with SIDS including premature birth, smoking within the home, and
hyperthermia. There may also be differences in both brain structure and function in infants that die from
SIDS (Berkowitz, 2012; Mage & Donner, 2006; Thach, 2005).
The substantial amount of research on SIDS has led to a number of recommendations to parents to protect
their children (Figure 4.15). For one, research suggests that infants should be placed on their backs when
put down to sleep, and their cribs should not contain any items which pose suffocation threats, such as
blankets, pillows or padded crib bumpers (cushions that cover the bars of a crib). Infants should not have
caps placed on their heads when put down to sleep in order to prevent overheating, and people in the
child’s household should abstain from smoking in the home. Recommendations like these have helped
to decrease the number of infant deaths from SIDS in recent years (Mitchell, 2009; Task Force on Sudden
Infant Death Syndrome, 2011).
Figure 4.15 The Safe to Sleep campaign educates the public about how to minimize risk factors associated with
SIDS. This campaign is sponsored in part by the National Institute of Child Health and Human Development.
Unlike the other sleep disorders described in this section, a person with narcolepsy cannot resist falling
asleep at inopportune times. These sleep episodes are often associated with cataplexy, which is a lack of
muscle tone or muscle weakness, and in some cases involves complete paralysis of the voluntary muscles.
This is similar to the kind of paralysis experienced by healthy individuals during REM sleep (Burgess
& Scammell, 2012; Hishikawa & Shimizu, 1995; Luppi et al., 2011). Narcoleptic episodes take on other
features of REM sleep. For example, around one third of individuals diagnosed with narcolepsy experience
vivid, dream-like hallucinations during narcoleptic attacks (Chokroverty, 2010).
Surprisingly, narcoleptic episodes are often triggered by states of heightened arousal or stress. The typical
episode can last from a minute or two to half an hour. Once awakened from a narcoleptic attack, people
report that they feel refreshed (Chokroverty, 2010). Obviously, regular narcoleptic episodes could interfere
with the ability to perform one’s job or complete schoolwork, and in some situations, narcolepsy can result
Chapter 4 | States of Consciousness 129

in significant harm and injury (e.g., driving a car or operating machinery or other potentially dangerous
Generally, narcolepsy is treated using psychomotor stimulant drugs, such as amphetamines (Mignot,
2012). These drugs promote increased levels of neural activity. Narcolepsy is associated with reduced
levels of the signaling molecule hypocretin in some areas of the brain (De la Herrán-Arita & Drucker-Colín,
2012; Han, 2012), and the traditional stimulant drugs do not have direct effects on this system. Therefore,
it is quite likely that new medications that are developed to treat narcolepsy will be designed to target the
hypocretin system.
There is a tremendous amount of variability among sufferers, both in terms of how symptoms of
narcolepsy manifest and the effectiveness of currently available treatment options. This is illustrated by
McCarty’s (2010) case study of a 50-year-old woman who sought help for the excessive sleepiness during
normal waking hours that she had experienced for several years. She indicated that she had fallen asleep
at inappropriate or dangerous times, including while eating, while socializing with friends, and while
driving her car. During periods of emotional arousal, the woman complained that she felt some weakness
in the right side of her body. Although she did not experience any dream-like hallucinations, she was
diagnosed with narcolepsy as a result of sleep testing. In her case, the fact that her cataplexy was confined
to the right side of her body was quite unusual. Early attempts to treat her condition with a stimulant
drug alone were unsuccessful. However, when a stimulant drug was used in conjunction with a popular
antidepressant, her condition improved dramatically.
4.5 Substance Use and Abuse
Learning Objectives
By the end of this section, you will be able to:
• Describe the diagnostic criteria for substance use disorders
• Identify the neurotransmitter systems affected by various categories of drugs
• Describe how different categories of drugs effect behavior and experience
While we all experience altered states of consciousness in the form of sleep on a regular basis, some
people use drugs and other substances that result in altered states of consciousness as well. This section
will present information relating to the use of various psychoactive drugs and problems associated with
such use. This will be followed by brief descriptions of the effects of some of the more well-known drugs
commonly used today.
The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) is used by
clinicians to diagnose individuals suffering from various psychological disorders. Drug use disorders are
addictive disorders, and the criteria for specific substance (drug) use disorders are described in DSM-5. A
person who has a substance use disorder often uses more of the substance than they originally intended to
and continues to use that substance despite experiencing significant adverse consequences. In individuals
diagnosed with a substance use disorder, there is a compulsive pattern of drug use that is often associated
with both physical and psychological dependence.
Physical dependence involves changes in normal bodily functions—the user will experience withdrawal
from the drug upon cessation of use. In contrast, a person who has psychological dependence has an
emotional, rather than physical, need for the drug and may use the drug to relieve psychological distress.
Tolerance is linked to physiological dependence, and it occurs when a person requires more and more
drug to achieve effects previously experienced at lower doses. Tolerance can cause the user to increase the
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amount of drug used to a dangerous level—even to the point of overdose and death.
Drug withdrawal includes a variety of negative symptoms experienced when drug use is discontinued.
These symptoms usually are opposite of the effects of the drug. For example, withdrawal from sedative
drugs often produces unpleasant arousal and agitation. In addition to withdrawal, many individuals who
are diagnosed with substance use disorders will also develop tolerance to these substances. Psychological
dependence, or drug craving, is a recent addition to the diagnostic criteria for substance use disorder in
DSM-5. This is an important factor because we can develop tolerance and experience withdrawal from any
number of drugs that we do not abuse. In other words, physical dependence in and of itself is of limited
utility in determining whether or not someone has a substance use disorder.
The effects of all psychoactive drugs occur through their interactions with our endogenous
neurotransmitter systems. Many of these drugs, and their relationships, are shown in Figure 4.16. As you
have learned, drugs can act as agonists or antagonists of a given neurotransmitter system. An agonist
facilitates the activity of a neurotransmitter system, and antagonists impede neurotransmitter activity.
Figure 4.16 This figure illustrates various drug categories and overlap among them. (credit: modification of work by
Derrick Snider)
Alcohol and Other Depressants
Ethanol, which we commonly refer to as alcohol, is in a class of psychoactive drugs known as depressants
Chapter 4 | States of Consciousness 131

(Figure 4.17). A depressant is a drug that tends to suppress central nervous system activity. Other
depressants include barbiturates and benzodiazepines. These drugs share in common their ability to serve
as agonists of the gamma-Aminobutyric acid (GABA) neurotransmitter system. Because GABA has a
quieting effect on the brain, GABA agonists also have a quieting effect; these types of drugs are often
prescribed to treat both anxiety and insomnia.
Figure 4.17 The GABA-gated chloride (Cl-) channel is embedded in the cell membrane of certain neurons. The
channel has multiple receptor sites where alcohol, barbiturates, and benzodiazepines bind to exert their effects. The
binding of these molecules opens the chloride channel, allowing negatively-charged chloride ions (Cl-) into the
neuron’s cell body. Changing its charge in a negative direction pushes the neuron away from firing; thus, activating a
GABA neuron has a quieting effect on the brain.
Acute alcohol administration results in a variety of changes to consciousness. At rather low doses, alcohol
use is associated with feelings of euphoria. As the dose increases, people report feeling sedated. Generally,
alcohol is associated with decreases in reaction time and visual acuity, lowered levels of alertness, and
reduction in behavioral control. With excessive alcohol use, a person might experience a complete loss of
consciousness and/or difficulty remembering events that occurred during a period of intoxication (McKim
& Hancock, 2013). In addition, if a pregnant woman consumes alcohol, her infant may be born with a
cluster of birth defects and symptoms collectively called fetal alcohol spectrum disorder (FASD) or fetal
alcohol syndrome (FAS).
With repeated use of many central nervous system depressants, such as alcohol, a person becomes
physically dependent upon the substance and will exhibit signs of both tolerance and withdrawal.
Psychological dependence on these drugs is also possible. Therefore, the abuse potential of central nervous
system depressants is relatively high.
Drug withdrawal is usually an aversive experience, and it can be a life-threatening process in individuals
who have a long history of very high doses of alcohol and/or barbiturates. This is of such concern
that people who are trying to overcome addiction to these substances should only do so under medical
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Stimulants are drugs that tend to increase overall levels of neural activity. Many of these drugs act as
agonists of the dopamine neurotransmitter system. Dopamine activity is often associated with reward
and craving; therefore, drugs that affect dopamine neurotransmission often have abuse liability. Drugs in
this category include cocaine, amphetamines (including methamphetamine), cathinones (i.e., bath salts),
MDMA (ecstasy), nicotine, and caffeine.
Cocaine can be taken in multiple ways. While many users snort cocaine, intravenous injection and
ingestion are also common. The freebase version of cocaine, known as crack, is a potent, smokable version
of the drug. Like many other stimulants, cocaine agonizes the dopamine neurotransmitter system by
blocking the reuptake of dopamine in the neuronal synapse.
Crack Cocaine
Crack (Figure 4.18) is often considered to be more addictive than cocaine itself because it is smokable and
reaches the brain very quickly. Crack is often less expensive than other forms of cocaine; therefore, it tends
to be a more accessible drug for individuals from impoverished segments of society. During the 1980s, many
drug laws were rewritten to punish crack users more severely than cocaine users. This led to discriminatory
sentencing with low-income, inner-city minority populations receiving the harshest punishments. The wisdom
of these laws has recently been called into question, especially given research that suggests crack may not be
more addictive than other forms of cocaine, as previously thought (Haasen & Krausz, 2001; Reinerman, 2007).
Figure 4.18 Crack rocks like these are smoked to achieve a high. Compared with other routes of
administration, smoking a drug allows it to enter the brain more rapidly, which can often enhance the user’s
experience. (credit: modification of work by U.S. Department of Justice)
Read this interesting newspaper article (
describing myths about crack cocaine.
Amphetamines have a mechanism of action quite similar to cocaine in that they block the reuptake of
dopamine in addition to stimulating its release (Figure 4.19). While amphetamines are often abused, they
Chapter 4 | States of Consciousness 133

are also commonly prescribed to children diagnosed with attention deficit hyperactivity disorder (ADHD).
It may seem counterintuitive that stimulant medications are prescribed to treat a disorder that involves
hyperactivity, but the therapeutic effect comes from increases in neurotransmitter activity within certain
areas of the brain associated with impulse control.
Figure 4.19 As one of their mechanisms of action, cocaine and amphetamines block the reuptake of dopamine from
the synapse into the presynaptic cell.
In recent years, methamphetamine (meth) use has become increasingly widespread. Methamphetamine
is a type of amphetamine that can be made from ingredients that are readily available (e.g., medications
containing pseudoephedrine, a compound found in many over-the-counter cold and flu remedies).
Despite recent changes in laws designed to make obtaining pseudoephedrine more difficult,
methamphetamine continues to be an easily accessible and relatively inexpensive drug option (Shukla,
Crump, & Chrisco, 2012).
The cocaine, amphetamine, cathinones, and MDMA users seek a euphoric high, feelings of intense
elation and pleasure, especially in those users who take the drug via intravenous injection or smoking.
Repeated use of these stimulants can have significant adverse consequences. Users can experience physical
symptoms that include nausea, elevated blood pressure, and increased heart rate. In addition, these
drugs can cause feelings of anxiety, hallucinations, and paranoia (Fiorentini et al., 2011). Normal brain
functioning is altered after repeated use of these drugs. For example, repeated use can lead to overall
depletion among the monoamine neurotransmitters (dopamine, norepinephrine, and serotonin). People
may engage in compulsive use of these stimulant substances in part to try to reestablish normal levels of
these neurotransmitters (Jayanthi & Ramamoorthy, 2005; Rothman, Blough, & Baumann, 2007).
Caffeine is another stimulant drug. While it is probably the most commonly used drug in the world, the
potency of this particular drug pales in comparison to the other stimulant drugs described in this section.
Generally, people use caffeine to maintain increased levels of alertness and arousal. Caffeine is found in
many common medicines (such as weight loss drugs), beverages, foods, and even cosmetics (Herman &
Herman, 2013). While caffeine may have some indirect effects on dopamine neurotransmission, its primary
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mechanism of action involves antagonizing adenosine activity (Porkka-Heiskanen, 2011).
While caffeine is generally considered a relatively safe drug, high blood levels of caffeine can result
in insomnia, agitation, muscle twitching, nausea, irregular heartbeat, and even death (Reissig, Strain, &
Griffiths, 2009; Wolt, Ganetsky, & Babu, 2012). In 2012, Kromann and Nielson reported on a case study of
a 40-year-old woman who suffered significant ill effects from her use of caffeine. The woman used caffeine
in the past to boost her mood and to provide energy, but over the course of several years, she increased
her caffeine consumption to the point that she was consuming three liters of soda each day. Although she
had been taking a prescription antidepressant, her symptoms of depression continued to worsen and she
began to suffer physically, displaying significant warning signs of cardiovascular disease and diabetes.
Upon admission to an outpatient clinic for treatment of mood disorders, she met all of the diagnostic
criteria for substance dependence and was advised to dramatically limit her caffeine intake. Once she was
able to limit her use to less than 12 ounces of soda a day, both her mental and physical health gradually
improved. Despite the prevalence of caffeine use and the large number of people who confess to suffering
from caffeine addiction, this was the first published description of soda dependence appearing in scientific
Nicotine is highly addictive, and the use of tobacco products is associated with increased risks of heart
disease, stroke, and a variety of cancers. Nicotine exerts its effects through its interaction with acetylcholine
receptors. Acetylcholine functions as a neurotransmitter in motor neurons. In the central nervous system,
it plays a role in arousal and reward mechanisms. Nicotine is most commonly used in the form of
tobacco products like cigarettes or chewing tobacco; therefore, there is a tremendous interest in developing
effective smoking cessation techniques. To date, people have used a variety of nicotine replacement
therapies in addition to various psychotherapeutic options in an attempt to discontinue their use of
tobacco products. In general, smoking cessation programs may be effective in the short term, but it is
unclear whether these effects persist (Cropley, Theadom, Pravettoni, & Webb, 2008; Levitt, Shaw, Wong,
& Kaczorowski, 2007; Smedslund, Fisher, Boles, & Lichtenstein, 2004).
An opioid is one of a category of drugs that includes heroin, morphine, methadone, and codeine. Opioids
have analgesic properties; that is, they decrease pain. Humans have an endogenous opioid
neurotransmitter system—the body makes small quantities of opioid compounds that bind to opioid
receptors reducing pain and producing euphoria. Thus, opioid drugs, which mimic this endogenous
painkilling mechanism, have an extremely high potential for abuse. Natural opioids, called opiates, are
derivatives of opium, which is a naturally occurring compound found in the poppy plant. There are
now several synthetic versions of opiate drugs (correctly called opioids) that have very potent painkilling
effects, and they are often abused. For example, the National Institutes of Drug Abuse has sponsored
research that suggests the misuse and abuse of the prescription pain killers hydrocodone and oxycodone
are significant public health concerns (Maxwell, 2006). In 2013, the U.S. Food and Drug Administration
recommended tighter controls on their medical use.
Historically, heroin has been a major opioid drug of abuse (Figure 4.20). Heroin can be snorted, smoked,
or injected intravenously. Like the stimulants described earlier, the use of heroin is associated with an
initial feeling of euphoria followed by periods of agitation. Because heroin is often administered via
intravenous injection, users often bear needle track marks on their arms and, like all abusers of intravenous
drugs, have an increased risk for contraction of both tuberculosis and HIV.
Chapter 4 | States of Consciousness 135

Figure 4.20 (a) Common paraphernalia for heroin preparation and use are shown here in a needle exchange kit. (b)
Heroin is cooked on a spoon over a candle. (credit a: modification of work by Todd Huffman)
Aside from their utility as analgesic drugs, opioid-like compounds are often found in cough suppressants,
anti-nausea, and anti-diarrhea medications. Given that withdrawal from a drug often involves an
experience opposite to the effect of the drug, it should be no surprise that opioid withdrawal resembles
a severe case of the flu. While opioid withdrawal can be extremely unpleasant, it is not life-threatening
(Julien, 2005). Still, people experiencing opioid withdrawal may be given methadone to make withdrawal
from the drug less difficult. Methadone is a synthetic opioid that is less euphorigenic than heroin and
similar drugs. Methadone clinics help people who previously struggled with opioid addiction manage
withdrawal symptoms through the use of methadone. Other drugs, including the opioid buprenorphine,
have also been used to alleviate symptoms of opiate withdrawal.
Codeine is an opioid with relatively low potency. It is often prescribed for minor pain, and it is available
over-the-counter in some other countries. Like all opioids, codeine does have abuse potential. In fact, abuse
of prescription opioid medications is becoming a major concern worldwide (Aquina, Marques-Baptista,
Bridgeman, & Merlin, 2009; Casati, Sedefov, & Pfeiffer-Gerschel, 2012).
A hallucinogen is one of a class of drugs that results in profound alterations in sensory and perceptual
experiences (Figure 4.21). In some cases, users experience vivid visual hallucinations. It is also common
for these types of drugs to cause hallucinations of body sensations (e.g., feeling as if you are a giant) and a
skewed perception of the passage of time.
Figure 4.21 Psychedelic images like this are often associated with hallucinogenic compounds. (credit: modification
of work by “new 1lluminati”/Flickr)
As a group, hallucinogens are incredibly varied in terms of the neurotransmitter systems they affect.
Mescaline and LSD are serotonin agonists, and PCP (angel dust) and ketamine (an animal anesthetic) act
as antagonists of the NMDA glutamate receptor. In general, these drugs are not thought to possess the
same sort of abuse potential as other classes of drugs discussed in this section.
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To learn more about some of the most commonly abused prescription and street
drugs, check out the Commonly Abused Drugs Chart
( and the Commonly Abused
Prescription Drugs Chart ( from the
National Institute on Drug Abuse.
Medical Marijuana
While the possession and use of marijuana is illegal in most states, it is now legal in Washington and Colorado
to possess limited quantities of marijuana for recreational use (Figure 4.22). In contrast, medical marijuana use
is now legal in nearly half of the United States and in the District of Columbia. Medical marijuana is marijuana
that is prescribed by a doctor for the treatment of a health condition. For example, people who undergo
chemotherapy will often be prescribed marijuana to stimulate their appetites and prevent excessive weight
loss resulting from the side effects of chemotherapy treatment. Marijuana may also have some promise in the
treatment of a variety of medical conditions (Mather, Rauwendaal, Moxham-Hall, & Wodak, 2013; Robson,
2014; Schicho & Storr, 2014).
Figure 4.22 Medical marijuana shops are becoming more and more common in the United States. (credit:
Laurie Avocado)
While medical marijuana laws have been passed on a state-by-state basis, federal laws still classify this as
an illicit substance, making conducting research on the potentially beneficial medicinal uses of marijuana
problematic. There is quite a bit of controversy within the scientific community as to the extent to which
marijuana might have medicinal benefits due to a lack of large-scale, controlled research (Bostwick, 2012). As
a result, many scientists have urged the federal government to allow for relaxation of current marijuana laws
and classifications in order to facilitate a more widespread study of the drug’s effects (Aggarwal et al., 2009;
Bostwick, 2012; Kogan & Mechoulam, 2007).
Until recently, the United States Department of Justice routinely arrested people involved and seized marijuana
used in medicinal settings. In the latter part of 2013, however, the United States Department of Justice issued
statements indicating that they would not continue to challenge state medical marijuana laws. This shift in
policy may be in response to the scientific community’s recommendations and/or reflect changing public
opinion regarding marijuana.
Chapter 4 | States of Consciousness 137

4.6 Other States of Consciousness
Learning Objectives
By the end of this section, you will be able to:
• Define hypnosis and meditation
• Understand the similarities and differences of hypnosis and meditation
Our states of consciousness change as we move from wakefulness to sleep. We also alter our consciousness
through the use of various psychoactive drugs. This final section will consider hypnotic and meditative
states as additional examples of altered states of consciousness experienced by some individuals.
Hypnosis is a state of extreme self-focus and attention in which minimal attention is given to external
stimuli. In the therapeutic setting, a clinician may use relaxation and suggestion in an attempt to alter the
thoughts and perceptions of a patient. Hypnosis has also been used to draw out information believed to be
buried deeply in someone’s memory. For individuals who are especially open to the power of suggestion,
hypnosis can prove to be a very effective technique, and brain imaging studies have demonstrated
that hypnotic states are associated with global changes in brain functioning (Del Casale et al., 2012;
Guldenmund, Vanhaudenhuyse, Boly, Laureys, & Soddu, 2012).
Historically, hypnosis has been viewed with some suspicion because of its portrayal in popular media
and entertainment (Figure 4.23). Therefore, it is important to make a distinction between hypnosis as
an empirically based therapeutic approach versus as a form of entertainment. Contrary to popular belief,
individuals undergoing hypnosis usually have clear memories of the hypnotic experience and are in
control of their own behaviors. While hypnosis may be useful in enhancing memory or a skill, such
enhancements are very modest in nature (Raz, 2011).
Figure 4.23 Popular portrayals of hypnosis have led to some widely-held misconceptions.
How exactly does a hypnotist bring a participant to a state of hypnosis? While there are variations, there
are four parts that appear consistent in bringing people into the state of suggestibility associated with
hypnosis (National Research Council, 1994). These components include:
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• The participant is guided to focus on one thing, such as the hypnotist’s words or a ticking watch.
• The participant is made comfortable and is directed to be relaxed and sleepy.
• The participant is told to be open to the process of hypnosis, trust the hypnotist and let go.
• The participant is encouraged to use his or her imagination.
These steps are conducive to being open to the heightened suggestibility of hypnosis.
People vary in terms of their ability to be hypnotized, but a review of available research suggests that
most people are at least moderately hypnotizable (Kihlstrom, 2013). Hypnosis in conjunction with other
techniques is used for a variety of therapeutic purposes and has shown to be at least somewhat effective
for pain management, treatment of depression and anxiety, smoking cessation, and weight loss (Alladin,
2012; Elkins, Johnson, & Fisher, 2012; Golden, 2012; Montgomery, Schnur, & Kravits, 2012).
Some scientists are working to determine whether the power of suggestion can affect cognitive processes
such as learning, with a view to using hypnosis in educational settings (Wark, 2011). Furthermore, there
is some evidence that hypnosis can alter processes that were once thought to be automatic and outside
the purview of voluntary control, such as reading (Lifshitz, Aubert Bonn, Fischer, Kashem, & Raz, 2013;
Raz, Shapiro, Fan, & Posner, 2002). However, it should be noted that others have suggested that the
automaticity of these processes remains intact (Augustinova & Ferrand, 2012).
How does hypnosis work? Two theories attempt to answer this question: One theory views hypnosis as
dissociation and the other theory views it as the performance of a social role. According to the dissociation
view, hypnosis is effectively a dissociated state of consciousness, much like our earlier example where you
may drive to work, but you are only minimally aware of the process of driving because your attention
is focused elsewhere. This theory is supported by Ernest Hilgard’s research into hypnosis and pain. In
Hilgard’s experiments, he induced participants into a state of hypnosis, and placed their arms into ice
water. Participants were told they would not feel pain, but they could press a button if they did; while they
reported not feeling pain, they did, in fact, press the button, suggesting a dissociation of consciousness
while in the hypnotic state (Hilgard & Hilgard, 1994).
Taking a different approach to explain hypnosis, the social-cognitive theory of hypnosis sees people
in hypnotic states as performing the social role of a hypnotized person. As you will learn when you
study social roles, people’s behavior can be shaped by their expectations of how they should act in
a given situation. Some view a hypnotized person’s behavior not as an altered or dissociated state of
consciousness, but as their fulfillment of the social expectations for that role.
Meditation is the act of focusing on a single target (such as the breath or a repeated sound) to increase
awareness of the moment. While hypnosis is generally achieved through the interaction of a therapist and
the person being treated, an individual can perform meditation alone. Often, however, people wishing
to learn to meditate receive some training in techniques to achieve a meditative state. A meditative state,
as shown by EEG recordings of newly-practicing meditators, is not an altered state of consciousness per
se; however, patterns of brain waves exhibited by expert meditators may represent a unique state of
consciousness (Fell, Axmacher, & Haupt, 2010).
Although there are a number of different techniques in use, the central feature of all meditation is clearing
the mind in order to achieve a state of relaxed awareness and focus (Chen et al., 2013; Lang et al., 2012).
Mindfulness meditation has recently become popular. In the variation of meditation, the meditator’s
attention is focused on some internal process or an external object (Zeidan, Grant, Brown, McHaffie, &
Coghill, 2012).
Meditative techniques have their roots in religious practices (Figure 4.24), but their use has grown in
popularity among practitioners of alternative medicine. Research indicates that meditation may help
reduce blood pressure, and the American Heart Association suggests that meditation might be used in
Chapter 4 | States of Consciousness 139

conjunction with more traditional treatments as a way to manage hypertension, although there is not
sufficient data for a recommendation to be made (Brook et al., 2013). Like hypnosis, meditation also
shows promise in stress management, sleep quality (Caldwell, Harrison, Adams, Quin, & Greeson, 2010),
treatment of mood and anxiety disorders (Chen et al., 2013; Freeman et al., 2010; Vøllestad, Nielsen, &
Nielsen, 2012), and pain management (Reiner, Tibi, & Lipsitz, 2013).
Figure 4.24 (a) This is a statue of a meditating Buddha, representing one of the many religious traditions of which
meditation plays a part. (b) People practicing meditation may experience an alternate state of consciousness. (credit
a: modification of work by Jim Epler; credit b: modification of work by Caleb Roenigk)
Feeling stressed? Think meditation might help? This instructional video
( teaches how to use Buddhist meditation
techniques to alleviate stress.
Watch this video ( describe the results
of a brain imaging study in individuals who underwent specific mindfulness-
meditative techniques.
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alpha wave
biological rhythm
central sleep apnea
circadian rhythm
cognitive-behavioral therapy
collective unconscious
continuous positive airway pressure (CPAP)
delta wave
euphoric high
evolutionary psychology
jet lag
latent content
lucid dream
Key Terms
type of relatively low frequency, relatively high amplitude brain wave that becomes
synchronized; characteristic of the beginning of stage 1 sleep
internal cycle of biological activity
lack of muscle tone or muscle weakness, and in some cases complete paralysis of the voluntary
sleep disorder with periods of interrupted breathing due to a disruption in signals
sent from the brain that regulate breathing
biological rhythm that occurs over approximately 24 hours
opiate with relatively low potency often prescribed for minor pain
psychotherapy that focuses on cognitive processes and problem behaviors
that is sometimes used to treat sleep disorders such as insomnia
theoretical repository of information shared by all people across cultures, as
described by Carl Jung
awareness of internal and external stimuli
device used to treat sleep apnea; includes a mask that fits
over the sleeper’s nose and mouth, which is connected to a pump that pumps air into the person’s
airways, forcing them to remain open
type of low frequency, high amplitude brain wave characteristic of stage 3 and stage 4 sleep
drug that tends to suppress central nervous system activity
feelings of intense elation and pleasure from drug use
discipline that studies how universal patterns of behavior and cognitive
processes have evolved over time as a result of natural selection
one of a class of drugs that results in profound alterations in sensory and perceptual
experiences, often with vivid hallucinations
tendency to maintain a balance, or optimal level, within a biological system
state of extreme self-focus and attention in which minimal attention is given to external stimuli
consistent difficulty in falling or staying asleep for at least three nights a week over a month’s
collection of symptoms brought on by travel from one time zone to another that results from the
mismatch between our internal circadian cycles and our environment
very high amplitude pattern of brain activity associated with stage 2 sleep that may occur in
response to environmental stimuli
hidden meaning of a dream, per Sigmund Freud’s view of the function of dreams
people become aware that they are dreaming and can control the dream’s content
Chapter 4 | States of Consciousness 141

manifest content
methadone clinic
night terror
non-REM (NREM)
obstructive sleep apnea
physical dependence
pineal gland
psychological dependence
rapid eye movement (REM) sleep
REM sleep behavior disorder (RBD)
restless leg syndrome
rotating shift work
storyline of events that occur during a dream, per Sigmund Freud’s view of the
function of dreams
clearing the mind in order to achieve a state of relaxed awareness and focus
hormone secreted by the endocrine gland that serves as an important regulator of the sleep-
wake cycle
study that combines the results of several related studies
synthetic opioid that is less euphorogenic than heroin and similar drugs; used to manage
withdrawal symptoms in opiate users
uses methadone to treat withdrawal symptoms in opiate users
type of amphetamine that can be made from pseudoephedrine, an over-the-counter
drug; widely manufactured and abused
sleep disorder in which the sufferer cannot resist falling to sleep at inopportune times
sleep disorder in which the sleeper experiences a sense of panic and may scream or attempt
to escape from the immediate environment
period of sleep outside periods of rapid eye movement (REM) sleep
sleep disorder defined by episodes when breathing stops during sleep as a
result of blockage of the airway
one of a category of drugs that has strong analgesic properties; opiates are produced from
the resin of the opium poppy; includes heroin, morphine, methadone, and codeine
one of a group of sleep disorders characterized by unwanted, disruptive motor activity
and/or experiences during sleep
changes in normal bodily functions that cause a drug user to experience
withdrawal symptoms upon cessation of use
endocrine structure located inside the brain that releases melatonin
emotional, rather than a physical, need for a drug which may be used to
relieve psychological distress
period of sleep characterized by brain waves very similar to those
during wakefulness and by darting movements of the eyes under closed eyelids
sleep disorder in which the muscle paralysis associated with the
REM sleep phase does not occur; sleepers have high levels of physical activity during REM sleep,
especially during disturbing dreams
sleep disorder in which the sufferer has uncomfortable sensations in the legs
when trying to fall asleep that are relieved by moving the legs
work schedule that changes from early to late on a daily or weekly basis
state marked by relatively low levels of physical activity and reduced sensory awareness that is
distinct from periods of rest that occur during wakefulness
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sleep apnea
sleep debt
sleep rebound
sleep regulation
sleep spindle
stage 1 sleep
stage 2 sleep
stage 3 sleep
stage 4 sleep
sudden infant death syndrome (SIDS)
suprachiasmatic nucleus (SCN)
theta wave
sleep disorder defined by episodes during which breathing stops during sleep
result of insufficient sleep on a chronic basis
sleep-deprived individuals will experience shorter sleep latencies during subsequent
opportunities for sleep
brain’s control of switching between sleep and wakefulness as well as coordinating this
cycle with the outside world
rapid burst of high frequency brain waves during stage 2 sleep that may be important for
learning and memory
(also, somnambulism) sleep disorder in which the sleeper engages in relatively complex
first stage of sleep; transitional phase that occurs between wakefulness and sleep; the
period during which a person drifts off to sleep
second stage of sleep; the body goes into deep relaxation; characterized by the appearance
of sleep spindles
third stage of sleep; deep sleep characterized by low frequency, high amplitude delta waves
fourth stage of sleep; deep sleep characterized by low frequency, high amplitude delta
drug that tends to increase overall levels of neural activity; includes caffeine, nicotine,
amphetamines, and cocaine
infant (one year old or younger) with no apparent medical
condition suddenly dies during sleep
area of the hypothalamus in which the body’s biological clock is located
type of low frequency, low amplitude brain wave characteristic of the end of stage 1 sleep
state of requiring increasing quantities of the drug to gain the desired effect
characterized by high levels of sensory awareness, thought, and behavior
variety of negative symptoms experienced when drug use is discontinued
4.1 What Is Consciousness?
States of consciousness vary over the course of the day and throughout our lives. Important factors
in these changes are the biological rhythms, and, more specifically, the circadian rhythms generated
by the suprachiasmatic nucleus (SCN). Typically, our biological clocks are aligned with our external
environment, and light tends to be an important cue in setting this clock. When people travel across
multiple time zones or work rotating shifts, they can experience disruptions of their circadian cycles that
can lead to insomnia, sleepiness, and decreased alertness. Bright light therapy has shown to be promising
in dealing with circadian disruptions. If people go extended periods of time without sleep, they will
accrue a sleep debt and potentially experience a number of adverse psychological and physiological
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4.2 Sleep and Why We Sleep
We devote a very large portion of time to sleep, and our brains have complex systems that control various
aspects of sleep. Several hormones important for physical growth and maturation are secreted during
sleep. While the reason we sleep remains something of a mystery, there is some evidence to suggest that
sleep is very important to learning and memory.
4.3 Stages of Sleep
The different stages of sleep are characterized by the patterns of brain waves associated with each stage.
As a person transitions from being awake to falling asleep, alpha waves are replaced by theta waves.
Sleep spindles and K-complexes emerge in stage 2 sleep. Stage 3 and stage 4 are described as slow-wave
sleep that is marked by a predominance of delta waves. REM sleep involves rapid movements of the
eyes, paralysis of voluntary muscles, and dreaming. Both NREM and REM sleep appear to play important
roles in learning and memory. Dreams may represent life events that are important to the dreamer.
Alternatively, dreaming may represent a state of protoconsciousness, or a virtual reality, in the mind that
helps a person during consciousness.
4.4 Sleep Problems and Disorders
Many individuals suffer from some type of sleep disorder or disturbance at some point in their lives.
Insomnia is a common experience in which people have difficulty falling or staying asleep. Parasomnias
involve unwanted motor behavior or experiences throughout the sleep cycle and include RBD,
sleepwalking, restless leg syndrome, and night terrors. Sleep apnea occurs when individuals stop
breathing during their sleep, and in the case of sudden infant death syndrome, infants will stop breathing
during sleep and die. Narcolepsy involves an irresistible urge to fall asleep during waking hours and is
often associated with cataplexy and hallucination.
4.5 Substance Use and Abuse
Substance use disorder is defined in DSM-5 as a compulsive pattern of drug use despite negative
consequences. Both physical and psychological dependence are important parts of this disorder. Alcohol,
barbiturates, and benzodiazepines are central nervous system depressants that affect GABA
neurotransmission. Cocaine, amphetamine, cathinones, and MDMA are all central nervous stimulants
that agonize dopamine neurotransmission, while nicotine and caffeine affect acetylcholine and adenosine,
respectively. Opiate drugs serve as powerful analgesics through their effects on the endogenous opioid
neurotransmitter system, and hallucinogenic drugs cause pronounced changes in sensory and perceptual
experiences. The hallucinogens are variable with regards to the specific neurotransmitter systems they
4.6 Other States of Consciousness
Hypnosis is a focus on the self that involves suggested changes of behavior and experience. Meditation
involves relaxed, yet focused, awareness. Both hypnotic and meditative states may involve altered states of
consciousness that have potential application for the treatment of a variety of physical and psychological
Review Questions
1. The body’s biological clock is located in the
a. hippocampus
b. thalamus
c. hypothalamus
d. pituitary gland
2. ________ occurs when there is a chronic
deficiency in sleep.
a. jet lag
b. rotating shift work
c. circadian rhythm
d. sleep debt
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3. ________ cycles occur roughly once every 24
a. biological
b. circadian
c. rotating
d. conscious
4. ________ is one way in which people can help
reset their biological clocks.
a. Light-dark exposure
b. coffee consumption
c. alcohol consumption
d. napping
5. Growth hormone is secreted by the ________
while we sleep.
a. pineal gland
b. thyroid
c. pituitary gland
d. pancreas
6. The ________ plays a role in controlling slow-
wave sleep.
a. hypothalamus
b. thalamus
c. pons
d. both a and b
7. ________ is a hormone secreted by the pineal
gland that plays a role in regulating biological
rhythms and immune function.
a. growth hormone
b. melatonin
c. LH
d. FSH
8. ________ appears to be especially important for
enhanced performance on recently learned tasks.
a. melatonin
b. slow-wave sleep
c. sleep deprivation
d. growth hormone
9. ________ is(are) described as slow-wave sleep.
a. stage 1
b. stage 2
c. stage 3 and stage 4
d. REM sleep
10. Sleep spindles and K-complexes are most
often associated with ________ sleep.
a. stage 1
b. stage 2
c. stage 3 and stage 4
d. REM
11. Symptoms of ________ may be improved by
REM deprivation.
a. schizophrenia
b. Parkinson’s disease
c. depression
d. generalized anxiety disorder
12. The ________ content of a dream refers to the
true meaning of the dream.
a. latent
b. manifest
c. collective unconscious
d. important
13. ________ is loss of muscle tone or control that
is often associated with narcolepsy.
a. RBD
c. cataplexy
d. insomnia
14. An individual may suffer from ________ if
there is a disruption in the brain signals that are
sent to the muscles that regulate breathing.
a. central sleep apnea
b. obstructive sleep apnea
c. narcolepsy
15. The most common treatment for ________
involves the use of amphetamine-like medications.
a. sleep apnea
b. RBD
d. narcolepsy
16. ________ is another word for sleepwalking.
a. insomnia
b. somnambulism
c. cataplexy
d. narcolepsy
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17. ________ occurs when a drug user requires
more and more of a given drug in order to
experience the same effects of the drug.
a. withdrawal
b. psychological dependence
c. tolerance
d. reuptake
18. Cocaine blocks the reuptake of ________.
b. glutamate
c. acetylcholine
d. dopamine
19. ________ refers to drug craving.
a. psychological dependence
b. antagonism
c. agonism
d. physical dependence
20. LSD affects ________ neurotransmission.
a. dopamine
b. serotonin
c. acetylcholine
d. norepinephrine
21. ________ is most effective in individuals that
are very open to the power of suggestion.
a. hypnosis
b. meditation
c. mindful awareness
d. cognitive therapy
22. ________ has its roots in religious practice.
a. hypnosis
b. meditation
c. cognitive therapy
d. behavioral therapy
23. Meditation may be helpful in ________.
a. pain management
b. stress control
c. treating the flu
d. both a and b
24. Research suggests that cognitive processes,
such as learning, may be affected by ________.
a. hypnosis
b. meditation
c. mindful awareness
d. progressive relaxation
Critical Thinking Questions
25. Healthcare professionals often work rotating shifts. Why is this problematic? What can be done to deal
with potential problems?
26. Generally, humans are considered diurnal which means we are awake during the day and asleep
during the night. Many rodents, on the other hand, are nocturnal. Why do you think different animals
have such different sleep-wake cycles?
27. If theories that assert sleep is necessary for restoration and recovery from daily energetic demands
are correct, what do you predict about the relationship that would exist between individuals’ total sleep
duration and their level of activity?
28. How could researchers determine if given areas of the brain are involved in the regulation of sleep?
29. Differentiate the evolutionary theories of sleep and make a case for the one with the most compelling
30. Freud believed that dreams provide important insight into the unconscious mind. He maintained that
a dream’s manifest content could provide clues into an individual’s unconscious. What potential criticisms
exist for this particular perspective?
31. Some people claim that sleepwalking and talking in your sleep involve individuals acting out their
dreams. Why is this particular explanation unlikely?
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32. One of the recommendations that therapists will make to people who suffer from insomnia is to spend
less waking time in bed. Why do you think spending waking time in bed might interfere with the ability
to fall asleep later?
33. How is narcolepsy with cataplexy similar to and different from REM sleep?
34. The negative health consequences of both alcohol and tobacco products are well-documented. A drug
like marijuana, on the other hand, is generally considered to be as safe, if not safer than these legal drugs.
Why do you think marijuana use continues to be illegal in many parts of the United States?
35. Why are programs designed to educate people about the dangers of using tobacco products just as
important as developing tobacco cessation programs?
36. What advantages exist for researching the potential health benefits of hypnosis?
37. What types of studies would be most convincing regarding the effectiveness of meditation in the
treatment for some type of physical or mental disorder?
Personal Application Questions
38. We experience shifts in our circadian clocks in the fall and spring of each year with time changes
associated with daylight saving time. Is springing ahead or falling back easier for you to adjust to, and
why do you think that is?
39. What do you do to adjust to the differences in your daily schedule throughout the week? Are you
running a sleep debt when daylight saving time begins or ends?
40. Have you (or someone you know) ever experienced significant periods of sleep deprivation because of
simple insomnia, high levels of stress, or as a side effect from a medication? What were the consequences
of missing out on sleep?
41. Researchers believe that one important function of sleep is to facilitate learning and memory. How
does knowing this help you in your college studies? What changes could you make to your study and
sleep habits to maximize your mastery of the material covered in class?
42. What factors might contribute to your own experiences with insomnia?
43. Many people experiment with some sort of psychoactive substance at some point in their lives. Why
do you think people are motivated to use substances that alter consciousness?
44. Under what circumstances would you be willing to consider hypnosis and/or meditation as a
treatment option? What kind of information would you need before you made a decision to use these
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Chapter 5
Sensation and Perception
Figure 5.1 If you were standing in the midst of this street scene, you would be absorbing and processing numerous
pieces of sensory input. (credit: modification of work by Cory Zanker)
Chapter Outline
5.1 Sensation versus Perception
5.2 Waves and Wavelengths
5.3 Vision
5.4 Hearing
5.5 The Other Senses
5.6 Gestalt Principles of Perception
Imagine standing on a city street corner. You might be struck by movement everywhere as cars and people
go about their business, by the sound of a street musician’s melody or a horn honking in the distance,
by the smell of exhaust fumes or of food being sold by a nearby vendor, and by the sensation of hard
pavement under your feet.
We rely on our sensory systems to provide important information about our surroundings. We use this
information to successfully navigate and interact with our environment so that we can find nourishment,
seek shelter, maintain social relationships, and avoid potentially dangerous situations.
This chapter will provide an overview of how sensory information is received and processed by the
nervous system and how that affects our conscious experience of the world. We begin by learning the
distinction between sensation and perception. Then we consider the physical properties of light and sound
stimuli, along with an overview of the basic structure and function of the major sensory systems. The
chapter will close with a discussion of a historically important theory of perception called Gestalt.
Chapter 5 | Sensation and Perception 149

5.1 Sensation versus Perception
Learning Objectives
By the end of this section, you will be able to:
• Distinguish between sensation and perception
• Describe the concepts of absolute threshold and difference threshold
• Discuss the roles attention, motivation, and sensory adaptation play in perception
What does it mean to sense something? Sensory receptors are specialized neurons that respond to specific
types of stimuli. When sensory information is detected by a sensory receptor, sensation has occurred. For
example, light that enters the eye causes chemical changes in cells that line the back of the eye. These
cells relay messages, in the form of action potentials (as you learned when studying biopsychology), to
the central nervous system. The conversion from sensory stimulus energy to action potential is known as
You have probably known since elementary school that we have five senses: vision, hearing (audition),
smell (olfaction), taste (gustation), and touch (somatosensation). It turns out that this notion of five
senses is oversimplified. We also have sensory systems that provide information about balance (the
vestibular sense), body position and movement (proprioception and kinesthesia), pain (nociception), and
temperature (thermoception).
The sensitivity of a given sensory system to the relevant stimuli can be expressed as an absolute threshold.
Absolute threshold refers to the minimum amount of stimulus energy that must be present for the
stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light
be or how soft can a sound be and still be detected half of the time. The sensitivity of our sensory receptors
can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the
back of the eye can detect a candle flame 30 miles away (Okawa & Sampath, 2007). Under quiet conditions,
the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962).
It is also possible for us to get messages that are presented below the threshold for conscious
awareness—these are called subliminal messages. A stimulus reaches a physiological threshold when it
is strong enough to excite sensory receptors and send nerve impulses to the brain: This is an absolute
threshold. A message below that threshold is said to be subliminal: We receive it, but we are not
consciously aware of it. Over the years there has been a great deal of speculation about the use of
subliminal messages in advertising, rock music, and self-help audio programs. Research evidence shows
that in laboratory settings, people can process and respond to information outside of awareness. But
this does not mean that we obey these messages like zombies; in fact, hidden messages have little effect
on behavior outside the laboratory (Kunst-Wilson & Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel,
Sarrazin, Legrain, & Gobancé, 2009; Loersch, Durso, & Petty, 2013).
Absolute thresholds are generally measured under incredibly controlled conditions in situations that are
optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required
to detect a difference between them. This is known as the just noticeable difference (jnd) or difference
threshold. Unlike the absolute threshold, the difference threshold changes depending on the stimulus
intensity. As an example, imagine yourself in a very dark movie theater. If an audience member were
to receive a text message on her cell phone which caused her screen to light up, chances are that many
people would notice the change in illumination in the theater. However, if the same thing happened in
a brightly lit arena during a basketball game, very few people would notice. The cell phone brightness
does not change, but its ability to be detected as a change in illumination varies dramatically between the
two contexts. Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has
become known as Weber’s law: The difference threshold is a constant fraction of the original stimulus, as
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the example illustrates.
While our sensory receptors are constantly collecting information from the environment, it is ultimately
how we interpret that information that affects how we interact with the world. Perception refers to the
way sensory information is organized, interpreted, and consciously experienced. Perception involves both
bottom-up and top-down processing. Bottom-up processing refers to the fact that perceptions are built
from sensory input. On the other hand, how we interpret those sensations is influenced by our available
knowledge, our experiences, and our thoughts. This is called top-down processing.
One way to think of this concept is that sensation is a physical process, whereas perception is
psychological. For example, upon walking into a kitchen and smelling the scent of baking cinnamon rolls,
the sensation is the scent receptors detecting the odor of cinnamon, but the perception may be “Mmm, this
smells like the bread Grandma used to bake when the family gathered for holidays.”
Although our perceptions are built from sensations, not all sensations result in perception. In fact, we often
don’t perceive stimuli that remain relatively constant over prolonged periods of time. This is known as
sensory adaptation. Imagine entering a classroom with an old analog clock. Upon first entering the room,
you can hear the ticking of the clock; as you begin to engage in conversation with classmates or listen
to your professor greet the class, you are no longer aware of the ticking. The clock is still ticking, and
that information is still affecting sensory receptors of the auditory system. The fact that you no longer
perceive the sound demonstrates sensory adaptation and shows that while closely associated, sensation
and perception are different.
There is another factor that affects sensation and perception: attention. Attention plays a significant role
in determining what is sensed versus what is perceived. Imagine you are at a party full of music, chatter,
and laughter. You get involved in an interesting conversation with a friend, and you tune out all the
background noise. If someone interrupted you to ask what song had just finished playing, you would
probably be unable to answer that question.
See for yourself how inattentional blindness works by checking out this selective
attention test ( from Simons and Chabris
One of the most interesting demonstrations of how important attention is in determining our perception of
the environment occurred in a famous study conducted by Daniel Simons and Christopher Chabris (1999).
In this study, participants watched a video of people dressed in black and white passing basketballs.
Participants were asked to count the number of times the team in white passed the ball. During the video,
a person dressed in a black gorilla costume walks among the two teams. You would think that someone
would notice the gorilla, right? Nearly half of the people who watched the video didn’t notice the gorilla at
all, despite the fact that he was clearly visible for nine seconds. Because participants were so focused on the
number of times the white team was passing the ball, they completely tuned out other visual information.
Failure to notice something that is completely visible because of a lack of attention is called inattentional
In a similar experiment, researchers tested inattentional blindness by asking participants to observe
images moving across a computer screen. They were instructed to focus on either white or black objects,
disregarding the other color. When a red cross passed across the screen, about one third of subjects did not
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notice it (Figure 5.2) (Most, Simons, Scholl, & Chabris, 2000).
Figure 5.2 Nearly one third of participants in a study did not notice that a red cross passed on the screen because
their attention was focused on the black or white figures. (credit: Cory Zanker)
Motivation can also affect perception. Have you ever been expecting a really important phone call and,
while taking a shower, you think you hear the phone ringing, only to discover that it is not? If so, then
you have experienced how motivation to detect a meaningful stimulus can shift our ability to discriminate
between a true sensory stimulus and background noise. The ability to identify a stimulus when it is
embedded in a distracting background is called signal detection theory. This might also explain why a
mother is awakened by a quiet murmur from her baby but not by other sounds that occur while she is
asleep. Signal detection theory has practical applications, such as increasing air traffic controller accuracy.
Controllers need to be able to detect planes among many signals (blips) that appear on the radar screen
and follow those planes as they move through the sky. In fact, the original work of the researcher who
developed signal detection theory was focused on improving the sensitivity of air traffic controllers to
plane blips (Swets, 1964).
Our perceptions can also be affected by our beliefs, values, prejudices, expectations, and life experiences.
As you will see later in this chapter, individuals who are deprived of the experience of binocular vision
during critical periods of development have trouble perceiving depth (Fawcett, Wang, & Birch, 2005). The
shared experiences of people within a given cultural context can have pronounced effects on perception.
For example, Marshall Segall, Donald Campbell, and Melville Herskovits (1963) published the results of a
multinational study in which they demonstrated that individuals from Western cultures were more prone
to experience certain types of visual illusions than individuals from non-Western cultures, and vice versa.
One such illusion that Westerners were more likely to experience was the Müller-Lyer illusion (Figure
5.3): The lines appear to be different lengths, but they are actually the same length.
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Figure 5.3 In the Müller-Lyer illusion, lines appear to be different lengths although they are identical. (a) Arrows at
the ends of lines may make the line on the right appear longer, although the lines are the same length. (b) When
applied to a three-dimensional image, the line on the right again may appear longer although both black lines are the
same length.
These perceptual differences were consistent with differences in the types of environmental features
experienced on a regular basis by people in a given cultural context. People in Western cultures, for
example, have a perceptual context of buildings with straight lines, what Segall’s study called a
carpentered world (Segall et al., 1966). In contrast, people from certain non-Western cultures with an
uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged
in circles, are less susceptible to this illusion (Segall et al., 1999). It is not just vision that is affected
by cultural factors. Indeed, research has demonstrated that the ability to identify an odor, and rate its
pleasantness and its intensity, varies cross-culturally (Ayabe-Kanamura, Saito, Distel, Martínez-Gómez, &
Hudson, 1998).
Children described as thrill seekers are more likely to show taste preferences for intense sour flavors (Liem,
Westerbeek, Wolterink, Kok, & de Graaf, 2004), which suggests that basic aspects of personality might
affect perception. Furthermore, individuals who hold positive attitudes toward reduced-fat foods are more
likely to rate foods labeled as reduced fat as tasting better than people who have less positive attitudes
about these products (Aaron, Mela, & Evans, 1994).
5.2 Waves and Wavelengths
Learning Objectives
By the end of this section, you will be able to:
• Describe important physical features of wave forms
• Show how physical properties of light waves are associated with perceptual experience
• Show how physical properties of sound waves are associated with perceptual experience
Visual and auditory stimuli both occur in the form of waves. Although the two stimuli are very different in
terms of composition, wave forms share similar characteristics that are especially important to our visual
and auditory perceptions. In this section, we describe the physical properties of the waves as well as the
perceptual experiences associated with them.
Two physical characteristics of a wave are amplitude and wavelength (Figure 5.4). The amplitude of a
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wave is the height of a wave as measured from the highest point on the wave (peak or crest) to the lowest
point on the wave (trough). Wavelength refers to the length of a wave from one peak to the next.
Figure 5.4 The amplitude or height of a wave is measured from the peak to the trough. The wavelength is measured
from peak to peak.
Wavelength is directly related to the frequency of a given wave form. Frequency refers to the number of
waves that pass a given point in a given time period and is often expressed in terms of hertz (Hz), or cycles
per second. Longer wavelengths will have lower frequencies, and shorter wavelengths will have higher
frequencies (Figure 5.5).
Figure 5.5 This figure illustrates waves of differing wavelengths/frequencies. At the top of the figure, the red wave
has a long wavelength/short frequency. Moving from top to bottom, the wavelengths decrease and frequencies
The visible spectrum is the portion of the larger electromagnetic spectrum that we can see. As Figure 5.6
shows, the electromagnetic spectrum encompasses all of the electromagnetic radiation that occurs in our
environment and includes gamma rays, x-rays, ultraviolet light, visible light, infrared light, microwaves,
and radio waves. The visible spectrum in humans is associated with wavelengths that range from 380 to
740 nm—a very small distance, since a nanometer (nm) is one billionth of a meter. Other species can detect
other portions of the electromagnetic spectrum. For instance, honeybees can see light in the ultraviolet
range (Wakakuwa, Stavenga, & Arikawa, 2007), and some snakes can detect infrared radiation in addition
to more traditional visual light cues (Chen, Deng, Brauth, Ding, & Tang, 2012; Hartline, Kass, & Loop,
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Figure 5.6 Light that is visible to humans makes up only a small portion of the electromagnetic spectrum.
In humans, light wavelength is associated with perception of color (Figure 5.7). Within the visible
spectrum, our experience of red is associated with longer wavelengths, greens are intermediate, and blues
and violets are shorter in wavelength. (An easy way to remember this is the mnemonic ROYGBIV: red,
orange, yellow, green, blue, indigo, violet.) The amplitude of light waves is associated with our experience
of brightness or intensity of color, with larger amplitudes appearing brighter.
Figure 5.7 Different wavelengths of light are associated with our perception of different colors. (credit: modification
of work by Johannes Ahlmann)
Like light waves, the physical properties of sound waves are associated with various aspects of our
perception of sound. The frequency of a sound wave is associated with our perception of that sound’s
pitch. High-frequency sound waves are perceived as high-pitched sounds, while low-frequency sound
waves are perceived as low-pitched sounds. The audible range of sound frequencies is between 20 and
20000 Hz, with greatest sensitivity to those frequencies that fall in the middle of this range.
As was the case with the visible spectrum, other species show differences in their audible ranges. For
instance, chickens have a very limited audible range, from 125 to 2000 Hz. Mice have an audible range
from 1000 to 91000 Hz, and the beluga whale’s audible range is from 1000 to 123000 Hz. Our pet dogs and
cats have audible ranges of about 70–45000 Hz and 45–64000 Hz, respectively (Strain, 2003).
The loudness of a given sound is closely associated with the amplitude of the sound wave. Higher
amplitudes are associated with louder sounds. Loudness is measured in terms of decibels (dB), a
logarithmic unit of sound intensity. A typical conversation would correlate with 60 dB; a rock concert
might check in at 120 dB (Figure 5.8). A whisper 5 feet away or rustling leaves are at the low end of our
hearing range; sounds like a window air conditioner, a normal conversation, and even heavy traffic or
a vacuum cleaner are within a tolerable range. However, there is the potential for hearing damage from
Chapter 5 | Sensation and Perception 155

about 80 dB to 130 dB: These are sounds of a food processor, power lawnmower, heavy truck (25 feet
away), subway train (20 feet away), live rock music, and a jackhammer. The threshold for pain is about 130
dB, a jet plane taking off or a revolver firing at close range (Dunkle, 1982).
Figure 5.8 This figure illustrates the loudness of common sounds. (credit “planes”: modification of work by Max
Pfandl; credit “crowd”: modification of work by Christian Holmér; credit “blender”: modification of work by Jo Brodie;
credit “car”: modification of work by NRMA New Cars/Flickr; credit “talking”: modification of work by Joi Ito; credit
“leaves”: modification of work by Aurelijus Valeiša)
Although wave amplitude is generally associated with loudness, there is some interaction between
frequency and amplitude in our perception of loudness within the audible range. For example, a 10 Hz
sound wave is inaudible no matter the amplitude of the wave. A 1000 Hz sound wave, on the other hand,
would vary dramatically in terms of perceived loudness as the amplitude of the wave increased.
Watch this brief video ( demonstrating
how frequency and amplitude interact in our perception of loudness.
Of course, different musical instruments can play the same musical note at the same level of loudness, yet
they still sound quite different. This is known as the timbre of a sound. Timbre refers to a sound’s purity,
and it is affected by the complex interplay of frequency, amplitude, and timing of sound waves.
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5.3 Vision
Learning Objectives
By the end of this section, you will be able to:
• Describe the basic anatomy of the visual system
• Discuss how rods and cones contribute to different aspects of vision
• Describe how monocular and binocular cues are used in the perception of depth
The visual system constructs a mental representation of the world around us (Figure 5.9). This contributes
to our ability to successfully navigate through physical space and interact with important individuals and
objects in our environments. This section will provide an overview of the basic anatomy and function of
the visual system. In addition, we will explore our ability to perceive color and depth.
Figure 5.9 Our eyes take in sensory information that helps us understand the world around us. (credit “top left”:
modification of work by “rajkumar1220″/Flickr”; credit “top right”: modification of work by Thomas Leuthard; credit
“middle left”: modification of work by Demietrich Baker; credit “middle right”: modification of work by
“kaybee07″/Flickr; credit “bottom left”: modification of work by “Isengardt”/Flickr; credit “bottom right”: modification of
work by Willem Heerbaart)
The eye is the major sensory organ involved in vision (Figure 5.10). Light waves are transmitted across the
cornea and enter the eye through the pupil. The cornea is the transparent covering over the eye. It serves
as a barrier between the inner eye and the outside world, and it is involved in focusing light waves that
enter the eye. The pupil is the small opening in the eye through which light passes, and the size of the
pupil can change as a function of light levels as well as emotional arousal. When light levels are low, the
pupil will become dilated, or expanded, to allow more light to enter the eye. When light levels are high,
the pupil will constrict, or become smaller, to reduce the amount of light that enters the eye. The pupil’s
size is controlled by muscles that are connected to the iris, which is the colored portion of the eye.
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Figure 5.10 The anatomy of the eye is illustrated in this diagram.
After passing through the pupil, light crosses the lens, a curved, transparent structure that serves to
provide additional focus. The lens is attached to muscles that can change its shape to aid in focusing
light that is reflected from near or far objects. In a normal-sighted individual, the lens will focus images
perfectly on a small indentation in the back of the eye known as the fovea, which is part of the retina, the
light-sensitive lining of the eye. The fovea contains densely packed specialized photoreceptor cells (Figure
5.11). These photoreceptor cells, known as cones, are light-detecting cells. The cones are specialized types
of photoreceptors that work best in bright light conditions. Cones are very sensitive to acute detail and
provide tremendous spatial resolution. They also are directly involved in our ability to perceive color.
While cones are concentrated in the fovea, where images tend to be focused, rods, another type of
photoreceptor, are located throughout the remainder of the retina. Rods are specialized photoreceptors
that work well in low light conditions, and while they lack the spatial resolution and color function of the
cones, they are involved in our vision in dimly lit environments as well as in our perception of movement
on the periphery of our visual field.
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Figure 5.11 The two types of photoreceptors are shown in this image. Rods are colored green and cones are blue.
We have all experienced the different sensitivities of rods and cones when making the transition from
a brightly lit environment to a dimly lit environment. Imagine going to see a blockbuster movie on a
clear summer day. As you walk from the brightly lit lobby into the dark theater, you notice that you
immediately have difficulty seeing much of anything. After a few minutes, you begin to adjust to the
darkness and can see the interior of the theater. In the bright environment, your vision was dominated
primarily by cone activity. As you move to the dark environment, rod activity dominates, but there is a
delay in transitioning between the phases. If your rods do not transform light into nerve impulses as easily
and efficiently as they should, you will have difficulty seeing in dim light, a condition known as night
Rods and cones are connected (via several interneurons) to retinal ganglion cells. Axons from the retinal
ganglion cells converge and exit through the back of the eye to form the optic nerve. The optic nerve carries
visual information from the retina to the brain. There is a point in the visual field called the blind spot:
Even when light from a small object is focused on the blind spot, we do not see it. We are not consciously
aware of our blind spots for two reasons: First, each eye gets a slightly different view of the visual field;
therefore, the blind spots do not overlap. Second, our visual system fills in the blind spot so that although
we cannot respond to visual information that occurs in that portion of the visual field, we are also not
aware that information is missing.
The optic nerve from each eye merges just below the brain at a point called the optic chiasm. As Figure
5.12 shows, the optic chiasm is an X-shaped structure that sits just below the cerebral cortex at the front of
the brain. At the point of the optic chiasm, information from the right visual field (which comes from both
eyes) is sent to the left side of the brain, and information from the left visual field is sent to the right side
of the brain.
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Figure 5.12 This illustration shows the optic chiasm at the front of the brain and the pathways to the occipital lobe at
the back of the brain, where visual sensations are processed into meaningful perceptions.
Once inside the brain, visual information is sent via a number of structures to the occipital lobe at the
back of the brain for processing. Visual information might be processed in parallel pathways which can
generally be described as the “what pathway” and the “where/how” pathway. The “what pathway”
is involved in object recognition and identification, while the “where/how pathway” is involved with
location in space and how one might interact with a particular visual stimulus (Milner & Goodale, 2008;
Ungerleider & Haxby, 1994). For example, when you see a ball rolling down the street, the “what pathway”
identifies what the object is, and the “where/how pathway” identifies its location or movement in space.
We do not see the world in black and white; neither do we see it as two-dimensional (2-D) or flat (just
height and width, no depth). Let’s look at how color vision works and how we perceive three dimensions
(height, width, and depth).
Color Vision
Normal-sighted individuals have three different types of cones that mediate color vision. Each of these
cone types is maximally sensitive to a slightly different wavelength of light. According to the trichromatic
theory of color vision, shown in Figure 5.13, all colors in the spectrum can be produced by combining
red, green, and blue. The three types of cones are each receptive to one of the colors.
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Figure 5.13 This figure illustrates the different sensitivities for the three cone types found in a normal-sighted
individual. (credit: modification of work by Vanessa Ezekowitz)
The trichromatic theory of color vision is not the only theory—another major theory of color vision is
known as the opponent-process theory. According to this theory, color is coded in opponent pairs: black-
white, yellow-blue, and green-red. The basic idea is that some cells of the visual system are excited
by one of the opponent colors and inhibited by the other. So, a cell that was excited by wavelengths
associated with green would be inhibited by wavelengths associated with red, and vice versa. One of
the implications of opponent processing is that we do not experience greenish-reds or yellowish-blues
as colors. Another implication is that this leads to the experience of negative afterimages. An afterimage
describes the continuation of a visual sensation after removal of the stimulus. For example, when you stare
briefly at the sun and then look away from it, you may still perceive a spot of light although the stimulus
(the sun) has been removed. When color is involved in the stimulus, the color pairings identified in the
opponent-process theory lead to a negative afterimage. You can test this concept using the flag in Figure
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Figure 5.14 Stare at the white dot for 30–60 seconds and then move your eyes to a blank piece of white paper.
What do you see? This is known as a negative afterimage, and it provides empirical support for the opponent-process
theory of color vision.
But these two theories—the trichromatic theory of color vision and the opponent-process theory—are not
mutually exclusive. Research has shown that they just apply to different levels of the nervous system. For
visual processing on the retina, trichromatic theory applies: the cones are responsive to three different
wavelengths that represent red, blue, and green. But once the signal moves past the retina on its way to
the brain, the cells respond in a way consistent with opponent-process theory (Land, 1959; Kaiser, 1997).
Watch this video ( to see the first part of
a documentary explaining color vision in more detail.
Depth Perception
Our ability to perceive spatial relationships in three-dimensional (3-D) space is known as depth
perception. With depth perception, we can describe things as being in front, behind, above, below, or to
the side of other things.
Our world is three-dimensional, so it makes sense that our mental representation of the world has three-
dimensional properties. We use a variety of cues in a visual scene to establish our sense of depth. Some of
these are binocular cues, which means that they rely on the use of both eyes. One example of a binocular
depth cue is binocular disparity, the slightly different view of the world that each of our eyes receives. To
experience this slightly different view, do this simple exercise: extend your arm fully and extend one of
your fingers and focus on that finger. Now, close your left eye without moving your head, then open your
left eye and close your right eye without moving your head. You will notice that your finger seems to shift
as you alternate between the two eyes because of the slightly different view each eye has of your finger.
A 3-D movie works on the same principle: the special glasses you wear allow the two slightly different
images projected onto the screen to be seen separately by your left and your right eye. As your brain
processes these images, you have the illusion that the leaping animal or running person is coming right
toward you.
Although we rely on binocular cues to experience depth in our 3-D world, we can also perceive depth in
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2-D arrays. Think about all the paintings and photographs you have seen. Generally, you pick up on depth
in these images even though the visual stimulus is 2-D. When we do this, we are relying on a number of
monocular cues, or cues that require only one eye. If you think you can’t see depth with one eye, note
that you don’t bump into things when using only one eye while walking—and, in fact, we have more
monocular cues than binocular cues.
An example of a monocular cue would be what is known as linear perspective. Linear perspective refers to
the fact that we perceive depth when we see two parallel lines that seem to converge in an image (Figure
5.15). Some other monocular depth cues are interposition, the partial overlap of objects, and the relative
size and closeness of images to the horizon.
Figure 5.15 We perceive depth in a two-dimensional figure like this one through the use of monocular cues like
linear perspective, like the parallel lines converging as the road narrows in the distance. (credit: Marc Dalmulder)
Bruce Bridgeman was born with an extreme case of lazy eye that resulted in him being stereoblind, or unable
to respond to binocular cues of depth. He relied heavily on monocular depth cues, but he never had a true
appreciation of the 3-D nature of the world around him. This all changed one night in 2012 while Bruce was
seeing a movie with his wife.
The movie the couple was going to see was shot in 3-D, and even though he thought it was a waste of money,
Bruce paid for the 3-D glasses when he purchased his ticket. As soon as the film began, Bruce put on the
glasses and experienced something completely new. For the first time in his life he appreciated the true depth
of the world around him. Remarkably, his ability to perceive depth persisted outside of the movie theater.
There are cells in the nervous system that respond to binocular depth cues. Normally, these cells require
activation during early development in order to persist, so experts familiar with Bruce’s case (and others like
his) assume that at some point in his development, Bruce must have experienced at least a fleeting moment of
binocular vision. It was enough to ensure the survival of the cells in the visual system tuned to binocular cues.
The mystery now is why it took Bruce nearly 70 years to have these cells activated (Peck, 2012).
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5.4 Hearing
Learning Objectives
By the end of this section, you will be able to:
• Describe the basic anatomy and function of the auditory system
• Explain how we encode and perceive pitch
• Discuss how we localize sound
Our auditory system converts pressure waves into meaningful sounds. This translates into our ability
to hear the sounds of nature, to appreciate the beauty of music, and to communicate with one another
through spoken language. This section will provide an overview of the basic anatomy and function of the
auditory system. It will include a discussion of how the sensory stimulus is translated into neural impulses,
where in the brain that information is processed, how we perceive pitch, and how we know where sound
is coming from.
The ear can be separated into multiple sections. The outer ear includes the pinna, which is the visible
part of the ear that protrudes from our heads, the auditory canal, and the tympanic membrane, or
eardrum. The middle ear contains three tiny bones known as the ossicles, which are named the malleus
(or hammer), incus (or anvil), and the stapes (or stirrup). The inner ear contains the semi-circular canals,
which are involved in balance and movement (the vestibular sense), and the cochlea. The cochlea is a fluid-
filled, snail-shaped structure that contains the sensory receptor cells (hair cells) of the auditory system
(Figure 5.16).
Figure 5.16 The ear is divided into outer (pinna and tympanic membrane), middle (the three ossicles: malleus,
incus, and stapes), and inner (cochlea and basilar membrane) divisions.
Sound waves travel along the auditory canal and strike the tympanic membrane, causing it to vibrate. This
vibration results in movement of the three ossicles. As the ossicles move, the stapes presses into a thin
membrane of the cochlea known as the oval window. As the stapes presses into the oval window, the fluid
inside the cochlea begins to move, which in turn stimulates hair cells, which are auditory receptor cells of
the inner ear embedded in the basilar membrane. The basilar membrane is a thin strip of tissue within the
The activation of hair cells is a mechanical process: the stimulation of the hair cell ultimately leads to
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activation of the cell. As hair cells become activated, they generate neural impulses that travel along
the auditory nerve to the brain. Auditory information is shuttled to the inferior colliculus, the medial
geniculate nucleus of the thalamus, and finally to the auditory cortex in the temporal lobe of the brain
for processing. Like the visual system, there is also evidence suggesting that information about auditory
recognition and localization is processed in parallel streams (Rauschecker & Tian, 2000; Renier et al., 2009).
Different frequencies of sound waves are associated with differences in our perception of the pitch of those
sounds. Low-frequency sounds are lower pitched, and high-frequency sounds are higher pitched. How
does the auditory system differentiate among various pitches?
Several theories have been proposed to account for pitch perception. We’ll discuss two of them here:
temporal theory and place theory. The temporal theory of pitch perception asserts that frequency is coded
by the activity level of a sensory neuron. This would mean that a given hair cell would fire action potentials
related to the frequency of the sound wave. While this is a very intuitive explanation, we detect such a
broad range of frequencies (20–20,000 Hz) that the frequency of action potentials fired by hair cells cannot
account for the entire range. Because of properties related to sodium channels on the neuronal membrane
that are involved in action potentials, there is a point at which a cell cannot fire any faster (Shamma, 2001).
The place theory of pitch perception suggests that different portions of the basilar membrane are sensitive
to sounds of different frequencies. More specifically, the base of the basilar membrane responds best to
high frequencies and the tip of the basilar membrane responds best to low frequencies. Therefore, hair
cells that are in the base portion would be labeled as high-pitch receptors, while those in the tip of basilar
membrane would be labeled as low-pitch receptors (Shamma, 2001).
In reality, both theories explain different aspects of pitch perception. At frequencies up to about 4000 Hz,
it is clear that both the rate of action potentials and place contribute to our perception of pitch. However,
much higher frequency sounds can only be encoded using place cues (Shamma, 2001).
The ability to locate sound in our environments is an important part of hearing. Localizing sound could be
considered similar to the way that we perceive depth in our visual fields. Like the monocular and binocular
cues that provided information about depth, the auditory system uses both monaural (one-eared) and
binaural (two-eared) cues to localize sound.
Each pinna interacts with incoming sound waves differently, depending on the sound’s source relative to
our bodies. This interaction provides a monaural cue that is helpful in locating sounds that occur above or
below and in front or behind us. The sound waves received by your two ears from sounds that come from
directly above, below, in front, or behind you would be identical; therefore, monaural cues are essential
(Grothe, Pecka, & McAlpine, 2010).
Binaural cues, on the other hand, provide information on the location of a sound along a horizontal axis
by relying on differences in patterns of vibration of the eardrum between our two ears. If a sound comes
from an off-center location, it creates two types of binaural cues: interaural level differences and interaural
timing differences. Interaural level difference refers to the fact that a sound coming from the right side of
your body is more intense at your right ear than at your left ear because of the attenuation of the sound
wave as it passes through your head. Interaural timing difference refers to the small difference in the
time at which a given sound wave arrives at each ear (Figure 5.17). Certain brain areas monitor these
differences to construct where along a horizontal axis a sound originates (Grothe et al., 2010).
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Figure 5.17 Localizing sound involves the use of both monaural and binaural cues. (credit “plane”: modification of
work by Max Pfandl)
Deafness is the partial or complete inability to hear. Some people are born deaf, which is known as
congenital deafness. Many others begin to suffer from conductive hearing loss because of age, genetic
predisposition, or environmental effects, including exposure to extreme noise (noise-induced hearing loss,
as shown in Figure 5.18), certain illnesses (such as measles or mumps), or damage due to toxins (such as
those found in certain solvents and metals).
Figure 5.18 Environmental factors that can lead to conductive hearing loss include regular exposure to loud music
or construction equipment. (a) Rock musicians and (b) construction workers are at risk for this type of hearing loss.
(credit a: modification of work by Kenny Sun; credit b: modification of work by Nick Allen)
Given the mechanical nature by which the sound wave stimulus is transmitted from the eardrum through
the ossicles to the oval window of the cochlea, some degree of hearing loss is inevitable. With conductive
hearing loss, hearing problems are associated with a failure in the vibration of the eardrum and/or
movement of the ossicles. These problems are often dealt with through devices like hearing aids that
amplify incoming sound waves to make vibration of the eardrum and movement of the ossicles more likely
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to occur.
When the hearing problem is associated with a failure to transmit neural signals from the cochlea to the
brain, it is called sensorineural hearing loss. One disease that results in sensorineural hearing loss is
Ménière’s disease. Although not well understood, Ménière’s disease results in a degeneration of inner ear
structures that can lead to hearing loss, tinnitus (constant ringing or buzzing), vertigo (a sense of spinning),
and an increase in pressure within the inner ear (Semaan & Megerian, 2011). This kind of loss cannot be
treated with hearing aids, but some individuals might be candidates for a cochlear implant as a treatment
option. Cochlear implants are electronic devices that consist of a microphone, a speech processor, and
an electrode array. The device receives incoming sound information and directly stimulates the auditory
nerve to transmit information to the brain.
Watch this video ( describe
cochlear implant surgeries and how they work.
Deaf Culture
In the United States and other places around the world, deaf people have their own language, schools, and
customs. This is called deaf culture. In the United States, deaf individuals often communicate using American
Sign Language (ASL); ASL has no verbal component and is based entirely on visual signs and gestures. The
primary mode of communication is signing. One of the values of deaf culture is to continue traditions like using
sign language rather than teaching deaf children to try to speak, read lips, or have cochlear implant surgery.
When a child is diagnosed as deaf, parents have difficult decisions to make. Should the child be enrolled in
mainstream schools and taught to verbalize and read lips? Or should the child be sent to a school for deaf
children to learn ASL and have significant exposure to deaf culture? Do you think there might be differences in
the way that parents approach these decisions depending on whether or not they are also deaf?
5.5 The Other Senses
Learning Objectives
By the end of this section, you will be able to:
• Describe the basic functions of the chemical senses
• Explain the basic functions of the somatosensory, nociceptive, and thermoceptive sensory
• Describe the basic functions of the vestibular, proprioceptive, and kinesthetic sensory
Vision and hearing have received an incredible amount of attention from researchers over the years.
While there is still much to be learned about how these sensory systems work, we have a much better
understanding of them than of our other sensory modalities. In this section, we will explore our chemical
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senses (taste and smell) and our body senses (touch, temperature, pain, balance, and body position).
Taste (gustation) and smell (olfaction) are called chemical senses because both have sensory receptors that
respond to molecules in the food we eat or in the air we breathe. There is a pronounced interaction between
our chemical senses. For example, when we describe the flavor of a given food, we are really referring to
both gustatory and olfactory properties of the food working in combination.
Taste (Gustation)
You have learned since elementary school that there are four basic groupings of taste: sweet, salty, sour,
and bitter. Research demonstrates, however, that we have at least six taste groupings. Umami is our fifth
taste. Umami is actually a Japanese word that roughly translates to yummy, and it is associated with
a taste for monosodium glutamate (Kinnamon & Vandenbeuch, 2009). There is also a growing body of
experimental evidence suggesting that we possess a taste for the fatty content of a given food (Mizushige,
Inoue, & Fushiki, 2007).
Molecules from the food and beverages we consume dissolve in our saliva and interact with taste receptors
on our tongue and in our mouth and throat. Taste buds are formed by groupings of taste receptor cells
with hair-like extensions that protrude into the central pore of the taste bud (Figure 5.19). Taste buds
have a life cycle of ten days to two weeks, so even destroying some by burning your tongue won’t have
any long-term effect; they just grow right back. Taste molecules bind to receptors on this extension and
cause chemical changes within the sensory cell that result in neural impulses being transmitted to the brain
via different nerves, depending on where the receptor is located. Taste information is transmitted to the
medulla, thalamus, and limbic system, and to the gustatory cortex, which is tucked underneath the overlap
between the frontal and temporal lobes (Maffei, Haley, & Fontanini, 2012; Roper, 2013).
Figure 5.19 (a) Taste buds are composed of a number of individual taste receptors cells that transmit information to
nerves. (b) This micrograph shows a close-up view of the tongue’s surface. (credit a: modification of work by Jonas
Töle; credit b: scale-bar data from Matt Russell)
Smell (Olfaction)
Olfactory receptor cells are located in a mucous membrane at the top of the nose. Small hair-like
extensions from these receptors serve as the sites for odor molecules dissolved in the mucus to interact
with chemical receptors located on these extensions (Figure 5.20). Once an odor molecule has bound a
given receptor, chemical changes within the cell result in signals being sent to the olfactory bulb: a bulb-
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like structure at the tip of the frontal lobe where the olfactory nerves begin. From the olfactory bulb,
information is sent to regions of the limbic system and to the primary olfactory cortex, which is located
very near the gustatory cortex (Lodovichi & Belluscio, 2012; Spors et al., 2013).
Figure 5.20 Olfactory receptors are the hair-like parts that extend from the olfactory bulb into the mucous membrane
of the nasal cavity.
There is tremendous variation in the sensitivity of the olfactory systems of different species. We often think
of dogs as having far superior olfactory systems than our own, and indeed, dogs can do some remarkable
things with their noses. There is some evidence to suggest that dogs can “smell” dangerous drops in blood
glucose levels as well as cancerous tumors (Wells, 2010). Dogs’ extraordinary olfactory abilities may be
due to the increased number of functional genes for olfactory receptors (between 800 and 1200), compared
to the fewer than 400 observed in humans and other primates (Niimura & Nei, 2007).
Many species respond to chemical messages, known as pheromones, sent by another individual (Wysocki
& Preti, 2004). Pheromonal communication often involves providing information about the reproductive
status of a potential mate. So, for example, when a female rat is ready to mate, she secretes pheromonal
signals that draw attention from nearby male rats. Pheromonal activation is actually an important
component in eliciting sexual behavior in the male rat (Furlow, 1996, 2012; Purvis & Haynes, 1972; Sachs,
1997). There has also been a good deal of research (and controversy) about pheromones in humans
(Comfort, 1971; Russell, 1976; Wolfgang-Kimball, 1992; Weller, 1998).
A number of receptors are distributed throughout the skin to respond to various touch-related stimuli
(Figure 5.21). These receptors include Meissner’s corpuscles, Pacinian corpuscles, Merkel’s disks, and
Ruffini corpuscles. Meissner’s corpuscles respond to pressure and lower frequency vibrations, and
Pacinian corpuscles detect transient pressure and higher frequency vibrations. Merkel’s disks respond to
light pressure, while Ruffini corpuscles detect stretch (Abraira & Ginty, 2013).
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Figure 5.21 There are many types of sensory receptors located in the skin, each attuned to specific touch-related
In addition to the receptors located in the skin, there are also a number of free nerve endings that
serve sensory functions. These nerve endings respond to a variety of different types of touch-related
stimuli and serve as sensory receptors for both thermoception (temperature perception) and nociception
(a signal indicating potential harm and maybe pain) (Garland, 2012; Petho & Reeh, 2012; Spray, 1986).
Sensory information collected from the receptors and free nerve endings travels up the spinal cord and is
transmitted to regions of the medulla, thalamus, and ultimately to somatosensory cortex, which is located
in the postcentral gyrus of the parietal lobe.
Pain Perception
Pain is an unpleasant experience that involves both physical and psychological components. Feeling pain
is quite adaptive because it makes us aware of an injury, and it motivates us to remove ourselves from the
cause of that injury. In addition, pain also makes us less likely to suffer additional injury because we will
be gentler with our injured body parts.
Generally speaking, pain can be considered to be neuropathic or inflammatory in nature. Pain that signals
some type of tissue damage is known as inflammatory pain. In some situations, pain results from damage
to neurons of either the peripheral or central nervous system. As a result, pain signals that are sent to the
brain get exaggerated. This type of pain is known as neuropathic pain. Multiple treatment options for pain
relief range from relaxation therapy to the use of analgesic medications to deep brain stimulation. The most
effective treatment option for a given individual will depend on a number of considerations, including the
severity and persistence of the pain and any medical/psychological conditions.
Some individuals are born without the ability to feel pain. This very rare genetic disorder is known as
congenital insensitivity to pain (or congenital analgesia). While those with congenital analgesia can
detect differences in temperature and pressure, they cannot experience pain. As a result, they often suffer
significant injuries. Young children have serious mouth and tongue injuries because they have bitten
themselves repeatedly. Not surprisingly, individuals suffering from this disorder have much shorter life
expectancies due to their injuries and secondary infections of injured sites (U.S. National Library of
Medicine, 2013).
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Watch this video ( to learn more about
congenital insensitivity to pain.
The vestibular sense contributes to our ability to maintain balance and body posture. As Figure 5.22
shows, the major sensory organs (utricle, saccule, and the three semicircular canals) of this system are
located next to the cochlea in the inner ear. The vestibular organs are fluid-filled and have hair cells, similar
to the ones found in the auditory system, which respond to movement of the head and gravitational forces.
When these hair cells are stimulated, they send signals to the brain via the vestibular nerve. Although we
may not be consciously aware of our vestibular system’s sensory information under normal circumstances,
its importance is apparent when we experience motion sickness and/or dizziness related to infections of
the inner ear (Khan & Chang, 2013).
Figure 5.22 The major sensory organs of the vestibular system are located next to the cochlea in the inner ear.
These include the utricle, saccule, and the three semicircular canals (posterior, superior, and horizontal).
In addition to maintaining balance, the vestibular system collects information critical for controlling
movement and the reflexes that move various parts of our bodies to compensate for changes in body
position. Therefore, both proprioception (perception of body position) and kinesthesia (perception of the
body’s movement through space) interact with information provided by the vestibular system.
These sensory systems also gather information from receptors that respond to stretch and tension in
muscles, joints, skin, and tendons (Lackner & DiZio, 2005; Proske, 2006; Proske & Gandevia, 2012).
Proprioceptive and kinesthetic information travels to the brain via the spinal column. Several cortical
regions in addition to the cerebellum receive information from and send information to the sensory organs
of the proprioceptive and kinesthetic systems.
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5.6 Gestalt Principles of Perception
Learning Objectives
By the end of this section, you will be able to:
• Explain the figure-ground relationship
• Define Gestalt principles of grouping
• Describe how perceptual set is influenced by an individual’s characteristics and mental state
In the early part of the 20th century, Max Wertheimer published a paper demonstrating that individuals
perceived motion in rapidly flickering static images—an insight that came to him as he used a child’s toy
tachistoscope. Wertheimer, and his assistants Wolfgang Köhler and Kurt Koffka, who later became his
partners, believed that perception involved more than simply combining sensory stimuli. This belief led to
a new movement within the field of psychology known as Gestalt psychology. The word gestalt literally
means form or pattern, but its use reflects the idea that the whole is different from the sum of its parts. In
other words, the brain creates a perception that is more than simply the sum of available sensory inputs,
and it does so in predictable ways. Gestalt psychologists translated these predictable ways into principles
by which we organize sensory information. As a result, Gestalt psychology has been extremely influential
in the area of sensation and perception (Rock & Palmer, 1990).
One Gestalt principle is the figure-ground relationship. According to this principle, we tend to segment
our visual world into figure and ground. Figure is the object or person that is the focus of the visual
field, while the ground is the background. As Figure 5.23 shows, our perception can vary tremendously,
depending on what is perceived as figure and what is perceived as ground. Presumably, our ability to
interpret sensory information depends on what we label as figure and what we label as ground in any
particular case, although this assumption has been called into question (Peterson & Gibson, 1994; Vecera
& O’Reilly, 1998).
Figure 5.23 The concept of figure-ground relationship explains why this image can be perceived either as a vase or
as a pair of faces.
Another Gestalt principle for organizing sensory stimuli into meaningful perception is proximity. This
principle asserts that things that are close to one another tend to be grouped together, as Figure 5.24
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Figure 5.24 The Gestalt principle of proximity suggests that you see (a) one block of dots on the left side and (b)
three columns on the right side.
How we read something provides another illustration of the proximity concept. For example, we read this
sentence like this, notl iket hiso rt hat. We group the letters of a given word together because there are no
spaces between the letters, and we perceive words because there are spaces between each word. Here are
some more examples: Cany oum akes enseo ft hiss entence? What doth es e wor dsmea n?
We might also use the principle of similarity to group things in our visual fields. According to this
principle, things that are alike tend to be grouped together (Figure 5.25). For example, when watching
a football game, we tend to group individuals based on the colors of their uniforms. When watching an
offensive drive, we can get a sense of the two teams simply by grouping along this dimension.
Figure 5.25 When looking at this array of dots, we likely perceive alternating rows of colors. We are grouping these
dots according to the principle of similarity.
Two additional Gestalt principles are the law of continuity (or good continuation) and closure. The law
of continuity suggests that we are more likely to perceive continuous, smooth flowing lines rather than
jagged, broken lines (Figure 5.26). The principle of closure states that we organize our perceptions into
complete objects rather than as a series of parts (Figure 5.27).
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Figure 5.26 Good continuation would suggest that we are more likely to perceive this as two overlapping lines,
rather than four lines meeting in the center.
Figure 5.27 Closure suggests that we will perceive a complete circle and rectangle rather than a series of
Watch this video ( showing real world
illustrations of Gestalt principles.
According to Gestalt theorists, pattern perception, or our ability to discriminate among different figures
and shapes, occurs by following the principles described above. You probably feel fairly certain that
your perception accurately matches the real world, but this is not always the case. Our perceptions are
based on perceptual hypotheses: educated guesses that we make while interpreting sensory information.
These hypotheses are informed by a number of factors, including our personalities, experiences, and
expectations. We use these hypotheses to generate our perceptual set. For instance, research has
demonstrated that those who are given verbal priming produce a biased interpretation of complex
ambiguous figures (Goolkasian & Woodbury, 2010).
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The Depths of Perception: Bias, Prejudice, and Cultural Factors
In this chapter, you have learned that perception is a complex process. Built from sensations, but influenced
by our own experiences, biases, prejudices, and cultures, perceptions can be very different from person
to person. Research suggests that implicit racial prejudice and stereotypes affect perception. For instance,
several studies have demonstrated that non-Black participants identify weapons faster and are more likely to
identify non-weapons as weapons when the image of the weapon is paired with the image of a Black person
(Payne, 2001; Payne, Shimizu, & Jacoby, 2005). Furthermore, White individuals’ decisions to shoot an armed
target in a video game is made more quickly when the target is Black (Correll, Park, Judd, & Wittenbrink, 2002;
Correll, Urland, & Ito, 2006). This research is important, considering the number of very high-profile cases in
the last few decades in which young Blacks were killed by people who claimed to believe that the unarmed
individuals were armed and/or represented some threat to their personal safety.
Chapter 5 | Sensation and Perception 175

absolute threshold
basilar membrane
binaural cue
binocular cue
binocular disparity
blind spot
bottom-up processing
cochlear implant
conductive hearing loss
congenital deafness
congenital insensitivity to pain (congenital analgesia)
decibel (dB)
depth perception
electromagnetic spectrum
figure-ground relationship
Gestalt psychology
good continuation
Key Terms
minimum amount of stimulus energy that must be present for the stimulus to be
detected 50% of the time
continuation of a visual sensation after removal of the stimulus
height of a wave
thin strip of tissue within the cochlea that contains the hair cells which serve as the
sensory receptors for the auditory system
two-eared cue to localize sound
cue that relies on the use of both eyes
slightly different view of the world that each eye receives
point where we cannot respond to visual information in that portion of the visual field
system in which perceptions are built from sensory input
organizing our perceptions into complete objects rather than as a series of parts
fluid-filled, snail-shaped structure that contains the sensory receptor cells of the auditory system
electronic device that consists of a microphone, a speech processor, and an electrode
array to directly stimulate the auditory nerve to transmit information to the brain
failure in the vibration of the eardrum and/or movement of the ossicles
specialized photoreceptor that works best in bright light conditions and detects color
deafness from birth
genetic disorder that results in the inability to
experience pain
transparent covering over the eye
partial or complete inability to hear
logarithmic unit of sound intensity
ability to perceive depth
all the electromagnetic radiation that occurs in our environment
segmenting our visual world into figure and ground
small indentation in the retina that contains cones
number of waves that pass a given point in a given time period
field of psychology based on the idea that the whole is different from the sum of its
(also, continuity) we are more likely to perceive continuous, smooth flowing lines
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hair cell
hertz (Hz)
inattentional blindness
inflammatory pain
interaural level difference
interaural timing difference
just noticeable difference
linear perspective
Meissner’s corpuscle
Merkel’s disk
monaural cue
monocular cue
Ménière’s disease
neuropathic pain
olfactory bulb
olfactory receptor
opponent-process theory of color perception
optic chiasm
optic nerve
Pacinian corpuscle
rather than jagged, broken lines
auditory receptor cell of the inner ear
cycles per second; measure of frequency
failure to notice something that is completely visible because of a lack of
middle ear ossicle; also known as the anvil
signal that some type of tissue damage has occurred
sound coming from one side of the body is more intense at the closest ear
because of the attenuation of the sound wave as it passes through the head
small difference in the time at which a given sound wave arrives at each ear
colored portion of the eye
difference in stimuli required to detect a difference between the stimuli
perception of the body’s movement through space
curved, transparent structure that provides additional focus for light entering the eye
perceive depth in an image when two parallel lines seem to converge
middle ear ossicle; also known as the hammer
touch receptor that responds to pressure and lower frequency vibrations
touch receptor that responds to light touch
one-eared cue to localize sound
cue that requires only one eye
results in a degeneration of inner ear structures that can lead to hearing loss, tinnitus,
vertigo, and an increase in pressure within the inner ear
pain from damage to neurons of either the peripheral or central nervous system
sensory signal indicating potential harm and maybe pain
bulb-like structure at the tip of the frontal lobe, where the olfactory nerves begin
sensory cell for the olfactory system
color is coded in opponent pairs: black-white, yellow-blue,
and red-green
X-shaped structure that sits just below the brain’s ventral surface; represents the merging of
the optic nerves from the two eyes and the separation of information from the two sides of the visual field
to the opposite side of the brain
carries visual information from the retina to the brain
touch receptor that detects transient pressure and higher frequency vibrations
Chapter 5 | Sensation and Perception 177

pattern perception
perceptual hypothesis
place theory of pitch perception
principle of closure
Ruffini corpuscle
sensorineural hearing loss
sensory adaptation
signal detection theory
subliminal message
taste bud
temporal theory of pitch perception
top-down processing
ability to discriminate among different figures and shapes
(also, crest) highest point of a wave
way that sensory information is interpreted and consciously experienced
educated guess used to interpret sensory information
chemical message sent by another individual
light-detecting cell
visible part of the ear that protrudes from the head
perception of a sound’s frequency
different portions of the basilar membrane are sensitive to sounds of
different frequencies
organize perceptions into complete objects rather than as a series of parts
perception of body position
things that are close to one another tend to be grouped together
small opening in the eye through which light passes
light-sensitive lining of the eye
specialized photoreceptor that works well in low light conditions
touch receptor that detects stretch
what happens when sensory information is detected by a sensory receptor
failure to transmit neural signals from the cochlea to the brain
not perceiving stimuli that remain relatively constant over prolonged periods of time
change in stimulus detection as a function of current mental state
things that are alike tend to be grouped together
middle ear ossicle; also known as the stirrup
message presented below the threshold of conscious awareness
grouping of taste receptor cells with hair-like extensions that protrude into the central pore of
the taste bud
sound’s frequency is coded by the activity level of a sensory neuron
temperature perception
sound’s purity
interpretation of sensations is influenced by available knowledge, experiences, and
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trichromatic theory of color perception
tympanic membrane
vestibular sense
visible spectrum
conversion from sensory stimulus energy to action potential
color vision is mediated by the activity across the three groups
of cones
lowest point of a wave
taste for monosodium glutamate
spinning sensation
contributes to our ability to maintain balance and body posture
portion of the electromagnetic spectrum that we can see
length of a wave from one peak to the next peak
5.1 Sensation versus Perception
Sensation occurs when sensory receptors detect sensory stimuli. Perception involves the organization,
interpretation, and conscious experience of those sensations. All sensory systems have both absolute and
difference thresholds, which refer to the minimum amount of stimulus energy or the minimum amount
of difference in stimulus energy required to be detected about 50% of the time, respectively. Sensory
adaptation, selective attention, and signal detection theory can help explain what is perceived and what is
not. In addition, our perceptions are affected by a number of factors, including beliefs, values, prejudices,
culture, and life experiences.
5.2 Waves and Wavelengths
Both light and sound can be described in terms of wave forms with physical characteristics like amplitude,
wavelength, and timbre. Wavelength and frequency are inversely related so that longer waves have lower
frequencies, and shorter waves have higher frequencies. In the visual system, a light wave’s wavelength is
generally associated with color, and its amplitude is associated with brightness. In the auditory system, a
sound’s frequency is associated with pitch, and its amplitude is associated with loudness.
5.3 Vision
Light waves cross the cornea and enter the eye at the pupil. The eye’s lens focuses this light so that the
image is focused on a region of the retina known as the fovea. The fovea contains cones that possess
high levels of visual acuity and operate best in bright light conditions. Rods are located throughout the
retina and operate best under dim light conditions. Visual information leaves the eye via the optic nerve.
Information from each visual field is sent to the opposite side of the brain at the optic chiasm. Visual
information then moves through a number of brain sites before reaching the occipital lobe, where it is
Two theories explain color perception. The trichromatic theory asserts that three distinct cone groups are
tuned to slightly different wavelengths of light, and it is the combination of activity across these cone
types that results in our perception of all the colors we see. The opponent-process theory of color vision
asserts that color is processed in opponent pairs and accounts for the interesting phenomenon of a negative
afterimage. We perceive depth through a combination of monocular and binocular depth cues.
5.4 Hearing
Sound waves are funneled into the auditory canal and cause vibrations of the eardrum; these vibrations
move the ossicles. As the ossicles move, the stapes presses against the oval window of the cochlea, which
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causes fluid inside the cochlea to move. As a result, hair cells embedded in the basilar membrane become
enlarged, which sends neural impulses to the brain via the auditory nerve.
Pitch perception and sound localization are important aspects of hearing. Our ability to perceive pitch
relies on both the firing rate of the hair cells in the basilar membrane as well as their location within the
membrane. In terms of sound localization, both monaural and binaural cues are used to locate where
sounds originate in our environment.
Individuals can be born deaf, or they can develop deafness as a result of age, genetic predisposition, and/
or environmental causes. Hearing loss that results from a failure of the vibration of the eardrum or the
resultant movement of the ossicles is called conductive hearing loss. Hearing loss that involves a failure of
the transmission of auditory nerve impulses to the brain is called sensorineural hearing loss.
5.5 The Other Senses
Taste (gustation) and smell (olfaction) are chemical senses that employ receptors on the tongue and in the
nose that bind directly with taste and odor molecules in order to transmit information to the brain for
processing. Our ability to perceive touch, temperature, and pain is mediated by a number of receptors
and free nerve endings that are distributed throughout the skin and various tissues of the body. The
vestibular sense helps us maintain a sense of balance through the response of hair cells in the utricle,
saccule, and semi-circular canals that respond to changes in head position and gravity. Our proprioceptive
and kinesthetic systems provide information about body position and body movement through receptors
that detect stretch and tension in the muscles, joints, tendons, and skin of the body.
5.6 Gestalt Principles of Perception
Gestalt theorists have been incredibly influential in the areas of sensation and perception. Gestalt
principles such as figure-ground relationship, grouping by proximity or similarity, the law of good
continuation, and closure are all used to help explain how we organize sensory information. Our
perceptions are not infallible, and they can be influenced by bias, prejudice, and other factors.
Review Questions
1. ________ refers to the minimum amount of
stimulus energy required to be detected 50% of the
a. absolute threshold
b. difference threshold
c. just noticeable difference
d. transduction
2. Decreased sensitivity to an unchanging
stimulus is known as ________.
a. transduction
b. difference threshold
c. sensory adaptation
d. inattentional blindness
3. ________ involves the conversion of sensory
stimulus energy into neural impulses.
a. sensory adaptation
b. inattentional blindness
c. difference threshold
d. transduction
4. ________ occurs when sensory information is
organized, interpreted, and consciously
a. sensation
b. perception
c. transduction
d. sensory adaptation
5. Which of the following correctly matches the
pattern in our perception of color as we move
from short wavelengths to long wavelengths?
a. red to orange to yellow
b. yellow to orange to red
c. yellow to red to orange
d. orange to yellow to red
6. The visible spectrum includes light that ranges
from about ________.
a. 400–700 nm
b. 200–900 nm
c. 20–20000 Hz
d. 10–20 dB
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7. The electromagnetic spectrum includes
a. radio waves
b. x-rays
c. infrared light
d. all of the above
8. The audible range for humans is ________.
a. 380–740 Hz
b. 10–20 dB
c. less than 300 dB
d. 20-20,000 Hz
9. The quality of a sound that is affected by
frequency, amplitude, and timing of the sound
wave is known as ________.
a. pitch
b. tone
c. electromagnetic
d. timbre
10. The ________ is a small indentation of the
retina that contains cones.
a. optic chiasm
b. optic nerve
c. fovea
d. iris
11. ________ operate best under bright light
a. cones
b. rods
c. retinal ganglion cells
d. striate cortex
12. ________ depth cues require the use of both
a. monocular
b. binocular
c. linear perspective
d. accommodating
13. If you were to stare at a green dot for a
relatively long period of time and then shift your
gaze to a blank white screen, you would see a
________ negative afterimage.
a. blue
b. yellow
c. black
d. red
14. Hair cells located near the base of the basilar
membrane respond best to ________ sounds.
a. low-frequency
b. high-frequency
c. low-amplitude
d. high-amplitude
15. The three ossicles of the middle ear are
known as ________.
a. malleus, incus, and stapes
b. hammer, anvil, and stirrup
c. pinna, cochlea, and utricle
d. both a and b
16. Hearing aids might be effective for treating
a. Ménière’s disease
b. sensorineural hearing loss
c. conductive hearing loss
d. interaural time differences
17. Cues that require two ears are referred to as
________ cues.
a. monocular
b. monaural
c. binocular
d. binaural
18. Chemical messages often sent between two
members of a species to communicate something
about reproductive status are called ________.
a. hormones
b. pheromones
c. Merkel’s disks
d. Meissner’s corpuscles
19. Which taste is associated with monosodium
a. sweet
b. bitter
c. umami
d. sour
20. ________ serve as sensory receptors for
temperature and pain stimuli.
a. free nerve endings
b. Pacinian corpuscles
c. Ruffini corpuscles
d. Meissner’s corpuscles
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21. Which of the following is involved in
maintaining balance and body posture?
a. auditory nerve
b. nociceptors
c. olfactory bulb
d. vestibular system
22. According to the principle of ________,
objects that occur close to one another tend to be
grouped together.
a. similarity
b. good continuation
c. proximity
d. closure
23. Our tendency to perceive things as complete
objects rather than as a series of parts is known as
the principle of ________.
a. closure
b. good continuation
c. proximity
d. similarity
24. According to the law of ________, we are
more likely to perceive smoothly flowing lines
rather than choppy or jagged lines.
a. closure
b. good continuation
c. proximity
d. similarity
25. The main point of focus in a visual display is
known as the ________.
a. closure
b. perceptual set
c. ground
d. figure
Critical Thinking Questions
26. Not everything that is sensed is perceived. Do you think there could ever be a case where something
could be perceived without being sensed?
27. Please generate a novel example of how just noticeable difference can change as a function of stimulus
28. Why do you think other species have such different ranges of sensitivity for both visual and auditory
stimuli compared to humans?
29. Why do you think humans are especially sensitive to sounds with frequencies that fall in the middle
portion of the audible range?
30. Compare the two theories of color perception. Are they completely different?
31. Color is not a physical property of our environment. What function (if any) do you think color vision
32. Given what you’ve read about sound localization, from an evolutionary perspective, how does sound
localization facilitate survival?
33. How can temporal and place theories both be used to explain our ability to perceive the pitch of sound
waves with frequencies up to 4000 Hz?
34. Many people experience nausea while traveling in a car, plane, or boat. How might you explain this
as a function of sensory interaction?
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35. If you heard someone say that they would do anything not to feel the pain associated with significant
injury, how would you respond given what you’ve just read?
36. Do you think women experience pain differently than men? Why do you think this is?
37. The central tenet of Gestalt psychology is that the whole is different from the sum of its parts. What
does this mean in the context of perception?
38. Take a look at the following figure. How might you influence whether people see a duck or a rabbit?
Figure 5.28
Personal Application Questions
39. Think about a time when you failed to notice something around you because your attention was
focused elsewhere. If someone pointed it out, were you surprised that you hadn’t noticed it right away?
40. If you grew up with a family pet, then you have surely noticed that they often seem to hear things that
you don’t hear. Now that you’ve read this section, you probably have some insight as to why this may be.
How would you explain this to a friend who never had the opportunity to take a class like this?
41. Take a look at a few of your photos or personal works of art. Can you find examples of linear
perspective as a potential depth cue?
42. If you had to choose to lose either your vision or your hearing, which would you choose and why?
43. As mentioned earlier, a food’s flavor represents an interaction of both gustatory and olfactory
information. Think about the last time you were seriously congested due to a cold or the flu. What changes
did you notice in the flavors of the foods that you ate during this time?
44. Have you ever listened to a song on the radio and sung along only to find out later that you have been
singing the wrong lyrics? Once you found the correct lyrics, did your perception of the song change?
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Chapter 6
Figure 6.1 Loggerhead sea turtle hatchlings are born knowing how to find the ocean and how to swim. Unlike the
sea turtle, humans must learn how to swim (and surf). (credit “turtle”: modification of work by Becky Skiba, USFWS;
credit “surfer”: modification of work by Mike Baird)
Chapter Outline
6.1 What Is Learning?
6.2 Classical Conditioning
6.3 Operant Conditioning
6.4 Observational Learning (Modeling)
The summer sun shines brightly on a deserted stretch of beach. Suddenly, a tiny grey head emerges
from the sand, then another and another. Soon the beach is teeming with loggerhead sea turtle hatchlings
(Figure 6.1). Although only minutes old, the hatchlings know exactly what to do. Their flippers are not
very efficient for moving across the hot sand, yet they continue onward, instinctively. Some are quickly
snapped up by gulls circling overhead and others become lunch for hungry ghost crabs that dart out of
their holes. Despite these dangers, the hatchlings are driven to leave the safety of their nest and find the
Not far down this same beach, Ben and his son, Julian, paddle out into the ocean on surfboards. A wave
approaches. Julian crouches on his board, then jumps up and rides the wave for a few seconds before
losing his balance. He emerges from the water in time to watch his father ride the face of the wave.
Unlike baby sea turtles, which know how to find the ocean and swim with no help from their parents, we
are not born knowing how to swim (or surf). Yet we humans pride ourselves on our ability to learn. In fact,
over thousands of years and across cultures, we have created institutions devoted entirely to learning. But
have you ever asked yourself how exactly it is that we learn? What processes are at work as we come to
know what we know? This chapter focuses on the primary ways in which learning occurs.
Chapter 6 | Learning 185

6.1 What Is Learning?
Learning Objectives
By the end of this section, you will be able to:
• Explain how learned behaviors are different from instincts and reflexes
• Define learning
• Recognize and define three basic forms of learning—classical conditioning, operant
conditioning, and observational learning
Birds build nests and migrate as winter approaches. Infants suckle at their mother’s breast. Dogs shake
water off wet fur. Salmon swim upstream to spawn, and spiders spin intricate webs. What do these
seemingly unrelated behaviors have in common? They all are unlearned behaviors. Both instincts and
reflexes are innate behaviors that organisms are born with. Reflexes are a motor or neural reaction to a
specific stimulus in the environment. They tend to be simpler than instincts, involve the activity of specific
body parts and systems (e.g., the knee-jerk reflex and the contraction of the pupil in bright light), and
involve more primitive centers of the central nervous system (e.g., the spinal cord and the medulla). In
contrast, instincts are innate behaviors that are triggered by a broader range of events, such as aging and
the change of seasons. They are more complex patterns of behavior, involve movement of the organism as
a whole (e.g., sexual activity and migration), and involve higher brain centers.
Both reflexes and instincts help an organism adapt to its environment and do not have to be learned. For
example, every healthy human baby has a sucking reflex, present at birth. Babies are born knowing how to
suck on a nipple, whether artificial (from a bottle) or human. Nobody teaches the baby to suck, just as no
one teaches a sea turtle hatchling to move toward the ocean. Learning, like reflexes and instincts, allows an
organism to adapt to its environment. But unlike instincts and reflexes, learned behaviors involve change
and experience: learning is a relatively permanent change in behavior or knowledge that results from
experience. In contrast to the innate behaviors discussed above, learning involves acquiring knowledge
and skills through experience. Looking back at our surfing scenario, Julian will have to spend much more
time training with his surfboard before he learns how to ride the waves like his father.
Learning to surf, as well as any complex learning process (e.g., learning about the discipline of
psychology), involves a complex interaction of conscious and unconscious processes. Learning has
traditionally been studied in terms of its simplest components—the associations our minds automatically
make between events. Our minds have a natural tendency to connect events that occur closely together or
in sequence. Associative learning occurs when an organism makes connections between stimuli or events
that occur together in the environment. You will see that associative learning is central to all three basic
learning processes discussed in this chapter; classical conditioning tends to involve unconscious processes,
operant conditioning tends to involve conscious processes, and observational learning adds social and
cognitive layers to all the basic associative processes, both conscious and unconscious. These learning
processes will be discussed in detail later in the chapter, but it is helpful to have a brief overview of each
as you begin to explore how learning is understood from a psychological perspective.
In classical conditioning, also known as Pavlovian conditioning, organisms learn to associate events—or
stimuli—that repeatedly happen together. We experience this process throughout our daily lives. For
example, you might see a flash of lightning in the sky during a storm and then hear a loud boom of
thunder. The sound of the thunder naturally makes you jump (loud noises have that effect by reflex).
Because lightning reliably predicts the impending boom of thunder, you may associate the two and jump
when you see lightning. Psychological researchers study this associative process by focusing on what can
be seen and measured—behaviors. Researchers ask if one stimulus triggers a reflex, can we train a different
stimulus to trigger that same reflex? In operant conditioning, organisms learn, again, to associate events—a
behavior and its consequence (reinforcement or punishment). A pleasant consequence encourages more
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of that behavior in the future, whereas a punishment deters the behavior. Imagine you are teaching your
dog, Hodor, to sit. You tell Hodor to sit, and give him a treat when he does. After repeated experiences,
Hodor begins to associate the act of sitting with receiving a treat. He learns that the consequence of sitting
is that he gets a doggie biscuit (Figure 6.2). Conversely, if the dog is punished when exhibiting a behavior,
it becomes conditioned to avoid that behavior (e.g., receiving a small shock when crossing the boundary
of an invisible electric fence).
Figure 6.2 In operant conditioning, a response is associated with a consequence. This dog has learned that certain
behaviors result in receiving a treat. (credit: Crystal Rolfe)
Observational learning extends the effective range of both classical and operant conditioning. In contrast to
classical and operant conditioning, in which learning occurs only through direct experience, observational
learning is the process of watching others and then imitating what they do. A lot of learning among
humans and other animals comes from observational learning. To get an idea of the extra effective range
that observational learning brings, consider Ben and his son Julian from the introduction. How might
observation help Julian learn to surf, as opposed to learning by trial and error alone? By watching his
father, he can imitate the moves that bring success and avoid the moves that lead to failure. Can you think
of something you have learned how to do after watching someone else?
All of the approaches covered in this chapter are part of a particular tradition in psychology, called
behaviorism, which we discuss in the next section. However, these approaches do not represent the entire
study of learning. Separate traditions of learning have taken shape within different fields of psychology,
such as memory and cognition, so you will find that other chapters will round out your understanding
of the topic. Over time these traditions tend to converge. For example, in this chapter you will see how
cognition has come to play a larger role in behaviorism, whose more extreme adherents once insisted that
behaviors are triggered by the environment with no intervening thought.
6.2 Classical Conditioning
Learning Objectives
By the end of this section, you will be able to:
• Explain how classical conditioning occurs
• Summarize the processes of acquisition, extinction, spontaneous recovery, generalization,
and discrimination
Does the name Ivan Pavlov ring a bell? Even if you are new to the study of psychology, chances are that
you have heard of Pavlov and his famous dogs.
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Pavlov (1849–1936), a Russian scientist, performed extensive research on dogs and is best known for
his experiments in classical conditioning (Figure 6.3). As we discussed briefly in the previous section,
classical conditioning is a process by which we learn to associate stimuli and, consequently, to anticipate
Figure 6.3 Ivan Pavlov’s research on the digestive system of dogs unexpectedly led to his discovery of the learning
process now known as classical conditioning.
Pavlov came to his conclusions about how learning occurs completely by accident. Pavlov was a
physiologist, not a psychologist. Physiologists study the life processes of organisms, from the molecular
level to the level of cells, organ systems, and entire organisms. Pavlov’s area of interest was the digestive
system (Hunt, 2007). In his studies with dogs, Pavlov surgically implanted tubes inside dogs’ cheeks to
collect saliva. He then measured the amount of saliva produced in response to various foods. Over time,
Pavlov (1927) observed that the dogs began to salivate not only at the taste of food, but also at the sight
of food, at the sight of an empty food bowl, and even at the sound of the laboratory assistants’ footsteps.
Salivating to food in the mouth is reflexive, so no learning is involved. However, dogs don’t naturally
salivate at the sight of an empty bowl or the sound of footsteps.
These unusual responses intrigued Pavlov, and he wondered what accounted for what he called the dogs’
“psychic secretions” (Pavlov, 1927). To explore this phenomenon in an objective manner, Pavlov designed
a series of carefully controlled experiments to see which stimuli would cause the dogs to salivate. He was
able to train the dogs to salivate in response to stimuli that clearly had nothing to do with food, such as the
sound of a bell, a light, and a touch on the leg. Through his experiments, Pavlov realized that an organism
has two types of responses to its environment: (1) unconditioned (unlearned) responses, or reflexes, and
(2) conditioned (learned) responses.
In Pavlov’s experiments, the dogs salivated each time meat powder was presented to them. The meat
powder in this situation was an unconditioned stimulus (UCS): a stimulus that elicits a reflexive response
in an organism. The dogs’ salivation was an unconditioned response (UCR): a natural (unlearned)
reaction to a given stimulus. Before conditioning, think of the dogs’ stimulus and response like this:
Meat powder (UCS) → Salivation (UCR)
In classical conditioning, a neutral stimulus is presented immediately before an unconditioned stimulus.
Pavlov would sound a tone (like ringing a bell) and then give the dogs the meat powder (Figure 6.4). The
tone was the neutral stimulus (NS), which is a stimulus that does not naturally elicit a response. Prior to
conditioning, the dogs did not salivate when they just heard the tone because the tone had no association
for the dogs. Quite simply this pairing means:
Tone (NS) + Meat Powder (UCS) → Salivation (UCR)
When Pavlov paired the tone with the meat powder over and over again, the previously neutral stimulus
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(the tone) also began to elicit salivation from the dogs. Thus, the neutral stimulus became the conditioned
stimulus (CS), which is a stimulus that elicits a response after repeatedly being paired with an
unconditioned stimulus. Eventually, the dogs began to salivate to the tone alone, just as they previously
had salivated at the sound of the assistants’ footsteps. The behavior caused by the conditioned stimulus is
called the conditioned response (CR). In the case of Pavlov’s dogs, they had learned to associate the tone
(CS) with being fed, and they began to salivate (CR) in anticipation of food.
Tone (CS) → Salivation (CR)
Figure 6.4 Before conditioning, an unconditioned stimulus (food) produces an unconditioned response (salivation),
and a neutral stimulus (bell) does not produce a response. During conditioning, the unconditioned stimulus (food) is
presented repeatedly just after the presentation of the neutral stimulus (bell). After conditioning, the neutral stimulus
alone produces a conditioned response (salivation), thus becoming a conditioned stimulus.
Now that you have learned about the process of classical conditioning, do you think
you can condition Pavlov’s dog? Visit this website (
pavlov1) to play the game.
View this video ( to learn more about Pavlov
and his dogs.
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How does classical conditioning work in the real world? Let’s say you have a cat named Tiger, who is
quite spoiled. You keep her food in a separate cabinet, and you also have a special electric can opener that
you use only to open cans of cat food. For every meal, Tiger hears the distinctive sound of the electric can
opener (“zzhzhz”) and then gets her food. Tiger quickly learns that when she hears “zzhzhz” she is about
to get fed. What do you think Tiger does when she hears the electric can opener? She will likely get excited
and run to where you are preparing her food. This is an example of classical conditioning. In this case,
what are the UCS, CS, UCR, and CR?
What if the cabinet holding Tiger’s food becomes squeaky? In that case, Tiger hears “squeak” (the cabinet),
“zzhzhz” (the electric can opener), and then she gets her food. Tiger will learn to get excited when she
hears the “squeak” of the cabinet. Pairing a new neutral stimulus (“squeak”) with the conditioned stimulus
(“zzhzhz”) is called higher-order conditioning, or second-order conditioning. This means you are using
the conditioned stimulus of the can opener to condition another stimulus: the squeaky cabinet (Figure 6.5).
It is hard to achieve anything above second-order conditioning. For example, if you ring a bell, open the
cabinet (“squeak”), use the can opener (“zzhzhz”), and then feed Tiger, Tiger will likely never get excited
when hearing the bell alone.
Figure 6.5 In higher-order conditioning, an established conditioned stimulus is paired with a new neutral stimulus
(the second-order stimulus), so that eventually the new stimulus also elicits the conditioned response, without the
initial conditioned stimulus being presented.
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Classical Conditioning at Stingray City
Kate and her husband Scott recently vacationed in the Cayman Islands, and booked a boat tour to Stingray
City, where they could feed and swim with the southern stingrays. The boat captain explained how the normally
solitary stingrays have become accustomed to interacting with humans. About 40 years ago, fishermen began
to clean fish and conch (unconditioned stimulus) at a particular sandbar near a barrier reef, and large numbers
of stingrays would swim in to eat (unconditioned response) what the fishermen threw into the water; this
continued for years. By the late 1980s, word of the large group of stingrays spread among scuba divers, who
then started feeding them by hand. Over time, the southern stingrays in the area were classically conditioned
much like Pavlov’s dogs. When they hear the sound of a boat engine (neutral stimulus that becomes a
conditioned stimulus), they know that they will get to eat (conditioned response).
As soon as Kate and Scott reached Stingray City, over two dozen stingrays surrounded their tour boat. The
couple slipped into the water with bags of squid, the stingrays’ favorite treat. The swarm of stingrays bumped
and rubbed up against their legs like hungry cats (Figure 6.6). Kate and Scott were able to feed, pet, and even
kiss (for luck) these amazing creatures. Then all the squid was gone, and so were the stingrays.
Figure 6.6 Kate holds a southern stingray at Stingray City in the Cayman Islands. These stingrays have
been classically conditioned to associate the sound of a boat motor with food provided by tourists. (credit:
Kathryn Dumper)
Classical conditioning also applies to humans, even babies. For example, Sara buys formula in blue
canisters for her six-month-old daughter, Angelina. Whenever Sara takes out a formula container,
Angelina gets excited, tries to reach toward the food, and most likely salivates. Why does Angelina get
excited when she sees the formula canister? What are the UCS, CS, UCR, and CR here?
So far, all of the examples have involved food, but classical conditioning extends beyond the basic need
to be fed. Consider our earlier example of a dog whose owners install an invisible electric dog fence.
A small electrical shock (unconditioned stimulus) elicits discomfort (unconditioned response). When the
unconditioned stimulus (shock) is paired with a neutral stimulus (the edge of a yard), the dog associates
the discomfort (unconditioned response) with the edge of the yard (conditioned stimulus) and stays within
the set boundaries. In this example, the edge of the yard elicits fear and anxiety in the dog. Fear and anxiety
are the conditioned response.
For a humorous look at conditioning, watch this video clip
( from the television show The Office, where
Jim conditions Dwight to expect a breath mint every time Jim’s computer makes a
specific sound.
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Now that you know how classical conditioning works and have seen several examples, let’s take a look at
some of the general processes involved. In classical conditioning, the initial period of learning is known
as acquisition, when an organism learns to connect a neutral stimulus and an unconditioned stimulus.
During acquisition, the neutral stimulus begins to elicit the conditioned response, and eventually the
neutral stimulus becomes a conditioned stimulus capable of eliciting the conditioned response by itself.
Timing is important for conditioning to occur. Typically, there should only be a brief interval between
presentation of the conditioned stimulus and the unconditioned stimulus. Depending on what is being
conditioned, sometimes this interval is as little as five seconds (Chance, 2009). However, with other types
of conditioning, the interval can be up to several hours.
Taste aversion is a type of conditioning in which an interval of several hours may pass between the
conditioned stimulus (something ingested) and the unconditioned stimulus (nausea or illness). Here’s how
it works. Between classes, you and a friend grab a quick lunch from a food cart on campus. You share a
dish of chicken curry and head off to your next class. A few hours later, you feel nauseous and become ill.
Although your friend is fine and you determine that you have intestinal flu (the food is not the culprit),
you’ve developed a taste aversion; the next time you are at a restaurant and someone orders curry, you
immediately feel ill. While the chicken dish is not what made you sick, you are experiencing taste aversion:
you’ve been conditioned to be averse to a food after a single, negative experience.
How does this occur—conditioning based on a single instance and involving an extended time lapse
between the event and the negative stimulus? Research into taste aversion suggests that this response may
be an evolutionary adaptation designed to help organisms quickly learn to avoid harmful foods (Garcia
& Rusiniak, 1980; Garcia & Koelling, 1966). Not only may this contribute to species survival via natural
selection, but it may also help us develop strategies for challenges such as helping cancer patients through
the nausea induced by certain treatments (Holmes, 1993; Jacobsen et al., 1993; Hutton, Baracos, & Wismer,
2007; Skolin et al., 2006).
Once we have established the connection between the unconditioned stimulus and the conditioned
stimulus, how do we break that connection and get the dog, cat, or child to stop responding? In Tiger’s
case, imagine what would happen if you stopped using the electric can opener for her food and began to
use it only for human food. Now, Tiger would hear the can opener, but she would not get food. In classical
conditioning terms, you would be giving the conditioned stimulus, but not the unconditioned stimulus.
Pavlov explored this scenario in his experiments with dogs: sounding the tone without giving the dogs the
meat powder. Soon the dogs stopped responding to the tone. Extinction is the decrease in the conditioned
response when the unconditioned stimulus is no longer presented with the conditioned stimulus. When
presented with the conditioned stimulus alone, the dog, cat, or other organism would show a weaker and
weaker response, and finally no response. In classical conditioning terms, there is a gradual weakening
and disappearance of the conditioned response.
What happens when learning is not used for a while—when what was learned lies dormant? As we
just discussed, Pavlov found that when he repeatedly presented the bell (conditioned stimulus) without
the meat powder (unconditioned stimulus), extinction occurred; the dogs stopped salivating to the bell.
However, after a couple of hours of resting from this extinction training, the dogs again began to salivate
when Pavlov rang the bell. What do you think would happen with Tiger’s behavior if your electric can
opener broke, and you did not use it for several months? When you finally got it fixed and started using
it to open Tiger’s food again, Tiger would remember the association between the can opener and her
food—she would get excited and run to the kitchen when she heard the sound. The behavior of Pavlov’s
dogs and Tiger illustrates a concept Pavlov called spontaneous recovery: the return of a previously
extinguished conditioned response following a rest period (Figure 6.7).
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Figure 6.7 This is the curve of acquisition, extinction, and spontaneous recovery. The rising curve shows the
conditioned response quickly getting stronger through the repeated pairing of the conditioned stimulus and the
unconditioned stimulus (acquisition). Then the curve decreases, which shows how the conditioned response weakens
when only the conditioned stimulus is presented (extinction). After a break or pause from conditioning, the
conditioned response reappears (spontaneous recovery).
Of course, these processes also apply in humans. For example, let’s say that every day when you walk to
campus, an ice cream truck passes your route. Day after day, you hear the truck’s music (neutral stimulus),
so you finally stop and purchase a chocolate ice cream bar. You take a bite (unconditioned stimulus) and
then your mouth waters (unconditioned response). This initial period of learning is known as acquisition,
when you begin to connect the neutral stimulus (the sound of the truck) and the unconditioned stimulus
(the taste of the chocolate ice cream in your mouth). During acquisition, the conditioned response gets
stronger and stronger through repeated pairings of the conditioned stimulus and unconditioned stimulus.
Several days (and ice cream bars) later, you notice that your mouth begins to water (conditioned response)
as soon as you hear the truck’s musical jingle—even before you bite into the ice cream bar. Then one day
you head down the street. You hear the truck’s music (conditioned stimulus), and your mouth waters
(conditioned response). However, when you get to the truck, you discover that they are all out of ice cream.
You leave disappointed. The next few days you pass by the truck and hear the music, but don’t stop to
get an ice cream bar because you’re running late for class. You begin to salivate less and less when you
hear the music, until by the end of the week, your mouth no longer waters when you hear the tune. This
illustrates extinction. The conditioned response weakens when only the conditioned stimulus (the sound
of the truck) is presented, without being followed by the unconditioned stimulus (chocolate ice cream in
the mouth). Then the weekend comes. You don’t have to go to class, so you don’t pass the truck. Monday
morning arrives and you take your usual route to campus. You round the corner and hear the truck again.
What do you think happens? Your mouth begins to water again. Why? After a break from conditioning,
the conditioned response reappears, which indicates spontaneous recovery.
Acquisition and extinction involve the strengthening and weakening, respectively, of a learned
association. Two other learning processes—stimulus discrimination and stimulus generalization—are
involved in distinguishing which stimuli will trigger the learned association. Animals (including humans)
need to distinguish between stimuli—for example, between sounds that predict a threatening event and
sounds that do not—so that they can respond appropriately (such as running away if the sound is
threatening). When an organism learns to respond differently to various stimuli that are similar, it is called
stimulus discrimination. In classical conditioning terms, the organism demonstrates the conditioned
response only to the conditioned stimulus. Pavlov’s dogs discriminated between the basic tone that
sounded before they were fed and other tones (e.g., the doorbell), because the other sounds did not predict
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the arrival of food. Similarly, Tiger, the cat, discriminated between the sound of the can opener and the
sound of the electric mixer. When the electric mixer is going, Tiger is not about to be fed, so she does not
come running to the kitchen looking for food.
On the other hand, when an organism demonstrates the conditioned response to stimuli that are similar to
the condition stimulus, it is called stimulus generalization, the opposite of stimulus discrimination. The
more similar a stimulus is to the condition stimulus, the more likely the organism is to give the conditioned
response. For instance, if the electric mixer sounds very similar to the electric can opener, Tiger may come
running after hearing its sound. But if you do not feed her following the electric mixer sound, and you
continue to feed her consistently after the electric can opener sound, she will quickly learn to discriminate
between the two sounds (provided they are sufficiently dissimilar that she can tell them apart).
Sometimes, classical conditioning can lead to habituation. Habituation occurs when we learn not to
respond to a stimulus that is presented repeatedly without change. As the stimulus occurs over and over,
we learn not to focus our attention on it. For example, imagine that your neighbor or roommate constantly
has the television blaring. This background noise is distracting and makes it difficult for you to focus when
you’re studying. However, over time, you become accustomed to the stimulus of the television noise, and
eventually you hardly notice it any longer.
John B. Watson, shown in Figure 6.8, is considered the founder of behaviorism. Behaviorism is a school
of thought that arose during the first part of the 20th century, which incorporates elements of Pavlov’s
classical conditioning (Hunt, 2007). In stark contrast with Freud, who considered the reasons for behavior
to be hidden in the unconscious, Watson championed the idea that all behavior can be studied as a
simple stimulus-response reaction, without regard for internal processes. Watson argued that in order for
psychology to become a legitimate science, it must shift its concern away from internal mental processes
because mental processes cannot be seen or measured. Instead, he asserted that psychology must focus on
outward observable behavior that can be measured.
Figure 6.8 John B. Watson used the principles of classical conditioning in the study of human emotion.
Watson’s ideas were influenced by Pavlov’s work. According to Watson, human behavior, just like animal
behavior, is primarily the result of conditioned responses. Whereas Pavlov’s work with dogs involved the
conditioning of reflexes, Watson believed the same principles could be extended to the conditioning of
human emotions (Watson, 1919). Thus began Watson’s work with his graduate student Rosalie Rayner
and a baby called Little Albert. Through their experiments with Little Albert, Watson and Rayner (1920)
demonstrated how fears can be conditioned.
In 1920, Watson was the chair of the psychology department at Johns Hopkins University. Through his
position at the university he came to meet Little Albert’s mother, Arvilla Merritte, who worked at a campus
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hospital (DeAngelis, 2010). Watson offered her a dollar to allow her son to be the subject of his experiments
in classical conditioning. Through these experiments, Little Albert was exposed to and conditioned to fear
certain things. Initially he was presented with various neutral stimuli, including a rabbit, a dog, a monkey,
masks, cotton wool, and a white rat. He was not afraid of any of these things. Then Watson, with the
help of Rayner, conditioned Little Albert to associate these stimuli with an emotion—fear. For example,
Watson handed Little Albert the white rat, and Little Albert enjoyed playing with it. Then Watson made
a loud sound, by striking a hammer against a metal bar hanging behind Little Albert’s head, each time
Little Albert touched the rat. Little Albert was frightened by the sound—demonstrating a reflexive fear of
sudden loud noises—and began to cry. Watson repeatedly paired the loud sound with the white rat. Soon
Little Albert became frightened by the white rat alone. In this case, what are the UCS, CS, UCR, and CR?
Days later, Little Albert demonstrated stimulus generalization—he became afraid of other furry things:
a rabbit, a furry coat, and even a Santa Claus mask (Figure 6.9). Watson had succeeded in conditioning
a fear response in Little Albert, thus demonstrating that emotions could become conditioned responses.
It had been Watson’s intention to produce a phobia—a persistent, excessive fear of a specific object or
situation— through conditioning alone, thus countering Freud’s view that phobias are caused by deep,
hidden conflicts in the mind. However, there is no evidence that Little Albert experienced phobias in later
years. Little Albert’s mother moved away, ending the experiment, and Little Albert himself died a few
years later of unrelated causes. While Watson’s research provided new insight into conditioning, it would
be considered unethical by today’s standards.
Figure 6.9 Through stimulus generalization, Little Albert came to fear furry things, including Watson in a Santa
Claus mask.
View scenes from John Watson’s experiment (
Watson1) in which Little Albert was conditioned to respond in fear to furry objects.
As you watch the video, look closely at Little Albert’s reactions and the manner in
which Watson and Rayner present the stimuli before and after conditioning. Based
on what you see, would you come to the same conclusions as the researchers?
Advertising and Associative Learning
Advertising executives are pros at applying the principles of associative learning. Think about the car
commercials you have seen on television. Many of them feature an attractive model. By associating the model
with the car being advertised, you come to see the car as being desirable (Cialdini, 2008). You may be asking
yourself, does this advertising technique actually work? According to Cialdini (2008), men who viewed a car
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commercial that included an attractive model later rated the car as being faster, more appealing, and better
designed than did men who viewed an advertisement for the same car minus the model.
Have you ever noticed how quickly advertisers cancel contracts with a famous athlete following a scandal?
As far as the advertiser is concerned, that athlete is no longer associated with positive feelings; therefore, the
athlete cannot be used as an unconditioned stimulus to condition the public to associate positive feelings (the
unconditioned response) with their product (the conditioned stimulus).
Now that you are aware of how associative learning works, see if you can find examples of these types of
advertisements on television, in magazines, or on the Internet.
6.3 Operant Conditioning
Learning Objectives
By the end of this section, you will be able to:
• Define operant conditioning
• Explain the difference between reinforcement and punishment
• Distinguish between reinforcement schedules
The previous section of this chapter focused on the type of associative learning known as classical
conditioning. Remember that in classical conditioning, something in the environment triggers a reflex
automatically, and researchers train the organism to react to a different stimulus. Now we turn to the
second type of associative learning, operant conditioning. In operant conditioning, organisms learn to
associate a behavior and its consequence (Table 6.1). A pleasant consequence makes that behavior more
likely to be repeated in the future. For example, Spirit, a dolphin at the National Aquarium in Baltimore,
does a flip in the air when her trainer blows a whistle. The consequence is that she gets a fish.
Table 6.1 Classical and Operant Conditioning Compared
Classical Conditioning Operant Conditioning
An unconditioned stimulus (such as
food) is paired with a neutral
stimulus (such as a bell). The neutral
stimulus eventually becomes the
conditioned stimulus, which brings
about the conditioned response
The target behavior is followed by
reinforcement or punishment to
either strengthen or weaken it, so
that the learner is more likely to
exhibit the desired behavior in the
Stimulus timing The stimulus occurs immediately
before the response.
The stimulus (either reinforcement
or punishment) occurs soon after the
Psychologist B. F. Skinner saw that classical conditioning is limited to existing behaviors that are
reflexively elicited, and it doesn’t account for new behaviors such as riding a bike. He proposed a theory
about how such behaviors come about. Skinner believed that behavior is motivated by the consequences
we receive for the behavior: the reinforcements and punishments. His idea that learning is the result of
consequences is based on the law of effect, which was first proposed by psychologist Edward Thorndike.
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According to the law of effect, behaviors that are followed by consequences that are satisfying to the
organism are more likely to be repeated, and behaviors that are followed by unpleasant consequences are
less likely to be repeated (Thorndike, 1911). Essentially, if an organism does something that brings about
a desired result, the organism is more likely to do it again. If an organism does something that does not
bring about a desired result, the organism is less likely to do it again. An example of the law of effect is in
employment. One of the reasons (and often the main reason) we show up for work is because we get paid
to do so. If we stop getting paid, we will likely stop showing up—even if we love our job.
Working with Thorndike’s law of effect as his foundation, Skinner began conducting scientific experiments
on animals (mainly rats and pigeons) to determine how organisms learn through operant conditioning
(Skinner, 1938). He placed these animals inside an operant conditioning chamber, which has come to be
known as a “Skinner box” (Figure 6.10). A Skinner box contains a lever (for rats) or disk (for pigeons) that
the animal can press or peck for a food reward via the dispenser. Speakers and lights can be associated
with certain behaviors. A recorder counts the number of responses made by the animal.
Figure 6.10 (a) B. F. Skinner developed operant conditioning for systematic study of how behaviors are
strengthened or weakened according to their consequences. (b) In a Skinner box, a rat presses a lever in an operant
conditioning chamber to receive a food reward. (credit a: modification of work by “Silly rabbit”/Wikimedia Commons)
Watch this brief video clip ( to learn more
about operant conditioning: Skinner is interviewed, and operant conditioning of
pigeons is demonstrated.
In discussing operant conditioning, we use several everyday words—positive, negative, reinforcement,
and punishment—in a specialized manner. In operant conditioning, positive and negative do not mean
good and bad. Instead, positive means you are adding something, and negative means you are taking
something away. Reinforcement means you are increasing a behavior, and punishment means you are
decreasing a behavior. Reinforcement can be positive or negative, and punishment can also be positive
or negative. All reinforcers (positive or negative) increase the likelihood of a behavioral response. All
punishers (positive or negative) decrease the likelihood of a behavioral response. Now let’s combine
these four terms: positive reinforcement, negative reinforcement, positive punishment, and negative
punishment (Table 6.2).
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Table 6.2 Positive and Negative Reinforcement and Punishment
Reinforcement Punishment
Positive Something is added to increase the
likelihood of a behavior.
Something is added to decrease the
likelihood of a behavior.
Negative Something is removed to increase the
likelihood of a behavior.
Something is removed to decrease the
likelihood of a behavior.
The most effective way to teach a person or animal a new behavior is with positive reinforcement. In
positive reinforcement, a desirable stimulus is added to increase a behavior.
For example, you tell your five-year-old son, Jerome, that if he cleans his room, he will get a toy. Jerome
quickly cleans his room because he wants a new art set. Let’s pause for a moment. Some people might
say, “Why should I reward my child for doing what is expected?” But in fact we are constantly and
consistently rewarded in our lives. Our paychecks are rewards, as are high grades and acceptance into
our preferred school. Being praised for doing a good job and for passing a driver’s test is also a reward.
Positive reinforcement as a learning tool is extremely effective. It has been found that one of the most
effective ways to increase achievement in school districts with below-average reading scores was to pay
the children to read. Specifically, second-grade students in Dallas were paid $2 each time they read a book
and passed a short quiz about the book. The result was a significant increase in reading comprehension
(Fryer, 2010). What do you think about this program? If Skinner were alive today, he would probably
think this was a great idea. He was a strong proponent of using operant conditioning principles to
influence students’ behavior at school. In fact, in addition to the Skinner box, he also invented what
he called a teaching machine that was designed to reward small steps in learning (Skinner, 1961)—an
early forerunner of computer-assisted learning. His teaching machine tested students’ knowledge as
they worked through various school subjects. If students answered questions correctly, they received
immediate positive reinforcement and could continue; if they answered incorrectly, they did not receive
any reinforcement. The idea was that students would spend additional time studying the material to
increase their chance of being reinforced the next time (Skinner, 1961).
In negative reinforcement, an undesirable stimulus is removed to increase a behavior. For example, car
manufacturers use the principles of negative reinforcement in their seatbelt systems, which go “beep,
beep, beep” until you fasten your seatbelt. The annoying sound stops when you exhibit the desired
behavior, increasing the likelihood that you will buckle up in the future. Negative reinforcement is also
used frequently in horse training. Riders apply pressure—by pulling the reins or squeezing their legs—and
then remove the pressure when the horse performs the desired behavior, such as turning or speeding up.
The pressure is the negative stimulus that the horse wants to remove.
Many people confuse negative reinforcement with punishment in operant conditioning, but they are two
very different mechanisms. Remember that reinforcement, even when it is negative, always increases a
behavior. In contrast, punishment always decreases a behavior. In positive punishment, you add an
undesirable stimulus to decrease a behavior. An example of positive punishment is scolding a student to
get the student to stop texting in class. In this case, a stimulus (the reprimand) is added in order to decrease
the behavior (texting in class). In negative punishment, you remove an aversive stimulus to decrease
behavior. For example, when a child misbehaves, a parent can take away a favorite toy. In this case, a
stimulus (the toy) is removed in order to decrease the behavior.
Punishment, especially when it is immediate, is one way to decrease undesirable behavior. For example,
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imagine your four-year-old son, Brandon, hit his younger brother. You have Brandon write 100 times
“I will not hit my brother” (positive punishment). Chances are he won’t repeat this behavior. While
strategies like this are common today, in the past children were often subject to physical punishment,
such as spanking. It’s important to be aware of some of the drawbacks in using physical punishment on
children. First, punishment may teach fear. Brandon may become fearful of the street, but he also may
become fearful of the person who delivered the punishment—you, his parent. Similarly, children who
are punished by teachers may come to fear the teacher and try to avoid school (Gershoff et al., 2010).
Consequently, most schools in the United States have banned corporal punishment. Second, punishment
may cause children to become more aggressive and prone to antisocial behavior and delinquency
(Gershoff, 2002). They see their parents resort to spanking when they become angry and frustrated, so, in
turn, they may act out this same behavior when they become angry and frustrated. For example, because
you spank Brenda when you are angry with her for her misbehavior, she might start hitting her friends
when they won’t share their toys.
While positive punishment can be effective in some cases, Skinner suggested that the use of punishment
should be weighed against the possible negative effects. Today’s psychologists and parenting experts favor
reinforcement over punishment—they recommend that you catch your child doing something good and
reward her for it.
In his operant conditioning experiments, Skinner often used an approach called shaping. Instead of
rewarding only the target behavior, in shaping, we reward successive approximations of a target behavior.
Why is shaping needed? Remember that in order for reinforcement to work, the organism must first
display the behavior. Shaping is needed because it is extremely unlikely that an organism will display
anything but the simplest of behaviors spontaneously. In shaping, behaviors are broken down into many
small, achievable steps. The specific steps used in the process are the following:
1. Reinforce any response that resembles the desired behavior.
2. Then reinforce the response that more closely resembles the desired behavior. You will no longer
reinforce the previously reinforced response.
3. Next, begin to reinforce the response that even more closely resembles the desired behavior.
4. Continue to reinforce closer and closer approximations of the desired behavior.
5. Finally, only reinforce the desired behavior.
Shaping is often used in teaching a complex behavior or chain of behaviors. Skinner used shaping to
teach pigeons not only such relatively simple behaviors as pecking a disk in a Skinner box, but also many
unusual and entertaining behaviors, such as turning in circles, walking in figure eights, and even playing
ping pong; the technique is commonly used by animal trainers today. An important part of shaping is
stimulus discrimination. Recall Pavlov’s dogs—he trained them to respond to the tone of a bell, and not
to similar tones or sounds. This discrimination is also important in operant conditioning and in shaping
Here is a brief video ( of Skinner’s pigeons
playing ping pong.
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It’s easy to see how shaping is effective in teaching behaviors to animals, but how does shaping work with
humans? Let’s consider parents whose goal is to have their child learn to clean his room. They use shaping
to help him master steps toward the goal. Instead of performing the entire task, they set up these steps and
reinforce each step. First, he cleans up one toy. Second, he cleans up five toys. Third, he chooses whether
to pick up ten toys or put his books and clothes away. Fourth, he cleans up everything except two toys.
Finally, he cleans his entire room.
Rewards such as stickers, praise, money, toys, and more can be used to reinforce learning. Let’s go back
to Skinner’s rats again. How did the rats learn to press the lever in the Skinner box? They were rewarded
with food each time they pressed the lever. For animals, food would be an obvious reinforcer.
What would be a good reinforce for humans? For your daughter Sydney, it was the promise of a toy if she
cleaned her room. How about Joaquin, the soccer player? If you gave Joaquin a piece of candy every time
he made a goal, you would be using a primary reinforcer. Primary reinforcers are reinforcers that have
innate reinforcing qualities. These kinds of reinforcers are not learned. Water, food, sleep, shelter, sex, and
touch, among others, are primary reinforcers. Pleasure is also a primary reinforcer. Organisms do not lose
their drive for these things. For most people, jumping in a cool lake on a very hot day would be reinforcing
and the cool lake would be innately reinforcing—the water would cool the person off (a physical need), as
well as provide pleasure.
A secondary reinforcer has no inherent value and only has reinforcing qualities when linked with a
primary reinforcer. Praise, linked to affection, is one example of a secondary reinforcer, as when you called
out “Great shot!” every time Joaquin made a goal. Another example, money, is only worth something
when you can use it to buy other things—either things that satisfy basic needs (food, water, shelter—all
primary reinforcers) or other secondary reinforcers. If you were on a remote island in the middle of the
Pacific Ocean and you had stacks of money, the money would not be useful if you could not spend it. What
about the stickers on the behavior chart? They also are secondary reinforcers.
Sometimes, instead of stickers on a sticker chart, a token is used. Tokens, which are also secondary
reinforcers, can then be traded in for rewards and prizes. Entire behavior management systems, known
as token economies, are built around the use of these kinds of token reinforcers. Token economies have
been found to be very effective at modifying behavior in a variety of settings such as schools, prisons,
and mental hospitals. For example, a study by Cangi and Daly (2013) found that use of a token economy
increased appropriate social behaviors and reduced inappropriate behaviors in a group of autistic school
children. Autistic children tend to exhibit disruptive behaviors such as pinching and hitting. When the
children in the study exhibited appropriate behavior (not hitting or pinching), they received a “quiet
hands” token. When they hit or pinched, they lost a token. The children could then exchange specified
amounts of tokens for minutes of playtime.
Behavior Modification in Children
Parents and teachers often use behavior modification to change a child’s behavior. Behavior modification
uses the principles of operant conditioning to accomplish behavior change so that undesirable behaviors are
switched for more socially acceptable ones. Some teachers and parents create a sticker chart, in which several
behaviors are listed (Figure 6.11). Sticker charts are a form of token economies, as described in the text. Each
time children perform the behavior, they get a sticker, and after a certain number of stickers, they get a prize,
or reinforcer. The goal is to increase acceptable behaviors and decrease misbehavior. Remember, it is best
to reinforce desired behaviors, rather than to use punishment. In the classroom, the teacher can reinforce a
wide range of behaviors, from students raising their hands, to walking quietly in the hall, to turning in their
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homework. At home, parents might create a behavior chart that rewards children for things such as putting
away toys, brushing their teeth, and helping with dinner. In order for behavior modification to be effective, the
reinforcement needs to be connected with the behavior; the reinforcement must matter to the child and be
done consistently.
Figure 6.11 Sticker charts are a form of positive reinforcement and a tool for behavior modification. Once
this little girl earns a certain number of stickers for demonstrating a desired behavior, she will be rewarded
with a trip to the ice cream parlor. (credit: Abigail Batchelder)
Time-out is another popular technique used in behavior modification with children. It operates on the principle
of negative punishment. When a child demonstrates an undesirable behavior, she is removed from the
desirable activity at hand (Figure 6.12). For example, say that Sophia and her brother Mario are playing with
building blocks. Sophia throws some blocks at her brother, so you give her a warning that she will go to time-
out if she does it again. A few minutes later, she throws more blocks at Mario. You remove Sophia from the
room for a few minutes. When she comes back, she doesn’t throw blocks.
There are several important points that you should know if you plan to implement time-out as a behavior
modification technique. First, make sure the child is being removed from a desirable activity and placed in a
less desirable location. If the activity is something undesirable for the child, this technique will backfire because
it is more enjoyable for the child to be removed from the activity. Second, the length of the time-out is important.
The general rule of thumb is one minute for each year of the child’s age. Sophia is five; therefore, she sits in
a time-out for five minutes. Setting a timer helps children know how long they have to sit in time-out. Finally,
as a caregiver, keep several guidelines in mind over the course of a time-out: remain calm when directing your
child to time-out; ignore your child during time-out (because caregiver attention may reinforce misbehavior);
and give the child a hug or a kind word when time-out is over.
Figure 6.12 Time-out is a popular form of negative punishment used by caregivers. When a child
misbehaves, he or she is removed from a desirable activity in an effort to decrease the unwanted behavior.
For example, (a) a child might be playing on the playground with friends and push another child; (b) the child
who misbehaved would then be removed from the activity for a short period of time. (credit a: modification of
work by Simone Ramella; credit b: modification of work by “JefferyTurner”/Flickr)
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Remember, the best way to teach a person or animal a behavior is to use positive reinforcement. For
example, Skinner used positive reinforcement to teach rats to press a lever in a Skinner box. At first, the rat
might randomly hit the lever while exploring the box, and out would come a pellet of food. After eating
the pellet, what do you think the hungry rat did next? It hit the lever again, and received another pellet
of food. Each time the rat hit the lever, a pellet of food came out. When an organism receives a reinforcer
each time it displays a behavior, it is called continuous reinforcement. This reinforcement schedule is the
quickest way to teach someone a behavior, and it is especially effective in training a new behavior. Let’s
look back at the dog that was learning to sit earlier in the chapter. Now, each time he sits, you give him
a treat. Timing is important here: you will be most successful if you present the reinforcer immediately
after he sits, so that he can make an association between the target behavior (sitting) and the consequence
(getting a treat).
Watch this video clip ( where veterinarian Dr.
Sophia Yin shapes a dog’s behavior using the steps outlined above.
Once a behavior is trained, researchers and trainers often turn to another type of reinforcement
schedule—partial reinforcement. In partial reinforcement, also referred to as intermittent reinforcement,
the person or animal does not get reinforced every time they perform the desired behavior. There are
several different types of partial reinforcement schedules (Table 6.3). These schedules are described as
either fixed or variable, and as either interval or ratio. Fixed refers to the number of responses between
reinforcements, or the amount of time between reinforcements, which is set and unchanging. Variable
refers to the number of responses or amount of time between reinforcements, which varies or changes.
Interval means the schedule is based on the time between reinforcements, and ratio means the schedule is
based on the number of responses between reinforcements.
Table 6.3 Reinforcement Schedules
Description Result Example
Fixed interval Reinforcement is
delivered at predictable
time intervals (e.g., after
5, 10, 15, and 20
Moderate response rate
with significant pauses
after reinforcement
Hospital patient uses
doctor-timed pain relief
Reinforcement is
delivered at
unpredictable time
intervals (e.g., after 5, 7,
10, and 20 minutes).
Moderate yet steady
response rate
Checking Facebook
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Table 6.3 Reinforcement Schedules
Description Result Example
Fixed ratio Reinforcement is
delivered after a
predictable number of
responses (e.g., after 2, 4,
6, and 8 responses).
High response rate with
pauses after
worker getting paid for
every x number of items
Variable ratio Reinforcement is
delivered after an
unpredictable number of
responses (e.g., after 1, 4,
5, and 9 responses).
High and steady
response rate
Now let’s combine these four terms. A fixed interval reinforcement schedule is when behavior is
rewarded after a set amount of time. For example, June undergoes major surgery in a hospital. During
recovery, she is expected to experience pain and will require prescription medications for pain relief. June
is given an IV drip with a patient-controlled painkiller. Her doctor sets a limit: one dose per hour. June
pushes a button when pain becomes difficult, and she receives a dose of medication. Since the reward
(pain relief) only occurs on a fixed interval, there is no point in exhibiting the behavior when it will not be
With a variable interval reinforcement schedule, the person or animal gets the reinforcement based
on varying amounts of time, which are unpredictable. Say that Manuel is the manager at a fast-food
restaurant. Every once in a while someone from the quality control division comes to Manuel’s restaurant.
If the restaurant is clean and the service is fast, everyone on that shift earns a $20 bonus. Manuel never
knows when the quality control person will show up, so he always tries to keep the restaurant clean and
ensures that his employees provide prompt and courteous service. His productivity regarding prompt
service and keeping a clean restaurant are steady because he wants his crew to earn the bonus.
With a fixed ratio reinforcement schedule, there are a set number of responses that must occur before
the behavior is rewarded. Carla sells glasses at an eyeglass store, and she earns a commission every time
she sells a pair of glasses. She always tries to sell people more pairs of glasses, including prescription
sunglasses or a backup pair, so she can increase her commission. She does not care if the person really
needs the prescription sunglasses, Carla just wants her bonus. The quality of what Carla sells does not
matter because her commission is not based on quality; it’s only based on the number of pairs sold.
This distinction in the quality of performance can help determine which reinforcement method is most
appropriate for a particular situation. Fixed ratios are better suited to optimize the quantity of output,
whereas a fixed interval, in which the reward is not quantity based, can lead to a higher quality of output.
In a variable ratio reinforcement schedule, the number of responses needed for a reward varies. This is
the most powerful partial reinforcement schedule. An example of the variable ratio reinforcement schedule
is gambling. Imagine that Sarah—generally a smart, thrifty woman—visits Las Vegas for the first time.
She is not a gambler, but out of curiosity she puts a quarter into the slot machine, and then another, and
another. Nothing happens. Two dollars in quarters later, her curiosity is fading, and she is just about to
quit. But then, the machine lights up, bells go off, and Sarah gets 50 quarters back. That’s more like it!
Sarah gets back to inserting quarters with renewed interest, and a few minutes later she has used up all
her gains and is $10 in the hole. Now might be a sensible time to quit. And yet, she keeps putting money
into the slot machine because she never knows when the next reinforcement is coming. She keeps thinking
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that with the next quarter she could win $50, or $100, or even more. Because the reinforcement schedule
in most types of gambling has a variable ratio schedule, people keep trying and hoping that the next time
they will win big. This is one of the reasons that gambling is so addictive—and so resistant to extinction.
In operant conditioning, extinction of a reinforced behavior occurs at some point after reinforcement stops,
and the speed at which this happens depends on the reinforcement schedule. In a variable ratio schedule,
the point of extinction comes very slowly, as described above. But in the other reinforcement schedules,
extinction may come quickly. For example, if June presses the button for the pain relief medication before
the allotted time her doctor has approved, no medication is administered. She is on a fixed interval
reinforcement schedule (dosed hourly), so extinction occurs quickly when reinforcement doesn’t come at
the expected time. Among the reinforcement schedules, variable ratio is the most productive and the most
resistant to extinction. Fixed interval is the least productive and the easiest to extinguish (Figure 6.13).
Figure 6.13 The four reinforcement schedules yield different response patterns. The variable ratio schedule is
unpredictable and yields high and steady response rates, with little if any pause after reinforcement (e.g., gambler). A
fixed ratio schedule is predictable and produces a high response rate, with a short pause after reinforcement (e.g.,
eyeglass saleswoman). The variable interval schedule is unpredictable and produces a moderate, steady response
rate (e.g., restaurant manager). The fixed interval schedule yields a scallop-shaped response pattern, reflecting a
significant pause after reinforcement (e.g., surgery patient).
Gambling and the Brain
Skinner (1953) stated, “If the gambling establishment cannot persuade a patron to turn over money with no return,
it may achieve the same effect by returning part of the patron’s money on a variable-ratio schedule” (p. 397).
Skinner uses gambling as an example of the power and effectiveness of conditioning behavior based on a variable
ratio reinforcement schedule. In fact, Skinner was so confident in his knowledge of gambling addiction that he
even claimed he could turn a pigeon into a pathological gambler (“Skinner’s Utopia,” 1971). Beyond the power
of variable ratio reinforcement, gambling seems to work on the brain in the same way as some addictive drugs.
The Illinois Institute for Addiction Recovery (n.d.) reports evidence suggesting that pathological gambling is an
addiction similar to a chemical addiction (Figure 6.14). Specifically, gambling may activate the reward centers
of the brain, much like cocaine does. Research has shown that some pathological gamblers have lower levels
of the neurotransmitter (brain chemical) known as norepinephrine than do normal gamblers (Roy, et al., 1988).
According to a study conducted by Alec Roy and colleagues, norepinephrine is secreted when a person feels
stress, arousal, or thrill; pathological gamblers use gambling to increase their levels of this neurotransmitter.
Another researcher, neuroscientist Hans Breiter, has done extensive research on gambling and its effects on the
brain. Breiter (as cited in Franzen, 2001) reports that “Monetary reward in a gambling-like experiment produces
brain activation very similar to that observed in a cocaine addict receiving an infusion of cocaine” (para. 1).
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Deficiencies in serotonin (another neurotransmitter) might also contribute to compulsive behavior, including a
gambling addiction.
It may be that pathological gamblers’ brains are different than those of other people, and perhaps this difference
may somehow have led to their gambling addiction, as these studies seem to suggest. However, it is very difficult
to ascertain the cause because it is impossible to conduct a true experiment (it would be unethical to try to turn
randomly assigned participants into problem gamblers). Therefore, it may be that causation actually moves in the
opposite direction—perhaps the act of gambling somehow changes neurotransmitter levels in some gamblers’
brains. It also is possible that some overlooked factor, or confounding variable, played a role in both the gambling
addiction and the differences in brain chemistry.
Figure 6.14 Some research suggests that pathological gamblers use gambling to compensate for abnormally
low levels of the hormone norepinephrine, which is associated with stress and is secreted in moments of arousal
and thrill. (credit: Ted Murphy)
Although strict behaviorists such as Skinner and Watson refused to believe that cognition (such as
thoughts and expectations) plays a role in learning, another behaviorist, Edward C. Tolman, had a
different opinion. Tolman’s experiments with rats demonstrated that organisms can learn even if they
do not receive immediate reinforcement (Tolman & Honzik, 1930; Tolman, Ritchie, & Kalish, 1946). This
finding was in conflict with the prevailing idea at the time that reinforcement must be immediate in order
for learning to occur, thus suggesting a cognitive aspect to learning.
In the experiments, Tolman placed hungry rats in a maze with no reward for finding their way through
it. He also studied a comparison group that was rewarded with food at the end of the maze. As the
unreinforced rats explored the maze, they developed a cognitive map: a mental picture of the layout of
the maze (Figure 6.15). After 10 sessions in the maze without reinforcement, food was placed in a goal
box at the end of the maze. As soon as the rats became aware of the food, they were able to find their way
through the maze quickly, just as quickly as the comparison group, which had been rewarded with food all
along. This is known as latent learning: learning that occurs but is not observable in behavior until there
is a reason to demonstrate it.
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Figure 6.15 Psychologist Edward Tolman found that rats use cognitive maps to navigate through a maze. Have you
ever worked your way through various levels on a video game? You learned when to turn left or right, move up or
down. In that case you were relying on a cognitive map, just like the rats in a maze. (credit: modification of work by
Latent learning also occurs in humans. Children may learn by watching the actions of their parents but
only demonstrate it at a later date, when the learned material is needed. For example, suppose that Ravi’s
dad drives him to school every day. In this way, Ravi learns the route from his house to his school, but
he’s never driven there himself, so he has not had a chance to demonstrate that he’s learned the way. One
morning Ravi’s dad has to leave early for a meeting, so he can’t drive Ravi to school. Instead, Ravi follows
the same route on his bike that his dad would have taken in the car. This demonstrates latent learning.
Ravi had learned the route to school, but had no need to demonstrate this knowledge earlier.
This Place Is Like a Maze
Have you ever gotten lost in a building and couldn’t find your way back out? While that can be frustrating,
you’re not alone. At one time or another we’ve all gotten lost in places like a museum, hospital, or university
library. Whenever we go someplace new, we build a mental representation—or cognitive map—of the location,
as Tolman’s rats built a cognitive map of their maze. However, some buildings are confusing because they
include many areas that look alike or have short lines of sight. Because of this, it’s often difficult to predict
what’s around a corner or decide whether to turn left or right to get out of a building. Psychologist Laura Carlson
(2010) suggests that what we place in our cognitive map can impact our success in navigating through the
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environment. She suggests that paying attention to specific features upon entering a building, such as a picture
on the wall, a fountain, a statue, or an escalator, adds information to our cognitive map that can be used later
to help find our way out of the building.
Watch this video ( to learn more about
Carlson’s studies on cognitive maps and navigation in buildings.
6.4 Observational Learning (Modeling)
Learning Objectives
By the end of this section, you will be able to:
• Define observational learning
• Discuss the steps in the modeling process
• Explain the prosocial and antisocial effects of observational learning
Previous sections of this chapter focused on classical and operant conditioning, which are forms of
associative learning. In observational learning, we learn by watching others and then imitating, or
modeling, what they do or say. The individuals performing the imitated behavior are called models.
Research suggests that this imitative learning involves a specific type of neuron, called a mirror neuron
(Hickock, 2010; Rizzolatti, Fadiga, Fogassi, & Gallese, 2002; Rizzolatti, Fogassi, & Gallese, 2006).
Humans and other animals are capable of observational learning. As you will see, the phrase “monkey see,
monkey do” really is accurate (Figure 6.16). The same could be said about other animals. For example,
in a study of social learning in chimpanzees, researchers gave juice boxes with straws to two groups of
captive chimpanzees. The first group dipped the straw into the juice box, and then sucked on the small
amount of juice at the end of the straw. The second group sucked through the straw directly, getting much
more juice. When the first group, the “dippers,” observed the second group, “the suckers,” what do you
think happened? All of the “dippers” in the first group switched to sucking through the straws directly. By
simply observing the other chimps and modeling their behavior, they learned that this was a more efficient
method of getting juice (Yamamoto, Humle, and Tanaka, 2013).
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Figure 6.16 This spider monkey learned to drink water from a plastic bottle by seeing the behavior modeled by a
human. (credit: U.S. Air Force, Senior Airman Kasey Close)
Imitation is much more obvious in humans, but is imitation really the sincerest form of flattery? Consider
Claire’s experience with observational learning. Claire’s nine-year-old son, Jay, was getting into trouble at
school and was defiant at home. Claire feared that Jay would end up like her brothers, two of whom were
in prison. One day, after yet another bad day at school and another negative note from the teacher, Claire,
at her wit’s end, beat her son with a belt to get him to behave. Later that night, as she put her children to
bed, Claire witnessed her four-year-old daughter, Anna, take a belt to her teddy bear and whip it. Claire
was horrified, realizing that Anna was imitating her mother. It was then that Claire knew she wanted to
discipline her children in a different manner.
Like Tolman, whose experiments with rats suggested a cognitive component to learning, psychologist
Albert Bandura’s ideas about learning were different from those of strict behaviorists. Bandura and other
researchers proposed a brand of behaviorism called social learning theory, which took cognitive processes
into account. According to Bandura, pure behaviorism could not explain why learning can take place in
the absence of external reinforcement. He felt that internal mental states must also have a role in learning
and that observational learning involves much more than imitation. In imitation, a person simply copies
what the model does. Observational learning is much more complex. According to Lefrançois (2012) there
are several ways that observational learning can occur:
1. You learn a new response. After watching your coworker get chewed out by your boss for coming
in late, you start leaving home 10 minutes earlier so that you won’t be late.
2. You choose whether or not to imitate the model depending on what you saw happen to the model.
Remember Julian and his father? When learning to surf, Julian might watch how his father pops
up successfully on his surfboard and then attempt to do the same thing. On the other hand, Julian
might learn not to touch a hot stove after watching his father get burned on a stove.
3. You learn a general rule that you can apply to other situations.
Bandura identified three kinds of models: live, verbal, and symbolic. A live model demonstrates a behavior
in person, as when Ben stood up on his surfboard so that Julian could see how he did it. A verbal
instructional model does not perform the behavior, but instead explains or describes the behavior, as when
a soccer coach tells his young players to kick the ball with the side of the foot, not with the toe. A symbolic
model can be fictional characters or real people who demonstrate behaviors in books, movies, television
shows, video games, or Internet sources (Figure 6.17).
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Figure 6.17 (a) Yoga students learn by observation as their yoga instructor demonstrates the correct stance and
movement for her students (live model). (b) Models don’t have to be present for learning to occur: through symbolic
modeling, this child can learn a behavior by watching someone demonstrate it on television. (credit a: modification of
work by Tony Cecala; credit b: modification of work by Andrew Hyde)
Latent learning and modeling are used all the time in the world of marketing and
advertising. This commercial ( played for
months across the New York, New Jersey, and Connecticut areas, Derek Jeter, an
award-winning baseball player for the New York Yankees, is advertising a Ford. The
commercial aired in a part of the country where Jeter is an incredibly well-known
athlete. He is wealthy, and considered very loyal and good looking. What message are the advertisers
sending by having him featured in the ad? How effective do you think it is?
Of course, we don’t learn a behavior simply by observing a model. Bandura described specific steps in the
process of modeling that must be followed if learning is to be successful: attention, retention, reproduction,
and motivation. First, you must be focused on what the model is doing—you have to pay attention. Next,
you must be able to retain, or remember, what you observed; this is retention. Then, you must be able to
perform the behavior that you observed and committed to memory; this is reproduction. Finally, you must
have motivation. You need to want to copy the behavior, and whether or not you are motivated depends
on what happened to the model. If you saw that the model was reinforced for her behavior, you will be
more motivated to copy her. This is known as vicarious reinforcement. On the other hand, if you observed
the model being punished, you would be less motivated to copy her. This is called vicarious punishment.
For example, imagine that four-year-old Allison watched her older sister Kaitlyn playing in their mother’s
makeup, and then saw Kaitlyn get a time out when their mother came in. After their mother left the room,
Allison was tempted to play in the make-up, but she did not want to get a time-out from her mother. What
do you think she did? Once you actually demonstrate the new behavior, the reinforcement you receive
plays a part in whether or not you will repeat the behavior.
Bandura researched modeling behavior, particularly children’s modeling of adults’ aggressive and violent
behaviors (Bandura, Ross, & Ross, 1961). He conducted an experiment with a five-foot inflatable doll that
he called a Bobo doll. In the experiment, children’s aggressive behavior was influenced by whether the
teacher was punished for her behavior. In one scenario, a teacher acted aggressively with the doll, hitting,
throwing, and even punching the doll, while a child watched. There were two types of responses by the
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children to the teacher’s behavior. When the teacher was punished for her bad behavior, the children
decreased their tendency to act as she had. When the teacher was praised or ignored (and not punished
for her behavior), the children imitated what she did, and even what she said. They punched, kicked, and
yelled at the doll.
Watch this video clip ( to see a portion of
the famous Bobo doll experiment, including an interview with Albert Bandura.
What are the implications of this study? Bandura concluded that we watch and learn, and that this learning
can have both prosocial and antisocial effects. Prosocial (positive) models can be used to encourage socially
acceptable behavior. Parents in particular should take note of this finding. If you want your children to
read, then read to them. Let them see you reading. Keep books in your home. Talk about your favorite
books. If you want your children to be healthy, then let them see you eat right and exercise, and spend time
engaging in physical fitness activities together. The same holds true for qualities like kindness, courtesy,
and honesty. The main idea is that children observe and learn from their parents, even their parents’
morals, so be consistent and toss out the old adage “Do as I say, not as I do,” because children tend to copy
what you do instead of what you say. Besides parents, many public figures, such as Martin Luther King,
Jr. and Mahatma Gandhi, are viewed as prosocial models who are able to inspire global social change. Can
you think of someone who has been a prosocial model in your life?
The antisocial effects of observational learning are also worth mentioning. As you saw from the example
of Claire at the beginning of this section, her daughter viewed Claire’s aggressive behavior and copied
it. Research suggests that this may help to explain why abused children often grow up to be abusers
themselves (Murrell, Christoff, & Henning, 2007). In fact, about 30% of abused children become abusive
parents (U.S. Department of Health & Human Services, 2013). We tend to do what we know. Abused
children, who grow up witnessing their parents deal with anger and frustration through violent and
aggressive acts, often learn to behave in that manner themselves. Sadly, it’s a vicious cycle that’s difficult
to break.
Some studies suggest that violent television shows, movies, and video games may also have antisocial
effects (Figure 6.18) although further research needs to be done to understand the correlational and
causational aspects of media violence and behavior. Some studies have found a link between viewing
violence and aggression seen in children (Anderson & Gentile, 2008; Kirsch, 2010; Miller, Grabell, Thomas,
Bermann, & Graham-Bermann, 2012). These findings may not be surprising, given that a child graduating
from high school has been exposed to around 200,000 violent acts including murder, robbery, torture,
bombings, beatings, and rape through various forms of media (Huston et al., 1992). Not only might
viewing media violence affect aggressive behavior by teaching people to act that way in real life situations,
but it has also been suggested that repeated exposure to violent acts also desensitizes people to it.
Psychologists are working to understand this dynamic.
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Figure 6.18 Can video games make us violent? Psychological researchers study this topic. (credit:
View this video ( to hear Brad
Bushman, a psychologist who has published extensively on human aggression and
violence, discuss his research.
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associative learning
classical conditioning
cognitive map
conditioned response (CR)
conditioned stimulus (CS)
continuous reinforcement
fixed interval reinforcement schedule
fixed ratio reinforcement schedule
higher-order conditioning
latent learning
law of effect
negative punishment
negative reinforcement
neutral stimulus (NS)
observational learning
operant conditioning
partial reinforcement
Key Terms
period of initial learning in classical conditioning in which a human or an animal begins to
connect a neutral stimulus and an unconditioned stimulus so that the neutral stimulus will begin to elicit
the conditioned response
form of learning that involves connecting certain stimuli or events that occur
together in the environment (classical and operant conditioning)
learning in which the stimulus or experience occurs before the behavior and then
gets paired or associated with the behavior
mental picture of the layout of the environment
response caused by the conditioned stimulus
stimulus that elicits a response due to its being paired with an unconditioned
rewarding a behavior every time it occurs
decrease in the conditioned response when the unconditioned stimulus is no longer paired
with the conditioned stimulus
behavior is rewarded after a set amount of time
set number of responses must occur before a behavior is rewarded
when we learn not to respond to a stimulus that is presented repeatedly without change
(also, second-order conditioning) using a conditioned stimulus to condition a
neutral stimulus
unlearned knowledge, involving complex patterns of behavior; instincts are thought to be more
prevalent in lower animals than in humans
learning that occurs, but it may not be evident until there is a reason to demonstrate it
behavior that is followed by consequences satisfying to the organism will be repeated and
behaviors that are followed by unpleasant consequences will be discouraged
change in behavior or knowledge that is the result of experience
person who performs a behavior that serves as an example (in observational learning)
taking away a pleasant stimulus to decrease or stop a behavior
taking away an undesirable stimulus to increase a behavior
stimulus that does not initially elicit a response
type of learning that occurs by watching others
form of learning in which the stimulus/experience happens after the behavior is
rewarding behavior only some of the time
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positive punishment
positive reinforcement
primary reinforcer
secondary reinforcer
spontaneous recovery
stimulus discrimination
stimulus generalization
unconditioned response (UCR)
unconditioned stimulus (UCS)
variable interval reinforcement schedule
variable ratio reinforcement schedule
vicarious punishment
vicarious reinforcement
adding an undesirable stimulus to stop or decrease a behavior
adding a desirable stimulus to increase a behavior
has innate reinforcing qualities (e.g., food, water, shelter, sex)
implementation of a consequence in order to decrease a behavior
unlearned, automatic response by an organism to a stimulus in the environment
implementation of a consequence in order to increase a behavior
has no inherent value unto itself and only has reinforcing qualities when linked
with something else (e.g., money, gold stars, poker chips)
rewarding successive approximations toward a target behavior
return of a previously extinguished conditioned response
ability to respond differently to similar stimuli
demonstrating the conditioned response to stimuli that are similar to the
conditioned stimulus
natural (unlearned) behavior to a given stimulus
stimulus that elicits a reflexive response
behavior is rewarded after unpredictable amounts of time
have passed
number of responses differ before a behavior is rewarded
process where the observer sees the model punished, making the observer less
likely to imitate the model’s behavior
process where the observer sees the model rewarded, making the observer
more likely to imitate the model’s behavior
6.1 What Is Learning?
Instincts and reflexes are innate behaviors—they occur naturally and do not involve learning. In contrast,
learning is a change in behavior or knowledge that results from experience. There are three main types
of learning: classical conditioning, operant conditioning, and observational learning. Both classical and
operant conditioning are forms of associative learning where associations are made between events that
occur together. Observational learning is just as it sounds: learning by observing others.
6.2 Classical Conditioning
Pavlov’s pioneering work with dogs contributed greatly to what we know about learning. His experiments
explored the type of associative learning we now call classical conditioning. In classical conditioning,
organisms learn to associate events that repeatedly happen together, and researchers study how a reflexive
response to a stimulus can be mapped to a different stimulus—by training an association between the
two stimuli. Pavlov’s experiments show how stimulus-response bonds are formed. Watson, the founder
of behaviorism, was greatly influenced by Pavlov’s work. He tested humans by conditioning fear in an
infant known as Little Albert. His findings suggest that classical conditioning can explain how some fears
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6.3 Operant Conditioning
Operant conditioning is based on the work of B. F. Skinner. Operant conditioning is a form of learning in
which the motivation for a behavior happens after the behavior is demonstrated. An animal or a human
receives a consequence after performing a specific behavior. The consequence is either a reinforcer or
a punisher. All reinforcement (positive or negative) increases the likelihood of a behavioral response.
All punishment (positive or negative) decreases the likelihood of a behavioral response. Several types of
reinforcement schedules are used to reward behavior depending on either a set or variable period of time.
6.4 Observational Learning (Modeling)
According to Bandura, learning can occur by watching others and then modeling what they do or say.
This is known as observational learning. There are specific steps in the process of modeling that must
be followed if learning is to be successful. These steps include attention, retention, reproduction, and
motivation. Through modeling, Bandura has shown that children learn many things both good and bad
simply by watching their parents, siblings, and others.
Review Questions
1. Which of the following is an example of a
reflex that occurs at some point in the
development of a human being?
a. child riding a bike
b. teen socializing
c. infant sucking on a nipple
d. toddler walking
2. Learning is best defined as a relatively
permanent change in behavior that ________.
a. is innate
b. occurs as a result of experience
c. is found only in humans
d. occurs by observing others
3. Two forms of associative learning are ________
and ________.
a. classical conditioning; operant conditioning
b. classical conditioning; Pavlovian
c. operant conditioning; observational
d. operant conditioning; learning conditioning
4. In ________ the stimulus or experience occurs
before the behavior and then gets paired with the
a. associative learning
b. observational learning
c. operant conditioning
d. classical conditioning
5. A stimulus that does not initially elicit a
response in an organism is a(n) ________.
a. unconditioned stimulus
b. neutral stimulus
c. conditioned stimulus
d. unconditioned response
6. In Watson and Rayner’s experiments, Little
Albert was conditioned to fear a white rat, and
then he began to be afraid of other furry white
objects. This demonstrates ________.
a. higher order conditioning
b. acquisition
c. stimulus discrimination
d. stimulus generalization
7. Extinction occurs when ________.
a. the conditioned stimulus is presented
repeatedly without being paired with an
unconditioned stimulus
b. the unconditioned stimulus is presented
repeatedly without being paired with a
conditioned stimulus
c. the neutral stimulus is presented repeatedly
without being paired with an
unconditioned stimulus
d. the neutral stimulus is presented repeatedly
without being paired with a conditioned
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8. In Pavlov’s work with dogs, the psychic
secretions were ________.
a. unconditioned responses
b. conditioned responses
c. unconditioned stimuli
d. conditioned stimuli
9. ________ is when you take away a pleasant
stimulus to stop a behavior.
a. positive reinforcement
b. negative reinforcement
c. positive punishment
d. negative punishment
10. Which of the following is not an example of a
primary reinforcer?
a. food
b. money
c. water
d. sex
11. Rewarding successive approximations toward
a target behavior is ________.
a. shaping
b. extinction
c. positive reinforcement
d. negative reinforcement
12. Slot machines reward gamblers with money
according to which reinforcement schedule?
a. fixed ratio
b. variable ratio
c. fixed interval
d. variable interval
13. The person who performs a behavior that
serves as an example is called a ________.
a. teacher
b. model
c. instructor
d. coach
14. In Bandura’s Bobo doll study, when the
children who watched the aggressive model were
placed in a room with the doll and other toys, they
a. ignored the doll
b. played nicely with the doll
c. played with tinker toys
d. kicked and threw the doll
15. Which is the correct order of steps in the
modeling process?
a. attention, retention, reproduction,
b. motivation, attention, reproduction,
c. attention, motivation, retention,
d. motivation, attention, retention,
16. Who proposed observational learning?
a. Ivan Pavlov
b. John Watson
c. Albert Bandura
d. B. F. Skinner
Critical Thinking Questions
17. Compare and contrast classical and operant conditioning. How are they alike? How do they differ?
18. What is the difference between a reflex and a learned behavior?
19. If the sound of your toaster popping up toast causes your mouth to water, what are the UCS, CS, and
20. Explain how the processes of stimulus generalization and stimulus discrimination are considered
21. How does a neutral stimulus become a conditioned stimulus?
22. What is a Skinner box and what is its purpose?
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23. What is the difference between negative reinforcement and punishment?
24. What is shaping and how would you use shaping to teach a dog to roll over?
25. What is the effect of prosocial modeling and antisocial modeling?
26. Cara is 17 years old. Cara’s mother and father both drink alcohol every night. They tell Cara that
drinking is bad and she shouldn’t do it. Cara goes to a party where beer is being served. What do you think
Cara will do? Why?
Personal Application Questions
27. What is your personal definition of learning? How do your ideas about learning compare with the
definition of learning presented in this text?
28. What kinds of things have you learned through the process of classical conditioning? Operant
conditioning? Observational learning? How did you learn them?
29. Can you think of an example in your life of how classical conditioning has produced a positive
emotional response, such as happiness or excitement? How about a negative emotional response, such as
fear, anxiety, or anger?
30. Explain the difference between negative reinforcement and punishment, and provide several
examples of each based on your own experiences.
31. Think of a behavior that you have that you would like to change. How could you use behavior
modification, specifically positive reinforcement, to change your behavior? What is your positive
32. What is something you have learned how to do after watching someone else?
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Chapter 7
Thinking and Intelligence
Figure 7.1 Thinking is an important part of our human experience, and one that has captivated people for centuries.
Today, it is one area of psychological study. The 19th-century Girl with a Book by José Ferraz de Almeida Júnior, the
20th-century sculpture The Thinker by August Rodin, and Shi Ke’s 10th-century painting Huike Thinking all reflect the
fascination with the process of human thought. (credit “middle”: modification of work by Jason Rogers; credit “right”:
modification of work by Tang Zu-Ming)
Chapter Outline
7.1 What Is Cognition?
7.2 Language
7.3 Problem Solving
7.4 What Are Intelligence and Creativity?
7.5 Measures of Intelligence
7.6 The Source of Intelligence
Why is it so difficult to break habits—like reaching for your ringing phone even when you shouldn’t, such
as when you’re driving? How does a person who has never seen or touched snow in real life develop an
understanding of the concept of snow? How do young children acquire the ability to learn language with
no formal instruction? Psychologists who study thinking explore questions like these.
Cognitive psychologists also study intelligence. What is intelligence, and how does it vary from person
to person? Are “street smarts” a kind of intelligence, and if so, how do they relate to other types of
intelligence? What does an IQ test really measure? These questions and more will be explored in this
chapter as you study thinking and intelligence.
In other chapters, we discussed the cognitive processes of perception, learning, and memory. In this
chapter, we will focus on high-level cognitive processes. As a part of this discussion, we will consider
thinking and briefly explore the development and use of language. We will also discuss problem solving
and creativity before ending with a discussion of how intelligence is measured and how our biology
and environments interact to affect intelligence. After finishing this chapter, you will have a greater
appreciation of the higher-level cognitive processes that contribute to our distinctiveness as a species.
Chapter 7 | Thinking and Intelligence 217

7.1 What Is Cognition?
Learning Objectives
By the end of this section, you will be able to:
• Describe cognition
• Distinguish concepts and prototypes
• Explain the difference between natural and artificial concepts
Imagine all of your thoughts as if they were physical entities, swirling rapidly inside your mind. How is it
possible that the brain is able to move from one thought to the next in an organized, orderly fashion? The
brain is endlessly perceiving, processing, planning, organizing, and remembering—it is always active. Yet,
you don’t notice most of your brain’s activity as you move throughout your daily routine. This is only one
facet of the complex processes involved in cognition. Simply put, cognition is thinking, and it encompasses
the processes associated with perception, knowledge, problem solving, judgment, language, and memory.
Scientists who study cognition are searching for ways to understand how we integrate, organize, and
utilize our conscious cognitive experiences without being aware of all of the unconscious work that our
brains are doing (for example, Kahneman, 2011).
Upon waking each morning, you begin thinking—contemplating the tasks that you must complete that
day. In what order should you run your errands? Should you go to the bank, the cleaners, or the grocery
store first? Can you get these things done before you head to class or will they need to wait until school
is done? These thoughts are one example of cognition at work. Exceptionally complex, cognition is an
essential feature of human consciousness, yet not all aspects of cognition are consciously experienced.
Cognitive psychology is the field of psychology dedicated to examining how people think. It attempts
to explain how and why we think the way we do by studying the interactions among human thinking,
emotion, creativity, language, and problem solving, in addition to other cognitive processes. Cognitive
psychologists strive to determine and measure different types of intelligence, why some people are better
at problem solving than others, and how emotional intelligence affects success in the workplace, among
countless other topics. They also sometimes focus on how we organize thoughts and information gathered
from our environments into meaningful categories of thought, which will be discussed later.
The human nervous system is capable of handling endless streams of information. The senses serve as
the interface between the mind and the external environment, receiving stimuli and translating it into
nervous impulses that are transmitted to the brain. The brain then processes this information and uses the
relevant pieces to create thoughts, which can then be expressed through language or stored in memory
for future use. To make this process more complex, the brain does not gather information from external
environments only. When thoughts are formed, the brain also pulls information from emotions and
memories (Figure 7.2). Emotion and memory are powerful influences on both our thoughts and behaviors.
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Figure 7.2 Sensations and information are received by our brains, filtered through emotions and memories, and
processed to become thoughts.
In order to organize this staggering amount of information, the brain has developed a file cabinet of sorts
in the mind. The different files stored in the file cabinet are called concepts. Concepts are categories or
groupings of linguistic information, images, ideas, or memories, such as life experiences. Concepts are,
in many ways, big ideas that are generated by observing details, and categorizing and combining these
details into cognitive structures. You use concepts to see the relationships among the different elements of
your experiences and to keep the information in your mind organized and accessible.
Concepts are informed by our semantic memory (you will learn more about semantic memory in a later
chapter) and are present in every aspect of our lives; however, one of the easiest places to notice concepts
is inside a classroom, where they are discussed explicitly. When you study United States history, for
example, you learn about more than just individual events that have happened in America’s past. You
absorb a large quantity of information by listening to and participating in discussions, examining maps,
and reading first-hand accounts of people’s lives. Your brain analyzes these details and develops an overall
understanding of American history. In the process, your brain gathers details that inform and refine your
understanding of related concepts like democracy, power, and freedom.
Concepts can be complex and abstract, like justice, or more concrete, like types of birds. In psychology,
for example, Piaget’s stages of development are abstract concepts. Some concepts, like tolerance, are
agreed upon by many people, because they have been used in various ways over many years. Other
concepts, like the characteristics of your ideal friend or your family’s birthday traditions, are personal and
individualized. In this way, concepts touch every aspect of our lives, from our many daily routines to the
guiding principles behind the way governments function.
Another technique used by your brain to organize information is the identification of prototypes for the
concepts you have developed. A prototype is the best example or representation of a concept. For example,
for the category of civil disobedience, your prototype could be Rosa Parks. Her peaceful resistance to
segregation on a city bus in Montgomery, Alabama, is a recognizable example of civil disobedience.
Or your prototype could be Mohandas Gandhi, sometimes called Mahatma Gandhi (“Mahatma” is an
honorific title) (Figure 7.3).
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Figure 7.3 In 1930, Mohandas Gandhi led a group in peaceful protest against a British tax on salt in India.
Mohandas Gandhi served as a nonviolent force for independence for India while simultaneously
demanding that Buddhist, Hindu, Muslim, and Christian leaders—both Indian and British—collaborate
peacefully. Although he was not always successful in preventing violence around him, his life provides
a steadfast example of the civil disobedience prototype (Constitutional Rights Foundation, 2013). Just as
concepts can be abstract or concrete, we can make a distinction between concepts that are functions of our
direct experience with the world and those that are more artificial in nature.
In psychology, concepts can be divided into two categories, natural and artificial. Natural concepts
are created “naturally” through your experiences and can be developed from either direct or indirect
experiences. For example, if you live in Essex Junction, Vermont, you have probably had a lot of direct
experience with snow. You’ve watched it fall from the sky, you’ve seen lightly falling snow that barely
covers the windshield of your car, and you’ve shoveled out 18 inches of fluffy white snow as you’ve
thought, “This is perfect for skiing.” You’ve thrown snowballs at your best friend and gone sledding down
the steepest hill in town. In short, you know snow. You know what it looks like, smells like, tastes like,
and feels like. If, however, you’ve lived your whole life on the island of Saint Vincent in the Caribbean,
you may never have actually seen snow, much less tasted, smelled, or touched it. You know snow from
the indirect experience of seeing pictures of falling snow—or from watching films that feature snow as
part of the setting. Either way, snow is a natural concept because you can construct an understanding of it
through direct observations or experiences of snow (Figure 7.4).
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Figure 7.4 (a) Our concept of snow is an example of a natural concept—one that we understand through direct
observation and experience. (b) In contrast, artificial concepts are ones that we know by a specific set of
characteristics that they always exhibit, such as what defines different basic shapes. (credit a: modification of work by
Maarten Takens; credit b: modification of work by “Shayan (USA)”/Flickr)
An artificial concept, on the other hand, is a concept that is defined by a specific set of characteristics.
Various properties of geometric shapes, like squares and triangles, serve as useful examples of artificial
concepts. A triangle always has three angles and three sides. A square always has four equal sides and
four right angles. Mathematical formulas, like the equation for area (length × width) are artificial concepts
defined by specific sets of characteristics that are always the same. Artificial concepts can enhance the
understanding of a topic by building on one another. For example, before learning the concept of “area of
a square” (and the formula to find it), you must understand what a square is. Once the concept of “area
of a square” is understood, an understanding of area for other geometric shapes can be built upon the
original understanding of area. The use of artificial concepts to define an idea is crucial to communicating
with others and engaging in complex thought. According to Goldstone and Kersten (2003), concepts act as
building blocks and can be connected in countless combinations to create complex thoughts.
A schema is a mental construct consisting of a cluster or collection of related concepts (Bartlett, 1932).
There are many different types of schemata, and they all have one thing in common: schemata are a
method of organizing information that allows the brain to work more efficiently. When a schema is
activated, the brain makes immediate assumptions about the person or object being observed.
There are several types of schemata. A role schema makes assumptions about how individuals in certain
roles will behave (Callero, 1994). For example, imagine you meet someone who introduces himself as a
firefighter. When this happens, your brain automatically activates the “firefighter schema” and begins
making assumptions that this person is brave, selfless, and community-oriented. Despite not knowing
this person, already you have unknowingly made judgments about him. Schemata also help you fill in
gaps in the information you receive from the world around you. While schemata allow for more efficient
information processing, there can be problems with schemata, regardless of whether they are accurate:
Perhaps this particular firefighter is not brave, he just works as a firefighter to pay the bills while studying
to become a children’s librarian.
An event schema, also known as a cognitive script, is a set of behaviors that can feel like a routine. Think
about what you do when you walk into an elevator (Figure 7.5). First, the doors open and you wait to
let exiting passengers leave the elevator car. Then, you step into the elevator and turn around to face
the doors, looking for the correct button to push. You never face the back of the elevator, do you? And
when you’re riding in a crowded elevator and you can’t face the front, it feels uncomfortable, doesn’t it?
Interestingly, event schemata can vary widely among different cultures and countries. For example, while
it is quite common for people to greet one another with a handshake in the United States, in Tibet, you
greet someone by sticking your tongue out at them, and in Belize, you bump fists (Cairns Regional Council,
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Figure 7.5 What event schema do you perform when riding in an elevator? (credit: “Gideon”/Flickr)
Because event schemata are automatic, they can be difficult to change. Imagine that you are driving home
from work or school. This event schema involves getting in the car, shutting the door, and buckling your
seatbelt before putting the key in the ignition. You might perform this script two or three times each day.
As you drive home, you hear your phone’s ring tone. Typically, the event schema that occurs when you
hear your phone ringing involves locating the phone and answering it or responding to your latest text
message. So without thinking, you reach for your phone, which could be in your pocket, in your bag, or
on the passenger seat of the car. This powerful event schema is informed by your pattern of behavior and
the pleasurable stimulation that a phone call or text message gives your brain. Because it is a schema, it is
extremely challenging for us to stop reaching for the phone, even though we know that we endanger our
own lives and the lives of others while we do it (Neyfakh, 2013) (Figure 7.6).
Figure 7.6 Texting while driving is dangerous, but it is a difficult event schema for some people to resist.
Remember the elevator? It feels almost impossible to walk in and not face the door. Our powerful event
schema dictates our behavior in the elevator, and it is no different with our phones. Current research
suggests that it is the habit, or event schema, of checking our phones in many different situations that
makes refraining from checking them while driving especially difficult (Bayer & Campbell, 2012). Because
texting and driving has become a dangerous epidemic in recent years, psychologists are looking at ways
to help people interrupt the “phone schema” while driving. Event schemata like these are the reason why
many habits are difficult to break once they have been acquired. As we continue to examine thinking, keep
in mind how powerful the forces of concepts and schemata are to our understanding of the world.
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7.2 Language
Learning Objectives
By the end of this section, you will be able to:
• Define language and demonstrate familiarity with the components of language
• Understand how the use of language develops
• Explain the relationship between language and thinking
Language is a communication system that involves using words and systematic rules to organize those
words to transmit information from one individual to another. While language is a form of
communication, not all communication is language. Many species communicate with one another through
their postures, movements, odors, or vocalizations. This communication is crucial for species that need to
interact and develop social relationships with their conspecifics. However, many people have asserted that
it is language that makes humans unique among all of the animal species (Corballis & Suddendorf, 2007;
Tomasello & Rakoczy, 2003). This section will focus on what distinguishes language as a special form of
communication, how the use of language develops, and how language affects the way we think.
Language, be it spoken, signed, or written, has specific components: a lexicon and grammar. Lexicon refers
to the words of a given language. Thus, lexicon is a language’s vocabulary. Grammar refers to the set
of rules that are used to convey meaning through the use of the lexicon (Fernández & Cairns, 2011). For
instance, English grammar dictates that most verbs receive an “-ed” at the end to indicate past tense.
Words are formed by combining the various phonemes that make up the language. A phoneme (e.g., the
sounds “ah” vs. “eh”) is a basic sound unit of a given language, and different languages have different
sets of phonemes. Phonemes are combined to form morphemes, which are the smallest units of language
that convey some type of meaning (e.g., “I” is both a phoneme and a morpheme). We use semantics and
syntax to construct language. Semantics and syntax are part of a language’s grammar. Semantics refers to
the process by which we derive meaning from morphemes and words. Syntax refers to the way words are
organized into sentences (Chomsky, 1965; Fernández & Cairns, 2011).
We apply the rules of grammar to organize the lexicon in novel and creative ways, which allow us to
communicate information about both concrete and abstract concepts. We can talk about our immediate
and observable surroundings as well as the surface of unseen planets. We can share our innermost
thoughts, our plans for the future, and debate the value of a college education. We can provide detailed
instructions for cooking a meal, fixing a car, or building a fire. The flexibility that language provides to
relay vastly different types of information is a property that makes language so distinct as a mode of
communication among humans.
Given the remarkable complexity of a language, one might expect that mastering a language would
be an especially arduous task; indeed, for those of us trying to learn a second language as adults, this
might seem to be true. However, young children master language very quickly with relative ease. B. F.
Skinner (1957) proposed that language is learned through reinforcement. Noam Chomsky (1965) criticized
this behaviorist approach, asserting instead that the mechanisms underlying language acquisition are
biologically determined. The use of language develops in the absence of formal instruction and appears
to follow a very similar pattern in children from vastly different cultures and backgrounds. It would
seem, therefore, that we are born with a biological predisposition to acquire a language (Chomsky, 1965;
Fernández & Cairns, 2011). Moreover, it appears that there is a critical period for language acquisition,
Chapter 7 | Thinking and Intelligence 223

such that this proficiency at acquiring language is maximal early in life; generally, as people age, the ease
with which they acquire and master new languages diminishes (Johnson & Newport, 1989; Lenneberg,
1967; Singleton, 1995).
Children begin to learn about language from a very early age (Table 7.1). In fact, it appears that this is
occurring even before we are born. Newborns show preference for their mother’s voice and appear to be
able to discriminate between the language spoken by their mother and other languages. Babies are also
attuned to the languages being used around them and show preferences for videos of faces that are moving
in synchrony with the audio of spoken language versus videos that do not synchronize with the audio
(Blossom & Morgan, 2006; Pickens, 1994; Spelke & Cortelyou, 1981).
Table 7.1 Stages of Language and Communication Development
Stage Age Developmental Language and Communication
1 0–3 months Reflexive communication
2 3–8 months Reflexive communication; interest in others
3 8–13 months Intentional communication; sociability
4 12–18 months First words
5 18–24 months Simple sentences of two words
6 2–3 years Sentences of three or more words
7 3–5 years Complex sentences; has conversations
The Case of Genie
In the fall of 1970, a social worker in the Los Angeles area found a 13-year-old girl who was being raised in
extremely neglectful and abusive conditions. The girl, who came to be known as Genie, had lived most of her
life tied to a potty chair or confined to a crib in a small room that was kept closed with the curtains drawn. For a
little over a decade, Genie had virtually no social interaction and no access to the outside world. As a result of
these conditions, Genie was unable to stand up, chew solid food, or speak (Fromkin, Krashen, Curtiss, Rigler,
& Rigler, 1974; Rymer, 1993). The police took Genie into protective custody.
Genie’s abilities improved dramatically following her removal from her abusive environment, and early on, it
appeared she was acquiring language—much later than would be predicted by critical period hypotheses that
had been posited at the time (Fromkin et al., 1974). Genie managed to amass an impressive vocabulary in
a relatively short amount of time. However, she never developed a mastery of the grammatical aspects of
language (Curtiss, 1981). Perhaps being deprived of the opportunity to learn language during a critical period
impeded Genie’s ability to fully acquire and use language.
You may recall that each language has its own set of phonemes that are used to generate morphemes,
words, and so on. Babies can discriminate among the sounds that make up a language (for example, they
can tell the difference between the “s” in vision and the “ss” in fission); early on, they can differentiate
between the sounds of all human languages, even those that do not occur in the languages that are used in
their environments. However, by the time that they are about 1 year old, they can only discriminate among
those phonemes that are used in the language or languages in their environments (Jensen, 2011; Werker &
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Lalonde, 1988; Werker & Tees, 1984).
Visit this website ( to learn more about how
babies lose the ability to discriminate among all possible human phonemes as they
After the first few months of life, babies enter what is known as the babbling stage, during which time they
tend to produce single syllables that are repeated over and over. As time passes, more variations appear in
the syllables that they produce. During this time, it is unlikely that the babies are trying to communicate;
they are just as likely to babble when they are alone as when they are with their caregivers (Fernández &
Cairns, 2011). Interestingly, babies who are raised in environments in which sign language is used will also
begin to show babbling in the gestures of their hands during this stage (Petitto, Holowka, Sergio, Levy, &
Ostry, 2004).
Generally, a child’s first word is uttered sometime between the ages of 1 year to 18 months, and for the
next few months, the child will remain in the “one word” stage of language development. During this
time, children know a number of words, but they only produce one-word utterances. The child’s early
vocabulary is limited to familiar objects or events, often nouns. Although children in this stage only make
one-word utterances, these words often carry larger meaning (Fernández & Cairns, 2011). So, for example,
a child saying “cookie” could be identifying a cookie or asking for a cookie.
As a child’s lexicon grows, she begins to utter simple sentences and to acquire new vocabulary at a very
rapid pace. In addition, children begin to demonstrate a clear understanding of the specific rules that
apply to their language(s). Even the mistakes that children sometimes make provide evidence of just how
much they understand about those rules. This is sometimes seen in the form of overgeneralization. In
this context, overgeneralization refers to an extension of a language rule to an exception to the rule. For
example, in English, it is usually the case that an “s” is added to the end of a word to indicate plurality.
For example, we speak of one dog versus two dogs. Young children will overgeneralize this rule to cases
that are exceptions to the “add an s to the end of the word” rule and say things like “those two gooses” or
“three mouses.” Clearly, the rules of the language are understood, even if the exceptions to the rules are
still being learned (Moskowitz, 1978).
When we speak one language, we agree that words are representations of ideas, people, places, and events.
The given language that children learn is connected to their culture and surroundings. But can words
themselves shape the way we think about things? Psychologists have long investigated the question of
whether language shapes thoughts and actions, or whether our thoughts and beliefs shape our language.
Two researchers, Edward Sapir and Benjamin Lee Whorf, began this investigation in the 1940s. They
wanted to understand how the language habits of a community encourage members of that community
to interpret language in a particular manner (Sapir, 1941/1964). Sapir and Whorf proposed that language
determines thought, suggesting, for example, that a person whose community language did not have past-
tense verbs would be challenged to think about the past (Whorf, 1956). Researchers have since identified
this view as too absolute, pointing out a lack of empiricism behind what Sapir and Whorf proposed
(Abler, 2013; Boroditsky, 2011; van Troyer, 1994). Today, psychologists continue to study and debate the
relationship between language and thought.
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The Meaning of Language
Think about what you know of other languages; perhaps you even speak multiple languages. Imagine for
a moment that your closest friend fluently speaks more than one language. Do you think that friend thinks
differently, depending on which language is being spoken? You may know a few words that are not translatable
from their original language into English. For example, the Portuguese word saudade originated during the
15th century, when Portuguese sailors left home to explore the seas and travel to Africa or Asia. Those left
behind described the emptiness and fondness they felt as saudade (Figure 7.7). The word came to express
many meanings, including loss, nostalgia, yearning, warm memories, and hope. There is no single word in
English that includes all of those emotions in a single description. Do words such as saudade indicate that
different languages produce different patterns of thought in people? What do you think??
Figure 7.7 These two works of art depict saudade. (a) Saudade de Nápoles, which is translated into
“missing Naples,” was painted by Bertha Worms in 1895. (b) Almeida Júnior painted Saudade in 1899.
Language may indeed influence the way that we think, an idea known as linguistic determinism. One
recent demonstration of this phenomenon involved differences in the way that English and Mandarin
Chinese speakers talk and think about time. English speakers tend to talk about time using terms that
describe changes along a horizontal dimension, for example, saying something like “I’m running behind
schedule” or “Don’t get ahead of yourself.” While Mandarin Chinese speakers also describe time in
horizontal terms, it is not uncommon to also use terms associated with a vertical arrangement. For
example, the past might be described as being “up” and the future as being “down.” It turns out that these
differences in language translate into differences in performance on cognitive tests designed to measure
how quickly an individual can recognize temporal relationships. Specifically, when given a series of
tasks with vertical priming, Mandarin Chinese speakers were faster at recognizing temporal relationships
between months. Indeed, Boroditsky (2001) sees these results as suggesting that “habits in language
encourage habits in thought” (p. 12).
One group of researchers who wanted to investigate how language influences thought compared how
English speakers and the Dani people of Papua New Guinea think and speak about color. The Dani have
two words for color: one word for light and one word for dark. In contrast, the English language has 11
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color words. Researchers hypothesized that the number of color terms could limit the ways that the Dani
people conceptualized color. However, the Dani were able to distinguish colors with the same ability as
English speakers, despite having fewer words at their disposal (Berlin & Kay, 1969). A recent review of
research aimed at determining how language might affect something like color perception suggests that
language can influence perceptual phenomena, especially in the left hemisphere of the brain. You may
recall from earlier chapters that the left hemisphere is associated with language for most people. However,
the right (less linguistic hemisphere) of the brain is less affected by linguistic influences on perception
(Regier & Kay, 2009)
7.3 Problem Solving
Learning Objectives
By the end of this section, you will be able to:
• Describe problem solving strategies
• Define algorithm and heuristic
• Explain some common roadblocks to effective problem solving
People face problems every day—usually, multiple problems throughout the day. Sometimes these
problems are straightforward: To double a recipe for pizza dough, for example, all that is required is
that each ingredient in the recipe be doubled. Sometimes, however, the problems we encounter are more
complex. For example, say you have a work deadline, and you must mail a printed copy of a report to your
supervisor by the end of the business day. The report is time-sensitive and must be sent overnight. You
finished the report last night, but your printer will not work today. What should you do? First, you need
to identify the problem and then apply a strategy for solving the problem.
When you are presented with a problem—whether it is a complex mathematical problem or a broken
printer, how do you solve it? Before finding a solution to the problem, the problem must first be clearly
identified. After that, one of many problem solving strategies can be applied, hopefully resulting in a
A problem-solving strategy is a plan of action used to find a solution. Different strategies have different
action plans associated with them (Table 7.2). For example, a well-known strategy is trial and error. The
old adage, “If at first you don’t succeed, try, try again” describes trial and error. In terms of your broken
printer, you could try checking the ink levels, and if that doesn’t work, you could check to make sure the
paper tray isn’t jammed. Or maybe the printer isn’t actually connected to your laptop. When using trial
and error, you would continue to try different solutions until you solved your problem. Although trial and
error is not typically one of the most time-efficient strategies, it is a commonly used one.
Table 7.2 Problem-Solving Strategies
Method Description Example
Trial and
Continue trying different
solutions until problem is
Restarting phone, turning off WiFi, turning off
bluetooth in order to determine why your phone is
Algorithm Step-by-step problem-
solving formula
Instruction manual for installing new software on your
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Table 7.2 Problem-Solving Strategies
Method Description Example
Heuristic General problem-solving
Working backwards; breaking a task into steps
Another type of strategy is an algorithm. An algorithm is a problem-solving formula that provides you
with step-by-step instructions used to achieve a desired outcome (Kahneman, 2011). You can think of an
algorithm as a recipe with highly detailed instructions that produce the same result every time they are
performed. Algorithms are used frequently in our everyday lives, especially in computer science. When
you run a search on the Internet, search engines like Google use algorithms to decide which entries will
appear first in your list of results. Facebook also uses algorithms to decide which posts to display on your
newsfeed. Can you identify other situations in which algorithms are used?
A heuristic is another type of problem solving strategy. While an algorithm must be followed exactly
to produce a correct result, a heuristic is a general problem-solving framework (Tversky & Kahneman,
1974). You can think of these as mental shortcuts that are used to solve problems. A “rule of thumb” is an
example of a heuristic. Such a rule saves the person time and energy when making a decision, but despite
its time-saving characteristics, it is not always the best method for making a rational decision. Different
types of heuristics are used in different types of situations, but the impulse to use a heuristic occurs when
one of five conditions is met (Pratkanis, 1989):
• When one is faced with too much information
• When the time to make a decision is limited
• When the decision to be made is unimportant
• When there is access to very little information to use in making the decision
• When an appropriate heuristic happens to come to mind in the same moment
Working backwards is a useful heuristic in which you begin solving the problem by focusing on the end
result. Consider this example: You live in Washington, D.C. and have been invited to a wedding at 4 PM
on Saturday in Philadelphia. Knowing that Interstate 95 tends to back up any day of the week, you need to
plan your route and time your departure accordingly. If you want to be at the wedding service by 3:30 PM,
and it takes 2.5 hours to get to Philadelphia without traffic, what time should you leave your house? You
use the working backwards heuristic to plan the events of your day on a regular basis, probably without
even thinking about it.
Another useful heuristic is the practice of accomplishing a large goal or task by breaking it into a series
of smaller steps. Students often use this common method to complete a large research project or long
essay for school. For example, students typically brainstorm, develop a thesis or main topic, research the
chosen topic, organize their information into an outline, write a rough draft, revise and edit the rough
draft, develop a final draft, organize the references list, and proofread their work before turning in the
project. The large task becomes less overwhelming when it is broken down into a series of small steps.
Solving Puzzles
Problem-solving abilities can improve with practice. Many people challenge themselves every day with puzzles
and other mental exercises to sharpen their problem-solving skills. Sudoku puzzles appear daily in most
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newspapers. Typically, a sudoku puzzle is a 9×9 grid. The simple sudoku below (Figure 7.8) is a 4×4 grid. To
solve the puzzle, fill in the empty boxes with a single digit: 1, 2, 3, or 4. Here are the rules: The numbers must
total 10 in each bolded box, each row, and each column; however, each digit can only appear once in a bolded
box, row, and column. Time yourself as you solve this puzzle and compare your time with a classmate.
Figure 7.8 How long did it take you to solve this sudoku puzzle? (You can see the answer at the end of this
Here is another popular type of puzzle (Figure 7.9) that challenges your spatial reasoning skills. Connect all
nine dots with four connecting straight lines without lifting your pencil from the paper:
Figure 7.9 Did you figure it out? (The answer is at the end of this section.) Once you understand how to
crack this puzzle, you won’t forget.
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Take a look at the “Puzzling Scales” logic puzzle below (Figure 7.10). Sam Loyd, a well-known puzzle master,
created and refined countless puzzles throughout his lifetime (Cyclopedia of Puzzles, n.d.).
Figure 7.10 What steps did you take to solve this puzzle? You can read the solution at the end of this
Not all problems are successfully solved, however. What challenges stop us from successfully solving a
problem? Albert Einstein once said, “Insanity is doing the same thing over and over again and expecting a
different result.” Imagine a person in a room that has four doorways. One doorway that has always been
open in the past is now locked. The person, accustomed to exiting the room by that particular doorway,
keeps trying to get out through the same doorway even though the other three doorways are open. The
person is stuck—but she just needs to go to another doorway, instead of trying to get out through the
locked doorway. A mental set is where you persist in approaching a problem in a way that has worked in
the past but is clearly not working now.
Functional fixedness is a type of mental set where you cannot perceive an object being used for something
other than what it was designed for. During the Apollo 13 mission to the moon, NASA engineers at Mission
Control had to overcome functional fixedness to save the lives of the astronauts aboard the spacecraft.
An explosion in a module of the spacecraft damaged multiple systems. The astronauts were in danger of
being poisoned by rising levels of carbon dioxide because of problems with the carbon dioxide filters. The
engineers found a way for the astronauts to use spare plastic bags, tape, and air hoses to create a makeshift
air filter, which saved the lives of the astronauts.
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Check out this Apollo 13 scene ( where the
group of NASA engineers are given the task of overcoming functional fixedness.
Researchers have investigated whether functional fixedness is affected by culture. In one experiment,
individuals from the Shuar group in Ecuador were asked to use an object for a purpose other than that
for which the object was originally intended. For example, the participants were told a story about a bear
and a rabbit that were separated by a river and asked to select among various objects, including a spoon,
a cup, erasers, and so on, to help the animals. The spoon was the only object long enough to span the
imaginary river, but if the spoon was presented in a way that reflected its normal usage, it took participants
longer to choose the spoon to solve the problem. (German & Barrett, 2005). The researchers wanted to
know if exposure to highly specialized tools, as occurs with individuals in industrialized nations, affects
their ability to transcend functional fixedness. It was determined that functional fixedness is experienced
in both industrialized and nonindustrialized cultures (German & Barrett, 2005).
In order to make good decisions, we use our knowledge and our reasoning. Often, this knowledge and
reasoning is sound and solid. Sometimes, however, we are swayed by biases or by others manipulating a
situation. For example, let’s say you and three friends wanted to rent a house and had a combined target
budget of $1,600. The realtor shows you only very run-down houses for $1,600 and then shows you a
very nice house for $2,000. Might you ask each person to pay more in rent to get the $2,000 home? Why
would the realtor show you the run-down houses and the nice house? The realtor may be challenging your
anchoring bias. An anchoring bias occurs when you focus on one piece of information when making a
decision or solving a problem. In this case, you’re so focused on the amount of money you are willing to
spend that you may not recognize what kinds of houses are available at that price point.
The confirmation bias is the tendency to focus on information that confirms your existing beliefs. For
example, if you think that your professor is not very nice, you notice all of the instances of rude behavior
exhibited by the professor while ignoring the countless pleasant interactions he is involved in on a daily
basis. Hindsight bias leads you to believe that the event you just experienced was predictable, even
though it really wasn’t. In other words, you knew all along that things would turn out the way they did.
Representative bias describes a faulty way of thinking, in which you unintentionally stereotype someone
or something; for example, you may assume that your professors spend their free time reading books and
engaging in intellectual conversation, because the idea of them spending their time playing volleyball or
visiting an amusement park does not fit in with your stereotypes of professors.
Finally, the availability heuristic is a heuristic in which you make a decision based on an example,
information, or recent experience that is that readily available to you, even though it may not be the best
example to inform your decision. Biases tend to “preserve that which is already established—to maintain
our preexisting knowledge, beliefs, attitudes, and hypotheses” (Aronson, 1995; Kahneman, 2011). These
biases are summarized in Table 7.3.
Table 7.3 Summary of Decision Biases
Bias Description
Anchoring Tendency to focus on one particular piece of information when making decisions
or problem-solving
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Table 7.3 Summary of Decision Biases
Bias Description
Confirmation Focuses on information that confirms existing beliefs
Hindsight Belief that the event just experienced was predictable
Representative Unintentional stereotyping of someone or something
Availability Decision is based upon either an available precedent or an example that may be
Please visit this site ( to see a clever music
video that a high school teacher made to explain these and other cognitive biases to
his AP psychology students.
Were you able to determine how many marbles are needed to balance the scales in Figure 7.10? You need
nine. Were you able to solve the problems in Figure 7.8 and Figure 7.9? Here are the answers (Figure
Figure 7.11
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7.4 What Are Intelligence and Creativity?
Learning Objectives
By the end of this section, you will be able to:
• Define intelligence
• Explain the triarchic theory of intelligence
• Identify the difference between intelligence theories
• Explain emotional intelligence
A four-and-a-half-year-old boy sits at the kitchen table with his father, who is reading a new story aloud
to him. He turns the page to continue reading, but before he can begin, the boy says, “Wait, Daddy!” He
points to the words on the new page and reads aloud, “Go, Pig! Go!” The father stops and looks at his son.
“Can you read that?” he asks. “Yes, Daddy!” And he points to the words and reads again, “Go, Pig! Go!”
This father was not actively teaching his son to read, even though the child constantly asked questions
about letters, words, and symbols that they saw everywhere: in the car, in the store, on the television. The
dad wondered about what else his son might understand and decided to try an experiment. Grabbing a
sheet of blank paper, he wrote several simple words in a list: mom, dad, dog, bird, bed, truck, car, tree. He
put the list down in front of the boy and asked him to read the words. “Mom, dad, dog, bird, bed, truck,
car, tree,” he read, slowing down to carefully pronounce bird and truck. Then, “Did I do it, Daddy?” “You
sure did! That is very good.” The father gave his little boy a warm hug and continued reading the story
about the pig, all the while wondering if his son’s abilities were an indication of exceptional intelligence
or simply a normal pattern of linguistic development. Like the father in this example, psychologists have
wondered what constitutes intelligence and how it can be measured.
What exactly is intelligence? The way that researchers have defined the concept of intelligence has been
modified many times since the birth of psychology. British psychologist Charles Spearman believed
intelligence consisted of one general factor, called g, which could be measured and compared among
individuals. Spearman focused on the commonalities among various intellectual abilities and
demphasized what made each unique. Long before modern psychology developed, however, ancient
philosophers, such as Aristotle, held a similar view (Cianciolo & Sternberg, 2004).
Others psychologists believe that instead of a single factor, intelligence is a collection of distinct abilities.
In the 1940s, Raymond Cattell proposed a theory of intelligence that divided general intelligence into
two components: crystallized intelligence and fluid intelligence (Cattell, 1963). Crystallized intelligence
is characterized as acquired knowledge and the ability to retrieve it. When you learn, remember, and
recall information, you are using crystallized intelligence. You use crystallized intelligence all the time in
your coursework by demonstrating that you have mastered the information covered in the course. Fluid
intelligence encompasses the ability to see complex relationships and solve problems. Navigating your
way home after being detoured onto an unfamiliar route because of road construction would draw upon
your fluid intelligence. Fluid intelligence helps you tackle complex, abstract challenges in your daily life,
whereas crystallized intelligence helps you overcome concrete, straightforward problems (Cattell, 1963).
Other theorists and psychologists believe that intelligence should be defined in more practical terms. For
example, what types of behaviors help you get ahead in life? Which skills promote success? Think about
this for a moment. Being able to recite all 44 presidents of the United States in order is an excellent party
trick, but will knowing this make you a better person?
Robert Sternberg developed another theory of intelligence, which he titled the triarchic theory of
intelligence because it sees intelligence as comprised of three parts (Sternberg, 1988): practical, creative,
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and analytical intelligence (Figure 7.12).
Figure 7.12 Sternberg’s theory identifies three types of intelligence: practical, creative, and analytical.
Practical intelligence, as proposed by Sternberg, is sometimes compared to “street smarts.” Being practical
means you find solutions that work in your everyday life by applying knowledge based on your
experiences. This type of intelligence appears to be separate from traditional understanding of IQ;
individuals who score high in practical intelligence may or may not have comparable scores in creative
and analytical intelligence (Sternberg, 1988).
This story about the 2007 Virginia Tech shootings illustrates both high and low practical intelligences.
During the incident, one student left her class to go get a soda in an adjacent building. She planned to
return to class, but when she returned to her building after getting her soda, she saw that the door she used
to leave was now chained shut from the inside. Instead of thinking about why there was a chain around
the door handles, she went to her class’s window and crawled back into the room. She thus potentially
exposed herself to the gunman. Thankfully, she was not shot. On the other hand, a pair of students was
walking on campus when they heard gunshots nearby. One friend said, “Let’s go check it out and see what
is going on.” The other student said, “No way, we need to run away from the gunshots.” They did just
that. As a result, both avoided harm. The student who crawled through the window demonstrated some
creative intelligence but did not use common sense. She would have low practical intelligence. The student
who encouraged his friend to run away from the sound of gunshots would have much higher practical
Analytical intelligence is closely aligned with academic problem solving and computations. Sternberg
says that analytical intelligence is demonstrated by an ability to analyze, evaluate, judge, compare, and
contrast. When reading a classic novel for literature class, for example, it is usually necessary to compare
the motives of the main characters of the book or analyze the historical context of the story. In a science
course such as anatomy, you must study the processes by which the body uses various minerals in
different human systems. In developing an understanding of this topic, you are using analytical
intelligence. When solving a challenging math problem, you would apply analytical intelligence to analyze
different aspects of the problem and then solve it section by section.
Creative intelligence is marked by inventing or imagining a solution to a problem or situation. Creativity
in this realm can include finding a novel solution to an unexpected problem or producing a beautiful work
of art or a well-developed short story. Imagine for a moment that you are camping in the woods with some
friends and realize that you’ve forgotten your camp coffee pot. The person in your group who figures out
a way to successfully brew coffee for everyone would be credited as having higher creative intelligence.
Multiple Intelligences Theory was developed by Howard Gardner, a Harvard psychologist and former
student of Erik Erikson. Gardner’s theory, which has been refined for more than 30 years, is a more
recent development among theories of intelligence. In Gardner’s theory, each person possesses at least
eight intelligences. Among these eight intelligences, a person typically excels in some and falters in others
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(Gardner, 1983). Table 7.4 describes each type of intelligence.
Table 7.4 Multiple Intelligences
Type Characteristics
Perceives different functions of language, different
sounds and meanings of words, may easily learn
multiple languages
Journalist, novelist,
poet, teacher
Capable of seeing numerical patterns, strong ability to
use reason and logic
Understands and appreciates rhythm, pitch, and tone;
may play multiple instruments or perform as a vocalist
Composer, performer
High ability to control the movements of the body and
use the body to perform various physical tasks
Dancer, athlete,
athletic coach, yoga
Ability to perceive the relationship between objects and
how they move in space
sculptor, architect,
aviator, sailor
Ability to understand and be sensitive to the various
emotional states of others
Counselor, social
worker, salesperson
Ability to access personal feelings and motivations, and
use them to direct behavior and reach personal goals
Key component of
personal success over
High capacity to appreciate the natural world and
interact with the species within it
Biologist, ecologist,
Gardner’s theory is relatively new and needs additional research to better establish empirical support. At
the same time, his ideas challenge the traditional idea of intelligence to include a wider variety of abilities,
although it has been suggested that Gardner simply relabeled what other theorists called “cognitive styles”
as “intelligences” (Morgan, 1996). Furthermore, developing traditional measures of Gardner’s intelligences
is extremely difficult (Furnham, 2009; Gardner & Moran, 2006; Klein, 1997).
Gardner’s inter- and intrapersonal intelligences are often combined into a single type: emotional
intelligence. Emotional intelligence encompasses the ability to understand the emotions of yourself and
others, show empathy, understand social relationships and cues, and regulate your own emotions and
respond in culturally appropriate ways (Parker, Saklofske, & Stough, 2009). People with high emotional
intelligence typically have well-developed social skills. Some researchers, including Daniel Goleman, the
author of Emotional Intelligence: Why It Can Matter More than IQ, argue that emotional intelligence is a better
predictor of success than traditional intelligence (Goleman, 1995). However, emotional intelligence has
been widely debated, with researchers pointing out inconsistencies in how it is defined and described,
as well as questioning results of studies on a subject that is difficulty to measure and study emperically
(Locke, 2005; Mayer, Salovey, & Caruso, 2004)
Intelligence can also have different meanings and values in different cultures. If you live on a small island,
Chapter 7 | Thinking and Intelligence 235

where most people get their food by fishing from boats, it would be important to know how to fish
and how to repair a boat. If you were an exceptional angler, your peers would probably consider you
intelligent. If you were also skilled at repairing boats, your intelligence might be known across the whole
island. Think about your own family’s culture. What values are important for Latino families? Italian
families? In Irish families, hospitality and telling an entertaining story are marks of the culture. If you are
a skilled storyteller, other members of Irish culture are likely to consider you intelligent.
Some cultures place a high value on working together as a collective. In these cultures, the importance of
the group supersedes the importance of individual achievement. When you visit such a culture, how well
you relate to the values of that culture exemplifies your cultural intelligence, sometimes referred to as
cultural competence.
Creativity is the ability to generate, create, or discover new ideas, solutions, and possibilities. Very creative
people often have intense knowledge about something, work on it for years, look at novel solutions, seek
out the advice and help of other experts, and take risks. Although creativity is often associated with the
arts, it is actually a vital form of intelligence that drives people in many disciplines to discover something
new. Creativity can be found in every area of life, from the way you decorate your residence to a new way
of understanding how a cell works.
Creativity is often assessed as a function of one’s ability to engage in divergent thinking. Divergent
thinking can be described as thinking “outside the box;” it allows an individual to arrive at unique,
multiple solutions to a given problem. In contrast, convergent thinking describes the ability to provide a
correct or well-established answer or solution to a problem (Cropley, 2006; Gilford, 1967)
Dr. Tom Steitz, the Sterling Professor of Biochemistry and Biophysics at Yale University, has spent his career
looking at the structure and specific aspects of RNA molecules and how their interactions cold help produce
antibiotics and ward off diseases. As a result of his lifetime of work, he won the Nobel Prize in Chemistry in
2009. He wrote, “Looking back over the development and progress of my career in science, I am reminded
how vitally important good mentorship is in the early stages of one’s career development and constant face-to-
face conversations, debate and discussions with colleagues at all stages of research. Outstanding discoveries,
insights and developments do not happen in a vacuum” (Steitz, 2010, para. 39). Based on Steitz’s comment, it
becomes clear that someone’s creativity, although an individual strength, benefits from interactions with others.
Think of a time when your creativity was sparked by a conversation with a friend or classmate. How did that
person influence you and what problem did you solve using creativity?
7.5 Measures of Intelligence
Learning Objectives
By the end of this section, you will be able to:
• Explain how intelligence tests are developed
• Describe the history of the use of IQ tests
• Describe the purposes and benefits of intelligence testing
While you’re likely familiar with the term “IQ” and associate it with the idea of intelligence, what does
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IQ really mean? IQ stands for intelligence quotient and describes a score earned on a test designed to
measure intelligence. You’ve already learned that there are many ways psychologists describe intelligence
(or more aptly, intelligences). Similarly, IQ tests—the tools designed to measure intelligence—have been
the subject of debate throughout their development and use.
When might an IQ test be used? What do we learn from the results, and how might people use this
information? IQ tests are expensive to administer and must be given by a licensed psychologist.
Intelligence testing has been considered both a bane and a boon for education and social policy. In
this section, we will explore what intelligence tests measure, how they are scored, and how they were
It seems that the human understanding of intelligence is somewhat limited when we focus on traditional or
academic-type intelligence. How then, can intelligence be measured? And when we measure intelligence,
how do we ensure that we capture what we’re really trying to measure (in other words, that IQ tests
function as valid measures of intelligence)? In the following paragraphs, we will explore the how
intelligence tests were developed and the history of their use.
The IQ test has been synonymous with intelligence for over a century. In the late 1800s, Sir Francis
Galton developed the first broad test of intelligence (Flanagan & Kaufman, 2004). Although he was not
a psychologist, his contributions to the concepts of intelligence testing are still felt today (Gordon, 1995).
Reliable intelligence testing (you may recall from earlier chapters that reliability refers to a test’s ability to
produce consistent results) began in earnest during the early 1900s with a researcher named Alfred Binet
(Figure 7.13). Binet was asked by the French government to develop an intelligence test to use on children
to determine which ones might have difficulty in school; it included many verbally based tasks. American
researchers soon realized the value of such testing. Louis Terman, a Stanford professor, modified Binet’s
work by standardizing the administration of the test and tested thousands of different-aged children to
establish an average score for each age. As a result, the test was normed and standardized, which means
that the test was administered consistently to a large enough representative sample of the population that
the range of scores resulted in a bell curve (bell curves will be discussed later). Standardization means that
the manner of administration, scoring, and interpretation of results is consistent. Norming involves giving
a test to a large population so data can be collected comparing groups, such as age groups. The resulting
data provide norms, or referential scores, by which to interpret future scores. Norms are not expectations
of what a given group should know but a demonstration of what that group does know. Norming and
standardizing the test ensures that new scores are reliable. This new version of the test was called the
Stanford-Binet Intelligence Scale (Terman, 1916). Remarkably, an updated version of this test is still widely
used today.
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Figure 7.13 French psychologist Alfred Binet helped to develop intelligence testing. (b) This page is from a 1908
version of the Binet-Simon Intelligence Scale. Children being tested were asked which face, of each pair, was prettier.
In 1939, David Wechsler, a psychologist who spent part of his career working with World War I veterans,
developed a new IQ test in the United States. Wechsler combined several subtests from other intelligence
tests used between 1880 and World War I. These subtests tapped into a variety of verbal and nonverbal
skills, because Wechsler believed that intelligence encompassed “the global capacity of a person to act
purposefully, to think rationally, and to deal effectively with his environment” (Wechsler, 1958, p. 7). He
named the test the Wechsler-Bellevue Intelligence Scale (Wechsler, 1981). This combination of subtests
became one of the most extensively used intelligence tests in the history of psychology. Although its name
was later changed to the Wechsler Adult Intelligence Scale (WAIS) and has been revised several times,
the aims of the test remain virtually unchanged since its inception (Boake, 2002). Today, there are three
intelligence tests credited to Wechsler, the Wechsler Adult Intelligence Scale-fourth edition (WAIS-IV),
the Wechsler Intelligence Scale for Children (WISC-V), and the Wechsler Preschool and Primary Scale of
Intelligence—IV (WPPSI-IV) (Wechsler, 2012). These tests are used widely in schools and communities
throughout the United States, and they are periodically normed and standardized as a means of
recalibration. Interestingly, the periodic recalibrations have led to an interesting observation known as the
Flynn effect. Named after James Flynn, who was among the first to describe this trend, the Flynn effect
refers to the observation that each generation has a significantly higher IQ than the last. Flynn himself
argues, however, that increased IQ scores do not necessarily mean that younger generations are more
intelligent per se (Flynn, Shaughnessy, & Fulgham, 2012). As a part of the recalibration process, the WISC-
V was given to thousands of children across the country, and children taking the test today are compared
with their same-age peers (Figure 7.13).
The WISC-V is composed of 14 subtests, which comprise five indices, which then render an IQ score. The
five indices are Verbal Comprehension, Visual Spatial, Fluid Reasoning, Working Memory, and Processing
Speed. When the test is complete, individuals receive a score for each of the five indices and a Full Scale IQ
score. The method of scoring reflects the understanding that intelligence is comprised of multiple abilities
in several cognitive realms and focuses on the mental processes that the child used to arrive at his or her
answers to each test item.
Ultimately, we are still left with the question of how valid intelligence tests are. Certainly, the most modern
versions of these tests tap into more than verbal competencies, yet the specific skills that should be assessed
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in IQ testing, the degree to which any test can truly measure an individual’s intelligence, and the use of the
results of IQ tests are still issues of debate (Gresham & Witt, 1997; Flynn, Shaughnessy, & Fulgham, 2012;
Richardson, 2002; Schlinger, 2003).
Intellectually Disabled Criminals and Capital Punishment
The case of Atkins v. Virginia was a landmark case in the United States Supreme Court. On August 16, 1996,
two men, Daryl Atkins and William Jones, robbed, kidnapped, and then shot and killed Eric Nesbitt, a local
airman from the U.S. Air Force. A clinical psychologist evaluated Atkins and testified at the trial that Atkins had
an IQ of 59. The mean IQ score is 100. The psychologist concluded that Atkins was mildly mentally retarded.
The jury found Atkins guilty, and he was sentenced to death. Atkins and his attorneys appealed to the Supreme
Court. In June 2002, the Supreme Court reversed a previous decision and ruled that executions of mentally
retarded criminals are ‘cruel and unusual punishments’ prohibited by the Eighth Amendment. The court wrote
in their decision:
Clinical definitions of mental retardation require not only subaverage intellectual functioning, but
also significant limitations in adaptive skills. Mentally retarded persons frequently know the
difference between right and wrong and are competent to stand trial. Because of their impairments,
however, by definition they have diminished capacities to understand and process information, to
communicate, to abstract from mistakes and learn from experience, to engage in logical reasoning,
to control impulses, and to understand others’ reactions. Their deficiencies do not warrant an
exemption from criminal sanctions, but diminish their personal culpability (Atkins v. Virginia, 2002,
par. 5).
The court also decided that there was a state legislature consensus against the execution of the mentally
retarded and that this consensus should stand for all of the states. The Supreme Court ruling left it up to
the states to determine their own definitions of mental retardation and intellectual disability. The definitions
vary among states as to who can be executed. In the Atkins case, a jury decided that because he had many
contacts with his lawyers and thus was provided with intellectual stimulation, his IQ had reportedly increased,
and he was now smart enough to be executed. He was given an execution date and then received a stay of
execution after it was revealed that lawyers for co-defendant, William Jones, coached Jones to “produce a
testimony against Mr. Atkins that did match the evidence” (Liptak, 2008). After the revelation of this misconduct,
Atkins was re-sentenced to life imprisonment.
Atkins v. Virginia (2002) highlights several issues regarding society’s beliefs around intelligence. In the Atkins
case, the Supreme Court decided that intellectual disability does affect decision making and therefore should
affect the nature of the punishment such criminals receive. Where, however, should the lines of intellectual
disability be drawn? In May 2014, the Supreme Court ruled in a related case (Hall v. Florida) that IQ scores
cannot be used as a final determination of a prisoner’s eligibility for the death penalty (Roberts, 2014).
The results of intelligence tests follow the bell curve, a graph in the general shape of a bell. When the bell
curve is used in psychological testing, the graph demonstrates a normal distribution of a trait, in this case,
intelligence, in the human population. Many human traits naturally follow the bell curve. For example,
if you lined up all your female schoolmates according to height, it is likely that a large cluster of them
would be the average height for an American woman: 5’4”–5’6”. This cluster would fall in the center of
the bell curve, representing the average height for American women (Figure 7.14). There would be fewer
women who stand closer to 4’11”. The same would be true for women of above-average height: those who
stand closer to 5’11”. The trick to finding a bell curve in nature is to use a large sample size. Without a
large sample size, it is less likely that the bell curve will represent the wider population. A representative
sample is a subset of the population that accurately represents the general population. If, for example, you
Chapter 7 | Thinking and Intelligence 239

measured the height of the women in your classroom only, you might not actually have a representative
sample. Perhaps the women’s basketball team wanted to take this course together, and they are all in your
class. Because basketball players tend to be taller than average, the women in your class may not be a good
representative sample of the population of American women. But if your sample included all the women
at your school, it is likely that their heights would form a natural bell curve.
Figure 7.14 Are you of below-average, average, or above-average height?
The same principles apply to intelligence tests scores. Individuals earn a score called an intelligence
quotient (IQ). Over the years, different types of IQ tests have evolved, but the way scores are interpreted
remains the same. The average IQ score on an IQ test is 100. Standard deviations describe how data are
dispersed in a population and give context to large data sets. The bell curve uses the standard deviation
to show how all scores are dispersed from the average score (Figure 7.15). In modern IQ testing, one
standard deviation is 15 points. So a score of 85 would be described as “one standard deviation below
the mean.” How would you describe a score of 115 and a score of 70? Any IQ score that falls within one
standard deviation above and below the mean (between 85 and 115) is considered average, and 68% of the
population has IQ scores in this range. An IQ score of 130 or above is considered a superior level.
240 Chapter 7 | Thinking and Intelligence
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Figure 7.15 The majority of people have an IQ score between 85 and 115.
Only 2.2% of the population has an IQ score below 70 (American Psychological Association [APA], 2013).
A score of 70 or below indicates significant cognitive delays, major deficits in adaptive functioning,
and difficulty meeting “community standards of personal independence and social responsibility” when
compared to same-aged peers (APA, 2013, p. 37). An individual in this IQ range would be considered
to have an intellectual disability and exhibit deficits in intellectual functioning and adaptive behavior
(American Association on Intellectual and Developmental Disabilities, 2013). Formerly known as mental
retardation, the accepted term now is intellectual disability, and it has four subtypes: mild, moderate,
severe, and profound (Table 7.5). The Diagnostic and Statistical Manual of Psychological Disorders lists criteria
for each subgroup (APA, 2013).
Table 7.5 Characteristics of Cognitive Disorders
Percentage of
Intellectually Disabled
Mild 85% 3rd- to 6th-grade skill level in reading, writing, and
math; may be employed and live independently
Moderate 10% Basic reading and writing skills; functional self-care
skills; requires some oversight
Severe 5% Functional self-care skills; requires oversight of
daily environment and activities
Profound <1% May be able to communicate verbally or nonverbally; requires intensive oversight On the other end of the intelligence spectrum are those individuals whose IQs fall into the highest ranges. Consistent with the bell curve, about 2% of the population falls into this category. People are considered gifted if they have an IQ score of 130 or higher, or superior intelligence in a particular area. Long ago, popular belief suggested that people of high intelligence were maladjusted. This idea was disproven through a groundbreaking study of gifted children. In 1921, Lewis Terman began a longitudinal study of over 1500 children with IQs over 135 (Terman, 1925). His findings showed that Chapter 7 | Thinking and Intelligence 241 these children became well-educated, successful adults who were, in fact, well-adjusted (Terman & Oden, 1947). Additionally, Terman’s study showed that the subjects were above average in physical build and attractiveness, dispelling an earlier popular notion that highly intelligent people were “weaklings.” Some people with very high IQs elect to join Mensa, an organization dedicated to identifying, researching, and fostering intelligence. Members must have an IQ score in the top 2% of the population, and they may be required to pass other exams in their application to join the group. What’s in a Name? Mental Retardation In the past, individuals with IQ scores below 70 and significant adaptive and social functioning delays were diagnosed with mental retardation. When this diagnosis was first named, the title held no social stigma. In time, however, the degrading word “retard” sprang from this diagnostic term. “Retard” was frequently used as a taunt, especially among young people, until the words “mentally retarded” and “retard” became an insult. As such, the DSM-5 now labels this diagnosis as “intellectual disability.” Many states once had a Department of Mental Retardation to serve those diagnosed with such cognitive delays, but most have changed their name to Department of Developmental Disabilities or something similar in language. The Social Security Administration still uses the term “mental retardation” but is considering eliminating it from its programming (Goad, 2013). Earlier in the chapter, we discussed how language affects how we think. Do you think changing the title of this department has any impact on how people regard those with developmental disabilities? Does a different name give people more dignity, and if so, how? Does it change the expectations for those with developmental or cognitive disabilities? Why or why not? WHY MEASURE INTELLIGENCE? The value of IQ testing is most evident in educational or clinical settings. Children who seem to be experiencing learning difficulties or severe behavioral problems can be tested to ascertain whether the child’s difficulties can be partly attributed to an IQ score that is significantly different from the mean for her age group. Without IQ testing—or another measure of intelligence—children and adults needing extra support might not be identified effectively. In addition, IQ testing is used in courts to determine whether a defendant has special or extenuating circumstances that preclude him from participating in some way in a trial. People also use IQ testing results to seek disability benefits from the Social Security Administration. While IQ tests have sometimes been used as arguments in support of insidious purposes, such as the eugenics movement (Severson, 2011), the following case study demonstrates the usefulness and benefits of IQ testing. Candace, a 14-year-old girl experiencing problems at school, was referred for a court-ordered psychological evaluation. She was in regular education classes in ninth grade and was failing every subject. Candace had never been a stellar student but had always been passed to the next grade. Frequently, she would curse at any of her teachers who called on her in class. She also got into fights with other students and occasionally shoplifted. When she arrived for the evaluation, Candace immediately said that she hated everything about school, including the teachers, the rest of the staff, the building, and the homework. Her parents stated that they felt their daughter was picked on, because she was of a different race than the teachers and most of the other students. When asked why she cursed at her teachers, Candace replied, “They only call on me when I don’t know the answer. I don’t want to say, ‘I don’t know’ all of the time and look like an idiot in front of my friends. The teachers embarrass me.” She was given a battery of tests, including an IQ test. Her score on the IQ test was 68. What does Candace’s score say about her ability to excel or even succeed in regular education classes without assistance? DIG DEEPER 242 Chapter 7 | Thinking and Intelligence This OpenStax book is available for free at 7.6 The Source of Intelligence Learning Objectives By the end of this section, you will be able to: • Describe how genetics and environment affect intelligence • Explain the relationship between IQ scores and socioeconomic status • Describe the difference between a learning disability and a developmental disorder A young girl, born of teenage parents, lives with her grandmother in rural Mississippi. They are poor—in serious poverty—but they do their best to get by with what they have. She learns to read when she is just 3 years old. As she grows older, she longs to live with her mother, who now resides in Wisconsin. She moves there at the age of 6 years. At 9 years of age, she is raped. During the next several years, several different male relatives repeatedly molest her. Her life unravels. She turns to drugs and sex to fill the deep, lonely void inside her. Her mother then sends her to Nashville to live with her father, who imposes strict behavioral expectations upon her, and over time, her wild life settles once again. She begins to experience success in school, and at 19 years old, becomes the youngest and first African-American female news anchor (“Dates and Events,” n.d.). The woman—Oprah Winfrey—goes on to become a media giant known for both her intelligence and her empathy. HIGH INTELLIGENCE: NATURE OR NURTURE? Where does high intelligence come from? Some researchers believe that intelligence is a trait inherited from a person’s parents. Scientists who research this topic typically use twin studies to determine the heritability of intelligence. The Minnesota Study of Twins Reared Apart is one of the most well-known twin studies. In this investigation, researchers found that identical twins raised together and identical twins raised apart exhibit a higher correlation between their IQ scores than siblings or fraternal twins raised together (Bouchard, Lykken, McGue, Segal, & Tellegen, 1990). The findings from this study reveal a genetic component to intelligence (Figure 7.16). At the same time, other psychologists believe that intelligence is shaped by a child’s developmental environment. If parents were to provide their children with intellectual stimuli from before they are born, it is likely that they would absorb the benefits of that stimulation, and it would be reflected in intelligence levels. Chapter 7 | Thinking and Intelligence 243 Figure 7.16 The correlations of IQs of unrelated versus related persons reared apart or together suggest a genetic component to intelligence. The reality is that aspects of each idea are probably correct. In fact, one study suggests that although genetics seem to be in control of the level of intelligence, the environmental influences provide both stability and change to trigger manifestation of cognitive abilities (Bartels, Rietveld, Van Baal, & Boomsma, 2002). Certainly, there are behaviors that support the development of intelligence, but the genetic component of high intelligence should not be ignored. As with all heritable traits, however, it is not always possible to isolate how and when high intelligence is passed on to the next generation. Range of Reaction is the theory that each person responds to the environment in a unique way based on his or her genetic makeup. According to this idea, your genetic potential is a fixed quantity, but whether you reach your full intellectual potential is dependent upon the environmental stimulation you experience, especially in childhood. Think about this scenario: A couple adopts a child who has average genetic intellectual potential. They raise her in an extremely stimulating environment. What will happen to the couple’s new daughter? It is likely that the stimulating environment will improve her intellectual outcomes over the course of her life. But what happens if this experiment is reversed? If a child with an extremely strong genetic background is placed in an environment that does not stimulate him: What happens? Interestingly, according to a longitudinal study of highly gifted individuals, it was found that “the two extremes of optimal and pathological experience are both represented disproportionately in the backgrounds of creative individuals”; however, those who experienced supportive family environments were more likely to report being happy (Csikszentmihalyi & Csikszentmihalyi, 1993, p. 187). Another challenge to determining origins of high intelligence is the confounding nature of our human social structures. It is troubling to note that some ethnic groups perform better on IQ tests than others—and it is likely that the results do not have much to do with the quality of each ethnic group’s intellect. The same is true for socioeconomic status. Children who live in poverty experience more pervasive, daily stress than children who do not worry about the basic needs of safety, shelter, and food. These worries can negatively affect how the brain functions and develops, causing a dip in IQ scores. Mark Kishiyama and his colleagues determined that children living in poverty demonstrated reduced prefrontal brain functioning comparable to children with damage to the lateral prefrontal cortex (Kishyama, Boyce, Jimenez, Perry, & Knight, 2009). The debate around the foundations and influences on intelligence exploded in 1969, when an educational psychologist named Arthur Jensen published the article “How Much Can We Boost I.Q. and Achievement” in the Harvard Educational Review. Jensen had administered IQ tests to diverse groups of students, and 244 Chapter 7 | Thinking and Intelligence This OpenStax book is available for free at his results led him to the conclusion that IQ is determined by genetics. He also posited that intelligence was made up of two types of abilities: Level I and Level II. In his theory, Level I is responsible for rote memorization, whereas Level II is responsible for conceptual and analytical abilities. According to his findings, Level I remained consistent among the human race. Level II, however, exhibited differences among ethnic groups (Modgil & Routledge, 1987). Jensen’s most controversial conclusion was that Level II intelligence is prevalent among Asians, then Caucasians, then African Americans. Robert Williams was among those who called out racial bias in Jensen’s results (Williams, 1970). Obviously, Jensen’s interpretation of his own data caused an intense response in a nation that continued to grapple with the effects of racism (Fox, 2012). However, Jensen’s ideas were not solitary or unique; rather, they represented one of many examples of psychologists asserting racial differences in IQ and cognitive ability. In fact, Rushton and Jensen (2005) reviewed three decades worth of research on the relationship between race and cognitive ability. Jensen’s belief in the inherited nature of intelligence and the validity of the IQ test to be the truest measure of intelligence are at the core of his conclusions. If, however, you believe that intelligence is more than Levels I and II, or that IQ tests do not control for socioeconomic and cultural differences among people, then perhaps you can dismiss Jensen’s conclusions as a single window that looks out on the complicated and varied landscape of human intelligence. In a related story, parents of African American students filed a case against the State of California in 1979, because they believed that the testing method used to identify students with learning disabilities was culturally unfair as the tests were normed and standardized using white children (Larry P. v. Riles). The testing method used by the state disproportionately identified African American children as mentally retarded. This resulted in many students being incorrectly classified as “mentally retarded.” According to a summary of the case, Larry P. v. Riles: In violation of Title VI of the Civil Rights Act of 1964, the Rehabilitation Act of 1973, and the Education for All Handicapped Children Act of 1975, defendants have utilized standardized intelligence tests that are racially and culturally biased, have a discriminatory impact against black children, and have not been validated for the purpose of essentially permanent placements of black children into educationally dead-end, isolated, and stigmatizing classes for the so- called educable mentally retarded. Further, these federal laws have been violated by defendants' general use of placement mechanisms that, taken together, have not been validated and result in a large over-representation of black children in the special E.M.R. classes. (Larry P. v. Riles, par. 6) Once again, the limitations of intelligence testing were revealed. WHAT ARE LEARNING DISABILITIES? Learning disabilities are cognitive disorders that affect different areas of cognition, particularly language or reading. It should be pointed out that learning disabilities are not the same thing as intellectual disabilities. Learning disabilities are considered specific neurological impairments rather than global intellectual or developmental disabilities. A person with a language disability has difficulty understanding or using spoken language, whereas someone with a reading disability, such as dyslexia, has difficulty processing what he or she is reading. Often, learning disabilities are not recognized until a child reaches school age. One confounding aspect of learning disabilities is that they often affect children with average to above-average intelligence. At the same time, learning disabilities tend to exhibit comorbidity with other disorders, like attention- deficit hyperactivity disorder (ADHD). Anywhere between 30–70% of individuals with diagnosed cases of ADHD also have some sort of learning disability (Riccio, Gonzales, & Hynd, 1994). Let’s take a look at two examples of common learning disabilities: dysgraphia and dyslexia. Chapter 7 | Thinking and Intelligence 245 Dysgraphia Children with dysgraphia have a learning disability that results in a struggle to write legibly. The physical task of writing with a pen and paper is extremely challenging for the person. These children often have extreme difficulty putting their thoughts down on paper (Smits-Engelsman & Van Galen, 1997). This difficulty is inconsistent with a person’s IQ. That is, based on the child’s IQ and/or abilities in other areas, a child with dysgraphia should be able to write, but can’t. Children with dysgraphia may also have problems with spatial abilities. Students with dysgraphia need academic accommodations to help them succeed in school. These accommodations can provide students with alternative assessment opportunities to demonstrate what they know (Barton, 2003). For example, a student with dysgraphia might be permitted to take an oral exam rather than a traditional paper-and-pencil test. Treatment is usually provided by an occupational therapist, although there is some question as to how effective such treatment is (Zwicker, 2005). Dyslexia Dyslexia is the most common learning disability in children. An individual with dyslexia exhibits an inability to correctly process letters. The neurological mechanism for sound processing does not work properly in someone with dyslexia. As a result, dyslexic children may not understand sound-letter correspondence. A child with dyslexia may mix up letters within words and sentences—letter reversals, such as those shown in Figure 7.17, are a hallmark of this learning disability—or skip whole words while reading. A dyslexic child may have difficulty spelling words correctly while writing. Because of the disordered way that the brain processes letters and sound, learning to read is a frustrating experience. Some dyslexic individuals cope by memorizing the shapes of most words, but they never actually learn to read (Berninger, 2008). Figure 7.17 These written words show variations of the word “teapot” as written by individuals with dyslexia. 246 Chapter 7 | Thinking and Intelligence This OpenStax book is available for free at algorithm analytical intelligence anchoring bias artificial concept availability heuristic cognition cognitive psychology cognitive script concept confirmation bias convergent thinking creative intelligence creativity crystallized intelligence cultural intelligence divergent thinking dysgraphia dyslexia emotional intelligence event schema fluid intelligence Flynn effect functional fixedness grammar heuristic hindsight bias Key Terms problem-solving strategy characterized by a specific set of instructions aligned with academic problem solving and computations faulty heuristic in which you fixate on a single aspect of a problem to find a solution concept that is defined by a very specific set of characteristics faulty heuristic in which you make a decision based on information readily available to you thinking, including perception, learning, problem solving, judgment, and memory field of psychology dedicated to studying every aspect of how people think set of behaviors that are performed the same way each time; also referred to as an event schema category or grouping of linguistic information, objects, ideas, or life experiences faulty heuristic in which you focus on information that confirms your beliefs providing correct or established answers to problems ability to produce new products, ideas, or inventing a new, novel solution to a problem ability to generate, create, or discover new ideas, solutions, and possibilities characterized by acquired knowledge and the ability to retrieve it ability with which people can understand and relate to those in another culture ability to think “outside the box” to arrive at novel solutions to a problem learning disability that causes extreme difficulty in writing legibly common learning disability in which letters are not processed properly by the brain ability to understand emotions and motivations in yourself and others set of behaviors that are performed the same way each time; also referred to as a cognitive script ability to see complex relationships and solve problems observation that each generation has a significantly higher IQ than the previous generation inability to see an object as useful for any other use other than the one for which it was intended set of rules that are used to convey meaning through the use of a lexicon mental shortcut that saves time when solving a problem belief that the event just experienced was predictable, even though it really wasn’t Chapter 7 | Thinking and Intelligence 247 intelligence quotient language lexicon mental set morpheme Multiple Intelligences Theory natural concept norming overgeneralization phoneme practical intelligence problem-solving strategy prototype range of reaction representative bias representative sample role schema schema semantics standard deviation standardization syntax trial and error triarchic theory of intelligence working backwards (also, IQ) score on a test designed to measure intelligence communication system that involves using words to transmit information from one individual to another the words of a given language continually using an old solution to a problem without results smallest unit of language that conveys some type of meaning Gardner’s theory that each person possesses at least eight types of intelligence mental groupings that are created “naturally” through your experiences administering a test to a large population so data can be collected to reference the normal scores for a population and its groups extension of a rule that exists in a given language to an exception to the rule basic sound unit of a given language aka “street smarts” method for solving problems best representation of a concept each person’s response to the environment is unique based on his or her genetic make- up faulty heuristic in which you stereotype someone or something without a valid basis for your judgment subset of the population that accurately represents the general population set of expectations that define the behaviors of a person occupying a particular role (plural = schemata) mental construct consisting of a cluster or collection of related concepts process by which we derive meaning from morphemes and words measure of variability that describes the difference between a set of scores and their mean method of testing in which administration, scoring, and interpretation of results are consistent manner by which words are organized into sentences problem-solving strategy in which multiple solutions are attempted until the correct one is found Sternberg’s theory of intelligence; three facets of intelligence: practical, creative, and analytical heuristic in which you begin to solve a problem by focusing on the end result 248 Chapter 7 | Thinking and Intelligence This OpenStax book is available for free at Summary 7.1 What Is Cognition? In this section, you were introduced to cognitive psychology, which is the study of cognition, or the brain’s ability to think, perceive, plan, analyze, and remember. Concepts and their corresponding prototypes help us quickly organize our thinking by creating categories into which we can sort new information. We also develop schemata, which are clusters of related concepts. Some schemata involve routines of thought and behavior, and these help us function properly in various situations without having to “think twice” about them. Schemata show up in social situations and routines of daily behavior. 7.2 Language Language is a communication system that has both a lexicon and a system of grammar. Language acquisition occurs naturally and effortlessly during the early stages of life, and this acquisition occurs in a predictable sequence for individuals around the world. Language has a strong influence on thought, and the concept of how language may influence cognition remains an area of study and debate in psychology. 7.3 Problem Solving Many different strategies exist for solving problems. Typical strategies include trial and error, applying algorithms, and using heuristics. To solve a large, complicated problem, it often helps to break the problem into smaller steps that can be accomplished individually, leading to an overall solution. Roadblocks to problem solving include a mental set, functional fixedness, and various biases that can cloud decision making skills. 7.4 What Are Intelligence and Creativity? Intelligence is a complex characteristic of cognition. Many theories have been developed to explain what intelligence is and how it works. Sternberg generated his triarchic theory of intelligence, whereas Gardner posits that intelligence is comprised of many factors. Still others focus on the importance of emotional intelligence. Finally, creativity seems to be a facet of intelligence, but it is extremely difficult to measure objectively. 7.5 Measures of Intelligence In this section, we learned about the history of intelligence testing and some of the challenges regarding intelligence testing. Intelligence tests began in earnest with Binet; Wechsler later developed intelligence tests that are still in use today: the WAIS-IV and WISC-V. The Bell curve shows the range of scores that encompass average intelligence as well as standard deviations. 7.6 The Source of Intelligence Genetics and environment affect intelligence and the challenges of certain learning disabilities. The intelligence levels of all individuals seem to benefit from rich stimulation in their early environments. Highly intelligent individuals, however, may have a built-in resiliency that allows them to overcome difficult obstacles in their upbringing. Learning disabilities can cause major challenges for children who are learning to read and write. Unlike developmental disabilities, learning disabilities are strictly neurological in nature and are not related to intelligence levels. Students with dyslexia, for example, may have extreme difficulty learning to read, but their intelligence levels are typically average or above average. Chapter 7 | Thinking and Intelligence 249 Review Questions 1. Cognitive psychology is the branch of psychology that focuses on the study of ________. a. human development b. human thinking c. human behavior d. human society 2. Which of the following is an example of a prototype for the concept of leadership on an athletic team? a. the equipment manager b. the scorekeeper c. the team captain d. the quietest member of the team 3. Which of the following is an example of an artificial concept? a. mammals b. a triangle’s area c. gemstones d. teachers 4. An event schema is also known as a cognitive ________. a. stereotype b. concept c. script d. prototype 5. ________ provides general principles for organizing words into meaningful sentences. a. Linguistic determinism b. Lexicon c. Semantics d. Syntax 6. ________ are the smallest unit of language that carry meaning. a. Lexicon b. Phonemes c. Morphemes d. Syntax 7. The meaning of words and phrases is determined by applying the rules of ________. a. lexicon b. phonemes c. overgeneralization d. semantics 8. ________ is (are) the basic sound units of a spoken language. a. Syntax b. Phonemes c. Morphemes d. Grammar 9. A specific formula for solving a problem is called ________. a. an algorithm b. a heuristic c. a mental set d. trial and error 10. A mental shortcut in the form of a general problem-solving framework is called ________. a. an algorithm b. a heuristic c. a mental set d. trial and error 11. Which type of bias involves becoming fixated on a single trait of a problem? a. anchoring bias b. confirmation bias c. representative bias d. availability bias 12. Which type of bias involves relying on a false stereotype to make a decision? a. anchoring bias b. confirmation bias c. representative bias d. availability bias 13. Fluid intelligence is characterized by ________. a. being able to recall information b. being able to create new products c. being able to understand and communicate with different cultures d. being able to see complex relationships and solve problems 250 Chapter 7 | Thinking and Intelligence This OpenStax book is available for free at 14. Which of the following is not one of Gardner’s Multiple Intelligences? a. creative b. spatial c. linguistic d. musical 15. Which theorist put forth the triarchic theory of intelligence? a. Goleman b. Gardner c. Sternberg d. Steitz 16. When you are examining data to look for trends, which type of intelligence are you using most? a. practical b. analytical c. emotional d. creative 17. In order for a test to be normed and standardized it must be tested on ________. a. a group of same-age peers b. a representative sample c. children with mental disabilities d. children of average intelligence 18. The mean score for a person with an average IQ is ________. a. 70 b. 130 c. 85 d. 100 19. Who developed the IQ test most widely used today? a. Sir Francis Galton b. Alfred Binet c. Louis Terman d. David Wechsler 20. The DSM-5 now uses ________ as a diagnostic label for what was once referred to as mental retardation. a. autism and developmental disabilities b. lowered intelligence c. intellectual disability d. cognitive disruption 21. Where does high intelligence come from? a. genetics b. environment c. both A and B d. neither A nor B 22. Arthur Jensen believed that ________. a. genetics was solely responsible for intelligence b. environment was solely responsible for intelligence c. intelligence level was determined by race d. IQ tests do not take socioeconomic status into account 23. What is a learning disability? a. a developmental disorder b. a neurological disorder c. an emotional disorder d. an intellectual disorder 24. Which of the following statements is true? a. Poverty always affects whether individuals are able to reach their full intellectual potential. b. An individual’s intelligence is determined solely by the intelligence levels of his siblings. c. The environment in which an individual is raised is the strongest predictor of her future intelligence d. There are many factors working together to influence an individual’s intelligence level. Critical Thinking Questions 25. Describe an event schema that you would notice at a sporting event. 26. Explain why event schemata have so much power over human behavior. 27. How do words not only represent our thoughts but also represent our values? Chapter 7 | Thinking and Intelligence 251 28. How could grammatical errors actually be indicative of language acquisition in children? 29. How do words not only represent our thoughts but also represent our values? 30. What is functional fixedness and how can overcoming it help you solve problems? 31. How does an algorithm save you time and energy when solving a problem? 32. Describe a situation in which you would need to use practical intelligence. 33. Describe a situation in which cultural intelligence would help you communicate better. 34. Why do you think different theorists have defined intelligence in different ways? 35. Compare and contrast the benefits of the Stanford-Binet IQ test and Wechsler’s IQ tests. 36. What evidence exists for a genetic component to an individual’s IQ? 37. Describe the relationship between learning disabilities and intellectual disabilities to intelligence. Personal Application Questions 38. Describe a natural concept that you know fully but that would be difficult for someone else to understand and explain why it would be difficult. 39. Can you think of examples of how language affects cognition? 40. Which type of bias do you recognize in your own decision making processes? How has this bias affected how you’ve made decisions in the past and how can you use your awareness of it to improve your decisions making skills in the future? 41. What influence do you think emotional intelligence plays in your personal life? 42. In thinking about the case of Candace described earlier, do you think that Candace benefitted or suffered as a result of consistently being passed on to the next grade? 43. Do you believe your level of intelligence was improved because of the stimuli in your childhood environment? Why or why not? 252 Chapter 7 | Thinking and Intelligence This OpenStax book is available for free at Chapter 8 Memory Figure 8.1 Photographs can trigger our memories and bring past experiences back to life. (credit: modification of work by Cory Zanker) Chapter Outline 8.1 How Memory Functions 8.2 Parts of the Brain Involved with Memory 8.3 Problems with Memory 8.4 Ways to Enhance Memory Introduction We may be top-notch learners, but if we don’t have a way to store what we’ve learned, what good is the knowledge we’ve gained? Take a few minutes to imagine what your day might be like if you could not remember anything you had learned. You would have to figure out how to get dressed. What clothing should you wear, and how do buttons and zippers work? You would need someone to teach you how to brush your teeth and tie your shoes. Who would you ask for help with these tasks, since you wouldn’t recognize the faces of these people in your house? Wait . . . is this even your house? Uh oh, your stomach begins to rumble and you feel hungry. You’d like something to eat, but you don’t know where the food is kept or even how to prepare it. Oh dear, this is getting confusing. Maybe it would be best just go back to bed. A bed . . . what is a bed? We have an amazing capacity for memory, but how, exactly, do we process and store information? Are there different kinds of memory, and if so, what characterizes the different types? How, exactly, do we retrieve our memories? And why do we forget? This chapter will explore these questions as we learn about memory. Chapter 8 | Memory 253 8.1 How Memory Functions Learning Objectives By the end of this section, you will be able to: • Discuss the three basic functions of memory • Describe the three stages of memory storage • Describe and distinguish between procedural and declarative memory and semantic and episodic memory Memory is an information processing system; therefore, we often compare it to a computer. Memory is the set of processes used to encode, store, and retrieve information over different periods of time (Figure 8.2). Figure 8.2 Encoding involves the input of information into the memory system. Storage is the retention of the encoded information. Retrieval, or getting the information out of memory and back into awareness, is the third function. Watch this video ( for more information on some unexpected facts about memory. ENCODING We get information into our brains through a process called encoding, which is the input of information into the memory system. Once we receive sensory information from the environment, our brains label or code it. We organize the information with other similar information and connect new concepts to existing concepts. Encoding information occurs through automatic processing and effortful processing. If someone asks you what you ate for lunch today, more than likely you could recall this information quite easily. This is known as automatic processing, or the encoding of details like time, space, frequency, and the meaning of words. Automatic processing is usually done without any conscious awareness. Recalling the last time you studied for a test is another example of automatic processing. But what about the actual test material you studied? It probably required a lot of work and attention on your part in order to encode that information. This is known as effortful processing (Figure 8.3). LINK TO LEARNING 254 Chapter 8 | Memory This OpenStax book is available for free at Figure 8.3 When you first learn new skills such as driving a car, you have to put forth effort and attention to encode information about how to start a car, how to brake, how to handle a turn, and so on. Once you know how to drive, you can encode additional information about this skill automatically. (credit: Robert Couse-Baker) What are the most effective ways to ensure that important memories are well encoded? Even a simple sentence is easier to recall when it is meaningful (Anderson, 1984). Read the following sentences (Bransford & McCarrell, 1974), then look away and count backwards from 30 by threes to zero, and then try to write down the sentences (no peeking back at this page!). 1. The notes were sour because the seams split. 2. The voyage wasn't delayed because the bottle shattered. 3. The haystack was important because the cloth ripped. How well did you do? By themselves, the statements that you wrote down were most likely confusing and difficult for you to recall. Now, try writing them again, using the following prompts: bagpipe, ship christening, and parachutist. Next count backwards from 40 by fours, then check yourself to see how well you recalled the sentences this time. You can see that the sentences are now much more memorable because each of the sentences was placed in context. Material is far better encoded when you make it meaningful. There are three types of encoding. The encoding of words and their meaning is known as semantic encoding. It was first demonstrated by William Bousfield (1935) in an experiment in which he asked people to memorize words. The 60 words were actually divided into 4 categories of meaning, although the participants did not know this because the words were randomly presented. When they were asked to remember the words, they tended to recall them in categories, showing that they paid attention to the meanings of the words as they learned them. Visual encoding is the encoding of images, and acoustic encoding is the encoding of sounds, words in particular. To see how visual encoding works, read over this list of words: car, level, dog, truth, book, value. If you were asked later to recall the words from this list, which ones do you think you’d most likely remember? You would probably have an easier time recalling the words car, dog, and book, and a more difficult time recalling the words level, truth, and value. Why is this? Because you can recall images (mental pictures) more easily than words alone. When you read the words car, dog, and book you created images of these things in your mind. These are concrete, high-imagery words. On the other hand, abstract words like level, truth, and value are low-imagery words. High-imagery words are encoded both visually and semantically (Paivio, 1986), thus building a stronger memory. Now let’s turn our attention to acoustic encoding. You are driving in your car and a song comes on the radio that you haven’t heard in at least 10 years, but you sing along, recalling every word. In the United States, children often learn the alphabet through song, and they learn the number of days in each month through rhyme: “Thirty days hath September, / April, June, and November; / All the rest have thirty- one, / Save February, with twenty-eight days clear, / And twenty-nine each leap year.” These lessons are Chapter 8 | Memory 255 easy to remember because of acoustic encoding. We encode the sounds the words make. This is one of the reasons why much of what we teach young children is done through song, rhyme, and rhythm. Which of the three types of encoding do you think would give you the best memory of verbal information? Some years ago, psychologists Fergus Craik and Endel Tulving (1975) conducted a series of experiments to find out. Participants were given words along with questions about them. The questions required the participants to process the words at one of the three levels. The visual processing questions included such things as asking the participants about the font of the letters. The acoustic processing questions asked the participants about the sound or rhyming of the words, and the semantic processing questions asked the participants about the meaning of the words. After participants were presented with the words and questions, they were given an unexpected recall or recognition task. Words that had been encoded semantically were better remembered than those encoded visually or acoustically. Semantic encoding involves a deeper level of processing than the shallower visual or acoustic encoding. Craik and Tulving concluded that we process verbal information best through semantic encoding, especially if we apply what is called the self-reference effect. The self-reference effect is the tendency for an individual to have better memory for information that relates to oneself in comparison to material that has less personal relevance (Rogers, Kuiper & Kirker, 1977). Could semantic encoding be beneficial to you as you attempt to memorize the concepts in this chapter? STORAGE Once the information has been encoded, we have to somehow have to retain it. Our brains take the encoded information and place it in storage. Storage is the creation of a permanent record of information. In order for a memory to go into storage (i.e., long-term memory), it has to pass through three distinct stages: Sensory Memory, Short-Term Memory, and finally Long-Term Memory. These stages were first proposed by Richard Atkinson and Richard Shiffrin (1968). Their model of human memory (Figure 8.4), called Atkinson-Shiffrin (A-S), is based on the belief that we process memories in the same way that a computer processes information. Figure 8.4 According to the Atkinson-Shiffrin model of memory, information passes through three distinct stages in order for it to be stored in long-term memory. But A-S is just one model of memory. Others, such as Baddeley and Hitch (1974), have proposed a model where short-term memory itself has different forms. In this model, storing memories in short-term memory is like opening different files on a computer and adding information. The type of short-term memory (or computer file) depends on the type of information received. There are memories in visual- spatial form, as well as memories of spoken or written material, and they are stored in three short-term systems: a visuospatial sketchpad, an episodic buffer, and a phonological loop. According to Baddeley and Hitch, a central executive part of memory supervises or controls the flow of information to and from the 256 Chapter 8 | Memory This OpenStax book is available for free at three short-term systems. Sensory Memory In the Atkinson-Shiffrin model, stimuli from the environment are processed first in sensory memory: storage of brief sensory events, such as sights, sounds, and tastes. It is very brief storage—up to a couple of seconds. We are constantly bombarded with sensory information. We cannot absorb all of it, or even most of it. And most of it has no impact on our lives. For example, what was your professor wearing the last class period? As long as the professor was dressed appropriately, it does not really matter what she was wearing. Sensory information about sights, sounds, smells, and even textures, which we do not view as valuable information, we discard. If we view something as valuable, the information will move into our short-term memory system. One study of sensory memory researched the significance of valuable information on short-term memory storage. J. R. Stroop discovered a memory phenomenon in the 1930s: you will name a color more easily if it appears printed in that color, which is called the Stroop effect. In other words, the word “red” will be named more quickly, regardless of the color the word appears in, than any word that is colored red. Try an experiment: name the colors of the words you are given in Figure 8.5. Do not read the words, but say the color the word is printed in. For example, upon seeing the word “yellow” in green print, you should say “green,” not “yellow.” This experiment is fun, but it’s not as easy as it seems. Figure 8.5 The Stroop effect describes why it is difficult for us to name a color when the word and the color of the word are different. Short-Term Memory Short-term memory (STM) is a temporary storage system that processes incoming sensory memory; sometimes it is called working memory. Short-term memory takes information from sensory memory and sometimes connects that memory to something already in long-term memory. Short-term memory storage lasts about 20 seconds. George Miller (1956), in his research on the capacity of memory, found that most people can retain about 7 items in STM. Some remember 5, some 9, so he called the capacity of STM 7 plus or minus 2. Think of short-term memory as the information you have displayed on your computer screen—a document, a spreadsheet, or a web page. Then, information in short-term memory goes to long-term memory (you save it to your hard drive), or it is discarded (you delete a document or close a web browser). This step of rehearsal, the conscious repetition of information to be remembered, to move STM into long- term memory is called memory consolidation. You may find yourself asking, “How much information can our memory handle at once?” To explore the Chapter 8 | Memory 257 capacity and duration of your short-term memory, have a partner read the strings of random numbers (Figure 8.6) out loud to you, beginning each string by saying, “Ready?” and ending each by saying, “Recall,” at which point you should try to write down the string of numbers from memory. Figure 8.6 Work through this series of numbers using the recall exercise explained above to determine the longest string of digits that you can store. Note the longest string at which you got the series correct. For most people, this will be close to 7, Miller’s famous 7 plus or minus 2. Recall is somewhat better for random numbers than for random letters (Jacobs, 1887), and also often slightly better for information we hear (acoustic encoding) rather than see (visual encoding) (Anderson, 1969). Long-term Memory Long-term memory (LTM) is the continuous storage of information. Unlike short-term memory, the storage capacity of LTM has no limits. It encompasses all the things you can remember that happened more than just a few minutes ago to all of the things that you can remember that happened days, weeks, and years ago. In keeping with the computer analogy, the information in your LTM would be like the information you have saved on the hard drive. It isn’t there on your desktop (your short-term memory), but you can pull up this information when you want it, at least most of the time. Not all long-term memories are strong memories. Some memories can only be recalled through prompts. For example, you might easily recall a fact— “What is the capital of the United States?”—or a procedure—“How do you ride a bike?”—but you might struggle to recall the name of the restaurant you had dinner when you were on vacation in France last summer. A prompt, such as that the restaurant was named after its owner, who spoke to you about your shared interest in soccer, may help you recall the name of the restaurant. Long-term memory is divided into two types: explicit and implicit (Figure 8.7). Understanding the different types is important because a person’s age or particular types of brain trauma or disorders can leave certain types of LTM intact while having disastrous consequences for other types. Explicit memories are those we consciously try to remember and recall. For example, if you are studying for your chemistry exam, the material you are learning will be part of your explicit memory. (Note: Sometimes, but not always, the terms explicit memory and declarative memory are used interchangeably.) Implicit memories are memories that are not part of our consciousness. They are memories formed from behaviors. Implicit memory is also called non-declarative memory. 258 Chapter 8 | Memory This OpenStax book is available for free at Figure 8.7 There are two components of long-term memory: explicit and implicit. Explicit memory includes episodic and semantic memory. Implicit memory includes procedural memory and things learned through conditioning. Procedural memory is a type of implicit memory: it stores information about how to do things. It is the memory for skilled actions, such as how to brush your teeth, how to drive a car, how to swim the crawl (freestyle) stroke. If you are learning how to swim freestyle, you practice the stroke: how to move your arms, how to turn your head to alternate breathing from side to side, and how to kick your legs. You would practice this many times until you become good at it. Once you learn how to swim freestyle and your body knows how to move through the water, you will never forget how to swim freestyle, even if you do not swim for a couple of decades. Similarly, if you present an accomplished guitarist with a guitar, even if he has not played in a long time, he will still be able to play quite well. Declarative memory has to do with the storage of facts and events we personally experienced. Explicit (declarative) memory has two parts: semantic memory and episodic memory. Semantic means having to do with language and knowledge about language. An example would be the question “what does argumentative mean?” Stored in our semantic memory is knowledge about words, concepts, and language- based knowledge and facts. For example, answers to the following questions are stored in your semantic memory: • Who was the first President of the United States? • What is democracy? • What is the longest river in the world? Episodic memory is information about events we have personally experienced. The concept of episodic memory was first proposed about 40 years ago (Tulving, 1972). Since then, Tulving and others have looked at scientific evidence and reformulated the theory. Currently, scientists believe that episodic memory is memory about happenings in particular places at particular times, the what, where, and when of an event (Tulving, 2002). It involves recollection of visual imagery as well as the feeling of familiarity (Hassabis & Maguire, 2007). Chapter 8 | Memory 259 Can You Remember Everything You Ever Did or Said? Episodic memories are also called autobiographical memories. Let’s quickly test your autobiographical memory. What were you wearing exactly five years ago today? What did you eat for lunch on April 10, 2009? You probably find it difficult, if not impossible, to answer these questions. Can you remember every event you have experienced over the course of your life—meals, conversations, clothing choices, weather conditions, and so on? Most likely none of us could even come close to answering these questions; however, American actress Marilu Henner, best known for the television show Taxi, can remember. She has an amazing and highly superior autobiographical memory (Figure 8.8). Figure 8.8 Marilu Henner’s super autobiographical memory is known as hyperthymesia. (credit: Mark Richardson) Very few people can recall events in this way; right now, only 12 known individuals have this ability, and only a few have been studied (Parker, Cahill & McGaugh 2006). And although hyperthymesia normally appears in adolescence, two children in the United States appear to have memories from well before their tenth birthdays. Watch these Part 1 ( and Part 2 ( video clips on superior autobiographical memory from the television news show 60 Minutes. RETRIEVAL So you have worked hard to encode (via effortful processing) and store some important information for your upcoming final exam. How do you get that information back out of storage when you need it? The act of getting information out of memory storage and back into conscious awareness is known as retrieval. This would be similar to finding and opening a paper you had previously saved on your computer’s hard drive. Now it’s back on your desktop, and you can work with it again. Our ability to retrieve information from long-term memory is vital to our everyday functioning. You must be able to retrieve information from memory in order to do everything from knowing how to brush your hair and teeth, to driving to work, to knowing how to perform your job once you get there. There are three ways you can retrieve information out of your long-term memory storage system: recall, recognition, and relearning. Recall is what we most often think about when we talk about memory retrieval: it means you can access information without cues. For example, you would use recall for an EVERYDAY CONNECTION LINK TO LEARNING 260 Chapter 8 | Memory This OpenStax book is available for free at essay test. Recognition happens when you identify information that you have previously learned after encountering it again. It involves a process of comparison. When you take a multiple-choice test, you are relying on recognition to help you choose the correct answer. Here is another example. Let’s say you graduated from high school 10 years ago, and you have returned to your hometown for your 10-year reunion. You may not be able to recall all of your classmates, but you recognize many of them based on their yearbook photos. The third form of retrieval is relearning, and it’s just what it sounds like. It involves learning information that you previously learned. Whitney took Spanish in high school, but after high school she did not have the opportunity to speak Spanish. Whitney is now 31, and her company has offered her an opportunity to work in their Mexico City office. In order to prepare herself, she enrolls in a Spanish course at the local community center. She’s surprised at how quickly she’s able to pick up the language after not speaking it for 13 years; this is an example of relearning. 8.2 Parts of the Brain Involved with Memory Learning Objectives By the end of this section, you will be able to: • Explain the brain functions involved in memory • Recognize the roles of the hippocampus, amygdala, and cerebellum Are memories stored in just one part of the brain, or are they stored in many different parts of the brain? Karl Lashley began exploring this problem, about 100 years ago, by making lesions in the brains of animals such as rats and monkeys. He was searching for evidence of the engram: the group of neurons that serve as the “physical representation of memory” (Josselyn, 2010). First, Lashley (1950) trained rats to find their way through a maze. Then, he used the tools available at the time—in this case a soldering iron—to create lesions in the rats’ brains, specifically in the cerebral cortex. He did this because he was trying to erase the engram, or the original memory trace that the rats had of the maze. Lashley did not find evidence of the engram, and the rats were still able to find their way through the maze, regardless of the size or location of the lesion. Based on his creation of lesions and the animals’ reaction, he formulated the equipotentiality hypothesis: if part of one area of the brain involved in memory is damaged, another part of the same area can take over that memory function (Lashley, 1950). Although Lashley’s early work did not confirm the existence of the engram, modern psychologists are making progress locating it. Eric Kandel, for example, spent decades working on the synapse, the basic structure of the brain, and its role in controlling the flow of information through neural circuits needed to store memories (Mayford, Siegelbaum, & Kandel, 2012). Many scientists believe that the entire brain is involved with memory. However, since Lashley’s research, other scientists have been able to look more closely at the brain and memory. They have argued that memory is located in specific parts of the brain, and specific neurons can be recognized for their involvement in forming memories. The main parts of the brain involved with memory are the amygdala, the hippocampus, the cerebellum, and the prefrontal cortex (Figure 8.9). Chapter 8 | Memory 261 Figure 8.9 The amygdala is involved in fear and fear memories. The hippocampus is associated with declarative and episodic memory as well as recognition memory. The cerebellum plays a role in processing procedural memories, such as how to play the piano. The prefrontal cortex appears to be involved in remembering semantic tasks. THE AMYGDALA First, let’s look at the role of the amygdala in memory formation. The main job of the amygdala is to regulate emotions, such as fear and aggression (Figure 8.9). The amygdala plays a part in how memories are stored because storage is influenced by stress hormones. For example, one researcher experimented with rats and the fear response (Josselyn, 2010). Using Pavlovian conditioning, a neutral tone was paired with a foot shock to the rats. This produced a fear memory in the rats. After being conditioned, each time they heard the tone, they would freeze (a defense response in rats), indicating a memory for the impending shock. Then the researchers induced cell death in neurons in the lateral amygdala, which is the specific area of the brain responsible for fear memories. They found the fear memory faded (became extinct). Because of its role in processing emotional information, the amygdala is also involved in memory consolidation: the process of transferring new learning into long-term memory. The amygdala seems to facilitate encoding memories at a deeper level when the event is emotionally arousing. In this TED Talk called “A Mouse. A Laser Beam. A Manipulated Memory,” ( Steve Ramirez and Xu Liu from MIT talk about using laser beams to manipulate fear memory in rats. Find out why their work caused a media frenzy once it was published in Science. THE HIPPOCAMPUS Another group of researchers also experimented with rats to learn how the hippocampus functions in memory processing (Figure 8.9). They created lesions in the hippocampi of the rats, and found that the rats demonstrated memory impairment on various tasks, such as object recognition and maze running. They concluded that the hippocampus is involved in memory, specifically normal recognition memory as well as spatial memory (when the memory tasks are like recall tests) (Clark, Zola, & Squire, 2000). Another job of the hippocampus is to project information to cortical regions that give memories meaning and connect them with other connected memories. It also plays a part in memory consolidation: the process of LINK TO LEARNING 262 Chapter 8 | Memory This OpenStax book is available for free at transferring new learning into long-term memory. Injury to this area leaves us unable to process new declarative memories. One famous patient, known for years only as H. M., had both his left and right temporal lobes (hippocampi) removed in an attempt to help control the seizures he had been suffering from for years (Corkin, Amaral, González, Johnson, & Hyman, 1997). As a result, his declarative memory was significantly affected, and he could not form new semantic knowledge. He lost the ability to form new memories, yet he could still remember information and events that had occurred prior to the surgery. For a closer look at how memory works, view this video ( on quirks of memory, and read more in this article ( about patient HM. THE CEREBELLUM AND PREFRONTAL CORTEX Although the hippocampus seems to be more of a processing area for explicit memories, you could still lose it and be able to create implicit memories (procedural memory, motor learning, and classical conditioning), thanks to your cerebellum (Figure 8.9). For example, one classical conditioning experiment is to accustom subjects to blink when they are given a puff of air. When researchers damaged the cerebellums of rabbits, they discovered that the rabbits were not able to learn the conditioned eye-blink response (Steinmetz, 1999; Green & Woodruff-Pak, 2000). Other researchers have used brain scans, including positron emission tomography (PET) scans, to learn how people process and retain information. From these studies, it seems the prefrontal cortex is involved. In one study, participants had to complete two different tasks: either looking for the letter a in words (considered a perceptual task) or categorizing a noun as either living or non-living (considered a semantic task) (Kapur et al., 1994). Participants were then asked which words they had previously seen. Recall was much better for the semantic task than for the perceptual task. According to PET scans, there was much more activation in the left inferior prefrontal cortex in the semantic task. In another study, encoding was associated with left frontal activity, while retrieval of information was associated with the right frontal region (Craik et al., 1999). NEUROTRANSMITTERS There also appear to be specific neurotransmitters involved with the process of memory, such as epinephrine, dopamine, serotonin, glutamate, and acetylcholine (Myhrer, 2003). There continues to be discussion and debate among researchers as to which neurotransmitter plays which specific role (Blockland, 1996). Although we don’t yet know which role each neurotransmitter plays in memory, we do know that communication among neurons via neurotransmitters is critical for developing new memories. Repeated activity by neurons leads to increased neurotransmitters in the synapses and more efficient and more synaptic connections. This is how memory consolidation occurs. It is also believed that strong emotions trigger the formation of strong memories, and weaker emotional experiences form weaker memories; this is called arousal theory (Christianson, 1992). For example, strong emotional experiences can trigger the release of neurotransmitters, as well as hormones, which strengthen memory; therefore, our memory for an emotional event is usually better than our memory for a non- emotional event. When humans and animals are stressed, the brain secretes more of the neurotransmitter glutamate, which helps them remember the stressful event (McGaugh, 2003). This is clearly evidenced by what is known as the flashbulb memory phenomenon. LINK TO LEARNING Chapter 8 | Memory 263 A flashbulb memory is an exceptionally clear recollection of an important event (Figure 8.10). Where were you when you first heard about the 9/11 terrorist attacks? Most likely you can remember where you were and what you were doing. In fact, a Pew Research Center (2011) survey found that for those Americans who were age 8 or older at the time of the event, 97% can recall the moment they learned of this event, even a decade after it happened. Figure 8.10 Most people can remember where they were when they first heard about the 9/11 terrorist attacks. This is an example of a flashbulb memory: a record of an atypical and unusual event that has very strong emotional associations. (credit: Michael Foran) Inaccurate and False Memories Even flashbulb memories can have decreased accuracy with the passage of time, even with very important events. For example, on at least three occasions, when asked how he heard about the terrorist attacks of 9/ 11, President George W. Bush responded inaccurately. In January 2002, less than 4 months after the attacks, the then sitting President Bush was asked how he heard about the attacks. He responded: I was sitting there, and my Chief of Staff—well, first of all, when we walked into the classroom, I had seen this plane fly into the first building. There was a TV set on. And you know, I thought it was pilot error and I was amazed that anybody could make such a terrible mistake. (Greenberg, 2004, p. 2) Contrary to what President Bush recalled, no one saw the first plane hit, except people on the ground near the twin towers. The first plane was not videotaped because it was a normal Tuesday morning in New York City, until the first plane hit. Some people attributed Bush’s wrong recall of the event to conspiracy theories. However, there is a much more benign explanation: human memory, even flashbulb memories, can be frail. In fact, memory can be so frail that we can convince a person an event happened to them, even when it did not. In studies, research participants will recall hearing a word, even though they never heard the word. For example, participants were given a list of 15 sleep-related words, but the word “sleep” was not on the list. Participants recalled hearing the word “sleep” even though they did not actually hear it (Roediger & McDermott, 2000). The researchers who discovered this named the theory after themselves and a fellow researcher, calling it the Deese-Roediger- McDermott paradigm. DIG DEEPER 264 Chapter 8 | Memory This OpenStax book is available for free at 8.3 Problems with Memory Learning Objectives By the end of this section, you will be able to: • Compare and contrast the two types of amnesia • Discuss the unreliability of eyewitness testimony • Discuss encoding failure • Discuss the various memory errors • Compare and contrast the two types of interference You may pride yourself on your amazing ability to remember the birthdates and ages of all of your friends and family members, or you may be able recall vivid details of your 5th birthday party at Chuck E. Cheese’s. However, all of us have at times felt frustrated, and even embarrassed, when our memories have failed us. There are several reasons why this happens. AMNESIA Amnesia is the loss of long-term memory that occurs as the result of disease, physical trauma, or psychological trauma. Psychologist Tulving (2002) and his colleagues at the University of Toronto studied K. C. for years. K. C. suffered a traumatic head injury in a motorcycle accident and then had severe amnesia. Tulving writes, the outstanding fact about K.C.'s mental make-up is his utter inability to remember any events, circumstances, or situations from his own life. His episodic amnesia covers his whole life, from birth to the present. The only exception is the experiences that, at any time, he has had in the last minute or two. (Tulving, 2002, p. 14) Anterograde Amnesia There are two common types of amnesia: anterograde amnesia and retrograde amnesia (Figure 8.11). Anterograde amnesia is commonly caused by brain trauma, such as a blow to the head. With anterograde amnesia, you cannot remember new information, although you can remember information and events that happened prior to your injury. The hippocampus is usually affected (McLeod, 2011). This suggests that damage to the brain has resulted in the inability to transfer information from short-term to long-term memory; that is, the inability to consolidate memories. Many people with this form of amnesia are unable to form new episodic or semantic memories, but are still able to form new procedural memories (Bayley & Squire, 2002). This was true of H. M., which was discussed earlier. The brain damage caused by his surgery resulted in anterograde amnesia. H. M. would read the same magazine over and over, having no memory of ever reading it—it was always new to him. He also could not remember people he had met after his surgery. If you were introduced to H. M. and then you left the room for a few minutes, he would not know you upon your return and would introduce himself to you again. However, when presented the same puzzle several days in a row, although he did not remember having seen the puzzle before, his speed at solving it became faster each day (because of relearning) (Corkin, 1965, 1968). Chapter 8 | Memory 265 Figure 8.11 This diagram illustrates the timeline of retrograde and anterograde amnesia. Memory problems that extend back in time before the injury and prevent retrieval of information previously stored in long-term memory are known as retrograde amnesia. Conversely, memory problems that extend forward in time from the point of injury and prevent the formation of new memories are called anterograde amnesia. Retrograde Amnesia Retrograde amnesia is loss of memory for events that occurred prior to the trauma. People with retrograde amnesia cannot remember some or even all of their past. They have difficulty remembering episodic memories. What if you woke up in the hospital one day and there were people surrounding your bed claiming to be your spouse, your children, and your parents? The trouble is you don’t recognize any of them. You were in a car accident, suffered a head injury, and now have retrograde amnesia. You don’t remember anything about your life prior to waking up in the hospital. This may sound like the stuff of Hollywood movies, and Hollywood has been fascinated with the amnesia plot for nearly a century, going all the way back to the film Garden of Lies from 1915 to more recent movies such as the Jason Bourne spy thrillers. However, for real-life sufferers of retrograde amnesia, like former NFL football player Scott Bolzan, the story is not a Hollywood movie. Bolzan fell, hit his head, and deleted 46 years of his life in an instant. He is now living with one of the most extreme cases of retrograde amnesia on record. View the video story ( profiling Scott Bolzan’s amnesia and his attempts to get his life back. MEMORY CONSTRUCTION AND RECONSTRUCTION The formulation of new memories is sometimes called construction, and the process of bringing up old memories is called reconstruction. Yet as we retrieve our memories, we also tend to alter and modify them. A memory pulled from long-term storage into short-term memory is flexible. New events can be added and we can change what we think we remember about past events, resulting in inaccuracies and distortions. People may not intend to distort facts, but it can happen in the process of retrieving old memories and combining them with new memories (Roediger and DeSoto, in press). Suggestibility When someone witnesses a crime, that person’s memory of the details of the crime is very important in catching the suspect. Because memory is so fragile, witnesses can be easily (and often accidentally) misled due to the problem of suggestibility. Suggestibility describes the effects of misinformation from external sources that leads to the creation of false memories. In the fall of 2002, a sniper in the DC area shot people at a gas station, leaving Home Depot, and walking down the street. These attacks went on in a variety of places for over three weeks and resulted in the deaths of ten people. During this time, as you can imagine, people were terrified to leave their homes, go shopping, or even walk through their neighborhoods. Police officers and the FBI worked frantically to solve the crimes, and a tip hotline was set up. Law enforcement LINK TO LEARNING 266 Chapter 8 | Memory This OpenStax book is available for free at received over 140,000 tips, which resulted in approximately 35,000 possible suspects (Newseum, n.d.). Most of the tips were dead ends, until a white van was spotted at the site of one of the shootings. The police chief went on national television with a picture of the white van. After the news conference, several other eyewitnesses called to say that they too had seen a white van fleeing from the scene of the shooting. At the time, there were more than 70,000 white vans in the area. Police officers, as well as the general public, focused almost exclusively on white vans because they believed the eyewitnesses. Other tips were ignored. When the suspects were finally caught, they were driving a blue sedan. As illustrated by this example, we are vulnerable to the power of suggestion, simply based on something we see on the news. Or we can claim to remember something that in fact is only a suggestion someone made. It is the suggestion that is the cause of the false memory. Eyewitness Misidentification Even though memory and the process of reconstruction can be fragile, police officers, prosecutors, and the courts often rely on eyewitness identification and testimony in the prosecution of criminals. However, faulty eyewitness identification and testimony can lead to wrongful convictions (Figure 8.12). Figure 8.12 In studying cases where DNA evidence has exonerated people from crimes, the Innocence Project discovered that eyewitness misidentification is the leading cause of wrongful convictions (Benjamin N. Cardozo School of Law, Yeshiva University, 2009). How does this happen? In 1984, Jennifer Thompson, then a 22-year-old college student in North Carolina, was brutally raped at knifepoint. As she was being raped, she tried to memorize every detail of her rapist’s face and physical characteristics, vowing that if she survived, she would help get him convicted. After the police were contacted, a composite sketch was made of the suspect, and Jennifer was shown six photos. She chose two, one of which was of Ronald Cotton. After looking at the photos for 4–5 minutes, she said, “Yeah. This is the one,” and then she added, “I think this is the guy.” When questioned about this by the detective who asked, “You’re sure? Positive?” She said that it was him. Then she asked the detective if she did OK, and he reinforced her choice by telling her she did great. These kinds of unintended cues and suggestions by police officers can lead witnesses to identify the wrong suspect. The district attorney was concerned about her lack of certainty the first time, so she viewed a lineup of seven men. She said she was trying to decide between numbers 4 and 5, finally deciding that Cotton, number 5, “Looks most like him.” He was 22 years old. Chapter 8 | Memory 267 By the time the trial began, Jennifer Thompson had absolutely no doubt that she was raped by Ronald Cotton. She testified at the court hearing, and her testimony was compelling enough that it helped convict him. How did she go from, “I think it’s the guy” and it “Looks most like him,” to such certainty? Gary Wells and Deah Quinlivan (2009) assert it’s suggestive police identification procedures, such as stacking lineups to make the defendant stand out, telling the witness which person to identify, and confirming witnesses choices by telling them “Good choice,” or “You picked the guy.” After Cotton was convicted of the rape, he was sent to prison for life plus 50 years. After 4 years in prison, he was able to get a new trial. Jennifer Thompson once again testified against him. This time Ronald Cotton was given two life sentences. After serving 11 years in prison, DNA evidence finally demonstrated that Ronald Cotton did not commit the rape, was innocent, and had served over a decade in prison for a crime he did not commit. To learn more about Ronald Cotton and the fallibility of memory, watch these excellent Part 1 ( and Part 2 ( videos by 60 Minutes. Ronald Cotton’s story, unfortunately, is not unique. There are also people who were convicted and placed on death row, who were later exonerated. The Innocence Project is a non-profit group that works to exonerate falsely convicted people, including those convicted by eyewitness testimony. To learn more, you can visit Preserving Eyewitness Memory: The Elizabeth Smart Case Contrast the Cotton case with what happened in the Elizabeth Smart case. When Elizabeth was 14 years old and fast asleep in her bed at home, she was abducted at knifepoint. Her nine-year-old sister, Mary Katherine, was sleeping in the same bed and watched, terrified, as her beloved older sister was abducted. Mary Katherine was the sole eyewitness to this crime and was very fearful. In the coming weeks, the Salt Lake City police and the FBI proceeded with caution with Mary Katherine. They did not want to implant any false memories or mislead her in any way. They did not show her police line-ups or push her to do a composite sketch of the abductor. They knew if they corrupted her memory, Elizabeth might never be found. For several months, there was little or no progress on the case. Then, about 4 months after the kidnapping, Mary Katherine first recalled that she had heard the abductor’s voice prior to that night (he had worked one time as a handyman at the family’s home) and then she was able to name the person whose voice it was. The family contacted the press and others recognized him—after a total of nine months, the suspect was caught and Elizabeth Smart was returned to her family. The Misinformation Effect Cognitive psychologist Elizabeth Loftus has conducted extensive research on memory. She has studied false memories as well as recovered memories of childhood sexual abuse. Loftus also developed the misinformation effect paradigm, which holds that after exposure to incorrect information, a person may misremember the original event. According to Loftus, an eyewitness’s memory of an event is very flexible due to the misinformation effect. LINK TO LEARNING DIG DEEPER 268 Chapter 8 | Memory This OpenStax book is available for free at To test this theory, Loftus and John Palmer (1974) asked 45 U.S. college students to estimate the speed of cars using different forms of questions (Figure 8.13). The participants were shown films of car accidents and were asked to play the role of the eyewitness and describe what happened. They were asked, “About how fast were the cars going when they (smashed, collided, bumped, hit, contacted) each other?” The participants estimated the speed of the cars based on the verb used. Participants who heard the word “smashed” estimated that the cars were traveling at a much higher speed than participants who heard the word “contacted.” The implied information about speed, based on the verb they heard, had an effect on the participants’ memory of the accident. In a follow-up one week later, participants were asked if they saw any broken glass (none was shown in the accident pictures). Participants who had been in the “smashed” group were more than twice as likely to indicate that they did remember seeing glass. Loftus and Palmer demonstrated that a leading question encouraged them to not only remember the cars were going faster, but to also falsely remember that they saw broken glass. Figure 8.13 When people are asked leading questions about an event, their memory of the event may be altered. (credit a: modification of work by Rob Young) Controversies over Repressed and Recovered Memories Other researchers have described how whole events, not just words, can be falsely recalled, even when they did not happen. The idea that memories of traumatic events could be repressed has been a theme in the field of psychology, beginning with Sigmund Freud, and the controversy surrounding the idea continues today. Recall of false autobiographical memories is called false memory syndrome. This syndrome has received a lot of publicity, particularly as it relates to memories of events that do not have independent witnesses—often the only witnesses to the abuse are the perpetrator and the victim (e.g., sexual abuse). On one side of the debate are those who have recovered memories of childhood abuse years after it occurred. These researchers argue that some children’s experiences have been so traumatizing and distressing that they must lock those memories away in order to lead some semblance of a normal life. They believe that repressed memories can be locked away for decades and later recalled intact through hypnosis and guided imagery techniques (Devilly, 2007). Research suggests that having no memory of childhood sexual abuse is quite common in adults. For instance, one large-scale study conducted by John Briere and Jon Conte (1993) revealed that 59% of 450 men and women who were receiving treatment for sexual abuse that had occurred before age 18 had forgotten their experiences. Ross Cheit (2007) suggested that repressing these memories created Chapter 8 | Memory 269 psychological distress in adulthood. The Recovered Memory Project was created so that victims of childhood sexual abuse can recall these memories and allow the healing process to begin (Cheit, 2007; Devilly, 2007). On the other side, Loftus has challenged the idea that individuals can repress memories of traumatic events from childhood, including sexual abuse, and then recover those memories years later through therapeutic techniques such as hypnosis, guided visualization, and age regression. Loftus is not saying that childhood sexual abuse doesn’t happen, but she does question whether or not those memories are accurate, and she is skeptical of the questioning process used to access these memories, given that even the slightest suggestion from the therapist can lead to misinformation effects. For example, researchers Stephen Ceci and Maggie Brucks (1993, 1995) asked three-year-old children to use an anatomically correct doll to show where their pediatricians had touched them during an exam. Fifty-five percent of the children pointed to the genital/anal area on the dolls, even when they had not received any form of genital exam. Ever since Loftus published her first studies on the suggestibility of eyewitness testimony in the 1970s, social scientists, police officers, therapists, and legal practitioners have been aware of the flaws in interview practices. Consequently, steps have been taken to decrease suggestibility of witnesses. One way is to modify how witnesses are questioned. When interviewers use neutral and less leading language, children more accurately recall what happened and who was involved (Goodman, 2006; Pipe, 1996; Pipe, Lamb, Orbach, & Esplin, 2004). Another change is in how police lineups are conducted. It’s recommended that a blind photo lineup be used. This way the person administering the lineup doesn’t know which photo belongs to the suspect, minimizing the possibility of giving leading cues. Additionally, judges in some states now inform jurors about the possibility of misidentification. Judges can also suppress eyewitness testimony if they deem it unreliable. FORGETTING “I’ve a grand memory for forgetting,” quipped Robert Louis Stevenson. Forgetting refers to loss of information from long-term memory. We all forget things, like a loved one’s birthday, someone’s name, or where we put our car keys. As you’ve come to see, memory is fragile, and forgetting can be frustrating and even embarrassing. But why do we forget? To answer this question, we will look at several perspectives on forgetting. Encoding Failure Sometimes memory loss happens before the actual memory process begins, which is encoding failure. We can’t remember something if we never stored it in our memory in the first place. This would be like trying to find a book on your e-reader that you never actually purchased and downloaded. Often, in order to remember something, we must pay attention to the details and actively work to process the information (effortful encoding). Lots of times we don’t do this. For instance, think of how many times in your life you’ve seen a penny. Can you accurately recall what the front of a U.S. penny looks like? When researchers Raymond Nickerson and Marilyn Adams (1979) asked this question, they found that most Americans don’t know which one it is. The reason is most likely encoding failure. Most of us never encode the details of the penny. We only encode enough information to be able to distinguish it from other coins. If we don’t encode the information, then it’s not in our long-term memory, so we will not be able to remember it. 270 Chapter 8 | Memory This OpenStax book is available for free at Figure 8.14 Can you tell which coin, (a), (b), (c), or (d) is the accurate depiction of a US nickel? The correct answer is (c). Memory Errors Psychologist Daniel Schacter (2001), a well-known memory researcher, offers seven ways our memories fail us. He calls them the seven sins of memory and categorizes them into three groups: forgetting, distortion, and intrusion (Table 8.1). Table 8.1 Schacter’s Seven Sins of Memory Sin Type Description Example Transience Forgetting Accessibility of memory decreases over time Forget events that occurred long ago absentmindedness Forgetting Forgetting caused by lapses in attention Forget where your phone is Blocking Forgetting Accessibility of information is temporarily blocked Tip of the tongue Misattribution Distortion Source of memory is confused Recalling a dream memory as a waking memory Suggestibility Distortion False memories Result from leading questions Bias Distortion Memories distorted by current belief system Align memories to current beliefs Persistence Intrusion Inability to forget undesirable memories Traumatic events Let’s look at the first sin of the forgetting errors: transience, which means that memories can fade over time. Here’s an example of how this happens. Nathan’s English teacher has assigned his students to read the novel To Kill a Mockingbird. Nathan comes home from school and tells his mom he has to read this book for class. “Oh, I loved that book!” she says. Nathan asks her what the book is about, and after some hesitation she says, “Well . . . I know I read the book in high school, and I remember that one of the main characters is named Scout, and her father is an attorney, but I honestly don’t remember anything else.” Nathan wonders if his mother actually read the book, and his mother is surprised she can’t recall the plot. What is going on here is storage decay: unused information tends to fade with the passage of time. In 1885, German psychologist Hermann Ebbinghaus analyzed the process of memorization. First, he Chapter 8 | Memory 271 memorized lists of nonsense syllables. Then he measured how much he learned (retained) when he attempted to relearn each list. He tested himself over different periods of time from 20 minutes later to 30 days later. The result is his famous forgetting curve (Figure 8.15). Due to storage decay, an average person will lose 50% of the memorized information after 20 minutes and 70% of the information after 24 hours (Ebbinghaus, 1885/1964). Your memory for new information decays quickly and then eventually levels out. Figure 8.15 The Ebbinghaus forgetting curve shows how quickly memory for new information decays. Are you constantly losing your cell phone? Have you ever driven back home to make sure you turned off the stove? Have you ever walked into a room for something, but forgotten what it was? You probably answered yes to at least one, if not all, of these examples—but don’t worry, you are not alone. We are all prone to committing the memory error known as absentmindedness. These lapses in memory are caused by breaks in attention or our focus being somewhere else. Cynthia, a psychologist, recalls a time when she recently committed the memory error of absentmindedness. When I was completing court-ordered psychological evaluations, each time I went to the court, I was issued a temporary identification card with a magnetic strip which would open otherwise locked doors. As you can imagine, in a courtroom, this identification is valuable and important and no one wanted it to be lost or be picked up by a criminal. At the end of the day, I would hand in my temporary identification. One day, when I was almost done with an evaluation, my daughter’s day care called and said she was sick and needed to be picked up. It was flu season, I didn’t know how sick she was, and I was concerned. I finished up the evaluation in the next ten minutes, packed up my tools, and rushed to drive to my daughter’s day care. After I picked up my daughter, I could not remember if I had handed back my identification or if I had left it sitting out on a table. I immediately called the court to check. It turned out that I had handed back my identification. Why could I not remember that? (personal communication, September 5, 2013) When have you experienced absentmindedness? “I just went and saw this movie called Oblivion, and it had that famous actor in it. Oh, what’s his name? He’s been in all of those movies, like The Shawshank Redemption and The Dark Knight trilogy. I think he’s even won an Oscar. Oh gosh, I can picture his face in my mind, and hear his distinctive voice, but I just can’t think of his name! This is going to bug me until I can remember it!” This particular error can be so frustrating because you have the information right on the tip of your tongue. Have you ever experienced 272 Chapter 8 | Memory This OpenStax book is available for free at this? If so, you’ve committed the error known as blocking: you can’t access stored information (Figure 8.16). Figure 8.16 Blocking is also known as tip-of-the-tongue (TOT) phenomenon. The memory is right there, but you can’t seem to recall it, just like not being able to remember the name of that very famous actor, Morgan Freeman. (credit: modification of work by D. Miller) Now let’s take a look at the three errors of distortion: misattribution, suggestibility, and bias. Misattribution happens when you confuse the source of your information. Let’s say Alejandro was dating Lucia and they saw the first Hobbit movie together. Then they broke up and Alejandro saw the second Hobbit movie with someone else. Later that year, Alejandro and Lucia get back together. One day, they are discussing how the Hobbit books and movies are different and Alejandro says to Lucia, “I loved watching the second movie with you and seeing you jump out of your seat during that super scary part.” When Lucia responded with a puzzled and then angry look, Alejandro realized he’d committed the error of misattribution. What if someone is a victim of rape shortly after watching a television program? Is it possible that the victim could actually blame the rape on the person she saw on television because of misattribution? This is exactly what happened to Donald Thomson. Australian eyewitness expert Donald Thomson appeared on a live TV discussion about the unreliability of eyewitness memory. He was later arrested, placed in a lineup and identified by a victim as the man who had raped her. The police charged Thomson although the rape had occurred at the time he was on TV. They dismissed his alibi that he was in plain view of a TV audience and in the company of the other discussants, including an assistant commissioner of police. . . . Eventually, the investigators discovered that the rapist had attacked the woman as she was watching TV—the very program on which Thomson had appeared. Authorities eventually cleared Thomson. The woman had confused the rapist's face with the face that she had seen on TV. (Baddeley, 2004, p. 133) The second distortion error is suggestibility. Suggestibility is similar to misattribution, since it also involves false memories, but it’s different. With misattribution you create the false memory entirely on your own, which is what the victim did in the Donald Thomson case above. With suggestibility, it comes from someone else, such as a therapist or police interviewer asking leading questions of a witness during Chapter 8 | Memory 273 an interview. Memories can also be affected by bias, which is the final distortion error. Schacter (2001) says that your feelings and view of the world can actually distort your memory of past events. There are several types of bias: • Stereotypical bias involves racial and gender biases. For example, when Asian American and European American research participants were presented with a list of names, they more frequently incorrectly remembered typical African American names such as Jamal and Tyrone to be associated with the occupation basketball player, and they more frequently incorrectly remembered typical White names such as Greg and Howard to be associated with the occupation of politician (Payne, Jacoby, & Lambert, 2004). • Egocentric bias involves enhancing our memories of the past (Payne et al., 2004). Did you really score the winning goal in that big soccer match, or did you just assist? • Hindsight bias happens when we think an outcome was inevitable after the fact. This is the “I knew it all along” phenomenon. The reconstructive nature of memory contributes to hindsight bias (Carli, 1999). We remember untrue events that seem to confirm that we knew the outcome all along. Have you ever had a song play over and over in your head? How about a memory of a traumatic event, something you really do not want to think about? When you keep remembering something, to the point where you can’t “get it out of your head” and it interferes with your ability to concentrate on other things, it is called persistence. It’s Schacter’s seventh and last memory error. It’s actually a failure of our memory system because we involuntarily recall unwanted memories, particularly unpleasant ones (Figure 8.17). For instance, you witness a horrific car accident on the way to work one morning, and you can’t concentrate on work because you keep remembering the scene. Figure 8.17 Many veterans of military conflicts involuntarily recall unwanted, unpleasant memories. (credit: Department of Defense photo by U.S. Air Force Tech. Sgt. Michael R. Holzworth) Interference Sometimes information is stored in our memory, but for some reason it is inaccessible. This is known as interference, and there are two types: proactive interference and retroactive interference (Figure 8.18). Have you ever gotten a new phone number or moved to a new address, but right after you tell people the old (and wrong) phone number or address? When the new year starts, do you find you accidentally write the previous year? These are examples of proactive interference: when old information hinders the recall of newly learned information. Retroactive interference happens when information learned more recently hinders the recall of older information. For example, this week you are studying about Freud’s Psychoanalytic Theory. Next week you study the humanistic perspective of Maslow and Rogers. Thereafter, you have trouble remembering Freud’s Psychosexual Stages of Development because you can only remember Maslow’s Hierarchy of Needs. 274 Chapter 8 | Memory This OpenStax book is available for free at Figure 8.18 Sometimes forgetting is caused by a failure to retrieve information. This can be due to interference, either retroactive or proactive. 8.4 Ways to Enhance Memory Learning Objectives By the end of this section, you will be able to: • Recognize and apply memory-enhancing strategies • Recognize and apply effective study techniques Most of us suffer from memory failures of one kind or another, and most of us would like to improve our memories so that we don’t forget where we put the car keys or, more importantly, the material we need to know for an exam. In this section, we’ll look at some ways to help you remember better, and at some strategies for more effective studying. MEMORY-ENHANCING STRATEGIES What are some everyday ways we can improve our memory, including recall? To help make sure information goes from short-term memory to long-term memory, you can use memory-enhancing strategies. One strategy is rehearsal, or the conscious repetition of information to be remembered (Craik & Watkins, 1973). Think about how you learned your multiplication tables as a child. You may recall that 6 x 6 = 36, 6 x 7 = 42, and 6 x 8 = 48. Memorizing these facts is rehearsal. Another strategy is chunking: you organize information into manageable bits or chunks (Bodie, Powers, & Fitch-Hauser, 2006). Chunking is useful when trying to remember information like dates and phone numbers. Instead of trying to remember 5205550467, you remember the number as 520-555-0467. So, if you met an interesting person at a party and you wanted to remember his phone number, you would naturally chunk it, and you could repeat the number over and over, which is the rehearsal strategy. Chapter 8 | Memory 275 Try this fun activity ( that employs a memory-enhancing strategy. You could also enhance memory by using elaborative rehearsal: a technique in which you think about the meaning of the new information and its relation to knowledge already stored in your memory (Tigner, 1999). For example, in this case, you could remember that 520 is an area code for Arizona and the person you met is from Arizona. This would help you better remember the 520 prefix. If the information is retained, it goes into long-term memory. Mnemonic devices are memory aids that help us organize information for encoding (Figure 8.19). They are especially useful when we want to recall larger bits of information such as steps, stages, phases, and parts of a system (Bellezza, 1981). Brian needs to learn the order of the planets in the solar system, but he’s having a hard time remembering the correct order. His friend Kelly suggests a mnemonic device that can help him remember. Kelly tells Brian to simply remember the name Mr. VEM J. SUN, and he can easily recall the correct order of the planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. You might use a mnemonic device to help you remember someone’s name, a mathematical formula, or the seven levels of Bloom’s taxonomy. Figure 8.19 This is a knuckle mnemonic to help you remember the number of days in each month. Months with 31 days are represented by the protruding knuckles and shorter months fall in the spots between knuckles. (credit: modification of work by Cory Zanker) If you have ever watched the television show Modern Family, you might have seen Phil Dunphy explain how he remembers names: The other day I met this guy named Carl. Now, I might forget that name, but he was wearing a Grateful Dead t-shirt. What’s a band like the Grateful Dead? Phish. Where do fish live? The ocean. What else lives in the ocean? Coral. Hello, Co-arl. (Wrubel & Spiller, 2010) It seems the more vivid or unusual the mnemonic, the easier it is to remember. The key to using any mnemonic successfully is to find a strategy that works for you. LINK TO LEARNING 276 Chapter 8 | Memory This OpenStax book is available for free at Watch this fascinating TED Talks lecture ( titled “Feats of Memory Anyone Can Do.” The lecture is given by Joshua Foer, a science writer who “accidentally” won the U. S. Memory Championships. He explains a mnemonic device called the memory palace. Some other strategies that are used to improve memory include expressive writing and saying words aloud. Expressive writing helps boost your short-term memory, particularly if you write about a traumatic experience in your life. Masao Yogo and Shuji Fujihara (2008) had participants write for 20-minute intervals several times per month. The participants were instructed to write about a traumatic experience, their best possible future selves, or a trivial topic. The researchers found that this simple writing task increased short-term memory capacity after five weeks, but only for the participants who wrote about traumatic experiences. Psychologists can’t explain why this writing task works, but it does. What if you want to remember items you need to pick up at the store? Simply say them out loud to yourself. A series of studies (MacLeod, Gopie, Hourihan, Neary, & Ozubko, 2010) found that saying a word out loud improves your memory for the word because it increases the word’s distinctiveness. Feel silly, saying random grocery items aloud? This technique works equally well if you just mouth the words. Using these techniques increased participants’ memory for the words by more than 10%. These techniques can also be used to help you study. HOW TO STUDY EFFECTIVELY Based on the information presented in this chapter, here are some strategies and suggestions to help you hone your study techniques (Figure 8.20). The key with any of these strategies is to figure out what works best for you. Figure 8.20 Memory techniques can be useful when studying for class. (credit: Barry Pousman) • Use elaborative rehearsal: In a famous article, Craik and Lockhart (1972) discussed their belief that information we process more deeply goes into long-term memory. Their theory is called levels of processing. If we want to remember a piece of information, we should think about it more deeply and link it to other information and memories to make it more meaningful. For example, if we are trying to remember that the hippocampus is involved with memory processing, we might envision a hippopotamus with excellent memory and then we could better remember the hippocampus. LINK TO LEARNING Chapter 8 | Memory 277 • Apply the self-reference effect: As you go through the process of elaborative rehearsal, it would be even more beneficial to make the material you are trying to memorize personally meaningful to you. In other words, make use of the self-reference effect. Write notes in your own words. Write definitions from the text, and then rewrite them in your own words. Relate the material to something you have already learned for another class, or think how you can apply the concepts to your own life. When you do this, you are building a web of retrieval cues that will help you access the material when you want to remember it. • Don’t forget the forgetting curve: As you know, the information you learn drops off rapidly with time. Even if you think you know the material, study it again right before test time to increase the likelihood the information will remain in your memory. Overlearning can help prevent storage decay. • Rehearse, rehearse, rehearse: Review the material over time, in spaced and organized study sessions. Organize and study your notes, and take practice quizzes/exams. Link the new information to other information you already know well. • Be aware of interference: To reduce the likelihood of interference, study during a quiet time without interruptions or distractions (like television or music). • Keep moving: Of course you already know that exercise is good for your body, but did you also know it’s also good for your mind? Research suggests that regular aerobic exercise (anything that gets your heart rate elevated) is beneficial for memory (van Praag, 2008). Aerobic exercise promotes neurogenesis: the growth of new brain cells in the hippocampus, an area of the brain known to play a role in memory and learning. • Get enough sleep: While you are sleeping, your brain is still at work. During sleep the brain organizes and consolidates information to be stored in long-term memory (Abel & Bäuml, 2013). • Make use of mnemonic devices: As you learned earlier in this chapter, mnemonic devices often help us to remember and recall information. There are different types of mnemonic devices, such as the acronym. An acronym is a word formed by the first letter of each of the words you want to remember. For example, even if you live near one, you might have difficulty recalling the names of all five Great Lakes. What if I told you to think of the word Homes? HOMES is an acronym that represents Huron, Ontario, Michigan, Erie, and Superior: the five Great Lakes. Another type of mnemonic device is an acrostic: you make a phrase of all the first letters of the words. For example, if you are taking a math test and you are having difficulty remembering the order of operations, recalling the following sentence will help you: “Please Excuse My Dear Aunt Sally,” because the order of mathematical operations is Parentheses, Exponents, Multiplication, Division, Addition, Subtraction. There also are jingles, which are rhyming tunes that contain key words related to the concept, such as i before e, except after c. 278 Chapter 8 | Memory This OpenStax book is available for free at absentmindedness acoustic encoding amnesia anterograde amnesia arousal theory Atkinson-Shiffrin model (A-S) automatic processing bias blocking chunking construction declarative memory effortful processing elaborative rehearsal encoding engram episodic memory equipotentiality hypothesis explicit memory false memory syndrome flashbulb memory forgetting implicit memory levels of processing Key Terms lapses in memory that are caused by breaks in attention or our focus being somewhere else input of sounds, words, and music loss of long-term memory that occurs as the result of disease, physical trauma, or psychological trauma loss of memory for events that occur after the brain trauma strong emotions trigger the formation of strong memories and weaker emotional experiences form weaker memories memory model that states we process information through three systems: sensory memory, short-term memory, and long-term memory encoding of informational details like time, space, frequency, and the meaning of words how feelings and view of the world distort memory of past events memory error in which you cannot access stored information organizing information into manageable bits or chunks formulation of new memories type of long-term memory of facts and events we personally experience encoding of information that takes effort and attention thinking about the meaning of the new information and its relation to knowledge already stored in your memory input of information into the memory system physical trace of memory type of declarative memory that contains information about events we have personally experienced, also known as autobiographical memory some parts of the brain can take over for damaged parts in forming and storing memories memories we consciously try to remember and recall recall of false autobiographical memories exceptionally clear recollection of an important event loss of information from long-term memory memories that are not part of our consciousness information that is thought of more deeply becomes more meaningful and thus better committed to memory Chapter 8 | Memory 279 long-term memory (LTM) memory memory consolidation memory-enhancing strategy misattribution misinformation effect paradigm mnemonic device persistence proactive interference procedural memory recall recognition reconstruction rehearsal relearning retrieval retroactive interference retrograde amnesia self-reference effect semantic encoding semantic memory sensory memory short-term memory (STM) storage suggestibility continuous storage of information system or process that stores what we learn for future use active rehearsal to move information from short-term memory into long-term memory technique to help make sure information goes from short-term memory to long-term memory memory error in which you confuse the source of your information after exposure to incorrect information, a person may misremember the original event memory aids that help organize information for encoding failure of the memory system that involves the involuntary recall of unwanted memories, particularly unpleasant ones old information hinders the recall of newly learned information type of long-term memory for making skilled actions, such as how to brush your teeth, how to drive a car, and how to swim accessing information without cues identifying previously learned information after encountering it again, usually in response to a cue process of bringing up old memories that might be distorted by new information conscious repetition of information to be remembered learning information that was previously learned act of getting information out of long-term memory storage and back into conscious awareness information learned more recently hinders the recall of older information loss of memory for events that occurred prior to brain trauma tendency for an individual to have better memory for information that relates to oneself in comparison to material that has less personal relevance input of words and their meaning type of declarative memory about words, concepts, and language-based knowledge and facts storage of brief sensory events, such as sights, sounds, and tastes (also, working memory) holds about seven bits of information before it is forgotten or stored, as well as information that has been retrieved and is being used creation of a permanent record of information effects of misinformation from external sources that leads to the creation of false memories 280 Chapter 8 | Memory This OpenStax book is available for free at transience visual encoding memory error in which unused memories fade with the passage of time input of images Summary 8.1 How Memory Functions Memory is a system or process that stores what we learn for future use. Our memory has three basic functions: encoding, storing, and retrieving information. Encoding is the act of getting information into our memory system through automatic or effortful processing. Storage is retention of the information, and retrieval is the act of getting information out of storage and into conscious awareness through recall, recognition, and relearning. The idea that information is processed through three memory systems is called the Atkinson-Shiffrin (A-S) model of memory. First, environmental stimuli enter our sensory memory for a period of less than a second to a few seconds. Those stimuli that we notice and pay attention to then move into short-term memory (also called working memory). According to the A-S model, if we rehearse this information, then it moves into long-term memory for permanent storage. Other models like that of Baddeley and Hitch suggest there is more of a feedback loop between short- term memory and long-term memory. Long-term memory has a practically limitless storage capacity and is divided into implicit and explicit memory. Finally, retrieval is the act of getting memories out of storage and back into conscious awareness. This is done through recall, recognition, and relearning. 8.2 Parts of the Brain Involved with Memory Beginning with Karl Lashley, researchers and psychologists have been searching for the engram, which is the physical trace of memory. Lashley did not find the engram, but he did suggest that memories are distributed throughout the entire brain rather than stored in one specific area. Now we know that three brain areas do play significant roles in the processing and storage of different types of memories: cerebellum, hippocampus, and amygdala. The cerebellum’s job is to process procedural memories; the hippocampus is where new memories are encoded; the amygdala helps determine what memories to store, and it plays a part in determining where the memories are stored based on whether we have a strong or weak emotional response to the event. Strong emotional experiences can trigger the release of neurotransmitters, as well as hormones, which strengthen memory, so that memory for an emotional event is usually stronger than memory for a non-emotional event. This is shown by what is known as the flashbulb memory phenomenon: our ability to remember significant life events. However, our memory for life events (autobiographical memory) is not always accurate. 8.3 Problems with Memory All of us at times have felt dismayed, frustrated, and even embarrassed when our memories have failed us. Our memory is flexible and prone to many errors, which is why eyewitness testimony has been found to be largely unreliable. There are several reasons why forgetting occurs. In cases of brain trauma or disease, forgetting may be due to amnesia. Another reason we forget is due to encoding failure. We can’t remember something if we never stored it in our memory in the first place. Schacter presents seven memory errors that also contribute to forgetting. Sometimes, information is actually stored in our memory, but we cannot access it due to interference. Proactive interference happens when old information hinders the recall of newly learned information. Retroactive interference happens when information learned more recently hinders the recall of older information. 8.4 Ways to Enhance Memory There are many ways to combat the inevitable failures of our memory system. Some common strategies that can be used in everyday situations include mnemonic devices, rehearsal, self-referencing, and adequate sleep. These same strategies also can help you to study more effectively. Chapter 8 | Memory 281 Review Questions 1. ________ is another name for short-term memory. a. sensory memory b. episodic memory c. working memory d. implicit memory 2. The storage capacity of long-term memory is ________. a. one or two bits of information b. seven bits, plus or minus two c. limited d. essentially limitless 3. The three functions of memory are ________. a. automatic processing, effortful processing, and storage b. encoding, processing, and storage c. automatic processing, effortful processing, and retrieval d. encoding, storage, and retrieval 4. This physical trace of memory is known as the ________. a. engram b. Lashley effect c. Deese-Roediger-McDermott Paradigm d. flashbulb memory effect 5. An exceptionally clear recollection of an important event is a (an) ________. a. engram b. arousal theory c. flashbulb memory d. equipotentiality hypothesis 6. ________ is when our recollections of the past are done in a self-enhancing manner. a. stereotypical bias b. egocentric bias c. hindsight bias d. enhancement bias 7. Tip-of-the-tongue phenomenon is also known as ________. a. persistence b. misattribution c. transience d. blocking 8. The formulation of new memories is sometimes called ________, and the process of bringing up old memories is called ________. a. construction; reconstruction b. reconstruction; construction c. production; reproduction d. reproduction; production 9. When you are learning how to play the piano, the statement “Every good boy does fine” can help you remember the notes E, G, B, D, and F for the lines of the treble clef. This is an example of a (an) ________. a. jingle b. acronym c. acrostic d. acoustic 10. According to a study by Yogo and Fujihara (2008), if you want to improve your short-term memory, you should spend time writing about ________. a. your best possible future self b. a traumatic life experience c. a trivial topic d. your grocery list 11. The self-referencing effect refers to ________. a. making the material you are trying to memorize personally meaningful to you b. making a phrase of all the first letters of the words you are trying to memorize c. making a word formed by the first letter of each of the words you are trying to memorize d. saying words you want to remember out loud to yourself 12. Memory aids that help organize information for encoding are ________. a. mnemonic devices b. memory-enhancing strategies c. elaborative rehearsal d. effortful processing 282 Chapter 8 | Memory This OpenStax book is available for free at Critical Thinking Questions 13. Compare and contrast implicit and explicit memory. 14. According to the Atkinson-Shiffrin model, name and describe the three stages of memory. 15. Compare and contrast the two ways in which we encode information. 16. What might happen to your memory system if you sustained damage to your hippocampus? 17. Compare and contrast the two types of interference. 18. Compare and contrast the two types of amnesia. 19. What is the self-reference effect, and how can it help you study more effectively? 20. You and your roommate spent all of last night studying for your psychology test. You think you know the material; however, you suggest that you study again the next morning an hour prior to the test. Your roommate asks you to explain why you think this is a good idea. What do you tell her? Personal Application Questions 21. Describe something you have learned that is now in your procedural memory. Discuss how you learned this information. 22. Describe something you learned in high school that is now in your semantic memory. 23. Describe a flashbulb memory of a significant event in your life. 24. Which of the seven memory errors presented by Schacter have you committed? Provide an example of each one. 25. Jurors place a lot of weight on eyewitness testimony. Imagine you are an attorney representing a defendant who is accused of robbing a convenience store. Several eyewitnesses have been called to testify against your client. What would you tell the jurors about the reliability of eyewitness testimony? 26. Create a mnemonic device to help you remember a term or concept from this chapter. 27. What is an effective study technique that you have used? How is it similar to/different from the strategies suggested in this chapter? Chapter 8 | Memory 283 284 Chapter 8 | Memory This OpenStax book is available for free at Chapter 9 Lifespan Development Figure 9.1 How have you changed since childhood? How are you the same? What will your life be like 25 years from now? Fifty years from now? Lifespan development studies how you change as well as how you remain the same over the course of your life. (credit: modification of work by Giles Cook) Chapter Outline 9.1 What Is Lifespan Development? 9.2 Lifespan Theories 9.3 Stages of Development 9.4 Death and Dying Introduction Welcome to the story of your life. In this chapter we explore the fascinating tale of how you have grown and developed into the person you are today. We also look at some ideas about who you will grow into tomorrow. Yours is a story of lifespan development (Figure 9.1), from the start of life to the end. The process of human growth and development is more obvious in infancy and childhood, yet your development is happening this moment and will continue, minute by minute, for the rest of your life. Who you are today and who you will be in the future depends on a blend of genetics, environment, culture, relationships, and more, as you continue through each phase of life. You have experienced firsthand much of what is discussed in this chapter. Now consider what psychological science has to say about your physical, cognitive, and psychosocial development, from the womb to the tomb. Chapter 9 | Lifespan Development 285 9.1 What Is Lifespan Development? Learning Objectives By the end of this section, you will be able to: • Define and distinguish between the three domains of development: physical, cognitive and psychosocial • Discuss the normative approach to development • Understand the three major issues in development: continuity and discontinuity, one common course of development or many unique courses of development, and nature versus nurture My heart leaps up when I behold A rainbow in the sky: So was it when my life began; So is it now I am a man; So be it when I shall grow old, Or let me die! The Child is father of the Man; I could wish my days to be Bound each to each by natural piety. (Wordsworth, 1802) In this poem, William Wordsworth writes, “the child is father of the man.” What does this seemingly incongruous statement mean, and what does it have to do with lifespan development? Wordsworth might be suggesting that the person he is as an adult depends largely on the experiences he had in childhood. Consider the following questions: To what extent is the adult you are today influenced by the child you once were? To what extent is a child fundamentally different from the adult he grows up to be? These are the types of questions developmental psychologists try to answer, by studying how humans change and grow from conception through childhood, adolescence, adulthood, and death. They view development as a lifelong process that can be studied scientifically across three developmental domains—physical, cognitive, and psychosocial development. Physical development involves growth and changes in the body and brain, the senses, motor skills, and health and wellness. Cognitive development involves learning, attention, memory, language, thinking, reasoning, and creativity. Psychosocial development involves emotions, personality, and social relationships. We refer to these domains throughout the chapter. CONNECT THE CONCEPTS CONNECT THE CONCEPTS Research Methods in Developmental Psychology You’ve learned about a variety of research methods used by psychologists. Developmental psychologists use many of these approaches in order to better understand how individuals change mentally and physically over time. These methods include naturalistic observations, case studies, surveys, and experiments, among others. Naturalistic observations involve observing behavior in its natural context. A developmental psychologist might observe how children behave on a playground, at a daycare center, or in the child’s own home. While this research approach provides a glimpse into how children behave in their natural settings, researchers have very little control over the types and/or frequencies of displayed behavior. In a case study, developmental psychologists collect a great deal of information from one individual in order to better understand physical and psychological changes over the lifespan. This particular approach is an excellent way to better understand individuals, who are exceptional in some way, but it is especially prone to researcher 286 Chapter 9 | Lifespan Development This OpenStax book is available for free at bias in interpretation, and it is difficult to generalize conclusions to the larger population. In one classic example of this research method being applied to a study of lifespan development Sigmund Freud analyzed the development of a child known as “Little Hans” (Freud, 1909/1949). Freud’s findings helped inform his theories of psychosexual development in children, which you will learn about later in this chapter. Little Genie, the subject of a case study discussed in the chapter on thinking and intelligence, provides another example of how psychologists examine developmental milestones through detailed research on a single individual. In Genie’s case, her neglectful and abusive upbringing led to her being unable to speak until, at age 13, she was removed from that harmful environment. As she learned to use language, psychologists were able to compare how her language acquisition abilities differed when occurring in her late-stage development compared to the typical acquisition of those skills during the ages of infancy through early childhood (Fromkin, Krashen, Curtiss, Rigler, & Rigler, 1974; Curtiss, 1981). The survey method asks individuals to self-report important information about their thoughts, experiences, and beliefs. This particular method can provide large amounts of information in relatively short amounts of time; however, validity of data collected in this way relies on honest self-reporting, and the data is relatively shallow when compared to the depth of information collected in a case study. Experiments involve significant control over extraneous variables and manipulation of the independent variable. As such, experimental research allows developmental psychologists to make causal statements about certain variables that are important for the developmental process. Because experimental research must occur in a controlled environment, researchers must be cautious about whether behaviors observed in the laboratory translate to an individual’s natural environment. Later in this chapter, you will learn about several experiments in which toddlers and young children observe scenes or actions so that researchers can determine at what age specific cognitive abilities develop. For example, children may observe a quantity of liquid poured from a short, fat glass into a tall, skinny glass. As the experimenters question the children about what occurred, the subjects’ answers help psychologists understand at what age a child begins to comprehend that the volume of liquid remained the same although the shapes of the containers differs. Across these three domains—physical, cognitive, and psychosocial—the normative approach to development is also discussed. This approach asks, “What is normal development?” In the early decades of the 20th century, normative psychologists studied large numbers of children at various ages to determine norms (i.e., average ages) of when most children reach specific developmental milestones in each of the three domains (Gesell, 1933, 1939, 1940; Gesell & Ilg, 1946; Hall, 1904). Although children develop at slightly different rates, we can use these age-related averages as general guidelines to compare children with same-age peers to determine the approximate ages they should reach specific normative events called developmental milestones (e.g., crawling, walking, writing, dressing, naming colors, speaking in sentences, and starting puberty). Not all normative events are universal, meaning they are not experienced by all individuals across all cultures. Biological milestones, such as puberty, tend to be universal, but social milestones, such as the age when children begin formal schooling, are not necessarily universal; instead, they affect most individuals in a particular culture (Gesell & Ilg, 1946). For example, in developed countries children begin school around 5 or 6 years old, but in developing countries, like Nigeria, children often enter school at an advanced age, if at all (Huebler, 2005; United Nations Educational, Scientific, and Cultural Organization [UNESCO], 2013). To better understand the normative approach, imagine two new mothers, Louisa and Kimberly, who are close friends and have children around the same age. Louisa’s daughter is 14 months old, and Kimberly’s son is 12 months old. According to the normative approach, the average age a child starts to walk is 12 months. However, at 14 months Louisa’s daughter still isn’t walking. She tells Kimberly she is worried that something might be wrong with her baby. Kimberly is surprised because her son started walking when he was only 10 months old. Should Louisa be worried? Should she be concerned if her daughter is not walking by 15 months or 18 months? Chapter 9 | Lifespan Development 287 The Centers for Disease Control and Prevention (CDC) describes the developmental milestones for children from 2 months through 5 years old. After reviewing the information, take this quiz ( to see how well you recall what you’ve learned. If you are a parent with concerns about your child’s development, contact your pediatrician. ISSUES IN DEVELOPMENTAL PSYCHOLOGY There are many different theoretical approaches regarding human development. As we evaluate them in this chapter, recall that developmental psychology focuses on how people change, and keep in mind that all the approaches that we present in this chapter address questions of change: Is the change smooth or uneven (continuous versus discontinuous)? Is this pattern of change the same for everyone, or are there many different patterns of change (one course of development versus many courses)? How do genetics and environment interact to influence development (nature versus nurture)? Is Development Continuous or Discontinuous? Continuous development views development as a cumulative process, gradually improving on existing skills (Figure 9.2). With this type of development, there is gradual change. Consider, for example, a child’s physical growth: adding inches to her height year by year. In contrast, theorists who view development as discontinuous believe that development takes place in unique stages: It occurs at specific times or ages. With this type of development, the change is more sudden, such as an infant’s ability to conceive object permanence. Figure 9.2 The concept of continuous development can be visualized as a smooth slope of progression, whereas discontinuous development sees growth in more discrete stages. Is There One Course of Development or Many? Is development essentially the same, or universal, for all children (i.e., there is one course of development) or does development follow a different course for each child, depending on the child’s specific genetics and environment (i.e., there are many courses of development)? Do people across the world share more similarities or more differences in their development? How much do culture and genetics influence a child’s behavior? Stage theories hold that the sequence of development is universal. For example, in cross-cultural studies of language development, children from around the world reach language milestones in a similar sequence (Gleitman & Newport, 1995). Infants in all cultures coo before they babble. They begin babbling at about LINK TO LEARNING 288 Chapter 9 | Lifespan Development This OpenStax book is available for free at the same age and utter their first word around 12 months old. Yet we live in diverse contexts that have a unique effect on each of us. For example, researchers once believed that motor development follows one course for all children regardless of culture. However, child care practices vary by culture, and different practices have been found to accelerate or inhibit achievement of developmental milestones such as sitting, crawling, and walking (Karasik, Adolph, Tamis-LeMonda, & Bornstein, 2010). For instance, let’s look at the Aché society in Paraguay. They spend a significant amount of time foraging in forests. While foraging, Aché mothers carry their young children, rarely putting them down in order to protect them from getting hurt in the forest. Consequently, their children walk much later: They walk around 23–25 months old, in comparison to infants in Western cultures who begin to walk around 12 months old. However, as Aché children become older, they are allowed more freedom to move about, and by about age 9, their motor skills surpass those of U.S. children of the same age: Aché children are able to climb trees up to 25 feet tall and use machetes to chop their way through the forest (Kaplan & Dove, 1987). As you can see, our development is influenced by multiple contexts, so the timing of basic motor functions may vary across cultures. However, the functions themselves are present in all societies (Figure 9.3). Figure 9.3 All children across the world love to play. Whether in (a) Florida or (b) South Africa, children enjoy exploring sand, sunshine, and the sea. (credit a: modification of work by “Visit St. Pete/Clearwater”/Flickr; credit b: modification of work by "stringer_bel"/Flickr) How Do Nature and Nurture Influence Development? Are we who we are because of nature (biology and genetics), or are we who we are because of nurture (our environment and culture)? This longstanding question is known in psychology as the nature versus nurture debate. It seeks to understand how our personalities and traits are the product of our genetic makeup and biological factors, and how they are shaped by our environment, including our parents, peers, and culture. For instance, why do biological children sometimes act like their parents—is it because of genetics or because of early childhood environment and what the child has learned from the parents? What about children who are adopted—are they more like their biological families or more like their adoptive families? And how can siblings from the same family be so different? We are all born with specific genetic traits inherited from our parents, such as eye color, height, and certain personality traits. Beyond our basic genotype, however, there is a deep interaction between our genes and our environment: Our unique experiences in our environment influence whether and how particular traits are expressed, and at the same time, our genes influence how we interact with our environment (Diamond, 2009; Lobo, 2008). This chapter will show that there is a reciprocal interaction between nature and nurture as they both shape who we become, but the debate continues as to the relative contributions of each. Chapter 9 | Lifespan Development 289 The Achievement Gap: How Does Socioeconomic Status Affect Development? The achievement gap refers to the persistent difference in grades, test scores, and graduation rates that exist among students of different ethnicities, races, and—in certain subjects—sexes (Winerman, 2011). Research suggests that these achievement gaps are strongly influenced by differences in socioeconomic factors that exist among the families of these children. While the researchers acknowledge that programs aimed at reducing such socioeconomic discrepancies would likely aid in equalizing the aptitude and performance of children from different backgrounds, they recognize that such large-scale interventions would be difficult to achieve. Therefore, it is recommended that programs aimed at fostering aptitude and achievement among disadvantaged children may be the best option for dealing with issues related to academic achievement gaps (Duncan & Magnuson, 2005). Low-income children perform significantly more poorly than their middle- and high-income peers on a number of educational variables: They have significantly lower standardized test scores, graduation rates, and college entrance rates, and they have much higher school dropout rates. There have been attempts to correct the achievement gap through state and federal legislation, but what if the problems start before the children even enter school? Psychologists Betty Hart and Todd Risley (2006) spent their careers looking at early language ability and progression of children in various income levels. In one longitudinal study, they found that although all the parents in the study engaged and interacted with their children, middle- and high-income parents interacted with their children differently than low-income parents. After analyzing 1,300 hours of parent-child interactions, the researchers found that middle- and high-income parents talk to their children significantly more, starting when the children are infants. By 3 years old, high-income children knew almost double the number of words known by their low-income counterparts, and they had heard an estimated total of 30 million more words than the low-income counterparts (Hart & Risley, 2003). And the gaps only become more pronounced. Before entering kindergarten, high-income children score 60% higher on achievement tests than their low-income peers (Lee & Burkam, 2002). There are solutions to this problem. At the University of Chicago, experts are working with low-income families, visiting them at their homes, and encouraging them to speak more to their children on a daily and hourly basis. Other experts are designing preschools in which students from diverse economic backgrounds are placed in the same classroom. In this research, low-income children made significant gains in their language development, likely as a result of attending the specialized preschool (Schechter & Byeb, 2007). What other methods or interventions could be used to decrease the achievement gap? What types of activities could be implemented to help the children of your community or a neighboring community? 9.2 Lifespan Theories Learning Objectives By the end of this section, you will be able to: • Discuss Freud’s theory of psychosexual development • Describe the major tasks of child and adult psychosocial development according to Erikson • Discuss Piaget’s view of cognitive development and apply the stages to understanding childhood cognition • Describe Kohlberg’s theory of moral development There are many theories regarding how babies and children grow and develop into happy, healthy adults. We explore several of these theories in this section. DIG DEEPER 290 Chapter 9 | Lifespan Development This OpenStax book is available for free at PSYCHOSEXUAL THEORY OF DEVELOPMENT Sigmund Freud (1856–1939) believed that personality develops during early childhood. For Freud, childhood experiences shape our personalities and behavior as adults. Freud viewed development as discontinuous; he believed that each of us must pass through a series of stages during childhood, and that if we lack proper nurturance and parenting during a stage, we may become stuck, or fixated, in that stage. Freud’s stages are called the stages of psychosexual development. According to Freud, children’s pleasure-seeking urges are focused on a different area of the body, called an erogenous zone, at each of the five stages of development: oral, anal, phallic, latency, and genital. While most of Freud’s ideas have not found support in modern research, we cannot discount the contributions that Freud has made to the field of psychology. Psychologists today dispute Freud's psychosexual stages as a legitimate explanation for how one's personality develops, but what we can take away from Freud’s theory is that personality is shaped, in some part, by experiences we have in childhood. These stages are discussed in detail in the chapter on personality. PSYCHOSOCIAL THEORY OF DEVELOPMENT Erik Erikson (1902–1994) (Figure 9.4), another stage theorist, took Freud’s theory and modified it as psychosocial theory. Erikson’s psychosocial development theory emphasizes the social nature of our development rather than its sexual nature. While Freud believed that personality is shaped only in childhood, Erikson proposed that personality development takes place all through the lifespan. Erikson suggested that how we interact with others is what affects our sense of self, or what he called the ego identity. Figure 9.4 Erik Erikson proposed the psychosocial theory of development. In each stage of Erikson’s theory, there is a psychosocial task that we must master in order to feel a sense of competence. Erikson proposed that we are motivated by a need to achieve competence in certain areas of our lives. According to psychosocial theory, we experience eight stages of development over our lifespan, from infancy through late adulthood. At each stage there is a conflict, or task, that we need to resolve. Successful completion of each developmental task results in a sense of competence and a healthy personality. Failure to master these tasks leads to feelings of inadequacy. According to Erikson (1963), trust is the basis of our development during infancy (birth to 12 months). Therefore, the primary task of this stage is trust versus mistrust. Infants are dependent upon their caregivers, so caregivers who are responsive and sensitive to their infant’s needs help their baby to develop a sense of trust; their baby will see the world as a safe, predictable place. Unresponsive caregivers who do not meet their baby’s needs can engender feelings of anxiety, fear, and mistrust; their baby may see the world as unpredictable. As toddlers (ages 1–3 years) begin to explore their world, they learn that they can control their actions and act on the environment to get results. They begin to show clear preferences for certain elements of the Chapter 9 | Lifespan Development 291 environment, such as food, toys, and clothing. A toddler’s main task is to resolve the issue of autonomy versus shame and doubt, by working to establish independence. This is the “me do it” stage. For example, we might observe a budding sense of autonomy in a 2-year-old child who wants to choose her clothes and dress herself. Although her outfits might not be appropriate for the situation, her input in such basic decisions has an effect on her sense of independence. If denied the opportunity to act on her environment, she may begin to doubt her abilities, which could lead to low self-esteem and feelings of shame. Once children reach the preschool stage (ages 3–6 years), they are capable of initiating activities and asserting control over their world through social interactions and play. According to Erikson, preschool children must resolve the task of initiative versus guilt. By learning to plan and achieve goals while interacting with others, preschool children can master this task. Those who do will develop self-confidence and feel a sense of purpose. Those who are unsuccessful at this stage—with their initiative misfiring or stifled—may develop feelings of guilt. How might over-controlling parents stifle a child’s initiative? During the elementary school stage (ages 6–12), children face the task of industry versus inferiority. Children begin to compare themselves to their peers to see how they measure up. They either develop a sense of pride and accomplishment in their schoolwork, sports, social activities, and family life, or they feel inferior and inadequate when they don’t measure up. What are some things parents and teachers can do to help children develop a sense of competence and a belief in themselves and their abilities? In adolescence (ages 12–18), children face the task of identity versus role confusion. According to Erikson, an adolescent’s main task is developing a sense of self. Adolescents struggle with questions such as “Who am I?” and “What do I want to do with my life?” Along the way, most adolescents try on many different selves to see which ones fit. Adolescents who are successful at this stage have a strong sense of identity and are able to remain true to their beliefs and values in the face of problems and other people’s perspectives. What happens to apathetic adolescents, who do not make a conscious search for identity, or those who are pressured to conform to their parents’ ideas for the future? These teens will have a weak sense of self and experience role confusion. They are unsure of their identity and confused about the future. People in early adulthood (i.e., 20s through early 40s) are concerned with intimacy versus isolation. After we have developed a sense of self in adolescence, we are ready to share our life with others. Erikson said that we must have a strong sense of self before developing intimate relationships with others. Adults who do not develop a positive self-concept in adolescence may experience feelings of loneliness and emotional isolation. When people reach their 40s, they enter the time known as middle adulthood, which extends to the mid-60s. The social task of middle adulthood is generativity versus stagnation. Generativity involves finding your life’s work and contributing to the development of others, through activities such as volunteering, mentoring, and raising children. Those who do not master this task may experience stagnation, having little connection with others and little interest in productivity and self-improvement. From the mid-60s to the end of life, we are in the period of development known as late adulthood. Erikson’s task at this stage is called integrity versus despair. He said that people in late adulthood reflect on their lives and feel either a sense of satisfaction or a sense of failure. People who feel proud of their accomplishments feel a sense of integrity, and they can look back on their lives with few regrets. However, people who are not successful at this stage may feel as if their life has been wasted. They focus on what “would have,” “should have,” and “could have” been. They face the end of their lives with feelings of bitterness, depression, and despair. Table 9.1 summarizes the stages of Erikson’s theory. 292 Chapter 9 | Lifespan Development This OpenStax book is available for free at Table 9.1 Erikson’s Psychosocial Stages of Development Stage Age(years) Developmental Task Description 1 0–1 Trust vs. mistrust Trust (or mistrust) that basic needs, such as nourishment and affection, will be met 2 1–3 Autonomy vs. shame/doubt Develop a sense of independence in many tasks 3 3–6 Initiative vs. guilt Take initiative on some activities—may develop guilt when unsuccessful or boundaries overstepped 4 7–11 Industry vs. inferiority Develop self-confidence in abilities when competent or sense of inferiority when not 5 12–18 Identity vs. confusion Experiment with and develop identity and roles 6 19–29 Intimacy vs. isolation Establish intimacy and relationships with others 7 30–64 Generativity vs. stagnation Contribute to society and be part of a family 8 65– Integrity vs. despair Assess and make sense of life and meaning of contributions COGNITIVE THEORY OF DEVELOPMENT Jean Piaget (1896–1980) is another stage theorist who studied childhood development (Figure 9.5). Instead of approaching development from a psychoanalytical or psychosocial perspective, Piaget focused on children’s cognitive growth. He believed that thinking is a central aspect of development and that children are naturally inquisitive. However, he said that children do not think and reason like adults (Piaget, 1930, 1932). His theory of cognitive development holds that our cognitive abilities develop through specific stages, which exemplifies the discontinuity approach to development. As we progress to a new stage, there is a distinct shift in how we think and reason. Chapter 9 | Lifespan Development 293 Figure 9.5 Jean Piaget spent over 50 years studying children and how their minds develop. Piaget said that children develop schemata to help them understand the world. Schemata are concepts (mental models) that are used to help us categorize and interpret information. By the time children have reached adulthood, they have created schemata for almost everything. When children learn new information, they adjust their schemata through two processes: assimilation and accommodation. First, they assimilate new information or experiences in terms of their current schemata: assimilation is when they take in information that is comparable to what they already know. Accommodation describes when they change their schemata based on new information. This process continues as children interact with their environment. For example, 2-year-old Blake learned the schema for dogs because his family has a Labrador retriever. When Blake sees other dogs in his picture books, he says, “Look mommy, dog!” Thus, he has assimilated them into his schema for dogs. One day, Blake sees a sheep for the first time and says, “Look mommy, dog!” Having a basic schema that a dog is an animal with four legs and fur, Blake thinks all furry, four- legged creatures are dogs. When Blake’s mom tells him that the animal he sees is a sheep, not a dog, Blake must accommodate his schema for dogs to include more information based on his new experiences. Blake’s schema for dog was too broad, since not all furry, four-legged creatures are dogs. He now modifies his schema for dogs and forms a new one for sheep. Like Freud and Erikson, Piaget thought development unfolds in a series of stages approximately associated with age ranges. He proposed a theory of cognitive development that unfolds in four stages: sensorimotor, preoperational, concrete operational, and formal operational (Table 9.2). Table 9.2 Piaget’s Stages of Cognitive Development Age (years) Stage Description Developmental issues 0–2 Sensorimotor World experienced through senses and actions Object permanence Stranger anxiety 2–6 Preoperational Use words and images to represent things, but lack logical reasoning Pretend play Egocentrism Language development 294 Chapter 9 | Lifespan Development This OpenStax book is available for free at Table 9.2 Piaget’s Stages of Cognitive Development Age (years) Stage Description Developmental issues 7–11 Concrete operational Understand concrete events and analogies logically; perform arithmetical operations Conservation Mathematical transformations 12– Formal operational Formal operations Utilize abstract reasoning Abstract logic Moral reasoning The first stage is the sensorimotor stage, which lasts from birth to about 2 years old. During this stage, children learn about the world through their senses and motor behavior. Young children put objects in their mouths to see if the items are edible, and once they can grasp objects, they may shake or bang them to see if they make sounds. Between 5 and 8 months old, the child develops object permanence, which is the understanding that even if something is out of sight, it still exists (Bogartz, Shinskey, & Schilling, 2000). According to Piaget, young infants do not remember an object after it has been removed from sight. Piaget studied infants’ reactions when a toy was first shown to an infant and then hidden under a blanket. Infants who had already developed object permanence would reach for the hidden toy, indicating that they knew it still existed, whereas infants who had not developed object permanence would appear confused. Please take a few minutes to view this brief video ( piaget) demonstrating different children’s ability to understand object permanence. In Piaget’s view, around the same time children develop object permanence, they also begin to exhibit stranger anxiety, which is a fear of unfamiliar people. Babies may demonstrate this by crying and turning away from a stranger, by clinging to a caregiver, or by attempting to reach their arms toward familiar faces such as parents. Stranger anxiety results when a child is unable to assimilate the stranger into an existing schema; therefore, she can’t predict what her experience with that stranger will be like, which results in a fear response. Piaget’s second stage is the preoperational stage, which is from approximately 2 to 7 years old. In this stage, children can use symbols to represent words, images, and ideas, which is why children in this stage engage in pretend play. A child’s arms might become airplane wings as he zooms around the room, or a child with a stick might become a brave knight with a sword. Children also begin to use language in the preoperational stage, but they cannot understand adult logic or mentally manipulate information (the term operational refers to logical manipulation of information, so children at this stage are considered to be pre-operational). Children’s logic is based on their own personal knowledge of the world so far, rather than on conventional knowledge. For example, dad gave a slice of pizza to 10-year-old Keiko and another slice to her 3-year-old brother, Kenny. Kenny’s pizza slice was cut into five pieces, so Kenny told his sister that he got more pizza than she did. Children in this stage cannot perform mental operations because they have not developed an understanding of conservation, which is the idea that even if you change the appearance of something, it is still equal in size as long as nothing has been removed or added. LINK TO LEARNING Chapter 9 | Lifespan Development 295 This video ( shows a 4.5-year-old boy in the preoperational stage as he responds to Piaget’s conservation tasks. During this stage, we also expect children to display egocentrism, which means that the child is not able to take the perspective of others. A child at this stage thinks that everyone sees, thinks, and feels just as they do. Let’s look at Kenny and Keiko again. Keiko’s birthday is coming up, so their mom takes Kenny to the toy store to choose a present for his sister. He selects an Iron Man action figure for her, thinking that if he likes the toy, his sister will too. An egocentric child is not able to infer the perspective of other people and instead attributes his own perspective. Piaget developed the Three-Mountain Task to determine the level of egocentrism displayed by children. Children view a 3-dimensional mountain scene from one viewpoint, and are asked what another person at a different viewpoint would see in the same scene. Watch the Three-Mountain Task in action in this short video ( from the University of Minnesota and the Science Museum of Minnesota. Piaget’s third stage is the concrete operational stage, which occurs from about 7 to 11 years old. In this stage, children can think logically about real (concrete) events; they have a firm grasp on the use of numbers and start to employ memory strategies. They can perform mathematical operations and understand transformations, such as addition is the opposite of subtraction, and multiplication is the opposite of division. In this stage, children also master the concept of conservation: Even if something changes shape, its mass, volume, and number stay the same. For example, if you pour water from a tall, thin glass to a short, fat glass, you still have the same amount of water. Remember Keiko and Kenny and the pizza? How did Keiko know that Kenny was wrong when he said that he had more pizza? Children in the concrete operational stage also understand the principle of reversibility, which means that objects can be changed and then returned back to their original form or condition. Take, for example, water that you poured into the short, fat glass: You can pour water from the fat glass back to the thin glass and still have the same amount (minus a couple of drops). The fourth, and last, stage in Piaget’s theory is the formal operational stage, which is from about age 11 to adulthood. Whereas children in the concrete operational stage are able to think logically only about concrete events, children in the formal operational stage can also deal with abstract ideas and hypothetical situations. Children in this stage can use abstract thinking to problem solve, look at alternative solutions, and test these solutions. In adolescence, a renewed egocentrism occurs. For example, a 15-year-old with a very small pimple on her face might think it is huge and incredibly visible, under the mistaken impression that others must share her perceptions. Beyond Formal Operational Thought As with other major contributors of theories of development, several of Piaget’s ideas have come under LINK TO LEARNING LINK TO LEARNING 296 Chapter 9 | Lifespan Development This OpenStax book is available for free at criticism based on the results of further research. For example, several contemporary studies support a model of development that is more continuous than Piaget’s discrete stages (Courage & Howe, 2002; Siegler, 2005, 2006). Many others suggest that children reach cognitive milestones earlier than Piaget describes (Baillargeon, 2004; de Hevia & Spelke, 2010). According to Piaget, the highest level of cognitive development is formal operational thought, which develops between 11 and 20 years old. However, many developmental psychologists disagree with Piaget, suggesting a fifth stage of cognitive development, known as the postformal stage (Basseches, 1984; Commons & Bresette, 2006; Sinnott, 1998). In postformal thinking, decisions are made based on situations and circumstances, and logic is integrated with emotion as adults develop principles that depend on contexts. One way that we can see the difference between an adult in postformal thought and an adolescent in formal operations is in terms of how they handle emotionally charged issues. It seems that once we reach adulthood our problem solving abilities change: As we attempt to solve problems, we tend to think more deeply about many areas of our lives, such as relationships, work, and politics (Labouvie-Vief & Diehl, 1999). Because of this, postformal thinkers are able to draw on past experiences to help them solve new problems. Problem-solving strategies using postformal thought vary, depending on the situation. What does this mean? Adults can recognize, for example, that what seems to be an ideal solution to a problem at work involving a disagreement with a colleague may not be the best solution to a disagreement with a significant other. THEORY OF MORAL DEVELOPMENT A major task beginning in childhood and continuing into adolescence is discerning right from wrong. Psychologist Lawrence Kohlberg (1927–1987) extended upon the foundation that Piaget built regarding cognitive development. Kohlberg believed that moral development, like cognitive development, follows a series of stages. To develop this theory, Kohlberg posed moral dilemmas to people of all ages, and then he analyzed their answers to find evidence of their particular stage of moral development. Before reading about the stages, take a minute to consider how you would answer one of Kohlberg's best-known moral dilemmas, commonly known as the Heinz dilemma: In Europe, a woman was near death from a special kind of cancer. There was one drug that the doctors thought might save her. It was a form of radium that a druggist in the same town had recently discovered. The drug was expensive to make, but the druggist was charging ten times what the drug cost him to make. He paid $200 for the radium and charged $2,000 for a small dose of the drug. The sick woman's husband, Heinz, went to everyone he knew to borrow the money, but he could only get together about $1,000, which is half of what it cost. He told the druggist that his wife was dying and asked him to sell it cheaper or let him pay later. But the druggist said: “No, I discovered the drug and I'm going to make money from it.” So Heinz got desperate and broke into the man's store to steal the drug for his wife. Should the husband have done that? (Kohlberg, 1969, p. 379) How would you answer this dilemma? Kohlberg was not interested in whether you answer yes or no to the dilemma: Instead, he was interested in the reasoning behind your answer. After presenting people with this and various other moral dilemmas, Kohlberg reviewed people’s responses and placed them in different stages of moral reasoning (Figure 9.6). According to Kohlberg, an individual progresses from the capacity for pre-conventional morality (before age 9) to the capacity for conventional morality (early adolescence), and toward attaining post-conventional morality (once formal operational thought is attained), which only a few fully achieve. Kohlberg placed in the highest stage responses that reflected the reasoning that Heinz should steal the drug because his wife’s life is more important than the pharmacist making money. The value of a human life overrides the pharmacist’s greed. Chapter 9 | Lifespan Development 297 Figure 9.6 Kohlberg identified three levels of moral reasoning: pre-conventional, conventional, and post- conventional: Each level is associated with increasingly complex stages of moral development. It is important to realize that even those people who have the most sophisticated, post-conventional reasons for some choices may make other choices for the simplest of pre-conventional reasons. Many psychologists agree with Kohlberg's theory of moral development but point out that moral reasoning is very different from moral behavior. Sometimes what we say we would do in a situation is not what we actually do in that situation. In other words, we might “talk the talk,” but not “walk the walk.” How does this theory apply to males and females? Kohlberg (1969) felt that more males than females move past stage four in their moral development. He went on to note that women seem to be deficient in their moral reasoning abilities. These ideas were not well received by Carol Gilligan, a research assistant of Kohlberg, who consequently developed her own ideas of moral development. In her groundbreaking book, In a Different Voice: Psychological Theory and Women’s Development, Gilligan (1982) criticized her former mentor’s theory because it was based only on upper class White men and boys. She argued that women are not deficient in their moral reasoning—she proposed that males and females reason differently. Girls and women focus more on staying connected and the importance of interpersonal relationships. Therefore, in the Heinz dilemma, many girls and women respond that Heinz should not steal the medicine. Their reasoning is that if he steals the medicine, is arrested, and is put in jail, then he and his wife will be separated, and she could die while he is still in prison. 298 Chapter 9 | Lifespan Development This OpenStax book is available for free at 9.3 Stages of Development Learning Objectives By the end of this section, you will be able to: • Describe the stages of prenatal development and recognize the importance of prenatal care • Discuss physical, cognitive, and emotional development that occurs from infancy through childhood • Discuss physical, cognitive, and emotional development that occurs during adolescence • Discuss physical, cognitive, and emotional development that occurs in adulthood From the moment we are born until the moment we die, we continue to develop. As discussed at the beginning of this chapter, developmental psychologists often divide our development into three areas: physical development, cognitive development, and psychosocial development. Mirroring Erikson’s stages, lifespan development is divided into different stages that are based on age. We will discuss prenatal, infant, child, adolescent, and adult development. PRENATAL DEVELOPMENT How did you come to be who you are? From beginning as a one-cell structure to your birth, your prenatal development occurred in an orderly and delicate sequence. There are three stages of prenatal development: germinal, embryonic, and fetal. Let’s take a look at what happens to the developing baby in each of these stages. Germinal Stage (Weeks 1–2) In the discussion of biopsychology earlier in the book, you learned about genetics and DNA. A mother and father’s DNA is passed on to the child at the moment of conception. Conception occurs when sperm fertilizes an egg and forms a zygote (Figure 9.7). A zygote begins as a one-cell structure that is created when a sperm and egg merge. The genetic makeup and sex of the baby are set at this point. During the first week after conception, the zygote divides and multiplies, going from a one-cell structure to two cells, then four cells, then eight cells, and so on. This process of cell division is called mitosis. Mitosis is a fragile process, and fewer than one-half of all zygotes survive beyond the first two weeks (Hall, 2004). After 5 days of mitosis there are 100 cells, and after 9 months there are billions of cells. As the cells divide, they become more specialized, forming different organs and body parts. In the germinal stage, the mass of cells has yet to attach itself to the lining of the mother’s uterus. Once it does, the next stage begins. Figure 9.7 Sperm and ovum fuse at the point of conception. Embryonic Stage (Weeks 3–8) After the zygote divides for about 7–10 days and has 150 cells, it travels down the fallopian tubes and implants itself in the lining of the uterus. Upon implantation, this multi-cellular organism is called an embryo. Now blood vessels grow, forming the placenta. The placenta is a structure connected to the uterus Chapter 9 | Lifespan Development 299 that provides nourishment and oxygen from the mother to the developing embryo via the umbilical cord. Basic structures of the embryo start to develop into areas that will become the head, chest, and abdomen. During the embryonic stage, the heart begins to beat and organs form and begin to function. The neural tube forms along the back of the embryo, developing into the spinal cord and brain. Fetal Stage (Weeks 9–40) When the organism is about nine weeks old, the embryo is called a fetus. At this stage, the fetus is about the size of a kidney bean and begins to take on the recognizable form of a human being as the “tail” begins to disappear. From 9–12 weeks, the sex organs begin to differentiate. At about 16 weeks, the fetus is approximately 4.5 inches long. Fingers and toes are fully developed, and fingerprints are visible. By the time the fetus reaches the sixth month of development (24 weeks), it weighs up to 1.4 pounds. Hearing has developed, so the fetus can respond to sounds. The internal organs, such as the lungs, heart, stomach, and intestines, have formed enough that a fetus born prematurely at this point has a chance to survive outside of the mother’s womb. Throughout the fetal stage the brain continues to grow and develop, nearly doubling in size from weeks 16 to 28. Around 36 weeks, the fetus is almost ready for birth. It weighs about 6 pounds and is about 18.5 inches long, and by week 37 all of the fetus’s organ systems are developed enough that it could survive outside the mother’s uterus without many of the risks associated with premature birth. The fetus continues to gain weight and grow in length until approximately 40 weeks. By then, the fetus has very little room to move around and birth becomes imminent. The progression through the stages is shown in Figure 9.8. 300 Chapter 9 | Lifespan Development This OpenStax book is available for free at Figure 9.8 During the fetal stage, the baby's brain develops and the body adds size and weight, until the fetus reaches full-term development. For an amazing look at prenatal development and the process of birth, view the video Life’s Greatest Miracle ( from Nova and PBS. Prenatal Influences During each prenatal stage, genetic and environmental factors can affect development. The developing fetus is completely dependent on the mother for life. It is important that the mother takes good care of herself and receives prenatal care, which is medical care during pregnancy that monitors the health of both the mother and the fetus (Figure 9.9). According to the National Institutes of Health ([NIH], 2013), routine prenatal care is important because it can reduce the risk of complications to the mother and fetus during pregnancy. In fact, women who are trying to become pregnant or who may become pregnant should discuss pregnancy planning with their doctor. They may be advised, for example, to take a vitamin containing folic acid, which helps prevent certain birth defects, or to monitor aspects of their diet or LINK TO LEARNING Chapter 9 | Lifespan Development 301 exercise routines. Figure 9.9 A pregnant woman receives an ultrasound as part of her prenatal care. (credit: United States Agency for International Development) Recall that when the zygote attaches to the wall of the mother’s uterus, the placenta is formed. The placenta provides nourishment and oxygen to the fetus. Most everything the mother ingests, including food, liquid, and even medication, travels through the placenta to the fetus, hence the common phrase “eating for two.” Anything the mother is exposed to in the environment affects the fetus; if the mother is exposed to something harmful, the child can show life-long effects. A teratogen is any environmental agent—biological, chemical, or physical—that causes damage to the developing embryo or fetus. There are different types of teratogens. Alcohol and most drugs cross the placenta and affect the fetus. Alcohol is not safe to drink in any amount during pregnancy. Alcohol use during pregnancy has been found to be the leading preventable cause of mental retardation in children in the United States (Maier & West, 2001). Excessive maternal drinking while pregnant can cause fetal alcohol spectrum disorders with life-long consequences for the child ranging in severity from minor to major (Table 9.3). Fetal alcohol spectrum disorders (FASD) are a collection of birth defects associated with heavy consumption of alcohol during pregnancy. Physically, children with FASD may have a small head size and abnormal facial features. Cognitively, these children may have poor judgment, poor impulse control, higher rates of ADHD, learning issues, and lower IQ scores. These developmental problems and delays persist into adulthood (Streissguth et al., 2004). Based on studies conducted on animals, it also has been suggested that a mother’s alcohol consumption during pregnancy may predispose her child to like alcohol (Youngentob et al., 2007). Table 9.3 Fetal Alcohol Syndrome Facial Features Facial Feature Potential Effect of Fetal Alcohol Syndrome Head size Below-average head circumference Eyes Smaller than average eye opening, skin folds at corners of eyes Nose Low nasal bridge, short nose Midface Smaller than average midface size Lip and philtrum Thin upper lip, indistinct philtrum Smoking is also considered a teratogen because nicotine travels through the placenta to the fetus. When the mother smokes, the developing baby experiences a reduction in blood oxygen levels. According to the Centers for Disease Control and Prevention (2013), smoking while pregnant can result in premature birth, low-birth-weight infants, stillbirth, and sudden infant death syndrome (SIDS). Heroin, cocaine, methamphetamine, almost all prescription medicines, and most over-the counter medications are also considered teratogens. Babies born with a heroin addiction need heroin just like an adult addict. The child will need to be gradually weaned from the heroin under medical supervision; 302 Chapter 9 | Lifespan Development This OpenStax book is available for free at otherwise, the child could have seizures and die. Other teratogens include radiation, viruses such as HIV and herpes, and rubella (German measles). Women in the United States are much less likely to be afflicted with rubella because most women received childhood immunizations or vaccinations that protect the body from disease. Each organ of the fetus develops during a specific period in the pregnancy, called the critical or sensitive period (Figure 9.8). For example, research with primate models of FASD has demonstrated that the time during which a developing fetus is exposed to alcohol can dramatically affect the appearance of facial characteristics associated with fetal alcohol syndrome. Specifically, this research suggests that alcohol exposure that is limited to day 19 or 20 of gestation can lead to significant facial abnormalities in the offspring (Ashley, Magnuson, Omnell, & Clarren, 1999). Given regions of the brain also show sensitive periods during which they are most susceptible to the teratogenic effects of alcohol (Tran & Kelly, 2003). Should Women Who Use Drugs During Pregnancy Be Arrested and Jailed? As you now know, women who use drugs or alcohol during pregnancy can cause serious lifelong harm to their child. Some people have advocated mandatory screenings for women who are pregnant and have a history of drug abuse, and if the women continue using, to arrest, prosecute, and incarcerate them (Figdor & Kaeser, 1998). This policy was tried in Charleston, South Carolina, as recently as 20 years ago. The policy was called the Interagency Policy on Management of Substance Abuse During Pregnancy, and had disastrous results. The Interagency Policy applied to patients attending the obstetrics clinic at MUSC, which primarily serves patients who are indigent or on Medicaid. It did not apply to private obstetrical patients. The policy required patient education about the harmful effects of substance abuse during pregnancy. . . . [A] statement also warned patients that protection of unborn and newborn children from the harms of illegal drug abuse could involve the Charleston police, the Solicitor of the Ninth Judicial Court, and the Protective Services Division of the Department of Social Services (DSS). (Jos, Marshall, & Perlmutter, 1995, pp. 120–121) This policy seemed to deter women from seeking prenatal care, deterred them from seeking other social services, and was applied solely to low-income women, resulting in lawsuits. The program was canceled after 5 years, during which 42 women were arrested. A federal agency later determined that the program involved human experimentation without the approval and oversight of an institutional review board (IRB). What were the flaws in the program and how would you correct them? What are the ethical implications of charging pregnant women with child abuse? INFANCY THROUGH CHILDHOOD The average newborn weighs approximately 7.5 pounds. Although small, a newborn is not completely helpless because his reflexes and sensory capacities help him interact with the environment from the moment of birth. All healthy babies are born with newborn reflexes: inborn automatic responses to particular forms of stimulation. Reflexes help the newborn survive until it is capable of more complex behaviors—these reflexes are crucial to survival. They are present in babies whose brains are developing normally and usually disappear around 4–5 months old. Let’s take a look at some of these newborn reflexes. The rooting reflex is the newborn’s response to anything that touches her cheek: When you stroke a baby’s cheek, she naturally turns her head in that direction and begins to suck. The sucking reflex is the automatic, unlearned, sucking motions that infants do with their mouths. Several other interesting newborn reflexes can be observed. For instance, if you put your finger into a newborn’s hand, you will witness the grasping reflex, in which a baby automatically grasps anything that touches his palms. The Moro reflex is the newborn’s response when she feels like she is falling. The baby spreads her arms, pulls them back in, and then (usually) cries. How do you think these reflexes promote survival in the first WHAT DO YOU THINK? Chapter 9 | Lifespan Development 303 months of life? Take a few minutes to view this brief video clip ( newflexes) illustrating several newborn reflexes. What can young infants see, hear, and smell? Newborn infants’ sensory abilities are significant, but their senses are not yet fully developed. Many of a newborn’s innate preferences facilitate interaction with caregivers and other humans. Although vision is their least developed sense, newborns already show a preference for faces. Babies who are just a few days old also prefer human voices, they will listen to voices longer than sounds that do not involve speech (Vouloumanos & Werker, 2004), and they seem to prefer their mother’s voice over a stranger’s voice (Mills & Melhuish, 1974). In an interesting experiment, 3-week- old babies were given pacifiers that played a recording of the infant’s mother’s voice and of a stranger’s voice. When the infants heard their mother’s voice, they sucked more strongly at the pacifier (Mills & Melhuish, 1974). Newborns also have a strong sense of smell. For instance, newborn babies can distinguish the smell of their own mother from that of others. In a study by MacFarlane (1978), 1-week-old babies who were being breastfed were placed between two gauze pads. One gauze pad was from the bra of a nursing mother who was a stranger, and the other gauze pad was from the bra of the infant’s own mother. More than two-thirds of the week-old babies turned toward the gauze pad with their mother’s scent. Physical Development In infancy, toddlerhood, and early childhood, the body’s physical development is rapid (Figure 9.10). On average, newborns weigh between 5 and 10 pounds, and a newborn’s weight typically doubles in six months and triples in one year. By 2 years old the weight will have quadrupled, so we can expect that a 2 year old should weigh between 20 and 40 pounds. The average length of a newborn is 19.5 inches, increasing to 29.5 inches by 12 months and 34.4 inches by 2 years old (WHO Multicentre Growth Reference Study Group, 2006). Figure 9.10 Children experience rapid physical changes through infancy and early childhood. (credit "left": modification of work by Kerry Ceszyk; credit "middle-left": modification of work by Kristi Fausel; credit "middle-right": modification of work by "devinf"/Flickr; credit "right": modification of work by Rose Spielman) During infancy and childhood, growth does not occur at a steady rate (Carel, Lahlou, Roger, & Chaussain, 2004). Growth slows between 4 and 6 years old: During this time children gain 5–7 pounds and grow about 2–3 inches per year. Once girls reach 8–9 years old, their growth rate outpaces that of boys due to a pubertal growth spurt. This growth spurt continues until around 12 years old, coinciding with the start of the menstrual cycle. By 10 years old, the average girl weighs 88 pounds, and the average boy weighs 85 LINK TO LEARNING 304 Chapter 9 | Lifespan Development This OpenStax book is available for free at pounds. We are born with all of the brain cells that we will ever have—about 100–200 billion neurons (nerve cells) whose function is to store and transmit information (Huttenlocher & Dabholkar, 1997). However, the nervous system continues to grow and develop. Each neural pathway forms thousands of new connections during infancy and toddlerhood. This period of rapid neural growth is called blooming. Neural pathways continue to develop through puberty. The blooming period of neural growth is then followed by a period of pruning, where neural connections are reduced. It is thought that pruning causes the brain to function more efficiently, allowing for mastery of more complex skills (Hutchinson, 2011). Blooming occurs during the first few years of life, and pruning continues through childhood and into adolescence in various areas of the brain. The size of our brains increases rapidly. For example, the brain of a 2-year-old is 55% of its adult size, and by 6 years old the brain is about 90% of its adult size (Tanner, 1978). During early childhood (ages 3–6), the frontal lobes grow rapidly. Recalling our discussion of the 4 lobes of the brain earlier in this book, the frontal lobes are associated with planning, reasoning, memory, and impulse control. Therefore, by the time children reach school age, they are developmentally capable of controlling their attention and behavior. Through the elementary school years, the frontal, temporal, occipital, and parietal lobes all grow in size. The brain growth spurts experienced in childhood tend to follow Piaget’s sequence of cognitive development, so that significant changes in neural functioning account for cognitive advances (Kolb & Whishaw, 2009; Overman, Bachevalier, Turner, & Peuster, 1992). Motor development occurs in an orderly sequence as infants move from reflexive reactions (e.g., sucking and rooting) to more advanced motor functioning. For instance, babies first learn to hold their heads up, then to sit with assistance, and then to sit unassisted, followed later by crawling and then walking. Motor skills refer to our ability to move our bodies and manipulate objects. Fine motor skills focus on the muscles in our fingers, toes, and eyes, and enable coordination of small actions (e.g., grasping a toy, writing with a pencil, and using a spoon). Gross motor skills focus on large muscle groups that control our arms and legs and involve larger movements (e.g., balancing, running, and jumping). As motor skills develop, there are certain developmental milestones that young children should achieve (Table 9.4). For each milestone there is an average age, as well as a range of ages in which the milestone should be reached. An example of a developmental milestone is sitting. On average, most babies sit alone at 7 months old. Sitting involves both coordination and muscle strength, and 90% of babies achieve this milestone between 5 and 9 months old. In another example, babies on average are able to hold up their head at 6 weeks old, and 90% of babies achieve this between 3 weeks and 4 months old. If a baby is not holding up his head by 4 months old, he is showing a delay. If the child is displaying delays on several milestones, that is reason for concern, and the parent or caregiver should discuss this with the child’s pediatrician. Some developmental delays can be identified and addressed through early intervention. Table 9.4 Developmental Milestones, Ages 2–5 Years Age (years) Physical Personal/Social Language Cognitive 2 Kicks a ball; walks up and down stairs Plays alongside other children; copies adults Points to objects when named; puts 2–4 words together in a sentence Sorts shapes and colors; follows 2-step instructions Chapter 9 | Lifespan Development 305 Table 9.4 Developmental Milestones, Ages 2–5 Years Age (years) Physical Personal/Social Language Cognitive 3 Climbs and runs; pedals tricycle Takes turns; expresses many emotions; dresses self Names familiar things; uses pronouns Plays make believe; works toys with parts (levers, handles) 4 Catches balls; uses scissors Prefers social play to solo play; knows likes and interests Knows songs and rhymes by memory Names colors and numbers; begins writing letters 5 Hops and swings; uses fork and spoon Distinguishes real from pretend; likes to please friends Speaks clearly; uses full sentences Counts to 10 or higher; prints some letters and copies basic shapes Cognitive Development In addition to rapid physical growth, young children also exhibit significant development of their cognitive abilities. Piaget thought that children’s ability to understand objects—such as learning that a rattle makes a noise when shaken—was a cognitive skill that develops slowly as a child matures and interacts with the environment. Today, developmental psychologists think Piaget was incorrect. Researchers have found that even very young children understand objects and how they work long before they have experience with those objects (Baillargeon, 1987; Baillargeon, Li, Gertner, & Wu, 2011). For example, children as young as 3 months old demonstrated knowledge of the properties of objects that they had only viewed and did not have prior experience with them. In one study, 3-month-old infants were shown a truck rolling down a track and behind a screen. The box, which appeared solid but was actually hollow, was placed next to the track. The truck rolled past the box as would be expected. Then the box was placed on the track to block the path of the truck. When the truck was rolled down the track this time, it continued unimpeded. The infants spent significantly more time looking at this impossible event (Figure 9.11). Baillargeon (1987) concluded that they knew solid objects cannot pass through each other. Baillargeon’s findings suggest that very young children have an understanding of objects and how they work, which Piaget (1954) would have said is beyond their cognitive abilities due to their limited experiences in the world. Figure 9.11 In Baillargeon’s study, infants observed a truck (a) roll down an unobstructed track, (b) roll down an unobstructed track with an obstruction (box) beside it, and (c) roll down and pass through what appeared to be an obstruction. Just as there are physical milestones that we expect children to reach, there are also cognitive milestones. It is helpful to be aware of these milestones as children gain new abilities to think, problem solve, and communicate. For example, infants shake their head “no” around 6–9 months, and they respond to verbal 306 Chapter 9 | Lifespan Development This OpenStax book is available for free at requests to do things like “wave bye-bye” or “blow a kiss” around 9–12 months. Remember Piaget’s ideas about object permanence? We can expect children to grasp the concept that objects continue to exist even when they are not in sight by around 8 months old. Because toddlers (i.e., 12–24 months old) have mastered object permanence, they enjoy games like hide and seek, and they realize that when someone leaves the room they will come back (Loop, 2013). Toddlers also point to pictures in books and look in appropriate places when you ask them to find objects. Preschool-age children (i.e., 3–5 years old) also make steady progress in cognitive development. Not only can they count, name colors, and tell you their name and age, but they can also make some decisions on their own, such as choosing an outfit to wear. Preschool-age children understand basic time concepts and sequencing (e.g., before and after), and they can predict what will happen next in a story. They also begin to enjoy the use of humor in stories. Because they can think symbolically, they enjoy pretend play and inventing elaborate characters and scenarios. One of the most common examples of their cognitive growth is their blossoming curiosity. Preschool-age children love to ask “Why?” An important cognitive change occurs in children this age. Recall that Piaget described 2–3 year olds as egocentric, meaning that they do not have an awareness of others’ points of view. Between 3 and 5 years old, children come to understand that people have thoughts, feelings, and beliefs that are different from their own. This is known as theory-of-mind (TOM). Children can use this skill to tease others, persuade their parents to purchase a candy bar, or understand why a sibling might be angry. When children develop TOM, they can recognize that others have false beliefs (Dennett, 1987; Callaghan et al., 2005). False-belief tasks are useful in determining a child’s acquisition of theory-of-mind (TOM). Take a look at this video clip ( showing a false-belief task involving a box of crayons. Cognitive skills continue to expand in middle and late childhood (6–11 years old). Thought processes become more logical and organized when dealing with concrete information (Figure 9.12). Children at this age understand concepts such as the past, present, and future, giving them the ability to plan and work toward goals. Additionally, they can process complex ideas such as addition and subtraction and cause-and-effect relationships. However, children’s attention spans tend to be very limited until they are around 11 years old. After that point, it begins to improve through adulthood. Figure 9.12 Because they understand luck and fairness, children in middle and late childhood (6–11 years old) are able to follow rules for games. (credit: Edwin Martinez) One well-researched aspect of cognitive development is language acquisition. As mentioned earlier, the order in which children learn language structures is consistent across children and cultures (Hatch, 1983). You’ve also learned that some psychological researchers have proposed that children possess a biological LINK TO LEARNING Chapter 9 | Lifespan Development 307 predisposition for language acquisition. Starting before birth, babies begin to develop language and communication skills. At birth, babies apparently recognize their mother’s voice and can discriminate between the language(s) spoken by their mothers and foreign languages, and they show preferences for faces that are moving in synchrony with audible language (Blossom & Morgan, 2006; Pickens, 1994; Spelke & Cortelyou, 1981). Children communicate information through gesturing long before they speak, and there is some evidence that gesture usage predicts subsequent language development (Iverson & Goldin-Meadow, 2005). In terms of producing spoken language, babies begin to coo almost immediately. Cooing is a one-syllable combination of a consonant and a vowel sound (e.g., coo or ba). Interestingly, babies replicate sounds from their own languages. A baby whose parents speak French will coo in a different tone than a baby whose parents speak Spanish or Urdu. After cooing, the baby starts to babble. Babbling begins with repeating a syllable, such as ma-ma, da-da, or ba-ba. When a baby is about 12 months old, we expect her to say her first word for meaning, and to start combining words for meaning at about 18 months. At about 2 years old, a toddler uses between 50 and 200 words; by 3 years old they have a vocabulary of up to 1,000 words and can speak in sentences. During the early childhood years, children's vocabulary increases at a rapid pace. This is sometimes referred to as the “vocabulary spurt” and has been claimed to involve an expansion in vocabulary at a rate of 10–20 new words per week. Recent research may indicate that while some children experience these spurts, it is far from universal (as discussed in Ganger & Brent, 2004). It has been estimated that, 5 year olds understand about 6,000 words, speak 2,000 words, and can define words and question their meanings. They can rhyme and name the days of the week. Seven year olds speak fluently and use slang and clichés (Stork & Widdowson, 1974). What accounts for such dramatic language learning by children? Behaviorist B. F. Skinner thought that we learn language in response to reinforcement or feedback, such as through parental approval or through being understood. For example, when a two-year-old child asks for juice, he might say, “me juice,” to which his mother might respond by giving him a cup of apple juice. Noam Chomsky (1957) criticized Skinner’s theory and proposed that we are all born with an innate capacity to learn language. Chomsky called this mechanism a language acquisition device (LAD). Who is correct? Both Chomsky and Skinner are right. Remember that we are a product of both nature and nurture. Researchers now believe that language acquisition is partially inborn and partially learned through our interactions with our linguistic environment (Gleitman & Newport, 1995; Stork & Widdowson, 1974). Attachment Psychosocial development occurs as children form relationships, interact with others, and understand and manage their feelings. In social and emotional development, forming healthy attachments is very important and is the major social milestone of infancy. Attachment is a long-standing connection or bond with others. Developmental psychologists are interested in how infants reach this milestone. They ask such questions as: How do parent and infant attachment bonds form? How does neglect affect these bonds? What accounts for children’s attachment differences? Researchers Harry Harlow, John Bowlby, and Mary Ainsworth conducted studies designed to answer these questions. In the 1950s, Harlow conducted a series of experiments on monkeys. He separated newborn monkeys from their mothers. Each monkey was presented with two surrogate mothers. One surrogate monkey was made out of wire mesh, and she could dispense milk. The other monkey was softer and made from cloth: This monkey did not dispense milk. Research shows that the monkeys preferred the soft, cuddly cloth monkey, even though she did not provide any nourishment. The baby monkeys spent their time clinging to the cloth monkey and only went to the wire monkey when they needed to be fed. Prior to this study, the medical and scientific communities generally thought that babies become attached to the people who provide their nourishment. However, Harlow (1958) concluded that there was more to the mother-child bond than nourishment. Feelings of comfort and security are the critical components to maternal-infant bonding, which leads to healthy psychosocial development. 308 Chapter 9 | Lifespan Development This OpenStax book is available for free at Harlow’s studies of monkeys were performed before modern ethics guidelines were in place, and today his experiments are widely considered to be unethical and even cruel. Watch this video ( to see actual footage of Harlow’s monkey studies. Building on the work of Harlow and others, John Bowlby developed the concept of attachment theory. He defined attachment as the affectional bond or tie that an infant forms with the mother (Bowlby, 1969). An infant must form this bond with a primary caregiver in order to have normal social and emotional development. In addition, Bowlby proposed that this attachment bond is very powerful and continues throughout life. He used the concept of secure base to define a healthy attachment between parent and child (1988). A secure base is a parental presence that gives the child a sense of safety as he explores his surroundings. Bowlby said that two things are needed for a healthy attachment: The caregiver must be responsive to the child’s physical, social, and emotional needs; and the caregiver and child must engage in mutually enjoyable interactions (Bowlby, 1969) (Figure 9.13). Figure 9.13 Mutually enjoyable interactions promote the mother-infant bond. (credit: Peter Shanks) While Bowlby thought attachment was an all-or-nothing process, Mary Ainsworth’s (1970) research showed otherwise. Ainsworth wanted to know if children differ in the ways they bond, and if so, why. To find the answers, she used the Strange Situation procedure to study attachment between mothers and their infants (1970). In the Strange Situation, the mother (or primary caregiver) and the infant (age 12-18 months) are placed in a room together. There are toys in the room, and the caregiver and child spend some time alone in the room. After the child has had time to explore her surroundings, a stranger enters the room. The mother then leaves her baby with the stranger. After a few minutes, she returns to comfort her child. Based on how the infants/toddlers responded to the separation and reunion, Ainsworth identified three types of parent-child attachments: secure, avoidant, and resistant (Ainsworth & Bell, 1970). A fourth style, known as disorganized attachment, was later described (Main & Solomon, 1990). The most common type of attachment—also considered the healthiest—is called secure attachment (Figure 9.14). In this type of attachment, the toddler prefers his parent over a stranger. The attachment figure is used as a secure base to explore the environment and is sought out in times of stress. Securely attached children were distressed when their caregivers left the room in the Strange Situation experiment, but when their caregivers returned, the securely attached children were happy to see them. Securely attached children have caregivers who are sensitive and responsive to their needs. LINK TO LEARNING Chapter 9 | Lifespan Development 309 Figure 9.14 In secure attachment, the parent provides a secure base for the toddler, allowing him to securely explore his environment. (credit: Kerry Ceszyk) With avoidant attachment, the child is unresponsive to the parent, does not use the parent as a secure base, and does not care if the parent leaves. The toddler reacts to the parent the same way she reacts to a stranger. When the parent does return, the child is slow to show a positive reaction. Ainsworth theorized that these children were most likely to have a caregiver who was insensitive and inattentive to their needs (Ainsworth, Blehar, Waters, & Wall, 1978). In cases of resistant attachment, children tend to show clingy behavior, but then they reject the attachment figure’s attempts to interact with them (Ainsworth & Bell, 1970). These children do not explore the toys in the room, as they are too fearful. During separation in the Strange Situation, they became extremely disturbed and angry with the parent. When the parent returns, the children are difficult to comfort. Resistant attachment is the result of the caregivers’ inconsistent level of response to their child. Finally, children with disorganized attachment behaved oddly in the Strange Situation. They freeze, run around the room in an erratic manner, or try to run away when the caregiver returns (Main & Solomon, 1990). This type of attachment is seen most often in kids who have been abused. Research has shown that abuse disrupts a child’s ability to regulate their emotions. While Ainsworth’s research has found support in subsequent studies, it has also met criticism. Some researchers have pointed out that a child’s temperament may have a strong influence on attachment (Gervai, 2009; Harris, 2009), and others have noted that attachment varies from culture to culture, a factor not accounted for in Ainsworth’s research (Rothbaum, Weisz, Pott, Miyake, & Morelli, 2000; van Ijzendoorn & Sagi-Schwartz, 2008). Watch this video ( to view a clip of the Strange Situation. Try to identify which type of attachment baby Lisa exhibits. Self-Concept Just as attachment is the main psychosocial milestone of infancy, the primary psychosocial milestone of childhood is the development of a positive sense of self. How does self-awareness develop? Infants LINK TO LEARNING 310 Chapter 9 | Lifespan Development This OpenStax book is available for free at don’t have a self-concept, which is an understanding of who they are. If you place a baby in front of a mirror, she will reach out to touch her image, thinking it is another baby. However, by about 18 months a toddler will recognize that the person in the mirror is herself. How do we know this? In a well-known experiment, a researcher placed a red dot of paint on children’s noses before putting them in front of a mirror (Amsterdam, 1972). Commonly known as the mirror test, this behavior is demonstrated by humans and a few other species and is considered evidence of self-recognition (Archer, 1992). At 18 months old they would touch their own noses when they saw the paint, surprised to see a spot on their faces. By 24–36 months old children can name and/or point to themselves in pictures, clearly indicating self-recognition. Children from 2–4 years old display a great increase in social behavior once they have established a self- concept. They enjoy playing with other children, but they have difficulty sharing their possessions. Also, through play children explore and come to understand their gender roles and can label themselves as a girl or boy (Chick, Heilman-Houser, & Hunter, 2002). By 4 years old, children can cooperate with other children, share when asked, and separate from parents with little anxiety. Children at this age also exhibit autonomy, initiate tasks, and carry out plans. Success in these areas contributes to a positive sense of self. Once children reach 6 years old, they can identify themselves in terms of group memberships: “I’m a first grader!” School-age children compare themselves to their peers and discover that they are competent in some areas and less so in others (recall Erikson’s task of industry versus inferiority). At this age, children recognize their own personality traits as well as some other traits they would like to have. For example, 10-year-old Layla says, “I’m kind of shy. I wish I could be more talkative like my friend Alexa.” Development of a positive self-concept is important to healthy development. Children with a positive self- concept tend to be more confident, do better in school, act more independently, and are more willing to try new activities (Maccoby, 1980; Ferrer & Fugate, 2003). Formation of a positive self-concept begins in Erikson’s toddlerhood stage, when children establish autonomy and become confident in their abilities. Development of self-concept continues in elementary school, when children compare themselves to others. When the comparison is favorable, children feel a sense of competence and are motivated to work harder and accomplish more. Self-concept is re-evaluated in Erikson’s adolescence stage, as teens form an identity. They internalize the messages they have received regarding their strengths and weaknesses, keeping some messages and rejecting others. Adolescents who have achieved identity formation are capable of contributing positively to society (Erikson, 1968). What can parents do to nurture a healthy self-concept? Diana Baumrind (1971, 1991) thinks parenting style may be a factor. The way we parent is an important factor in a child’s socioemotional growth. Baumrind developed and refined a theory describing four parenting styles: authoritative, authoritarian, permissive, and uninvolved. With the authoritative style, the parent gives reasonable demands and consistent limits, expresses warmth and affection, and listens to the child’s point of view. Parents set rules and explain the reasons behind them. They are also flexible and willing to make exceptions to the rules in certain cases—for example, temporarily relaxing bedtime rules to allow for a nighttime swim during a family vacation. Of the four parenting styles, the authoritative style is the one that is most encouraged in modern American society. American children raised by authoritative parents tend to have high self-esteem and social skills. However, effective parenting styles vary as a function of culture and, as Small (1999) points out, the authoritative style is not necessarily preferred or appropriate in all cultures. In authoritarian style, the parent places high value on conformity and obedience. The parents are often strict, tightly monitor their children, and express little warmth. In contrast to the authoritative style, authoritarian parents probably would not relax bedtime rules during a vacation because they consider the rules to be set, and they expect obedience. This style can create anxious, withdrawn, and unhappy kids. However, it is important to point out that authoritarian parenting is as beneficial as the authoritative style in some ethnic groups (Russell, Crockett, & Chao, 2010). For instance, first-generation Chinese American children raised by authoritarian parents did just as well in school as their peers who were raised by authoritative parents (Russell et al., 2010). For parents who employ the permissive style of parenting, the kids run the show and anything goes. Permissive parents make few demands and rarely use punishment. They tend to be very nurturing and Chapter 9 | Lifespan Development 311 loving, and may play the role of friend rather than parent. In terms of our example of vacation bedtimes, permissive parents might not have bedtime rules at all—instead they allow the child to choose his bedtime whether on vacation or not. Not surprisingly, children raised by permissive parents tend to lack self- discipline, and the permissive parenting style is negatively associated with grades (Dornbusch, Ritter, Leiderman, Roberts, & Fraleigh, 1987). The permissive style may also contribute to other risky behaviors such as alcohol abuse (Bahr & Hoffman, 2010), risky sexual behavior especially among female children (Donenberg, Wilson, Emerson, & Bryant, 2002), and increased display of disruptive behaviors by male children (Parent et al., 2011). However, there are some positive outcomes associated with children raised by permissive parents. They tend to have higher self-esteem, better social skills, and report lower levels of depression (Darling, 1999). With the uninvolved style of parenting, the parents are indifferent, uninvolved, and sometimes referred to as neglectful. They don’t respond to the child’s needs and make relatively few demands. This could be because of severe depression or substance abuse, or other factors such as the parents’ extreme focus on work. These parents may provide for the child’s basic needs, but little else. The children raised in this parenting style are usually emotionally withdrawn, fearful, anxious, perform poorly in school, and are at an increased risk of substance abuse (Darling, 1999). As you can see, parenting styles influence childhood adjustment, but could a child’s temperament likewise influence parenting? Temperament refers to innate traits that influence how one thinks, behaves, and reacts with the environment. Children with easy temperaments demonstrate positive emotions, adapt well to change, and are capable of regulating their emotions. Conversely, children with difficult temperaments demonstrate negative emotions and have difficulty adapting to change and regulating their emotions. Difficult children are much more likely to challenge parents, teachers, and other caregivers (Thomas, 1984). Therefore, it’s possible that easy children (i.e., social, adaptable, and easy to soothe) tend to elicit warm and responsive parenting, while demanding, irritable, withdrawn children evoke irritation in their parents or cause their parents to withdraw (Sanson & Rothbart, 1995). The Importance of Play and Recess According to the American Academy of Pediatrics (2007), unstructured play is an integral part of a child’s development. It builds creativity, problem solving skills, and social relationships. Play also allows children to develop a theory-of-mind as they imaginatively take on the perspective of others. Outdoor play allows children the opportunity to directly experience and sense the world around them. While doing so, they may collect objects that they come across and develop lifelong interests and hobbies. They also benefit from increased exercise, and engaging in outdoor play can actually increase how much they enjoy physical activity. This helps support the development of a healthy heart and brain. Unfortunately, research suggests that today’s children are engaging in less and less outdoor play (Clements, 2004). Perhaps, it is no surprise to learn that lowered levels of physical activity in conjunction with easy access to calorie-dense foods with little nutritional value are contributing to alarming levels of childhood obesity (Karnik & Kanekar, 2012). Despite the adverse consequences associated with reduced play, some children are over scheduled and have little free time to engage in unstructured play. In addition, some schools have taken away recess time for children in a push for students to do better on standardized tests, and many schools commonly use loss of recess as a form of punishment. Do you agree with these practices? Why or why not? ADOLESCENCE Adolescence is a socially constructed concept. In pre-industrial society, children were considered adults when they reached physical maturity, but today we have an extended time between childhood and adulthood called adolescence. Adolescence is the period of development that begins at puberty and ends EVERYDAY CONNECTION 312 Chapter 9 | Lifespan Development This OpenStax book is available for free at at emerging adulthood, which is discussed later. In the United States, adolescence is seen as a time to develop independence from parents while remaining connected to them (Figure 9.15). The typical age range of adolescence is from 12 to 18 years, and this stage of development also has some predictable physical, cognitive, and psychosocial milestones. Figure 9.15 Peers are a primary influence on our development in adolescence. (credit: Sheila Tostes) Physical Development As noted above, adolescence begins with puberty. While the sequence of physical changes in puberty is predictable, the onset and pace of puberty vary widely. Several physical changes occur during puberty, such as adrenarche and gonadarche, the maturing of the adrenal glands and sex glands, respectively. Also during this time, primary and secondary sexual characteristics develop and mature. Primary sexual characteristics are organs specifically needed for reproduction, like the uterus and ovaries in females and testes in males. Secondary sexual characteristics are physical signs of sexual maturation that do not directly involve sex organs, such as development of breasts and hips in girls, and development of facial hair and a deepened voice in boys. Girls experience menarche, the beginning of menstrual periods, usually around 12–13 years old, and boys experience spermarche, the first ejaculation, around 13–14 years old. During puberty, both sexes experience a rapid increase in height (i.e., growth spurt). For girls this begins between 8 and 13 years old, with adult height reached between 10 and 16 years old. Boys begin their growth spurt slightly later, usually between 10 and 16 years old, and reach their adult height between 13 and 17 years old. Both nature (i.e., genes) and nurture (e.g., nutrition, medications, and medical conditions) can influence height. Because rates of physical development vary so widely among teenagers, puberty can be a source of pride or embarrassment. Early maturing boys tend to be stronger, taller, and more athletic than their later maturing peers. They are usually more popular, confident, and independent, but they are also at a greater risk for substance abuse and early sexual activity (Flannery, Rowe, & Gulley, 1993; Kaltiala-Heino, Rimpela, Rissanen, & Rantanen, 2001). Early maturing girls may be teased or overtly admired, which can cause them to feel self-conscious about their developing bodies. These girls are at a higher risk for depression, substance abuse, and eating disorders (Ge, Conger, & Elder, 2001; Graber, Lewinsohn, Seeley, & Brooks-Gunn, 1997; Striegel-Moore & Cachelin, 1999). Late blooming boys and girls (i.e., they develop more slowly than their peers) may feel self-conscious about their lack of physical development. Negative feelings are particularly a problem for late maturing boys, who are at a higher risk for depression and conflict with parents (Graber et al., 1997) and more likely to be bullied (Pollack & Shuster, 2000). The adolescent brain also remains under development. Up until puberty, brain cells continue to bloom in the frontal region. Adolescents engage in increased risk-taking behaviors and emotional outbursts possibly because the frontal lobes of their brains are still developing (Figure 9.16). Recall that this area is responsible for judgment, impulse control, and planning, and it is still maturing into early adulthood (Casey, Tottenham, Liston, & Durston, 2005). Chapter 9 | Lifespan Development 313 Figure 9.16 Brain growth continues into the early 20s. The development of the frontal lobe, in particular, is important during this stage. According to neuroscientist Jay Giedd in the Frontline video “Inside the Teenage Brain” (2013), “It’s sort of unfair to expect [teens] to have adult levels of organizational skills or decision-making before their brains are finished being built.” Watch this segment on “The Wiring of the Adolescent Brain” ( to find out more about the developing brain during adolescence. Cognitive Development More complex thinking abilities emerge during adolescence. Some researchers suggest this is due to increases in processing speed and efficiency rather than as the result of an increase in mental capacity—in other words, due to improvements in existing skills rather than development of new ones (Bjorkland, 1987; Case, 1985). During adolescence, teenagers move beyond concrete thinking and become capable of abstract thought. Recall that Piaget refers to this stage as formal operational thought. Teen thinking is also characterized by the ability to consider multiple points of view, imagine hypothetical situations, debate ideas and opinions (e.g., politics, religion, and justice), and form new ideas (Figure 9.17). In addition, it’s not uncommon for adolescents to question authority or challenge established societal norms. Cognitive empathy, also known as theory-of-mind (which we discussed earlier with regard to egocentrism), relates to the ability to take the perspective of others and feel concern for others (Shamay- Tsoory, Tomer, & Aharon-Peretz, 2005). Cognitive empathy begins to increase in adolescence and is an important component of social problem solving and conflict avoidance. According to one longitudinal study, levels of cognitive empathy begin rising in girls around 13 years old, and around 15 years old in boys (Van der Graaff et al., 2013). Teens who reported having supportive fathers with whom they could discuss their worries were found to be better able to take the perspective of others (Miklikowska, Duriez, & Soenens, 2011). LINK TO LEARNING 314 Chapter 9 | Lifespan Development This OpenStax book is available for free at Figure 9.17 Teenage thinking is characterized by the ability to reason logically and solve hypothetical problems such as how to design, plan, and build a structure. (credit: U.S. Army RDECOM) Psychosocial Development Adolescents continue to refine their sense of self as they relate to others. Erikson referred to the task of the adolescent as one of identity versus role confusion. Thus, in Erikson’s view, an adolescent’s main questions are “Who am I?” and “Who do I want to be?” Some adolescents adopt the values and roles that their parents expect for them. Other teens develop identities that are in opposition to their parents but align with a peer group. This is common as peer relationships become a central focus in adolescents’ lives. As adolescents work to form their identities, they pull away from their parents, and the peer group becomes very important (Shanahan, McHale, Osgood, & Crouter, 2007). Despite spending less time with their parents, most teens report positive feelings toward them (Moore, Guzman, Hair, Lippman, & Garrett, 2004). Warm and healthy parent-child relationships have been associated with positive child outcomes, such as better grades and fewer school behavior problems, in the United States as well as in other countries (Hair et al., 2005). It appears that most teens don’t experience adolescent storm and stress to the degree once famously suggested by G. Stanley Hall, a pioneer in the study of adolescent development. Only small numbers of teens have major conflicts with their parents (Steinberg & Morris, 2001), and most disagreements are minor. For example, in a study of over 1,800 parents of adolescents from various cultural and ethnic groups, Barber (1994) found that conflicts occurred over day-to-day issues such as homework, money, curfews, clothing, chores, and friends. These types of arguments tend to decrease as teens develop (Galambos & Almeida, 1992). Emerging Adulthood The next stage of development is emerging adulthood. This is a relatively newly defined period of lifespan development spanning from 18 years old to the mid-20s, characterized as an in-between time where identity exploration is focused on work and love. When does a person become an adult? There are many ways to answer this question. In the United States, you are legally considered an adult at 18 years old. But other definitions of adulthood vary widely; in sociology, for example, a person may be considered an adult when she becomes self-supporting, chooses a career, gets married, or starts a family. The ages at which we achieve these milestones vary from person to person as well as from culture to culture. For example, in the African country of Malawi, 15-year-old Njemile was married at 14 years old and had her first child at 15 years old. In her culture she is considered an adult. Children in Malawi take on adult responsibilities such as marriage and work (e.g., carrying water, tending babies, and working fields) as early as 10 years old. In stark contrast, independence in Western cultures is taking longer and longer, effectively delaying the onset of adult life. Why is it taking twentysomethings so long to grow up? It seems that emerging adulthood is a product of both Western culture and our current times (Arnett, 2000). People in developed countries are living longer, allowing the freedom to take an extra decade to start a career and family. Changes in the workforce also Chapter 9 | Lifespan Development 315 play a role. For example, 50 years ago, a young adult with a high school diploma could immediately enter the work force and climb the corporate ladder. That is no longer the case. Bachelor’s and even graduate degrees are required more and more often—even for entry-level jobs (Arnett, 2000). In addition, many students are taking longer (five or six years) to complete a college degree as a result of working and going to school at the same time. After graduation, many young adults return to the family home because they have difficulty finding a job. Changing cultural expectations may be the most important reason for the delay in entering adult roles. Young people are spending more time exploring their options, so they are delaying marriage and work as they change majors and jobs multiple times, putting them on a much later timetable than their parents (Arnett, 2000). ADULTHOOD Adulthood begins around 20 years old and has three distinct stages: early, middle, and late. Each stage brings its own set of rewards and challenges. Physical Development By the time we reach early adulthood (20 to early 40s), our physical maturation is complete, although our height and weight may increase slightly. In young adulthood, our physical abilities are at their peak, including muscle strength, reaction time, sensory abilities, and cardiac functioning. Most professional athletes are at the top of their game during this stage. Many women have children in the young adulthood years, so they may see additional weight gain and breast changes. Middle adulthood extends from the 40s to the 60s (Figure 9.18). Physical decline is gradual. The skin loses some elasticity, and wrinkles are among the first signs of aging. Visual acuity decreases during this time. Women experience a gradual decline in fertility as they approach the onset of menopause, the end of the menstrual cycle, around 50 years old. Both men and women tend to gain weight: in the abdominal area for men and in the hips and thighs for women. Hair begins to thin and turn gray. Figure 9.18 Physical declines of middle and late adulthood can be minimized with proper exercise, nutrition, and an active lifestyle. (credit: modification of work by Peter Stevens) Late adulthood is considered to extend from the 60s on. This is the last stage of physical change. The skin continues to lose elasticity, reaction time slows further, and muscle strength diminishes. Smell, taste, hearing, and vision, so sharp in our twenties, decline significantly. The brain may also no longer function at optimal levels, leading to problems like memory loss, dementia, and Alzheimer’s disease in later years. 316 Chapter 9 | Lifespan Development This OpenStax book is available for free at Aging doesn’t mean a person can’t explore new pursuits, learn new skills, and continue to grow. Watch this inspiring story about Neil Unger ( who is a newbie to the world of skateboarding at 60 years old. Cognitive Development Because we spend so many years in adulthood (more than any other stage), cognitive changes are numerous. In fact, research suggests that adult cognitive development is a complex, ever changing process that may be even more active than cognitive development in infancy and early childhood (Fischer, Yan, & Stewart, 2003). There is good news for the middle age brain. View this brief video ( to find out what it is. Unlike our physical abilities, which peak in our mid-20s and then begin a slow decline, our cognitive abilities remain steady throughout early and middle adulthood. Our crystalized intelligence (information, skills, and strategies we have gathered through a lifetime of experience) tends to hold steady as we age—it may even improve. For example, adults show relatively stable to increasing scores on intelligence tests until their mid-30s to mid-50s (Bayley & Oden, 1955). However, in late adulthood we begin to experience a decline in another area of our cognitive abilities—fluid intelligence (information processing abilities, reasoning, and memory). These processes become slower. How can we delay the onset of cognitive decline? Mental and physical activity seems to play a part (Figure 9.19). Research has found adults who engage in mentally and physically stimulating activities experience less cognitive decline and have a reduced incidence of mild cognitive impairment and dementia (Hertzog, Kramer, Wilson, & Lindenberger, 2009; Larson et al., 2006; Podewils et al., 2005). Figure 9.19 Cognitive activities such as playing mahjong, chess, or other games, can keep you mentally fit. The same is true for solo pastimes like reading and completing crossword puzzles. (credit: Philippe Put) Psychosocial Development There are many theories about the social and emotional aspects of aging. Some aspects of healthy aging LINK TO LEARNING LINK TO LEARNING Chapter 9 | Lifespan Development 317 include activities, social connectedness, and the role of a person’s culture. According to many theorists, including George Vaillant (2002), who studied and analyzed over 50 years of data, we need to have and continue to find meaning throughout our lives. For those in early and middle adulthood, meaning is found through work (Sterns & Huyck, 2001) and family life (Markus, Ryff, Curan, & Palmersheim, 2004). These areas relate to the tasks that Erikson referred to as generativity and intimacy. As mentioned previously, adults tend to define themselves by what they do—their careers. Earnings peak during this time, yet job satisfaction is more closely tied to work that involves contact with other people, is interesting, provides opportunities for advancement, and allows some independence (Mohr & Zoghi, 2006) than it is to salary (Iyengar, Wells, & Schwartz, 2006). How might being unemployed or being in a dead-end job challenge adult well-being? Positive relationships with significant others in our adult years have been found to contribute to a state of well-being (Ryff & Singer, 2009). Most adults in the United States identify themselves through their relationships with family—particularly with spouses, children, and parents (Markus et al., 2004). While raising children can be stressful, especially when they are young, research suggests that parents reap the rewards down the road, as adult children tend to have a positive effect on parental well-being (Umberson, Pudrovska, & Reczek, 2010). Having a stable marriage has also been found to contribute to well-being throughout adulthood (Vaillant, 2002). Another aspect of positive aging is believed to be social connectedness and social support. As we get older, socioemotional selectivity theory suggests that our social support and friendships dwindle in number, but remain as close, if not more close than in our earlier years (Carstensen, 1992) (Figure 9.20). Figure 9.20 Social support is important as we age. (credit: Gabriel Rocha) To learn more, view this video ( on aging in America. 9.4 Death and Dying Learning Objectives By the end of this section, you will be able to: • Discuss hospice care • Describe the five stages of grief • Define living will and DNR LINK TO LEARNING 318 Chapter 9 | Lifespan Development This OpenStax book is available for free at Every story has an ending. Death marks the end of your life story (Figure 9.21). Our culture and individual backgrounds influence how we view death. In some cultures, death is accepted as a natural part of life and is embraced. In contrast, until about 50 years ago in the United States, a doctor might not inform someone that they were dying, and the majority of deaths occurred in hospitals. In 1967 that reality began to change with Cicely Saunders, who created the first modern hospice in England. The aim of hospice is to help provide a death with dignity and pain management in a humane and comfortable environment, which is usually outside of a hospital setting. In 1974, Florence Wald founded the first hospice in the United States. Today, hospice provides care for 1.65 million Americans and their families. Because of hospice care, many terminally ill people are able to spend their last days at home. Figure 9.21 In some cultures, people’s bodies may be buried in a cemetery after death. (credit: Christina Rutz) Research has indicated that hospice care is beneficial for the patient (Brumley, Enquidanos, & Cherin, 2003; Brumley et al., 2007; Godkin, Krant, & Doster, 1984) and for the patient’s family (Rhodes, Mitchell, Miller, Connor, & Teno, 2008; Godkin et al., 1984). Hospice patients report high levels of satisfaction with hospice care because they are able to remain at home and are not completely dependent on strangers for care (Brumley et al., 2007). In addition, hospice patients tend to live longer than non-hospice patients (Connor, Pyenson, Fitch, Spence, & Iwasaki, 2007; Temel et al., 2010). Family members receive emotional support and are regularly informed of their loved one’s treatment and condition. The family member’s burden of care is also reduced (McMillan et al., 2006). Both the patient and the patient’s family members report increased family support, increased social support, and improved coping while receiving hospice services (Godkin et al., 1984). How do you think you might react if you were diagnosed with a terminal illness like cancer? Elizabeth Kübler-Ross (1969), who worked with the founders of hospice care, described the process of an individual accepting his own death. She proposed five stages of grief: denial, anger, bargaining, depression, and acceptance. Most individuals experience these stages, but the stages may occur in different orders, depending on the individual. In addition, not all people experience all of the stages. It is also important to note that some psychologists believe that the more a dying person fights death, the more likely he is to remain stuck in the denial phase. This could make it difficult for the dying person to face death with dignity. However, other psychologists believe that not facing death until the very end is an adaptive coping mechanism for some people. Whether due to illness or old age, not everyone facing death or the loss of a loved one experiences the negative emotions outlined in the Kübler-Ross model (Nolen-Hoeksema & Larson, 1999). For example, research suggests that people with religious or spiritual beliefs are better able to cope with death because of their hope in an afterlife and because of social support from religious or spiritual associations (Hood, Spilka, Hunsberger, & Corsuch, 1996; McIntosh, Silver, & Wortman, 1993; Paloutzian, 1996; Samarel, 1991; Wortman & Park, 2008). A prominent example of a person creating meaning through death is Randy Pausch, who was a well- loved and respected professor at Carnegie Mellon University. Diagnosed with terminal pancreatic cancer in his mid-40s and given only 3–6 months to live, Pausch focused on living in a fulfilling way in the time he had left. Instead of becoming angry and depressed, he presented his now famous last lecture called Chapter 9 | Lifespan Development 319 “Really Achieving Your Childhood Dreams.” In his moving, yet humorous talk, he shares his insights on seeing the good in others, overcoming obstacles, and experiencing zero gravity, among many other things. Despite his terminal diagnosis, Pausch lived the final year of his life with joy and hope, showing us that our plans for the future still matter, even if we know that we are dying. Really Achieving Your Childhood Dreams ( lastlecture) is Randy Pausch’s last lecture. Listen to his inspiring talk. LINK TO LEARNING 320 Chapter 9 | Lifespan Development This OpenStax book is available for free at accommodation adolescence adrenarche assimilation attachment authoritarian parenting style authoritative parenting style avoidant attachment cognitive development cognitive empathy conception concrete operational stage conservation continuous development critical (sensitive) period developmental milestone discontinuous development disorganized attachment egocentrism embryo emerging adulthood fine motor skills Key Terms adjustment of a schema by changing a scheme to accommodate new information different from what was already known period of development that begins at puberty and ends at early adulthood maturing of the adrenal glands adjustment of a schema by adding information similar to what is already known long-standing connection or bond with others parents place a high value on conformity and obedience, are often rigid, and express little warmth to the child parents give children reasonable demands and consistent limits, express warmth and affection, and listen to the child’s point of view characterized by child’s unresponsiveness to parent, does not use the parent as a secure base, and does not care if parent leaves domain of lifespan development that examines learning, attention, memory, language, thinking, reasoning, and creativity ability to take the perspective of others and to feel concern for others when a sperm fertilizes an egg and forms a zygote third stage in Piaget’s theory of cognitive development; from about 7 to 11 years old, children can think logically about real (concrete) events idea that even if you change the appearance of something, it is still equal in size, volume, or number as long as nothing is added or removed view that development is a cumulative process: gradually improving on existing skills time during fetal growth when specific parts or organs develop approximate ages at which children reach specific normative events view that development takes place in unique stages, which happen at specific times or ages characterized by the child’s odd behavior when faced with the parent; type of attachment seen most often with kids that are abused preoperational child’s difficulty in taking the perspective of others multi-cellular organism in its early stages of development newly defined period of lifespan development from 18 years old to the mid-20s; young people are taking longer to complete college, get a job, get married, and start a family use of muscles in fingers, toes, and eyes to coordinate small actions Chapter 9 | Lifespan Development 321 formal operational stage gonadarche gross motor skills hospice menarche mitosis motor skills nature newborn reflexes normative approach nurture object permanence permissive parenting style physical development placenta prenatal care preoperational stage primary sexual characteristics psychosexual development psychosocial development psychosocial development resistant attachment reversibility final stage in Piaget’s theory of cognitive development; from age 11 and up, children are able to deal with abstract ideas and hypothetical situations maturing of the sex glands use of large muscle groups to control arms and legs for large body movements service that provides a death with dignity; pain management in a humane and comfortable environment; usually outside of a hospital setting beginning of menstrual period; around 12–13 years old process of cell division ability to move our body and manipulate objects genes and biology inborn automatic response to a particular form of stimulation that all healthy babies are born with study of development using norms, or average ages, when most children reach specific developmental milestones environment and culture idea that even if something is out of sight, it still exists parents make few demands and rarely use punishment domain of lifespan development that examines growth and changes in the body and brain, the senses, motor skills, and health and wellness structure connected to the uterus that provides nourishment and oxygen to the developing baby medical care during pregnancy that monitors the health of both the mother and the fetus second stage in Piaget’s theory of cognitive development; from ages 2 to 7, children learn to use symbols and language but do not understand mental operations and often think illogically organs specifically needed for reproduction process proposed by Freud in which pleasure-seeking urges focus on different erogenous zones of the body as humans move through five stages of life domain of lifespan development that examines emotions, personality, and social relationships process proposed by Erikson in which social tasks are mastered as humans move through eight stages of life from infancy to adulthood characterized by the child’s tendency to show clingy behavior and rejection of the parent when she attempts to interact with the child principle that objects can be changed, but then returned back to their original form or 322 Chapter 9 | Lifespan Development This OpenStax book is available for free at schema secondary sexual characteristics secure attachment secure base sensorimotor stage socioemotional selectivity theory spermarche stage of moral reasoning temperament teratogen uninvolved parenting style zygote condition (plural = schemata) concept (mental model) that is used to help us categorize and interpret information physical signs of sexual maturation that do not directly involve sex organs characterized by the child using the parent as a secure base from which to explore parental presence that gives the infant/toddler a sense of safety as he explores his surroundings first stage in Piaget’s theory of cognitive development; from birth through age 2, a child learns about the world through senses and motor behavior social support/friendships dwindle in number, but remain as close, if not more close than in earlier years first male ejaculation process proposed by Kohlberg; humans move through three stages of moral development innate traits that influence how one thinks, behaves, and reacts with the environment biological, chemical, or physical environmental agent that causes damage to the developing embryo or fetus parents are indifferent, uninvolved, and sometimes referred to as neglectful; they don’t respond to the child’s needs and make relatively few demands structure created when a sperm and egg merge at conception; begins as a single cell and rapidly divides to form the embryo and placenta Summary 9.1 What Is Lifespan Development? Lifespan development explores how we change and grow from conception to death. This field of psychology is studied by developmental psychologists. They view development as a lifelong process that can be studied scientifically across three developmental domains: physical, cognitive development, and psychosocial. There are several theories of development that focus on the following issues: whether development is continuous or discontinuous, whether development follows one course or many, and the relative influence of nature versus nurture on development. 9.2 Lifespan Theories There are many theories regarding how babies and children grow and develop into happy, healthy adults. Sigmund Freud suggested that we pass through a series of psychosexual stages in which our energy is focused on certain erogenous zones on the body. Eric Erikson modified Freud’s ideas and suggested a theory of psychosocial development. Erikson said that our social interactions and successful completion of social tasks shape our sense of self. Jean Piaget proposed a theory of cognitive development that explains how children think and reason as they move through various stages. Finally, Lawrence Kohlberg turned his attention to moral development. He said that we pass through three levels of moral thinking that build on our cognitive development. Chapter 9 | Lifespan Development 323 9.3 Stages of Development At conception the egg and sperm cell are united to form a zygote, which will begin to divide rapidly. This marks the beginning of the first stage of prenatal development (germinal stage), which lasts about two weeks. Then the zygote implants itself into the lining of the woman’s uterus, marking the beginning of the second stage of prenatal development (embryonic stage), which lasts about six weeks. The embryo begins to develop body and organ structures, and the neural tube forms, which will later become the brain and spinal cord. The third phase of prenatal development (fetal stage) begins at 9 weeks and lasts until birth. The body, brain, and organs grow rapidly during this stage. During all stages of pregnancy it is important that the mother receive prenatal care to reduce health risks to herself and to her developing baby. Newborn infants weigh about 7.5 pounds. Doctors assess a newborn’s reflexes, such as the sucking, rooting, and Moro reflexes. Our physical, cognitive, and psychosocial skills grow and change as we move through developmental stages from infancy through late adulthood. Attachment in infancy is a critical component of healthy development. Parenting styles have been found to have an effect on childhood outcomes of well-being. The transition from adolescence to adulthood can be challenging due to the timing of puberty, and due to the extended amount of time spent in emerging adulthood. Although physical decline begins in middle adulthood, cognitive decline does not begin until later. Activities that keep the body and mind active can help maintain good physical and cognitive health as we age. Social supports through family and friends remain important as we age. 9.4 Death and Dying Death marks the endpoint of our lifespan. There are many ways that we might react when facing death. Kübler-Ross developed a five-stage model of grief as a way to explain this process. Many people facing death choose hospice care, which allows their last days to be spent at home in a comfortable, supportive environment. Review Questions 1. The view that development is a cumulative process, gradually adding to the same type of skills is known as ________. a. nature b. nurture c. continuous development d. discontinuous development 2. Developmental psychologists study human growth and development across three domains. Which of the following is not one of these domains? a. cognitive b. psychological c. physical d. psychosocial 3. How is lifespan development defined? a. The study of how we grow and change from conception to death. b. The study of how we grow and change in infancy and childhood. c. The study of physical, cognitive, and psychosocial growth in children. d. The study of emotions, personality, and social relationships. 4. The idea that even if something is out of sight, it still exists is called ________. a. egocentrism b. object permanence c. conservation d. reversibility 5. Which theorist proposed that moral thinking proceeds through a series of stages? a. Sigmund Freud b. Erik Erikson c. John Watson d. Lawrence Kohlberg 324 Chapter 9 | Lifespan Development This OpenStax book is available for free at 6. According to Erikson’s theory of psychosocial development, what is the main task of the adolescent? a. developing autonomy b. feeling competent c. forming an identity d. forming intimate relationships 7. Which of the following is the correct order of prenatal development? a. zygote, fetus, embryo b. fetus, embryo zygote c. fetus, zygote, embryo d. zygote, embryo, fetus 8. The time during fetal growth when specific parts or organs develop is known as ________. a. critical period b. mitosis c. conception d. pregnancy 9. What begins as a single-cell structure that is created when a sperm and egg merge at conception? a. embryo b. fetus c. zygote d. infant 10. Using scissors to cut out paper shapes is an example of ________. a. gross motor skills b. fine motor skills c. large motor skills d. small motor skills 11. The child uses the parent as a base from which to explore her world in which attachment style? a. secure b. insecure avoidant c. insecure ambivalent-resistant d. disorganized 12. The frontal lobes become fully developed ________. a. at birth b. at the beginning of adolescence c. at the end of adolescence d. by 25 years old 13. Who created the very first modern hospice? a. Elizabeth Kübler-Ross b. Cicely Saunders c. Florence Wald d. Florence Nightingale 14. Which of the following is the order of stages in Kübler-Ross’s five-stage model of grief? a. denial, bargaining, anger, depression, acceptance b. anger, depression, bargaining, acceptance, denial c. denial, anger, bargaining, depression, acceptance d. anger, acceptance, denial, depression, bargaining Critical Thinking Questions 15. Describe the nature versus nurture controversy, and give an example of a trait and how it might be influenced by each? 16. Compare and contrast continuous and discontinuous development. 17. Why should developmental milestones only be used as a general guideline for normal child development? 18. What is the difference between assimilation and accommodation? Provide examples of each. 19. Why was Carol Gilligan critical of Kohlberg’s theory of moral development? Chapter 9 | Lifespan Development 325 20. What is egocentrism? Provide an original example. 21. What are some known teratogens, and what kind of damage can they do to the developing fetus? 22. What is prenatal care and why is it important? 23. Describe what happens in the embryonic stage of development. Describe what happens in the fetal stage of development. 24. What makes a personal quality part of someone’s personality? 25. Describe some of the newborn reflexes. How might they promote survival? 26. Compare and contrast the four parenting styles and describe the kinds of childhood outcomes we can expect with each. 27. What is emerging adulthood and what are some factors that have contributed to this new stage of development? 28. Describe the five stages of grief and provide examples of how a person might react in each stage. 29. What is the purpose of hospice care? Personal Application Questions 30. How are you different today from the person you were at 6 years old? What about at 16 years old? How are you the same as the person you were at those ages? 31. Your 3-year-old daughter is not yet potty trained. Based on what you know about the normative approach, should you be concerned? Why or why not? 32. Explain how you would use your understanding of one of the major developmental theories to deal with each of the difficulties listed below: a. Your infant daughter puts everything in her mouth, including the dog's food. b. Your eight-year-old son is failing math; all he cares about is baseball. c. Your two-year-old daughter refuses to wear the clothes you pick for her every morning, which makes getting dressed a twenty-minute battle. d. Your sixty-eight-year-old neighbor is chronically depressed and feels she has wasted her life. e. Your 18-year-old daughter has decided not to go to college. Instead she’s moving to Colorado to become a ski instructor. f. Your 11-year-old son is the class bully. 33. Which parenting style describes how you were raised? Provide an example or two to support your answer. 34. Would you describe your experience of puberty as one of pride or embarrassment? Why? 35. Your best friend is a smoker who just found out she is pregnant. What would you tell her about smoking and pregnancy? 326 Chapter 9 | Lifespan Development This OpenStax book is available for free at 36. Imagine you are a nurse working at a clinic that provides prenatal care for pregnant women. Your patient, Anna, has heard that it’s a good idea to play music for her unborn baby, and she wants to know when her baby’s hearing will develop. What will you tell her? 37. Have you ever had to cope with the loss of a loved one? If so, what concepts described in this section provide context that may help you understand your experience and process of grieving? 38. If you were diagnosed with a terminal illness would you choose hospice care or a traditional death in a hospital? Why? Chapter 9 | Lifespan Development 327 328 Chapter 9 | Lifespan Development This OpenStax book is available for free at Chapter 10 Emotion and Motivation Figure 10.1 Emotions can change in an instant, especially in response to an unexpected event. Surprise, fear, anger, and sadness are some immediate emotions that people experienced in the aftermath of the April 15, 2013 Boston Marathon bombing. What are emotions? What causes them? What motivated some bystanders to immediately help others, while other people ran for safety? (credit: modification of work by Aaron "tango" Tang) Chapter Outline 10.1 Motivation 10.2 Hunger and Eating 10.3 Sexual Behavior 10.4 Emotion Introduction What makes us behave as we do? What drives us to eat? What drives us toward sex? Is there a biological basis to explain the feelings we experience? How universal are emotions? In this chapter, we will explore issues relating to both motivation and emotion. We will begin with a discussion of several theories that have been proposed to explain motivation and why we engage in a given behavior. You will learn about the physiological needs that drive some human behaviors, as well as the importance of our social experiences in influencing our actions. Next, we will consider both eating and having sex as examples of motivated behaviors. What are the physiological mechanisms of hunger and satiety? What understanding do scientists have of why obesity occurs, and what treatments exist for obesity and eating disorders? How has research into human sex and sexuality evolved over the past century? How do psychologists understand and study the human experience of sexual orientation and gender identity? These questions—and more—will be explored. This chapter will close with a discussion of emotion. You will learn about several theories that have been proposed to explain how emotion occurs, the biological underpinnings of emotion, and the universality of emotions. Chapter 10 | Emotion and Motivation 329 10.1 Motivation Learning Objectives By the end of this section, you will be able to: • Define intrinsic and extrinsic motivation • Understand that instincts, drive reduction, self-efficacy, and social motives have all been proposed as theories of motivation • Explain the basic concepts associated with Maslow’s hierarchy of needs Why do we do the things we do? What motivations underlie our behaviors? Motivation describes the wants or needs that direct behavior toward a goal. In addition to biological motives, motivations can be intrinsic (arising from internal factors) or extrinsic (arising from external factors) (Figure 10.2). Intrinsically motivated behaviors are performed because of the sense of personal satisfaction that they bring, while extrinsically motivated behaviors are performed in order to receive something from others. Figure 10.2 Intrinsic motivation comes from within the individual, while extrinsic motivation comes from outside the individual. Think about why you are currently in college. Are you here because you enjoy learning and want to pursue an education to make yourself a more well-rounded individual? If so, then you are intrinsically motivated. However, if you are here because you want to get a college degree to make yourself more marketable for a high-paying career or to satisfy the demands of your parents, then your motivation is more extrinsic in nature. In reality, our motivations are often a mix of both intrinsic and extrinsic factors, but the nature of the mix of these factors might change over time (often in ways that seem counter-intuitive). There is an old adage: “Choose a job that you love, and you will never have to work a day in your life,” meaning that if you enjoy your occupation, work doesn’t seem like . . . well, work. Some research suggests that this isn’t necessarily the case (Daniel & Esser, 1980; Deci, 1972; Deci, Koestner, & Ryan, 1999). According to this research, receiving some sort of extrinsic reinforcement (i.e., getting paid) for engaging in behaviors that we enjoy leads to those behaviors being thought of as work no longer providing that same enjoyment. As a result, we might spend less time engaging in these reclassified behaviors in the absence of any extrinsic reinforcement. For example, Odessa loves baking, so in her free time, she bakes for fun. Oftentimes, after stocking shelves at her grocery store job, she often whips up pastries in the evenings because she enjoys baking. When a coworker in the store’s bakery department leaves his job, Odessa applies for his position and gets transferred to the bakery department. Although she enjoys what she does in her new job, after a few months, she no longer has much desire to concoct tasty treats in her free time. Baking has become work in a way that changes her motivation to do it (Figure 10.3). What Odessa has experienced is called the overjustification effect—intrinsic motivation is diminished when extrinsic motivation is given. This can lead to extinguishing the intrinsic motivation and creating a dependence on extrinsic rewards for continued performance (Deci et al., 1999). 330 Chapter 10 | Emotion and Motivation This OpenStax book is available for free at Figure 10.3 Research suggests that when something we love to do, like icing cakes, becomes our job, our intrinsic and extrinsic motivations to do it may change. (credit: Agustín Ruiz) Other studies suggest that intrinsic motivation may not be so vulnerable to the effects of extrinsic reinforcements, and in fact, reinforcements such as verbal praise might actually increase intrinsic motivation (Arnold, 1976; Cameron & Pierce, 1994). In that case, Odessa’s motivation to bake in her free time might remain high if, for example, customers regularly compliment her baking or cake decorating skills. These apparent discrepancies in the researchers’ findings may be understood by considering several factors. For one, physical reinforcement (such as money) and verbal reinforcement (such as praise) may affect an individual in very different ways. In fact, tangible rewards (i.e., money) tend to have more negative effects on intrinsic motivation than do intangible rewards (i.e., praise). Furthermore, the expectation of the extrinsic motivator by an individual is crucial: If the person expects to receive an extrinsic reward, then intrinsic motivation for the task tends to be reduced. If, however, there is no such expectation, and the extrinsic motivation is presented as a surprise, then intrinsic motivation for the task tends to persist (Deci et al., 1999). In educational settings, students are more likely to experience intrinsic motivation to learn when they feel a sense of belonging and respect in the classroom. This internalization can be enhanced if the evaluative aspects of the classroom are de-emphasized and if students feel that they exercise some control over the learning environment. Furthermore, providing students with activities that are challenging, yet doable, along with a rationale for engaging in various learning activities can enhance intrinsic motivation for those tasks (Niemiec & Ryan, 2009). Consider Hakim, a first-year law student with two courses this semester: Family Law and Criminal Law. The Family Law professor has a rather intimidating classroom: He likes to put students on the spot with tough questions, which often leaves students feeling belittled or embarrassed. Grades are based exclusively on quizzes and exams, and the instructor posts results of each test on the classroom door. In contrast, the Criminal Law professor facilitates classroom discussions and respectful debates in small groups. The majority of the course grade is not exam-based, but centers on a student-designed research project on a crime issue of the student’s choice. Research suggests that Hakim will be less intrinsically motivated in his Family Law course, where students are intimidated in the classroom setting, and there is an emphasis on teacher-driven evaluations. Hakim is likely to experience a higher level of intrinsic motivation in his Criminal Law course, where the class setting encourages inclusive collaboration and a respect for ideas, and where students have more influence over their learning activities. THEORIES ABOUT MOTIVATION William James (1842–1910) was an important contributor to early research into motivation, and he is often referred to as the father of psychology in the United States. James theorized that behavior was driven by a number of instincts, which aid survival (Figure 10.4). From a biological perspective, an instinct is a species-specific pattern of behavior that is not learned. There was, however, considerable controversy among James and his contemporaries over the exact definition of instinct. James proposed several dozen special human instincts, but many of his contemporaries had their own lists that differed. Chapter 10 | Emotion and Motivation 331 A mother’s protection of her baby, the urge to lick sugar, and hunting prey were among the human behaviors proposed as true instincts during James’s era. This view—that human behavior is driven by instincts—received a fair amount of criticism because of the undeniable role of learning in shaping all sorts of human behavior. In fact, as early as the 1900s, some instinctive behaviors were experimentally demonstrated to result from associative learning (recall when you learned about Watson’s conditioning of fear response in “Little Albert”) (Faris, 1921). Figure 10.4 (a) William James proposed the instinct theory of motivation, asserting that behavior is driven by instincts. (b) In humans, instincts may include behaviors such as an infant’s rooting for a nipple and sucking. (credit b: modification of work by "Mothering Touch"/Flickr) Another early theory of motivation proposed that the maintenance of homeostasis is particularly important in directing behavior. You may recall from your earlier reading that homeostasis is the tendency to maintain a balance, or optimal level, within a biological system. In a body system, a control center (which is often part of the brain) receives input from receptors (which are often complexes of neurons). The control center directs effectors (which may be other neurons) to correct any imbalance detected by the control center. According to the drive theory of motivation, deviations from homeostasis create physiological needs. These needs result in psychological drive states that direct behavior to meet the need and, ultimately, bring the system back to homeostasis. For example, if it’s been a while since you ate, your blood sugar levels will drop below normal. This low blood sugar will induce a physiological need and a corresponding drive state (i.e., hunger) that will direct you to seek out and consume food (Figure 10.5). Eating will eliminate the hunger, and, ultimately, your blood sugar levels will return to normal. Interestingly, drive theory also emphasizes the role that habits play in the type of behavioral response in which we engage. A habit is a pattern of behavior in which we regularly engage. Once we have engaged in a behavior that successfully reduces a drive, we are more likely to engage in that behavior whenever faced with that drive in the future (Graham & Weiner, 1996). 332 Chapter 10 | Emotion and Motivation This OpenStax book is available for free at Figure 10.5 Hunger and subsequent eating are the result of complex physiological processes that maintain homeostasis. (credit "left": modification of work by "Gracie and Viv"/Flickr; credit "center": modification of work by Steven Depolo; credit "right": modification of work by Monica Renata) Extensions of drive theory take into account levels of arousal as potential motivators. As you recall from your study of learning, these theories assert that there is an optimal level of arousal that we all try to maintain (Figure 10.6). If we are underaroused, we become bored and will seek out some sort of stimulation. On the other hand, if we are overaroused, we will engage in behaviors to reduce our arousal (Berlyne, 1960). Most students have experienced this need to maintain optimal levels of arousal over the course of their academic career. Think about how much stress students experience toward the end of spring semester. They feel overwhelmed with seemingly endless exams, papers, and major assignments that must be completed on time. They probably yearn for the rest and relaxation that awaits them over the extended summer break. However, once they finish the semester, it doesn’t take too long before they begin to feel bored. Generally, by the time the next semester is beginning in the fall, many students are quite happy to return to school. This is an example of how arousal theory works. Figure 10.6 The concept of optimal arousal in relation to performance on a task is depicted here. Performance is maximized at the optimal level of arousal, and it tapers off during under- and overarousal. So what is the optimal level of arousal? What level leads to the best performance? Research shows that moderate arousal is generally best; when arousal is very high or very low, performance tends to suffer (Yerkes & Dodson, 1908). Think of your arousal level regarding taking an exam for this class. If your level is very low, such as boredom and apathy, your performance will likely suffer. Similarly, a very high level, such as extreme anxiety, can be paralyzing and hinder performance. Consider the example of a softball team facing a tournament. They are favored to win their first game by a large margin, so they go into the game with a lower level of arousal and get beat by a less skilled team. But optimal arousal level is more complex than a simple answer that the middle level is always best. Researchers Robert Yerkes (pronounced “Yerk-EES”) and John Dodson discovered that the optimal Chapter 10 | Emotion and Motivation 333 arousal level depends on the complexity and difficulty of the task to be performed (Figure 10.7). This relationship is known as Yerkes-Dodson law, which holds that a simple task is performed best when arousal levels are relatively high and complex tasks are best performed when arousal levels are lower. Figure 10.7 Task performance is best when arousal levels are in a middle range, with difficult tasks best performed under lower levels of arousal and simple tasks best performed under higher levels of arousal. Self-efficacy and Social Motives Self-efficacy is an individual’s belief in her own capability to complete a task, which may include a previous successful completion of the exact task or a similar task. Albert Bandura (1994) theorized that an individual’s sense of self-efficacy plays a pivotal role in motivating behavior. Bandura argues that motivation derives from expectations that we have about the consequences of our behaviors, and ultimately, it is the appreciation of our capacity to engage in a given behavior that will determine what we do and the future goals that we set for ourselves. For example, if you have a sincere belief in your ability to achieve at the highest level, you are more likely to take on challenging tasks and to not let setbacks dissuade you from seeing the task through to the end. A number of theorists have focused their research on understanding social motives (McAdams & Constantian, 1983; McClelland & Liberman, 1949; Murray et al., 1938). Among the motives they describe are needs for achievement, affiliation, and intimacy. It is the need for achievement that drives accomplishment and performance. The need for affiliation encourages positive interactions with others, and the need for intimacy causes us to seek deep, meaningful relationships. Henry Murray et al. (1938) categorized these needs into domains. For example, the need for achievement and recognition falls under the domain of ambition. Dominance and aggression were recognized as needs under the domain of human power, and play was a recognized need in the domain of interpersonal affection. Maslow’s Hierarchy of Needs While the theories of motivation described earlier relate to basic biological drives, individual characteristics, or social contexts, Abraham Maslow (1943) proposed a hierarchy of needs that spans the spectrum of motives ranging from the biological to the individual to the social. These needs are often depicted as a pyramid (Figure 10.8). 334 Chapter 10 | Emotion and Motivation This OpenStax book is available for free at Figure 10.8 Maslow’s hierarchy of needs is illustrated here. In some versions of the pyramid, cognitive and aesthetic needs are also included between esteem and self-actualization. Others include another tier at the top of the pyramid for self-transcendence. At the base of the pyramid are all of the physiological needs that are necessary for survival. These are followed by basic needs for security and safety, the need to be loved and to have a sense of belonging, and the need to have self-worth and confidence. The top tier of the pyramid is self-actualization, which is a need that essentially equates to achieving one’s full potential, and it can only be realized when needs lower on the pyramid have been met. To Maslow and humanistic theorists, self-actualization reflects the humanistic emphasis on positive aspects of human nature. Maslow suggested that this is an ongoing, life- long process and that only a small percentage of people actually achieve a self-actualized state (Francis & Kritsonis, 2006; Maslow, 1943). According to Maslow (1943), one must satisfy lower-level needs before addressing those needs that occur higher in the pyramid. So, for example, if someone is struggling to find enough food to meet his nutritional requirements, it is quite unlikely that he would spend an inordinate amount of time thinking about whether others viewed him as a good person or not. Instead, all of his energies would be geared toward finding something to eat. However, it should be pointed out that Maslow’s theory has been criticized for its subjective nature and its inability to account for phenomena that occur in the real world (Leonard, 1982). Other research has more recently addressed that late in life, Maslow proposed a self-transcendence level above self-actualization—to represent striving for meaning and purpose beyond the concerns of oneself (Koltko-Rivera, 2006). For example, people sometimes make self-sacrifices in order to make a political statement or in an attempt to improve the conditions of others. Mohandas K. Gandhi, a world- renowned advocate for independence through nonviolent protest, on several occasions went on hunger strikes to protest a particular situation. People may starve themselves or otherwise put themselves in danger displaying higher-level motives beyond their own needs. Chapter 10 | Emotion and Motivation 335 Check out this interactive exercise ( that illustrates some of the important concepts in Maslow’s hierarchy of needs. 10.2 Hunger and Eating Learning Objectives By the end of this section, you will be able to: • Describe how hunger and eating are regulated • Differentiate between levels of overweight and obesity and the associated health consequences • Explain the health consequences resulting from anorexia and bulimia nervosa Eating is essential for survival, and it is no surprise that a drive like hunger exists to ensure that we seek out sustenance. While this chapter will focus primarily on the physiological mechanisms that regulate hunger and eating, powerful social, cultural, and economic influences also play important roles. This section will explain the regulation of hunger, eating, and body weight, and we will discuss the adverse consequences of disordered eating. PHYSIOLOGICAL MECHANISMS There are a number of physiological mechanisms that serve as the basis for hunger. When our stomachs are empty, they contract, causing both hunger pangs and the secretion of chemical messages that travel to the brain to serve as a signal to initiate feeding behavior. When our blood glucose levels drop, the pancreas and liver generate a number of chemical signals that induce hunger (Konturek et al., 2003; Novin, Robinson, Culbreth, & Tordoff, 1985) and thus initiate feeding behavior. For most people, once they have eaten, they feel satiation, or fullness and satisfaction, and their eating behavior stops. Like the initiation of eating, satiation is also regulated by several physiological mechanisms. As blood glucose levels increase, the pancreas and liver send signals to shut off hunger and eating (Drazen & Woods, 2003; Druce, Small, & Bloom, 2004; Greary, 1990). The food’s passage through the gastrointestinal tract also provides important satiety signals to the brain (Woods, 2004), and fat cells release leptin, a satiety hormone. The various hunger and satiety signals that are involved in the regulation of eating are integrated in the brain. Research suggests that several areas of the hypothalamus and hindbrain are especially important sites where this integration occurs (Ahima & Antwi, 2008; Woods & D’Alessio, 2008). Ultimately, activity in the brain determines whether or not we engage in feeding behavior (Figure 10.9). LINK TO LEARNING 336 Chapter 10 | Emotion and Motivation This OpenStax book is available for free at Figure 10.9 Hunger and eating are regulated by a complex interplay of hunger and satiety signals that are integrated in the brain. METABOLISM AND BODY WEIGHT Our body weight is affected by a number of factors, including gene-environment interactions, and the number of calories we consume versus the number of calories we burn in daily activity. If our caloric intake exceeds our caloric use, our bodies store excess energy in the form of fat. If we consume fewer calories than we burn off, then stored fat will be converted to energy. Our energy expenditure is obviously affected by our levels of activity, but our body’s metabolic rate also comes into play. A person’s metabolic rate is the amount of energy that is expended in a given period of time, and there is tremendous individual variability in our metabolic rates. People with high rates of metabolism are able to burn off calories more easily than those with lower rates of metabolism. We all experience fluctuations in our weight from time to time, but generally, most people’s weights fluctuate within a narrow margin, in the absence of extreme changes in diet and/or physical activity. This observation led some to propose a set-point theory of body weight regulation. The set-point theory asserts that each individual has an ideal body weight, or set point, which is resistant to change. This set-point is genetically predetermined and efforts to move our weight significantly from the set-point are resisted by compensatory changes in energy intake and/or expenditure (Speakman et al., 2011). Some of the predictions generated from this particular theory have not received empirical support. For example, there are no changes in metabolic rate between individuals who had recently lost significant amounts of weight and a control group (Weinsier et al., 2000). In addition, the set-point theory fails to account for the influence of social and environmental factors in the regulation of body weight (Martin- Gronert & Ozanne, 2013; Speakman et al., 2011). Despite these limitations, set-point theory is still often used as a simple, intuitive explanation of how body weight is regulated. OBESITY When someone weighs more than what is generally accepted as healthy for a given height, they are considered overweight or obese. According to the Centers for Disease Control and Prevention (CDC), an Chapter 10 | Emotion and Motivation 337 adult with a body mass index (BMI) between 25 and 29.9 is considered overweight (Figure 10.10). An adult with a BMI of 30 or higher is considered obese (Centers for Disease Control and Prevention [CDC], 2012). People who are so overweight that they are at risk for death are classified as morbidly obese. Morbid obesity is defined as having a BMI over 40. Note that although BMI has been used as a healthy weight indicator by the World Health Organization (WHO), the CDC, and other groups, its value as an assessment tool has been questioned. The BMI is most useful for studying populations, which is the work of these organizations. It is less useful in assessing an individual since height and weight measurements fail to account for important factors like fitness level. An athlete, for example, may have a high BMI because the tool doesn’t distinguish between the body’s percentage of fat and muscle in a person’s weight. Figure 10.10 This chart shows how adult BMI is calculated. Individuals find their height on the y-axis and their weight on the x-axis to determine their BMI. Being extremely overweight or obese is a risk factor for several negative health consequences. These include, but are not limited to, an increased risk for cardiovascular disease, stroke, Type 2 diabetes, liver disease, sleep apnea, colon cancer, breast cancer, infertility, and arthritis. Given that it is estimated that in the United States around one-third of the adult population is obese and that nearly two-thirds of adults and one in six children qualify as overweight (CDC, 2012), there is substantial interest in trying to understand how to combat this important public health concern. What causes someone to be overweight or obese? You have already read that both genes and environment are important factors for determining body weight, and if more calories are consumed than expended, excess energy is stored as fat. However, socioeconomic status and the physical environment must also be considered as contributing factors (CDC, 2012). For example, an individual who lives in an impoverished neighborhood that is overrun with crime may never feel comfortable walking or biking to work or to the local market. This might limit the amount of physical activity in which he engages and result in an increased body weight. Similarly, some people may not be able to afford healthy food options from their market, or these options may be unavailable (especially in urban areas or poorer neighborhoods); therefore, some people rely primarily on available, inexpensive, high fat, and high calorie fast food as their primary source of nutrition. 338 Chapter 10 | Emotion and Motivation This OpenStax book is available for free at Generally, overweight and obese individuals are encouraged to try to reduce their weights through a combination of both diet and exercise. While some people are very successful with these approaches, many struggle to lose excess weight. In cases in which a person has had no success with repeated attempts to reduce weight or is at risk for death because of obesity, bariatric surgery may be recommended. Bariatric surgery is a type of surgery specifically aimed at weight reduction, and it involves modifying the gastrointestinal system to reduce the amount of food that can be eaten and/or limiting how much of the digested food can be absorbed (Figure 10.11) (Mayo Clinic, 2013). A recent meta-analysis suggests that bariatric surgery is more effective than non-surgical treatment for obesity in the two-years immediately following the procedure, but to date, no long-term studies yet exist (Gloy et al., 2013). Figure 10.11 Gastric banding surgery creates a small pouch of stomach, reducing the size of the stomach that can be used for digestion. Watch this video ( that describes two different types of bariatric surgeries. Prader-Willi Syndrome Prader-Willi Syndrome (PWS) is a genetic disorder that results in persistent feelings of intense hunger and reduced rates of metabolism. Typically, affected children have to be supervised around the clock to ensure that they do not engage in excessive eating. Currently, PWS is the leading genetic cause of morbid obesity in children, and it is associated with a number of cognitive deficits and emotional problems (Figure 10.12). LINK TO LEARNING DIG DEEPER Chapter 10 | Emotion and Motivation 339 Figure 10.12 Eugenia Martínez Vallejo, depicted in this 1680 painting, may have had Prader-Willi syndrome. At just eight years old, she weighed approximately 120 pounds, and she was nicknamed “La Monstrua” (the monster). While genetic testing can be used to make a diagnosis, there are a number of behavioral diagnostic criteria associated with PWS. From birth to 2 years of age, lack of muscle tone and poor sucking behavior may serve as early signs of PWS. Developmental delays are seen between the ages of 6 and 12, and excessive eating and cognitive deficits associated with PWS usually onset a little later. While the exact mechanisms of PWS are not fully understood, there is evidence that affected individuals have hypothalamic abnormalities. This is not surprising, given the hypothalamus’s role in regulating hunger and eating. However, as you will learn in the next section of this chapter, the hypothalamus is also involved in the regulation of sexual behavior. Consequently, many individuals suffering from PWS fail to reach sexual maturity during adolescence. There is no current treatment or cure for PWS. However, if weight can be controlled in these individuals, then their life expectancies are significantly increased (historically, sufferers of PWS often died in adolescence or early adulthood). Advances in the use of various psychoactive medications and growth hormones continue to enhance the quality of life for individuals with PWS (Cassidy & Driscoll, 2009; Prader-Willi Syndrome Association, 2012). EATING DISORDERS While nearly two out of three US adults struggle with issues related to being overweight, a smaller, but significant, portion of the population has eating disorders that typically result in being normal weight or underweight. Often, these individuals are fearful of gaining weight. Individuals who suffer from bulimia nervosa and anorexia nervosa face many adverse health consequences (Mayo Clinic, 2012a, 2012b). People suffering from bulimia nervosa engage in binge eating behavior that is followed by an attempt to compensate for the large amount of food consumed. Purging the food by inducing vomiting or through the use of laxatives are two common compensatory behaviors. Some affected individuals engage in excessive amounts of exercise to compensate for their binges. Bulimia is associated with many adverse health consequences that can include kidney failure, heart failure, and tooth decay. In addition, these individuals 340 Chapter 10 | Emotion and Motivation This OpenStax book is available for free at often suffer from anxiety and depression, and they are at an increased risk for substance abuse (Mayo Clinic, 2012b). The lifetime prevalence rate for bulimia nervosa is estimated at around 1% for women and less than 0.5% for men (Smink, van Hoeken, & Hoek, 2012). As of the 2013 release of the Diagnostic and Statistical Manual, fifth edition, Binge eating disorder is a disorder recognized by the American Psychiatric Association (APA). Unlike with bulimia, eating binges are not followed by inappropriate behavior, such as purging, but they are followed by distress, including feelings of guilt and embarrassment. The resulting psychological distress distinguishes binge eating disorder from overeating (American Psychiatric Association [APA], 2013). Anorexia nervosa is an eating disorder characterized by the maintenance of a body weight well below average through starvation and/or excessive exercise. Individuals suffering from anorexia nervosa often have a distorted body image, referenced in literature as a type of body dysmorphia, meaning that they view themselves as overweight even though they are not. Like bulimia nervosa, anorexia nervosa is associated with a number of significant negative health outcomes: bone loss, heart failure, kidney failure, amenorrhea (cessation of the menstrual period), reduced function of the gonads, and in extreme cases, death. Furthermore, there is an increased risk for a number of psychological problems, which include anxiety disorders, mood disorders, and substance abuse (Mayo Cli