chapter 1_introduction_to_psychology

CHAPTER 1
THE NATURE OF
PSYCHOLOGY
©
MARIAGRAZIA
ORLANDINI
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Reading opens the door to education and advancement. What’s the best
way to encourage kids to read? One American chain of pizza restau-
rants believes it has the answer: Reward kids for reading. Kids’ teachers set
monthly reading goals – in terms of books or pages read – and give them Pizza
Award Certificates when they reach the goals. The kid who brings a certificate
to a local participating restaurant gets a free pizza. Parents and teachers say
the program works – it gets their kids to read more. Through this program, for
nearly twenty years kids have been earning pizzas for reading across the United
States. Perhaps you or one of your siblings got a free meal this way.
But is this program PC? Is it ‘psychologically correct’? Let’s see what the
research says. You might already be aware of one of the fundamental tenets of
learning theory: When a reward follows a behavior, that behavior is strength-
ened. In Chapter 7 you’ll see that this powerful influence of rewards is termed
the law of effect.1
When kids are rewarded with pizzas for reading, they read
more. Seems like a great success, right?
Consider other outcomes – like how kids feel about reading and whether
they continue to read once the pizza program ends. Dozens of psychology
experiments, many conducted in school classrooms, have addressed these
questions. In one classic experiment (Greene, Sternberg, & Lepper, 1976),2
psychologists had teachers introduce several new math games to their students
and then for two weeks simply observe how much time kids spent playing
them. In the third week, kids in some classrooms were rewarded for playing
these same math games, and kids in other classrooms were not. As expected,
the rewards increased the amount of time kids played the math games; the law
of effect held. But what happened several weeks later, when the rewards were
discontinued? The kids who had received rewards suddenly lost interest in
the math games and spent hardly any time on them. By contrast, those who
were never rewarded continued to play the math games regularly.
This experiment demonstrates how rewards sometimes backfire and undermine
kids’ intrinsic interest in activities like reading and math. When people see that
their behavior is caused by some external, situational factor – like a free pizza –
they discount any internal, personal factors – like their own enjoyment of the
activity. So when kids ask themselves why they read, they’ll say it’s for the pizza.
And when there’s no more pizza to be had, they’ll see no particular reason to read.
CHAPTER OUTLINE
THE SCOPE OF PSYCHOLOGY
THE HISTORICAL ORIGINS OF
PSYCHOLOGY
Nature–nurture debate
The beginnings of scientific psychology
Structuralism and functionalism
Behaviorism
Gestalt psychology
Psychoanalysis
Later developments in twentieth-century
psychology
CONTEMPORARY PSYCHOLOGICAL
PERSPECTIVES
The biological perspective
The behavioral perspective
The cognitive perspective
The psychoanalytic perspective
The subjectivist perspective
Relationships between psychological
and biological perspectives
Major subfields of psychology
CUTTING EDGE RESEARCH:
TWENTY-FIRST–CENTURY
PSYCHOLOGY
HOW PSYCHOLOGICAL RESEARCH
IS DONE
Generating hypotheses
Experiments
Correlation
Observation
Literature reviews
Ethics of psychological research
SEEING BOTH SIDES: ARE WE
NATURALLY SELFISH?
1
Throughout this book you will find core concepts printed in bold type with their definitions provided
nearby. A list of these core concepts is also provided at the end of each chapter as a study aid.
2
Throughout this book you will also find references, cited by author and date, that document or
expand the statements made here. Detailed publishing information on these studies appears in the
reference list at the end of the book.
3

Even though they enjoyed reading, the rewards loomed
larger. This undermining influence of rewards is the over-
justification effect – going overboard and explaining one’s
own behavior with too much emphasis on salient situational
causes and not enough emphasis on personal causes.
You might be thinking that grades in college, or uni-
versity, are also rewards for learning. Do they backfire in
the same way as receiving pizza for reading? Not exactly.
One important difference is that the grade you get in a
college course depends on how well you perform.
Research has shown that performance-contingent
rewards are less likely to undermine interest – and at
times can even increase interest – because they tell you
that you are good at an activity (Tang & Hall, 1995).
Even so, a focus on grades can sometimes overshadow the
sheer interest you might have in a subject. It’s useful to
remind yourself that two reasons to study course work
can exist side by side: to get a good grade and to enjoy the
material. It can be ‘both-and’, not ‘either-or’.
Luckily, most students find psychology fascinating. We
do, too, and we do our best to convey this fascination to
you in the pages of this book. Psychology interests people
because it asks questions that touch virtually every aspect
of our lives: How does the way your parents raised you
affect the way you’ll raise your own children? What is the
best treatment for drug dependency? Can a man care for
an infant as capably as a woman can? Can you remember
a traumatic experience in more detail under hypnosis?
How should a nuclear power plant be designed to mini-
mize human error? What effects does prolonged stress
have on the immune system? Is psychotherapy more
effective than drugs in treating depression? Psychologists
are conducting research to find answers to these and
many other questions.
Psychology also affects our lives through its influence
on laws and public policy. Psychological theories and
research have influenced laws dealing with discrimina-
tion, capital punishment, courtroom practices, pornog-
raphy, sexual behavior, and personal responsibility for
actions. For example, so-called lie-detector tests are not
admissible evidence in U.S. courts because psychological
research has shown them to be unacceptably inaccurate.
Because psychology affects so many aspects of our
lives, even people who do not intend to specialize in it
need to know something about this dynamic field. An
introductory course in psychology should give you a
better understanding of why people think, feel, and act as
they do, as well as insights into your own attitudes and
reactions.
This course will also help you evaluate the many claims
made in the name of psychology. Everyone has seen
newspaper headlines like these:
l New Form of Psychotherapy Facilitates Recovery of
Repressed Memories
l Anxiety Controlled by Self-Regulation of Brain Waves
l Proof of Mental Telepathy Found
l Babies Learn Speech Sounds While Snoozing
l Emotional Stability Closely Related to Family Size
l Sweet Drink May Boost Exam Performance
l Transcendental Meditation Extends Life Expectancy
l Appearance Concerns Take Mental Toll
How can we decide whether to believe these claims? You
need to know two things to evaluate the validity of psy-
chological claims. First, you need to know what psycho-
logical facts are already firmly established. If the new claim
is not compatible with those facts, you should be cautious.
Second, you need to have the knowledge to determine
whether the arguments that support the new claim meet the
standards of scientific evidence. If they do not, again you
have reason for skepticism. This book aims to meet both
needs. First, it reviews the current state of knowledge in
psychology. It presents the most important findings in the
field so that you know the established facts. Second, it
examines the nature of research – how a psychologist
designs a research program that can provide strong evidence
Getting kids to read for external reasons – like for free pizzas –
can lead them to discount the contribution of any internal rea-
sons for reading – like their own interest. This overjustification
effect explains why rewarding desired behaviors sometimes
backfires.
4 CHAPTER 1 THE NATURE OF PSYCHOLOGY

for or against a hypothesis – so that you know the kind of
evidence needed to back up a new claim.
In this chapter, we begin by considering the kinds of
topics that are studied in psychology. After a brief review
of psychology’s historical origins, we discuss the
perspectives that psychologists adopt in investigating
these topics. Then we describe the research methods of
psychological investigation, including the ethical guide-
lines that have been proposed for such research.
THE SCOPE OF PSYCHOLOGY
Psychology can be defined as the scientific study of
behavior and mental processes. An astonishing variety
of topics fit this definition, as can be seen in the brief
examples presented next. (All of these topics are discussed
in more detail at various points in this book.)
Brain damage and face recognition
It is no surprise that when people suffer brain damage,
their behavior is affected. What is surprising is that
damage in a specific part of the brain may change a
person’s behavior in one way but not in any other ways.
In some cases, for example, people are unable to recog-
nize familiar faces as a result of damage to a particular
region on the right side of the brain – yet they can do
just about everything else normally, a condition called
prosopagnosia. A famous example of this condition was
described by neurologist Oliver Sacks (1985) in his book
The Man Who Mistook His Wife for a Hat. In another
case, a man with prosopagnosia complained to a waiter
that someone was staring at him, only to be informed
that he was looking in a mirror! Such cases tell us a lot
about the way the normal brain works. They indicate that
some psychological functions – like face recognition – are
localized in particular parts of the brain.
Attributing traits to people
Suppose that in a crowded department store a person
soliciting for a charity approaches a customer and
implores her to make a contribution. The woman donates
a small sum to the charity. Would you think the woman
was generous, or would you think she had been pressured
into making the donation because so many people were
watching her? Experiments designed to study situations
like this have shown that most people consider the
woman generous, even though the situational pressures
were so great that just about everybody would behave
similarly. When explaining the behavior of others, people
tend to overestimate the causal effect of personality
traits and underestimate those of situational factors – a
mistake social psychologists call the fundamental attribu-
tion error (see Figure 1.1). If we contrast the fundamental
attribution error with the overjustification effect (dis-
cussed in the context of earning pizzas for reading), we
begin to see some important distinctions between how we
judge others and how we judge ourselves. When making
sense of our own behavior, we often overestimate – not
underestimate – situational causes.
Childhood amnesia
Most adults can recall events from their early years, but
only back to a certain point. Almost no one can accu-
rately recall events from the first three years of life, a
phenomenon called childhood amnesia. Consider a sig-
nificant event like the birth of a sibling. If the birth
occurred after you were 3 years old, you may have some
memory of it. But if the birth occurred before age 3, you
probably remember very little about it, if anything at all
(see Figure 1.2). Childhood amnesia is particularly strik-
ing because our first three years are so rich in experience:
We develop from helpless newborns to crawling, babbling
infants to walking, talking children. But these remarkable
transitions leave few traces in our memories.
Traits
(e.g.,
generous,
sensitive)
Situational
pressures
(e.g., pressure
from solicitor,
other people
watching)
Figure 1.1 Trait Attribution. In deciding whether another per-
son’s substantial donation to charity is caused by the giver’s
traits or by the situation, we are biased toward believing that a
trait was the critical factor. This illustrates the fundamental attri-
bution error.
THE SCOPE OF PSYCHOLOGY 5

Obesity
More than a quarter of U.S. adults are obese; their weight
is 30 percent or more above the level that would be
appropriate for their body structure and height. Obesity is
dangerous. It increases vulnerability to diabetes, high
blood pressure, and heart disease. Psychologists are
interested in what factors lead people to eat too much.
One factor seems to be a history of deprivation. If rats are
first deprived of food, then allowed to eat until they
return to their normal weight, and finally allowed to eat
as much as they want, they eat more than rats that have
no history of deprivation.
Effects of media violence on children’s aggression
The question of whether watching violence on television
causes children to be more aggressive has long been con-
troversial. Although many observers believe that televised
violence affects children’s behavior, others suggest that
watching violence has a cathartic effect. It may actually
reduce aggression by allowing children to express it
vicariously and ‘get it out of their system’. But research
evidence does not support the cathartic effect view. In one
experiment, one group of children watched violent car-
toons while another group watched nonviolent cartoons
for the same amount of time. Children who watched vio-
lent cartoons became more aggressive in their interactions
with peers, but the children who viewed nonviolent
0
5
10
15
1 – 3 3 – 5 5 – 7 7 – 9 9+
Mean
number
of
questions
answered
Subject’s age when sibling was born
Figure 1.2 Recall of an Early Memory. In an experiment on
childhood amnesia, college-age participants were asked 20
questions about the events surrounding the birth of a younger
sibling. The average number of questions answered is plotted as
a function of the participant’s age when the sibling was born. If
the birth occurred before the participant’s 4th year of life, no
participant could recall a thing about it; if the birth occurred after
that, recall increased with the participant’s age at the time of the
event. (K. Sheingold and Y. J. Tenney (1982) ‘Recall of An Early Memory
adapted from ‘Memory for a Salient Childhood Event’ from U. Neisser (ed.)
Memory Observed: Remembering in Natural Context, copyright © 1982
by W. H. Freeman & Company. Adapted by permission of the publisher.)
ª
KATI
NEUDERT
j
DREAMSTIME.COM
Psychologists are interested in what causes people to eat too
much. Among the possible causes they have studied are genetic
factors and environmental influences, such as a tendency to
overeat in the presence of certain stimuli.
Peer-rated
aggression
(10
years
later)
Viewing of violence in childhood
0
50
100
150
200
Low Moderate High
Figure 1.3 The Relationship Between Childhood Viewing of
Violent Television and Adult Aggression. A classic study
shows that preference for viewing violent TV programs by boys
at age 9 is related to aggressive behavior as rated by peers at
age 19. (L. Eron, et al. (1972) ‘Does Television Violence Cause
Aggression?’ American Psychologist, 27:253–262. Copyright © 1972 by
The American Psychological Association. Adapted by permission.)

cartoons showed no change in aggressive behavior. These
effects can persist over time: The more violent programs a
boy watches at age 9, the more aggressive he is likely to be
at age 19 (see Figure 1.3).
INTERIM SUMMARY
l Psychology touches on many aspects of our lives and
influences laws and public policy.
l To evaluate new claims made about psychology, you
need to know (1) what psychological facts are already
firmly established and (2) the standards for scientific
evidence.
l Psychology is the scientific study of behavior and mental
processes.
l The scope of psychology is broad, covering topics such
as face recognition, social judgments, memory, obesity,
violence, and many more.
CRITICAL THINKING QUESTIONS
1 Review the newspaper headlines about psychology
printed on page 4. Find an article in the newspaper or
on the Internet that covers psychological findings. Do
you believe what the news account claims? Why or why
not?
2 How do you know when to trust a news article? What
more would you need to know to accept as fact the
psychological claim you located?
THE HISTORICAL ORIGINS OF
PSYCHOLOGY
The roots of psychology can be traced to the great phi-
losophers of ancient Greece. The most famous of them,
Socrates, Plato, and Aristotle, posed fundamental ques-
tions about mental life: What is consciousness? Are peo-
ple inherently rational or irrational? Is there really such a
thing as free choice? These questions, and many similar
ones, are as important today as they were thousands of
years ago. They deal with the nature of the mind and
mental processes, which are the key elements of the cog-
nitive perspective in psychology.
Other psychological questions deal with the nature of
the body and human behavior, and they have an equally
long history. Hippocrates, often called the ‘father of
medicine’, lived around the same time as Socrates. He was
deeply interested in physiology, the study of the functions
of the living organism and its parts. He made many
important observations about how the brain controls
various organs of the body. These observations set the
stage for what became the biological perspective in
psychology.
Nature–nurture debate
One of the earliest debates about human psychology is
still raging today. This nature–nurture debate centers on
the question of whether human capabilities are inborn or
acquired through experience. The nature view holds that
human beings enter the world with an inborn store of
knowledge and understanding of reality. Early philoso-
phers believed that this knowledge and understanding
could be accessed through careful reasoning and intro-
spection. In the seventeenth century, Descartes supported
the nature view by arguing that some ideas (such as God,
the self, geometric axioms, perfection, and infinity) are
innate. Descartes is also notable for his conception of the
body as a machine that can be studied much as other
machines are studied. This is the root of modern
ª
BILL
ARON/PHOTOEDIT
Psychological studies provide evidence that violent television
programming may have harmful effects on young viewers.
THE HISTORICAL ORIGINS OF PSYCHOLOGY 7

information-processing perspectives on the mind, dis-
cussed later in this chapter.
The nurture view holds that knowledge is acquired
through experiences and interactions with the world.
Although some of the early Greek philosophers had
this opinion, it is most strongly associated with the
seventeenth-century English philosopher John Locke.
According to Locke, at birth the human mind is a tabula
rasa, a blank slate on which experience ‘writes’ knowl-
edge and understanding as the individual matures. This
perspective gave birth to associationist psychology. Asso-
ciationists denied that there were inborn ideas or capa-
bilities. Instead, they argued that the mind is filled with
ideas that enter by way of the senses and then become
associated through principles such as similarity and con-
trast. Current research on memory and learning is related
to early association theory.
The classic nature–nurture debate has become much
more nuanced in recent decades. Although some psy-
chologists still argue that human thought and behavior
result primarily from biology or primarily from experi-
ence, most psychologists take a more integrated
approach. They acknowledge that biological processes
(such as heredity or processes in the brain) affect
thoughts, feelings, and behavior, but say that experience
leaves its mark, too. So the current question is not
whether nature or nurture shapes human psychology but
rather how nature and nurture combine to do so (Plomin
& Asbury, 2005). The nature–nurture issue comes up at
numerous points in later chapters.
The beginnings of scientific psychology
Although philosophers and scholars continued to be
interested in the functioning of both the mind and the
body through the centuries, scientific psychology is usu-
ally considered to have begun in the late nineteenth cen-
tury, when Wilhelm Wundt established the first
psychological laboratory at the University of Leipzig in
Germany in 1879. The impetus for the establishment of
Wundt’s lab was the belief that mind and behavior, like
planets or chemicals or human organs, could be the
subject of scientific analysis. Wundt’s own research was
concerned primarily with the senses, especially vision, but
he and his coworkers also studied attention, emotion, and
memory.
Wundt relied on introspection to study mental pro-
cesses. Introspection refers to observing and recording the
nature of one’s own perceptions, thoughts, and feelings.
Examples of introspections include people’s reports of
how heavy they perceive an object to be and how bright a
flash of light seems to be. The introspective method was
inherited from philosophy, but Wundt added a new
dimension to the concept. Pure self-observation was not
sufficient; it had to be supplemented by experiments.
Wundt’s experiments systematically varied some physical
dimension of a stimulus, such as its intensity, and used the
introspective method to determine how these physical
changes modified the participant’s conscious experience
of the stimulus.
The reliance on introspection, particularly for very
rapid mental events, proved unworkable. Even after
extensive training, different people produced very differ-
ent introspections about simple sensory experiences, and
few conclusions could be drawn from these differences.
As a result, introspection is not a central part of the
current cognitive perspective. And, as we will see, some
psychologists’ reactions to introspection played a role in
the development of other modern perspectives.
Structuralism and functionalism
During the nineteenth century, chemistry and physics
made great advances by analyzing complex compounds
(molecules) into their elements (atoms). These successes
encouraged psychologists to look for the mental elements
that combined to create more complex experiences. Just
as chemists analyzed water into hydrogen and oxygen,
perhaps psychologists could analyze the taste of lemonade
(perception) into elements such as sweet, bitter, and cold
(sensations). The leading proponent of this approach in
the United States was E. B. Titchener, a Cornell University
ª
BETTMANN/CORBIS
The ancient Greek philosopher Socrates posed fundamental
questions about mental life. Many of these questions are as
important today as they were in Socrates’ time.

psychologist who had been trained by Wundt. Titchener
introduced the term structuralism – the analysis of mental
structures – to describe this branch of psychology.
But some psychologists opposed the purely analytic
nature of structuralism. William James, a distinguished
psychologist at Harvard University, felt that analyzing the
elements of consciousness was less important than
understanding its fluid, personal nature. His approach
was named functionalism, studying how the mind works
to enable an organism to adapt to and function in its
environment.
Nineteenth-century psychologists’ interest in adapta-
tion stemmed from the publication of Charles Darwin’s
theory of evolution. Some argued that consciousness had
evolved only because it served some purpose in guiding
the individual’s activities. To find out how an organism
adapts to its environment, functionalists said that psy-
chologists must observe actual behavior. However, both
structuralists and functionalists still regarded psychology
as the science of conscious experience.
Behaviorism
Structuralism and functionalism played important roles in
the early development of twentieth-century psychology.
Because each viewpoint provided a systematic approach
to the field, they were considered competing schools of
psychology. By 1920, however, both were being displaced
by three newer schools: behaviorism, Gestalt psychology,
and psychoanalysis.
Of the three, behaviorism had the greatest influence on
scientific psychology in North America. Its founder, John
B. Watson, reacted against the view that conscious
experience was the province of psychology. Watson made
no assertions about consciousness when he studied the
behavior of animals and infants. He decided not only that
animal psychology and child psychology could stand on
their own as sciences but also that they set a pattern that
adult psychology might follow.
For psychology to be a science, Watson believed,
psychological data must be open to public inspection like
the data of any other science. Behavior is public; con-
sciousness is private. Science should deal only with public
facts. Because psychologists were growing impatient with
introspection, the new behaviorism caught on rapidly,
and many younger psychologists in the United States
called themselves ‘behaviorists’. (The Russian physiolo-
gist Ivan Pavlov’s research on the conditioned response
was regarded as an important area of behavioral research,
but it was Watson who was responsible for behaviorism’s
widespread influence.)
Watson, and others ascribing to behaviorism, argued
that nearly all behavior is a result of conditioning and the
environment shapes behavior by reinforcing specific
habits. For example, giving children cookies to stop them
from whining reinforces (rewards) the habit of whining.
The conditioned response was viewed as the smallest unit
of behavior, from which more complicated behaviors
could be created. All types of complex behavior patterns
coming from special training or education were regarded
as nothing more than an interlinked fabric of conditioned
responses.
Behaviorists tended to discuss psychological phenom-
ena in terms of stimuli and responses, giving rise to the
term stimulus–response (S–R) psychology. Note, how-
ever, that S-R psychology itself is not a theory or per-
spective but a set of terms that can be used to
communicate psychological information. S–R terminol-
ogy is still sometimes used in psychology today.
Gestalt psychology
About 1912, at the same time that behaviorism was
catching on in the United States, Gestalt psychology was
appearing in Germany. Gestalt is a German word mean-
ing ‘form’ or ‘configuration’, which referred to the
approach taken by Max Wertheimer and his colleagues
Kurt Koffka and Wolfgang Köhler, all of whom eventu-
ally emigrated to the United States.
The Gestalt psychologists’ primary interest was per-
ception, and they believed that perceptual experiences
depend on the patterns formed by stimuli and on the
organization of experience. What we actually see is
related to the background against which an object
appears, as well as to other aspects of the overall pattern
of stimulation (see Chapter 5). The whole is different
from the sum of its parts, because the whole depends on
the relationships among the parts. For example, when
we look at Figure 1.4, we see it as a single large triangle –
as a single form or Gestalt – rather than as three small
angles.
ARCHIVES
OF
THE
HISTORY
OF
AMERICAN
PSYCHOLOGY,
THE
UNIVERSITY
OF
AKRON
Wilhelm Wundt established the first psychological laboratory at
the University of Leipzig. Here he is shown (third from left) in the
laboratory with his associates.

Among the key interests of Gestalt psychologists were
the perception of motion, how people judge size, and the
appearance of colors under changes in illumination.
These interests led them to a number of perception-cen-
tered interpretations of learning, memory, and problem
solving that helped lay the groundwork for current
research in cognitive psychology.
The Gestalt psychologists also influenced key founders
of modern social psychology – including Kurt Lewin,
Solomon Asch, and Fritz Heider – who expanded on
Gestalt principles to understand interpersonal phenomena
(Jones, 1998). For instance, Asch (1946) extended the
Gestalt notion that people see wholes rather than isolated
parts from the simple case of object perception to the
more complex case of person perception (Taylor, 1998).
Plus, they saw the process of imposing meaning and
structure on incoming stimuli as automatic and outside
conscious awareness, a Gestalt view that continues to
infuse contemporary research on social cognition to this
day (see Chapter 18; Moskowitz, Skurnik, & Galinsky,
1999).
Psychoanalysis
Psychoanalysis is both a theory of personality and a
method of psychotherapy originated by Sigmund Freud
around the turn of the twentieth century.
At the center of Freud’s theory is the concept of the
unconscious – the thoughts, attitudes, impulses, wishes,
motivations, and emotions of which we are unaware.
Freud believed that childhood’s unacceptable (forbidden
or punished) wishes are driven out of conscious aware-
ness and become part of the unconscious, where they
continue to influence our thoughts, feelings, and actions.
Unconscious thoughts are expressed in dreams, slips of
the tongue, and physical mannerisms. During therapy
with patients, Freud used the method of free association,
in which the patient was instructed to say whatever comes
to mind as a way of bringing unconscious wishes into
awareness. The analysis of dreams served the same
purpose.
In classical Freudian theory, the motivations behind
unconscious wishes almost always involved sex or
aggression. For this reason, Freud’s theory was not widely
William James, John B. Watson, and Sigmund Freud were key figures in the early history of psychology. James developed the
approach known as functionalism, Watson was the founder of behaviorism, and Freud originated the theory and method of
psychoanalysis. ª
BETTMANN/CORBIS
.
ª
BETTMANN/CORBIS
.
ª
CORBIS
Figure 1.4 A Gestalt Image. When we look at the three angles
of an equilateral triangle, we see a single large triangle rather than
three small angles.

accepted when it was first proposed. Contemporary
psychologists do not accept Freud’s theory in its entirety,
but they tend to agree that people’s ideas, goals,
and motives can at times operate outside conscious
awareness.
Later developments in twentieth-century
psychology
Despite the important contributions of Gestalt psychol-
ogy and psychoanalysis, until World War II psychology
was dominated by behaviorism, particularly in the United
States. After the war, interest in psychology increased.
Sophisticated instruments and electronic equipment
became available, and a wider range of problems could be
examined. It became evident that earlier theoretical
approaches were too restrictive.
This viewpoint was strengthened by the development
of computers in the 1950s. Computers were able to per-
form tasks – such as playing chess and proving mathe-
matical theorems – that previously could be done only by
human beings. They offered psychologists a powerful tool
for theorizing about psychological processes. In a series of
papers published in the late 1950s, Herbert Simon (who
was later awarded a Nobel prize) and his colleagues
described how psychological phenomena could be simu-
lated with a computer. Many psychological issues were
recast in terms of information-processing models, which
viewed human beings as processors of information and
provided a more dynamic approach to psychology than
behaviorism. Similarly, the information-processing
approach made it possible to formulate some of the ideas
of Gestalt psychology and psychoanalysis more precisely.
Earlier ideas about the nature of the mind could be
expressed in concrete terms and checked against actual
data. For example, we can think of the operation of
memory as analogous to the way a computer stores and
retrieves information. Just as a computer can transfer
information from temporary storage in its internal
memory chips (RAM) to more permanent storage on the
hard drive, so, too, our working memory can act as a way
station to long-term memory (Atkinson & Shiffrin,
1971a; Raaijmakers & Shiffrin, 1992).
Another important influence on psychology in the
1950s was the development of modern linguistics. Lin-
guists began to theorize about the mental structures
required to comprehend and speak a language. A pioneer
in this area was Noam Chomsky, whose book Syntactic
Structures, published in 1957, stimulated the first signif-
icant psychological analyses of language and the emer-
gence of the field of psycholinguistics.
At the same time, important advances were occurring
in neuropsychology. Discoveries about the brain and
nervous system revealed clear relationships between
neurological events and mental processes. In recent dec-
ades, advances in biomedical technology have enabled
rapid progress in research on these relationships. In 1981
Roger Sperry was awarded a Nobel prize for demon-
strating the links between specific regions of the brain and
particular thought and behavioral processes, which we
discuss in Chapter 2.
The development of information-processing models,
psycholinguistics, and neuropsychology has produced
an approach to psychology that is highly cognitive in
orientation. Although its principal concern is the sci-
entific analysis of mental processes and structures,
cognitive psychology is not exclusively concerned with
thought and knowledge. As illustrated throughout this
book, this approach has been expanded to many other
areas of psychology, including perception, motivation,
emotion, clinical psychology, personality, and social
psychology.
In sum, during the twentieth century the focus of
psychology came full circle. After rejecting conscious
experience as ill-suited to scientific investigation and
turning to the study of overt, observable behavior,
psychologists are once again theorizing about covert
aspects of the mind, this time with new and more pow-
erful tools.
INTERIM SUMMARY
l The roots of psychology can be traced to the 4th and
5th centuries B.C. One of the earliest debates about
human psychology focused on the question of whether
human capabilities are inborn or acquired through
experience (the nature–nurture debate).
l Scientific psychology was born in the late nineteenth
century with the idea that mind and behavior could be
the subject of scientific analysis. The first experimental
laboratory in psychology was established by Wilhelm
Wundt at the University of Leipzig in 1879.
l Among the early ‘schools’ of psychology in the twentieth
century were structuralism, functionalism, behaviorism,
Gestalt psychology, and psychoanalysis.
l Later developments in twentieth-century psychology
included information-processing theory,
psycholinguistics, and neuropsychology.
1 What assumptions about human nature underlie the
various historical approaches to psychology?
2 Considering these underlying assumptions, which of the
historical approaches are compatible with one another?
Which are incompatible?

CONTEMPORARY
PSYCHOLOGICAL PERSPECTIVES
What is a psychological perspective? Basically, it is an
approach, a way of looking at topics within psychology.
Any topic in psychology can be approached from different
perspectives. Indeed, this is true of any action a person
takes. Suppose that, following an insult, you punch
someone in the face. From a biological perspective, we can
describe this act as involving certain brain areas and as the
firing of nerves that activate the muscles that move your
arm. From a behavioral perspective, we can describe the
act without reference to anything within your body;
rather, the insult is a stimulus to which you respond by
punching, a learned response that has been rewarded in the
past. A cognitive perspective on this action would focus on
the mental processes involved in producing the behavior,
and we might explain your punch in terms of your goals
and plans: Your goal is to defend your honor, and
aggressive behavior is part of your plan for achieving that
goal. From a psychoanalytic perspective, your action could
be described as an expression of an unconscious aggressive
instinct. And finally, from a subjectivist perspective, your
aggressive act can be understood as a reaction to inter-
preting the person’s utterance as a personal insult.
Despite the many possible ways to describe any psy-
chological act, these five perspectives represent the major
approaches to the contemporary study of psychology (see
Figure 1.5). Because these five perspectives are discussed
throughout the book, here we provide only a brief
description of some main points for each of them. Keep in
mind that these approaches need not be mutually
exclusive; rather, they may focus on different aspects of
the same complex phenomenon. In fact, understanding
many psychological topics requires an eclectic approach
that spans multiple perspectives.
The biological perspective
The human brain contains well over 10 billion nerve cells
and an almost infinite number of interconnections
between them. It may be the most complex structure in
the universe. In principle, all psychological events can be
related to the activity of the brain and nervous system.
The biological approach to the study of human beings
and other species attempts to relate overt behavior to
electrical and chemical events taking place inside the
body. Research from the biological perspective seeks to
specify the neurobiological processes that underlie
behavior and mental processes. The biological approach
to depression, for example, tries to understand this dis-
order in terms of abnormal changes in levels of neuro-
transmitters, which are chemicals produced in the brain
that make communication between nerve cells possible.
We can use one of the problems described earlier to
illustrate this perspective. The study of face recognition in
patients with brain damage indicates that particular
regions of the brain are specialized for face recognition.
The human brain is divided into right and left hemi-
spheres, and the regions devoted to face recognition seem
PSYCHOLOGY
Cognitive
perspective
Behavioral
perspective
Biological
perspective
Subjectivist
perspective
Psycho-
analytic
perspective
Figure 1.5 Perspectives in Psychology. The analysis of psy-
chological phenomena can be approached from several per-
spectives. Each offers a somewhat different account of why
individuals act as they do, and each can make a contribution to
our conception of the total person. The Greek letter psi (c) is
sometimes used as an abbreviation for psychology.
ª
VOLKER
STEOER/PETER
ARNOLD,
INC.
By imaging the human brain during psychological tasks,
researchers learn which brain structures underlie the targeted
phenomena. Here we see a 3-dimensional representation of the
human brain while listening to speech obtained through func-
tional MRI (magnetic resonance imaging). Red indicates the
greatest areas of activation, whereas yellow indicates areas of
moderate activation. The neural activity is located in Wernicke’s
area of the brain. This approach illustrates a biological perspec-
tive on psychology.

to be located mainly in the right hemisphere. There is
considerable hemispheric specialization in humans. In
most right-handed people, for example, the left hemi-
sphere is specialized for understanding language, and the
right hemisphere is specialized for interpreting spatial
relations.
The biological perspective has also assisted in the
study of memory. It emphasizes the importance of certain
brain structures, including the hippocampus, which is
involved in consolidating memories. Childhood amnesia
may be partly due to an immature hippocampus, a
structure that is not fully developed until a year or two
after birth.
The behavioral perspective
As described in our brief review of the history of psy-
chology, the behavioral perspective focuses on observable
stimuli and responses and regards nearly all behavior as
a result of conditioning and reinforcement. For example,
a behavioral analysis of your social life might focus on
which people you interact with (the social stimuli), the
kinds of responses you make to them (rewarding, pun-
ishing, or neutral), the kinds of responses they in turn
make to you (rewarding, punishing, or neutral), and
how the responses sustain or disrupt the interaction.
We can use our sample problems to further illustrate
this approach. With regard to obesity, some people may
overeat (a specific response) only in the presence of spe-
cific stimuli (such as watching television), and learning to
avoid these stimuli is part of many weight-control pro-
grams. With regard to aggression, children are more likely
to express aggressive responses, such as hitting another
child, when such responses are rewarded (the other child
withdraws) than when their responses are punished (the
other child counterattacks).
Historically, the strict behavioral approach did not
consider the individual’s mental processes at all, and
even contemporary behaviorists usually do not conjecture
about the mental processes that intervene between the
stimulus and the response. Nevertheless, psychologists
other than strict behaviorists often record what people
say about their conscious experiences (a verbal self-
report) and draw inferences about their mental activity
from these subjective data. Although few psychologists
today would define themselves as strict behaviorists,
many modern developments in psychology have evolved
from the work of the earlier behaviorists (Malone, 2003;
Skinner, 1981).
The cognitive perspective
The contemporary cognitive perspective is in part a return
to the cognitive roots of psychology and in part a reaction
to the narrowness of behaviorism, which tended to
neglect complex human activities like reasoning, plan-
ning, decision making, and communication. Like the
nineteenth-century version, the contemporary cognitive
perspective is concerned with mental processes such as
ª
MARY
KATE
DENNY/PHOTOEDIT
If the aggressive child has her way and the other child yields the
swing, the aggressive behavior will be rewarded and the child will
be more likely to behave aggressively in the future. This exem-
plifies a behavioral perspective on psychology.
ª
MARTIN
KUCERA
j
DREAMSTIME.COM
Events that happen early in childhood usually are not remem-
bered. This little boy probably will not remember the events
surrounding the birth of his baby brother. An explanation that
illustrates the cognitive perspective on psychology emphasizes
the important role that language plays in organizing memories.
CONTEMPORARY PSYCHOLOGICAL PERSPECTIVES 13

perceiving, remembering, reasoning, deciding, and prob-
lem solving. Unlike the nineteenth-century version, how-
ever, the contemporary cognitive approach is not based
on introspection. Instead, it assumes that (1) only by
studying mental processes can we fully understand what
organisms do, and (2) we can study mental processes in
an objective fashion by focusing on specific behaviors
(just as behaviorists do) but interpreting them in terms of
underlying mental processes. In making these inter-
pretations, cognitive psychologists have often relied on an
analogy between the mind and a computer. Incoming
information is processed in various ways: It is selected,
compared, and combined with other information already
in memory, transformed, rearranged, and so on.
Consider the phenomenon of childhood amnesia
described at the beginning of the chapter. Perhaps we
cannot remember events from the first few years of life
because of a major developmental change in the way
we organize our experience in memory. Such changes
may be particularly pronounced at about age 3, when our
language abilities increase immensely, and language offers
us a new way of organizing our memories.
The psychoanalytic perspective
Sigmund Freud developed the psychoanalytic conception
of human behavior in Europe at about the same time that
behaviorism was evolving in the United States. In some
respects, psychoanalysis was a blend of the nineteenth-
century versions of cognition and physiology. In partic-
ular, Freud combined cognitive notions of consciousness,
perception, and memory with ideas about biologically
based instincts to forge a bold new theory of human
behavior.
The basic assumption of the psychoanalytic perspective
is that behavior stems from unconscious processes,
meaning beliefs, fears, and desires that a person is
unaware of but that nonetheless influence behavior.
Freud believed that many of the impulses that are for-
bidden or punished by parents and society during
ª
KACTUS
FOTOS/SUPERSTOCK
In this painting by M. Morales, a dream conveys unconscious desires. This illustrates the psychoanalytic perspective on psychology.

childhood are derived from innate instincts. Because each
of us is born with these impulses, they exert a pervasive
influence that must be dealt with in some manner. For-
bidding them merely forces them out of awareness into
the unconscious. They do not disappear, however. They
may manifest themselves as emotional problems and
symptoms of mental illness or as socially approved
behavior such as artistic and literary activity. For exam-
ple, if you feel a lot of anger toward your father but you
cannot afford to alienate him, your anger may become
unconscious, perhaps expressed in a dream about him
being hurt in an atrocious accident.
Freud believed that we are driven by the same basic
instincts as animals (primarily sex and aggression) and
that we are continually struggling against a society that
stresses the control of these impulses. The psychoanalytic
perspective suggests new ways of looking at some of the
problems described at the beginning of the chapter. For
example, Freud claimed that aggressive behavior stems
from an innate instinct. Although this proposal is not
widely accepted in human psychology, it is in agreement
with the views of some biologists and psychologists who
study aggression in animals.
The subjectivist perspective
The subjectivist perspective contends that human behavior
is a function of the perceived world, not the objective
world. Like the cognitive approach, the subjectivist per-
spective drew from the Gestalt tradition and reacted
against the narrowness of behaviorism. Although allied
with cognitive psychology, subjectivism has been most
pervasive within social and personality psychology. To
understand human social behavior, this view holds, we
must grasp the person’s own ‘definition of the situation’,
which is expected to vary by culture, personal history,
and current motivational state. This perspective, then, is
the most open to cultural and individual differences and
to the effects of motivation and emotion.
In one sense, the idea that people actively construct
their own subjective realities calls for introspective
methods. Even so, subjectivists do not rely exclusively on
subjective self-reports because they also assume that
people fail to see their subjective realities as personal
constructions. This naïve realism refers to people’s ten-
dency to take their constructed, subjective realities to be
faithful renderings of an objective world. Therefore, a
subjectivist approach also involves systematic observation
of judgments and behaviors. A subjectivist perspective is
illustrated by a classic early study that found that people
reliably overestimate the physical size of valuable coins,
more so than for coins of lower value. This tendency is
exaggerated among poor children (Bruner & Goodman,
1947; note that coins in general probably seemed much
more valuable in the 1940s!).
Consider again the problem of trait attribution.
The study of how people make sense of other people’s
actions – in the example mentioned earlier, donating
money to charity – emerged from a subjectivist emphasis
on how situations are defined by the people in them
(Heider, 1958). One contemporary explanation for the
pervasive tendency to attribute other people’s actions to
their personality traits suggests that, because Western cul-
tures have long emphasized personal agency, Westerners
often fail to see the influence of situations (Nisbett, Peng,
Choi, & Norenzayan, 2001; see Chapter 18). Likewise, a
subjectivist view of the link between media violence and
aggression suggests that habitual consumption of violent
media instills and strengthens aggressive schemas and
scripts, which are later used to define subsequent inter-
personal encounters (Anderson & Bushman, 2001).
Relationships between psychological
and biological perspectives
The behaviorist, cognitive, psychoanalytic, and sub-
jectivist perspectives all rely on concepts that are purely
psychological (such as perception, the unconscious, and
attributions). Although these perspectives sometimes offer
different explanations for the same phenomenon, those
explanations are always psychological in nature. The
biological perspective is different. In addition to using
psychological concepts, it employs concepts (such as
neurotransmitters and hormones) drawn from physiology
and other branches of biology.
There is a way, though, in which the biological per-
spective makes direct contact with the psychological
perspectives. Biologically oriented researchers attempt to
explain psychological concepts and principles in terms of
their biological counterparts. For example, researchers
might attempt to explain the normal ability to recognize
ª
JASMIN
KRPAN
j
DREAMSTIME.COM
Is this woman generous? Westerners have a strong tendency to
say, ‘Yes, she is’, making a trait attribution for her behavior. An
emphasis on how people perceive and interpret their social world
characterizes the subjectivist perspective.

faces solely in terms of neurons and their interconnections
in a certain region of the brain. Such attempts are termed
reductionism because they involve reducing psychological
notions to biological ones. Throughout this book, we
present examples of successful reductionism – situations
in which what was once understood at only the psycho-
logical level is now understood at least in part at the
biological level.
If reductionism can be successful, why bother with
psychological explanations at all? Is psychology just
something to do until the biologists figure everything out?
The answer is clearly no.
First, psychological findings, concepts, and principles
direct biological researchers in their work. Given that the
brain contains billions of brain cells and countless inter-
connections between these cells, biological researchers
cannot hope to find something of interest by arbitrarily
selecting some brain cells to study. Rather, they must have
a way of directing their efforts to relevant groups of brain
cells. Psychological findings can supply this direction. For
example, psychological research indicates that our ability
to discriminate among spoken words and our ability to
discriminate among spatial positions obey different
principles. So, biological psychologists might look in
different regions of the brain for the neural basis of these
two kinds of discrimination capacities (the left hemi-
sphere for word discrimination and the right hemisphere
for spatial-position discrimination). As another example,
if psychological research indicates that learning a motor
skill is a slow process that is hard to undo, biological
psychologists can direct their attention to brain processes
that are relatively slow but permanently alter connections
between neurons (Churchland & Sejnowski, 1988).
Second, our biology always acts in concert with our past
circumstances and current environment. For example,
obesity can be the result of (1) a genetic predisposition to
gain weight (a biological factor), (2) learning bad eating
habits (a psychological factor), or (3) a reaction to cultural
pressures toward extreme thinness (a sociocultural factor).
The biologist can seek to understand the first factor, but it
is still up to the psychologist to explore and explain the
past experiences and current circumstances that influence a
person’s eating habits.
Nevertheless, the push for reductionism goes on at an
ever-increasing rate. For many topics in psychology, we
now have both psychological explanations and knowl-
edge about how the relevant psychological concepts are
implemented or executed in the brain (for example, what
particular parts of the brain are involved and how they
are interconnected). This kind of biological knowledge
typically falls short of total reductionism, but it is still
very important. Memory researchers, for example, have
long distinguished between working memory and long-
term memory (which are psychological notions), but now
they also know something about how these two kinds of
memory are actually coded differently in the brain. So, for
many of the topics discussed in this book, we review what
is known at the biological level as well as at the psycho-
logical level.
Indeed, a central theme of this book – and of con-
temporary psychology in general – is that psychological
phenomena can be understood at both the psychological
and biological levels. The biological analysis shows us
how the psychological notions can be implemented in the
brain. Both levels of analysis are clearly needed (although
for some topics, including many dealing with social
interactions, biological analyses have only just begun).
Major subfields of psychology
So far, we have gained a general understanding of the
nature of psychology by looking at its topics and per-
spectives. We can further our understanding by looking at
what different kinds of psychologists do and at emerging
fields of emphasis in twenty-first-century psychology (see
the Cutting Edge Research feature).
About half the people who have advanced degrees in
psychology work in colleges and universities. In addition
to teaching, they may devote much of their time to
research or counseling. Other psychologists work in
schools, hospitals or clinics, research institutes, govern-
ment agencies, or business and industry. Still others are in
private practice and offer their services to the public for a
fee. We now turn to a brief description of some of the
subfields of psychology.
CONCEPT REVIEW TABLE
Five perspectives within psychology
Biological
perspective
An orientation toward understanding the neu-
robiological processes that underlie behavior
and mental processes.
Behavioral
perspective
An orientation toward understanding observ-
able behavior in terms of conditioning and
reinforcement.
Cognitive
perspective
An orientation toward understanding mental
processes such as perceiving, remembering,
reasoning, deciding, and problem solving and
their relationship to behavior.
Psychoanalytic
perspective
An orientation toward understanding behavior
in terms of unconscious motives stemming
from sexual and aggressive impulses.
Subjectivist
perspective
An orientation toward understanding behavior
and mental processes in terms of the subjec-
tive realities people actively construct.

Biological psychology
Biological psychologists (also referred to as physiological
psychologists) look for the relationship between biologi-
cal processes and behavior.
Cognitive psychology
Cognitive psychologists are concerned with people’s
internal mental processes, such as problem-solving,
memory, and language and thought.
Developmental psychology
Developmental psychologists are concerned with human
development and the factors that shape behavior from
birth to old age. They might study a specific ability, such
as how language develops in children, or a particular
period of life, such as infancy.
Social and personality psychology
These two subfields overlap. Social psychologists are
interested in how people perceive and interpret their
social world and how their beliefs, emotions, and
behaviors are influenced by the real or imagined presence
of others. They are also concerned with the behavior of
groups and with social relationships between and among
people. Personality psychologists study the thoughts,
emotions, and behaviors that define an individual’s per-
sonal style of interacting with the world. Accordingly,
they are interested in differences between individuals, and
they also attempt to synthesize all the psychological
processes into an integrated account of the total person
(Swann & Seyle, 2005).
Clinical and counseling psychology
Clinical psychologists are the largest group of psycholo-
gists. They apply psychological principles to the diagnosis
and treatment of emotional and behavioral problems,
including mental illness, drug addiction, and marital and
family conflict. Counseling psychologists perform many of
the same functions as clinical psychologists, although they
often deal with less serious problems. They frequently
work with high school or university students.
School and educational psychology
Because serious emotional problems often make their first
appearance in the early grades, many elementary schools
employ psychologists whose training combines courses in
child development, education, and clinical psychology.
These school psychologists work with children to evaluate
learning and emotional problems. In contrast, educational
psychologists are specialists in learning and teaching.
They may work in schools, but more often they work in a
university’s school of education, where they do research
on teaching methods and help train teachers.
Organizational and engineering psychology
Organizational psychologists (sometimes called industrial
psychologists) typically work for a company. They are
concerned with selecting people who are most suitable
for particular jobs or designing structures that facilitate
collaboration and teamwork. Engineering psychologists
(sometimes called human factors engineers) try to
improve the relationship between people and machines.
For instance, they improve human–machine interaction
by designing machines with the most efficient placement
of gauges and controls, which leads to better perfor-
mance, safety, and comfort.
INTERIM SUMMARY
l The study of psychology can be approached from
several perspectives. Five contemporary perspectives are
the biological perspective, the behavioral perspective, the
cognitive perspective, the psychoanalytic perspective,
and the subjectivist perspective.
l The biological perspective differs from the other
perspectives in that its principles are partly drawn from
biology. Biological researchers often attempt to explain
psychological principles in terms of biological ones; this
is known as reductionism.
l Among the major subfields of psychology are biological
psychology, cognitive psychology, developmental
psychology, social and personality psychology, clinical
and counseling psychology, school and educational
psychology, and organizational and engineering
psychology.
l Many new areas of inquiry, including cognitive
neuroscience (as well as affective neuroscience and
social cognitive neuroscience), evolutionary psychology,
cultural psychology, and positive psychology, span
traditional subfields and disciplines.
1 Consider the question, ‘What are the determinants of an
individual’s sexual orientation?’ How would the different
perspectives outlined in this chapter approach this
question?
2 Many of the new approaches to twenty-first-century
psychology (described in the Cutting Edge Research
box) integrate divergent perspectives or fill prior gaps in
the field. What other new advances might be on the
horizon in twenty-first-century psychology? That is,
what other opportunities for integrating perspectives
and filling gaps do you predict?

HOW PSYCHOLOGICAL
RESEARCH IS DONE
Now that we have some idea of the topics psychologists
study and their perspectives, we can consider the research
strategies they use to investigate them. In general, doing
research involves two steps: (1) generating a scientific
hypothesis and (2) testing that hypothesis.
Generating hypotheses
The first step in any research project is to generate a
hypothesis – a statement that can be tested – about the
topic of interest. Regarding childhood amnesia, for
example, we might generate the hypothesis that people
can retrieve more memories of their early life if they are
back in the same place where the incidents originally
occurred. How does a researcher arrive at such a
hypothesis? There is no single answer. An astute observer
CUTTING EDGE RESEARCH
Twenty-first-century psychology
Increasingly, psychologists span multiple subfields in their
research and also stretch beyond psychology to forge collab-
orations with researchers in other disciplines. These cross-area
and interdisciplinary approaches have gained considerable
momentum at the start of the twenty-first century and promise
to be very important in the next few decades. Of particular
interest are cognitive neuroscience, evolutionary psychology,
cultural psychology, and positive psychology. Here we briefly
describe each of these approaches, with examples of the kinds
of research being done in each field.
Cognitive neuroscience
Cognitive neuroscience focuses on cognitive processes and
relies heavily on the methods and findings of neuroscience (the
branch of biology that deals with the brain and nervous sys-
tem). In essence, cognitive neuroscience attempts to learn
how mental activities are executed in the brain. The key idea is
that cognitive psychology provides hypotheses about specific
cognitive capacities – such as recognizing faces – and neuro-
science supplies proposals about how these specific functions
might be executed in the brain.
What is particularly distinctive about cognitive neuroscience
is its reliance on new techniques for studying the brains of
normal participants (as opposed to brain-damaged ones) while
they are performing a cognitive task. These neuroimaging or
brain-scanning techniques create visual images of a brain in
action, with an indication of which regions of the brain show the
most neural activity during a particular task. An example is the
study of how people remember information for brief or long
periods. When people are asked to remember information for a
few seconds, neuroimaging results show increases in neural
activity in regions in the front of the brain. When they are asked
to remember information for a long period, there is increased
activity in an entirely different region, one closer to the middle of
the brain. Thus, different mechanisms seem to be used for the
short-term and long-term storage of information (Smith &
Jonides, 1994; Squire, Knowlton, & Musen, 1993).
The connection between psychology and neuroscience is
not limited to cognitive psychology. Psychologists have also
initiated affective neuroscience (Panksepp, 1998) to discover
how emotional phenomena are executed in the brain, as well as
social neuroscience (Ochsner & Lieberman, 2001) to discover
how stereotyping, attitudes, person perception, and self-
knowledge are executed in the brain.
Evolutionary psychology
Evolutionary psychology is concerned with the biological ori-
gins of psychological mechanisms. In addition to psychology
and biology, the other disciplines involved in this approach
include anthropology and psychiatry. The key idea behind
evolutionary psychology is that, like biological mechanisms,
psychological mechanisms must have evolved over millions
of years through a process of natural selection. As such,
evolutionary psychology holds that psychological mecha-
nisms have a genetic basis and in the past increased our
ancestors’ chances of surviving and reproducing. To illustrate,
consider a liking for sweets. Such a preference can be thought
of as a psychological mechanism, and it has a genetic basis.
Moreover, we have this preference because it increased our
ancestors’ chances of survival: The fruit that tasted the
sweetest had the highest nutritional value, so by eating it they
increased the chances of continued survival of the relevant
genes (Symons, 1992).
An evolutionary perspective can affect the study of psy-
chological issues in several ways (Ploeger, 2008). Certain
topics are of particular importance because of their link to
survival or successful reproduction. Such topics include how
we select our mates and how we think and behave when
experiencing particular emotions (Buss, 1991). An evolutionary
perspective can also provide new insights into familiar topics.
Concerning obesity, we noted earlier that a history of depriva-
tion can lead to overeating in the future. Evolutionary psychol-
ogy provides an interpretation of this puzzling phenomenon.
Until comparatively recently in human history, people experi-
enced deprivation only when food was scarce. An adaptive

of naturally occurring situations may have an advantage
in coming up with hypotheses. For example, you might
have noticed that you can remember more about your
high school years when you are back home, which could
generate such a hypothesis. It also helps to be very
familiar with the relevant scientific literature – previously
published books and articles about the topic of interest.
The most important source for scientific hypotheses,
however, is often a scientific theory, an interrelated set
of propositions about a particular phenomenon. For
example, one theory of sexual motivation (discussed in
Chapter 10) proposes a genetic predisposition toward
heterosexuality or homosexuality. This leads to the test-
able scientific hypothesis that pairs of identical twins –
who have identical genes – should be more likely to have
the same sexual orientation than pairs of fraternal twins,
who share only about half their genes. A competing
theory emphasizes childhood events as the source of an
individual’s sexual orientation and generates a competing
set of hypotheses that can also be tested. As we will see
mechanism for dealing with scarcity is overeating when food is
available. So, evolution may have favored individuals with a
tendency to overeat following deprivation.
Cultural psychology
Scientific psychology in the West has often assumed that people
in all cultures have exactly the same psychological processes.
Increasingly, this assumption is being challenged by proponents
of cultural psychology, an interdisciplinary movement of
psychologists, anthropologists, sociologists, and other social
scientists. Cultural psychology is concerned with how the cul-
ture in which an individual lives – its traditions, language, and
worldview – influences that person’s mental representations and
psychological processes.
Here is an example. In the West – North America and much of
western and northern Europe – we think of ourselves as separate
and autonomous agents with unique abilities and traits. In con-
trast, many cultures in the East – including those of India, China,
and Japan – emphasize the interrelationships among people
rather than their individuality. Moreover, Easterners tend to pay
more attention to social situations than Westerners do. These
differences lead Easterners to explain the behavior of another
person differently than do Westerners. Rather than explaining a
piece of behavior solely in terms of a person’s traits, Easterners
also explain it in terms of the social situation in which it occurred
(Nisbett et al., 2001). This has profound implications for trait
attribution, one of the sample problems discussed at the
beginning of the chapter. These differences between East and
West in explaining behavior can also have educational implica-
tions. Because of their emphasis on collectivism rather than
individualism, Asian students tend to study together more than
American students. Such group study may be a useful tech-
nique, and it may be part of the reason why Asian students
outperform their American counterparts in math. In addition,
when an American student is having difficulty in math, both the
student and the teacher tend to attribute the difficulty to the
student’s individual abilities. When a comparable case arises in a
Japanese school, student and teacher are more likely to look to
the situation – the student–teacher interaction in the instructional
context – for an explanation of the poor performance (Stevenson,
Lee, & Graham, 1993).
Positive psychology
After World War II, psychology – especially clinical psychology –
became a science devoted to healing. It adopted a disease
model of human functioning from the medical sciences and
aimed to cure pathologies. Although this focus produced tre-
mendous advances in the field’s understanding and treatment of
mental illness (see Chapters 15 and 16), it had little to say about
what makes life worth living. Positive psychology emerged to
balance the field’s sophisticated scientific understanding of
mental illness with an equally sophisticated scientific under-
standing of human flourishing (Seligman, 2002). Although posi-
tive psychology shares with the earlier humanistic psychology a
concern with people’s development toward their full potential, it
departs from humanistic psychology by relying heavily on
empirical methods.
Positive psychology targets psychological phenomena at
levels ranging from the study of positive subjective experiences,
such as happiness and optimism, to the study of positive per-
sonality traits, such as courage and wisdom, and the study of
positive institutions – social structures that might cultivate civility
and responsible citizenship (Seligman & Csikszentmihalyi, 2000).
An example that combines the first two levels of analysis comes
from current research on positive emotions (see Chapter 11).
Unlike negative emotions, which narrow people’s ideas about
action (e.g., fight or flight), positive emotions have been found to
broaden people’s mindsets, encouraging them to discover novel
lines of thought or action. Joy, for instance, creates the urge to
play, and interest creates the urge to explore. A key incidental
outcome of these broadened mindsets is an increase in personal
resources: As individuals discover new ideas and actions, they
build physical, intellectual, social, and psychological resources.
Empirical studies support this new broaden-and-build theory of
positive emotions, showing that – through their effects on
broadened thinking – positive emotions fuel growth-positive
personality traits such as resilience and optimism (Fredrickson,
2001). The take-home message for positive psychology is that
positive emotions are worth cultivating, not just as end states in
themselves but also as a means of triggering upward spirals
toward psychological growth and flourishing.
HOW PSYCHOLOGICAL RESEARCH IS DONE 19

throughout this book, testing hypotheses derived from
competing theories is one of the most powerful ways of
advancing scientific knowledge.
The term scientific means that the research methods
used to collect the data are (1) unbiased (do not favor one
hypothesis over another) and (2) reliable (other qualified
people can repeat the observations and obtain the same
results). The methods considered in this section have these
two characteristics. Although some are better suited to
certain perspectives than to others, each method can be
used with each perspective.
Experiments
The most powerful scientific method is the experiment.
Experiments provide the strongest tests of hypotheses
about cause and effect. The investigator carefully controls
conditions – often in a laboratory – and takes measure-
ments in order to discover the causal relationships among
variables. A variable is something that can occur with
different values (see Concept Review Table: Terminology
of experimental research). For example, an experiment
might explore whether the amount of sleep causes mem-
ory changes (does recall of childhood events decrease with
lack of sleep?). If an experiment shows that memory
performance changes systematically with hours of sleep,
an orderly causal relationship between these two varia-
bles has been found.
The ability to exercise precise control over a variable
distinguishes the experimental method from other meth-
ods of scientific observation. For example, if the
hypothesis is that individuals will perform better on a
math problem if they are offered more money for a good
performance, the experimenter might randomly assign
participants to one of three conditions: One group is told
that they will be paid €10 if they perform well, the second
group is promised €5, and the third group is not offered
any money. The experimenter then measures and com-
pares the performance of all three groups to see if, in fact,
more money (the hypothesized cause) produces better
performance (the hypothesized effect).
In this experiment, the amount of money offered is the
independent variable because it is a variable that is
independent of what the participant does. In fact, the
independent variable is under the complete control of the
experimenter, who creates it and controls its variation.
In an experiment, the independent variable represents
the hypothesized ‘cause’. The hypothesized ‘effect’ in an
experiment is the dependent variable because it is
hypothesized to depend on the value of the independent
variable. In this experiment, the dependent variable is
performance on the math problems. The experimenter
manipulates the independent variable and observes the
dependent variable to learn the outcome of the experi-
ment. The dependent variable is almost always some
measure of the participants’ behavior. The phrase ‘is a
function of’ is often used to express the dependence
of one variable on another. For this experiment, we
could say that the participants’ performance on the math
problems is a function of the amount of money
offered. The groups that are paid money would be the
experimental groups, or groups in which the hypothesized
cause is present. The group that was not paid would be
the control group, the group in which the hypothesized
cause is absent. In general, a control group serves as a
baseline against which experimental groups can be
compared.
One important feature of the experiment just described
is random assignment of participants to groups or con-
ditions. Random assignment means that each participant
has an equal probability of being placed in any group.
Without random assignment, the experimenter cannot be
certain that something other than the independent vari-
able might have produced the results. For example, an
experimenter should never let participants choose which
group they would like to be in. Although most partic-
ipants might choose to be in the highest-paid group, those
who are made nervous by pressure might choose to be in
a ‘casual’ group that was not paid. In any case, the
problem is that the groups would now contain different
kinds of people, and the differences in their personalities,
rather than the amount of money offered, might cause
one group to do better than another. Or suppose that an
experimenter runs all the paid groups first and runs the
no-payment control group afterward. This introduces a
host of potential problems. Perhaps performance varies as
a function of the time of day (morning, afternoon, or
evening); maybe those who participate later in the
experiment are closer in time to their final exams than
earlier participants. In addition to these uncontrolled
variables, many others of which the experimenter is
unaware might bias the results. All such problems are
resolved by randomly assigning participants to con-
ditions. Only with random assignment can we be certain
that all extraneous variables – such as participant per-
sonality, time of day, or time of semester – are evenly
represented across conditions and therefore unlikely to
introduce bias. Random assignment is one of the most
important ingredients of an experiment.
The experimental method can be used outside the
laboratory as well. For example, in research on obesity,
the effects of different methods of weight control can be
investigated by trying these methods on separate but
similar groups of obese individuals. The experimental
method is a matter of logic, not location. Still, most
experiments take place in laboratories, chiefly because a
laboratory setting allows measuring behavior more pre-
cisely and controlling the variables more completely. And
again, it is often random assignment that is at issue: If two
obesity clinics use different methods and achieve different
results, we cannot conclude with confidence that the
different methods are responsible because the clinics

might attract different kinds of people to their programs
or have different staff cultures and expectations.
The experiments described so far examine the effect of
one independent variable on one dependent variable.
Limiting an investigation to only one independent vari-
able, however, is too restrictive for some problems.
Multivariate experiment – experiments manipulating sev-
eral independent variables at once – are common in
psychological research. In the hypothetical study in which
participants were offered different amounts of money for
solving math problems, the experimenter might also vary
the level of difficulty of the problems. Now there would
be six groups of participants, each combining one of three
different amounts of money with one of two levels of
difficulty (easy versus difficult).
Measurement
Psychologists using the experimental method often have
to make statements about amounts or quantities. Some-
times variables can be measured by physical means, such
as hours of sleep deprivation or dosage of a drug. At other
times, variables have to be scaled in a manner that places
them in some sort of order. In rating a patient’s feelings of
aggression, for example, a psychotherapist might use a
5-point scale ranging from never through rarely, some-
times, and often to always. For purposes of precise
communication, experiments require some form of mea-
surement, a system for assigning numbers to variables.
Experiments usually involve making measurements on
many participants, not just one. The results therefore are
data in the form of a set of numbers that can be sum-
marized and interpreted. To accomplish this task, the
experimenter needs to use statistics, the discipline that
deals with sampling data from a population of individuals
and then drawing inferences about the population from
those data. Statistics plays an important role not only in
experimental research but in other methods as well.3
The
most common statistic is the mean, which is simply the
technical term for an arithmetic average, the sum of a set
of scores divided by the number of scores in the set. In
studies with one experimental group and one control
group, there are two means to be compared: a mean for
the scores of the participants in the experimental group
and a mean for the scores of the participants in the
control group. The difference between these two means is,
of course, what interests the experimenters. If the differ-
ence between the means is large, it can be accepted at
face value. But what if the difference is small? What if
the measures used are subject to error? What if a few
extreme cases are producing the difference? Statisticians
have solved these problems by developing tests for deter-
mining the significance of a difference. A psychologist who
says that the difference between the experimental group
and the control group has statistical significance means that
a statistical test has been applied to the data and the
observed difference is unlikely to have arisen by chance or
because of a few extreme cases.
Correlation
Not all problems can be easily studied by using the
experimental method. In many situations the investigator
has no control over which participants go in which con-
ditions. For example, if we want to test the hypothesis
that anorexic people are more sensitive to changes in taste
than normal-weight people, we cannot select a group of
normal-weight participants and require half of them to
become anorexic! Rather, we select people who are
already anorexic or already of normal weight and see if
CONCEPT REVIEW TABLE
Terminology of experimental research
Hypothesis A statement about cause and effect that can be
tested.
Experiment A well-controlled test of a hypothesis about
cause and effect.
Variable Something that can occur with different values
and can be measured.
Independent
variable
A variable that represents the hypothesized
‘cause’ that is precisely controlled by the
experimenter and independent of what the par-
ticipant does.
Dependent
variable
A variable that represents the hypothesized
‘effect’ whose values ultimately depend on the
value of the independent variable.
Experimental
group
A group in which the hypothesized cause is
present.
Control group A group in which the hypothesized cause is
absent.
Random
assignment
A system for assigning participants to experi-
mental and control groups so that each partici-
pant has an equal chance of being assigned to
any group.
Measurement A system for assigning numbers to different
values of variables.
Statistics Mathematical techniques for determining the
certainty with which a sample of data can be
used to draw generalizations or inferences.
3
This discussion is designed to introduce the experimental tools of
measurement and statistics. A more thorough discussion is provided in
the Appendix.

they also differ in taste sensitivity. More generally, we can
use the correlational method to determine whether some
variable that is not under our control is associated – or
correlated – with another variable of interest.
In the example just given, there were only two values
of the weight variable: anorexic and normal. It is more
common to have many values of each variable and to
determine the degree to which values on one variable are
related to values on another. This is done by using a
descriptive statistic called the correlation coefficient, an
estimate of the degree to which two variables are related.
The correlation coefficient, symbolized by r, is expressed
as a number between 1.00 and þ1.00. A perfect rela-
tionship – which is rare – is indicated by 1.00 (1.00 if the
relationship is positive and 1.00 if the relationship is
negative). No relationship at all is indicated by a corre-
lation close to zero. As r goes from 0 to 1.00 (or from 0 to
1.00), the strength of the relationship increases.
A correlation can be either þ or . The sign of the
correlation indicates whether the two variables are posi-
tively correlated, meaning that the values of the two vari-
ables either increase together or decrease together, or
negatively correlated, meaning that as the value of one
variable increases, the value of the other decreases. Sup-
pose that the number of times a student is absent from
class correlates .40 with the final course grade (the more
absences, the lower the grade). On the other hand, the
correlation between the number of classes attended and
the course grade would be þ.40. The strength of the
relationship is the same, but the sign indicates whether we
are looking at classes missed or classes attended.4
To get a clearer picture of a correlation coefficient,
consider the hypothetical study presented in Figure 1.6.
As shown in Figure 1.6a, the study involves patients with
brain damage leading to problems in face recognition
(prosopagnosia). What is of interest is whether the degree
of deficit, or error, in face recognition increases with
the amount of brain tissue that is damaged. Each point on
the graph in Figure 1.6a represents the percentage of
errors made by one patient on a test of face recognition.
For example, a patient who had only 10% brain damage
The patients are ordered along the
horizontal axis with respect to the
amount of brain damage, with the
patient represented by the leftmost
point having the least brain damage
(10%) and the patient represented
by the rightmost point having the
most brain damage (55%). Each
point on the graph represents a
single patient’s score on a test of
face recognition. The correlation is
a positive .90.
0
20
40
60
80
100
10 20 30 40 50 60
0
a) Positive correlation
Percent
errors
in
face
recognition
Percentage of brain damage
in critical regions
0
20
40
60
80
100
10 20 30 40 50 60
0
b) Negative correlation
Percent
correct
in
face
recognition
Percentage of brain damage
in critical regions
The patients’ performance on
the face recognition test is
graphed as a function of their
height. Now the correlation
is 0.
The same data are depicted, but
we now focus on the percentage
of correct responses (rather than
errors). Now the correlation is a
negative .90.
0
20
40
60
80
100
64 66 68 70 72
c) Zero correlation
Percent
errors
in
face
recognition
Height of patient
(inches)
Figure 1.6 Scatter Diagrams Illustrating Correlations. These hypothesized data are based on 10 patients, all of whom have some
damage in regions of the brain known to be involved in face recognition.
4
The numerical method for calculating a correlation coefficient is
described in the Appendix.

made 15% errors on the face-recognition test, but a
patient who had 55% brain damage made 75% errors. If
errors in face recognition always increased along with the
amount of brain damage, the points in the graph would
consistently increase in moving from left to right; if the
points had all fallen on the diagonal line in the figure, the
correlation would have been r 1.0 – a perfect correlation.
A couple of points fall on either side of the line, though,
so the correlation is about .90. Such a high correlation
indicates a very strong relationship between amount
of the brain damage and errors in face recognition. In
Figure 1.6a, the correlation is positive because more
errors are associated with more brain damage.
If, instead of focusing on errors, we plot the percentage
of correct responses on the face recognition test, we end up
with the diagram in Figure 1.6b. Now the correlation is
negative – about .90 – because fewer correct responses
are associated with more brain damage. The diagonal
line in Figure 1.6b is simply the inverse of the one in
Figure 1.6a.
Finally, consider the diagram in Figure 1.6c. Here we
have graphed errors on the face recognition test as a
function of the patients’ height. Of course, there is no
reason to expect a relationship between height and face
recognition, and the graph shows that there is none. The
points neither consistently increase nor consistently
decrease in moving from left to right but rather bounce
around a horizontal line. The correlation is 0.
In psychological research, a correlation coefficient of
.60 or more is considered quite high. Correlations in the
range from .20 to .60 are of practical and theoretical
value and are useful in making predictions. Correlations
between 0 and .20 must be judged with caution and are
only minimally useful in making predictions.
Tests
The familiar use of the correlational method involves tests
that measure aptitudes, achievement, or other psycho-
logical traits, such as the test of face recognition just
discussed. A test presents a uniform situation to a group
of people who vary in a particular trait (such as brain
damage, math ability, manual dexterity, or aggression).
The variation in scores on the test can be correlated with
variations on another variable. For example, people’s
scores on a test of math ability can be correlated with
their subsequent grades in a college math course. If the
correlation is high, then the test score may be used to
determine which of a new group of students should be
placed in advanced sections of the course.
Correlation and causation
There is an important distinction between experimental
and correlational studies. In a typical experimental study,
one variable (the independent variable) is systematically
manipulated to determine its causal effect on some other
variable (the dependent variable). Such cause-and-effect
relationships cannot be inferred from correlational
studies.
For instance, studies have shown that the more TV
violence a young boy watches, the more aggressive he is.
But does watching violent TV cause the aggression, or do
more aggressive boys choose to watch more violent TV? If
all we have is a correlation, we cannot say which variable
is cause and which is effect. (As noted earlier in the
chapter, however, other studies do demonstrate a causal
relationship between watching violent TV and behaving
aggressively. Experimenters had control over the inde-
pendent variable and used random assignment of partic-
ipants to conditions.)
Two variables can also be correlated when neither is
the cause of the other. For example, many years before
careful medical experiments demonstrated that cigarette
smoking causes cancer, a correlation between smoking
and lung cancer was shown. That is, it was already
known that people who smoked were more likely to
contract cancer. But – as the tobacco companies rushed to
point out – this correlation left open the possibility that
some third cause was responsible. For example, if people
who live in smoggy urban areas are more likely to smoke
than people who live in rural areas with cleaner air, then
air pollution rather than smoking could cause higher
cancer rates in smokers.
In short, when two variables are correlated, variation
in one of them may possibly be the cause of variation in
the other. Indeed, correlation is a prerequisite for causa-
tion. But, without further experiments, no such conclu-
sion is justified from correlational studies, because
correlation does not necessarily imply causation.
Observation
Direct observation
In the early stages of research, the most efficient way of
making progress toward an explanation may be direct
observation – to simply observe the phenomenon under
study as it occurs naturally. Careful observation of ani-
mal and human behavior is the starting point for a great
deal of research in psychology. For example, observation
of primates in their native environment may tell us things
about their social organization that will help in later
laboratory investigations. Video recordings of newborn
babies reveal details of their activity shortly after birth
and the types of stimuli to which they respond. However,
investigators observing naturally occurring behavior
must be trained to observe and record events accurately
so that their own biases do not influence what they
report.
Observational methods may be used in a laboratory
if the problem being studied is partly biological. For
example, in their classic study of the physiological
aspects of human sexuality, William Masters and Virginia

Johnson (1966) developed techniques for directly
observing sexual responses in the laboratory. The data
included (1) observations of behavior, (2) recordings of
physiological changes, and (3) responses to questions
about the participants’ sensations before, during, and
after sexual stimulation. Although the researchers agreed
that human sexuality has many dimensions besides the
biological one, their observations of the anatomical and
physiological aspects of sexual response have been very
helpful in understanding the nature of human sexuality,
as well as in solving sexual problems.
The survey method
Some problems that are difficult to study by direct
observation may be studied by indirect observation
through the use of questionnaires or interviews. Rather
than observe people engaging in a particular behavior,
such as exercising regularly, researchers using the survey
method simply ask people if they engage in the behavior of
interest. The survey method is more open to bias than
direct observation, however. Of particular concern are
social desirability effects, which occur when some people
try to present themselves in a favorable light (for example,
by saying that they exercise more than they actually do).
Still, the survey method has produced many important
results. For example, before Masters and Johnson con-
ducted their research on the human sexual response, most
of the available information on how people behave sex-
ually (as opposed to how laws, religion, or society said
they should behave) came from extensive surveys
conducted by Alfred Kinsey and his associates twenty
years earlier. Information from thousands of interviews
was analyzed, resulting in the publication of two pio-
neering works: Sexual Behavior in the Human Male
(Kinsey, Pomeroy, Martin, 1948) and Sexual Behavior
in the Human Female (Kinsey, Pomeroy, Martin,
Gebhard, 1953).
Surveys have also been used to discover people’s
political opinions, product preferences, health care needs,
and so on. The Gallup poll and the U.S. census are
probably the most familiar surveys. An adequate survey
requires presenting a carefully pretested questionnaire to
a sample of people who have been selected by methods
designed to ensure that they are representative of the
larger population being studied.
Case histories
Still another form of indirect observation is to obtain a
case history, which is a partial biography of a particular
individual. This involves asking people to recall relevant
experiences from their past. For example, if the research is
concerned with the childhood antecedents of adult
depression, the researcher might begin by asking questions
about earlier life events. These case histories are biogra-
phies designed for scientific use, and they are important
sources of data for psychologists who are studying
individuals.
A major limitation of case histories is that they rely on a
person’s memories and reconstructions of earlier events,
which are frequently distorted or incomplete. Sometimes
other data can be used to corroborate information obtained
in a case history. For example, written records, such as
death certificates, can be used to check on specific dates, or
relatives of the person being interviewed can be asked to
report their own memories of the relevant events. Even so,
their limitations make case histories less useful for testing a
theory or hypothesis than for suggesting hypotheses that
can then be tested in more rigorous ways or checked with a
larger sample of participants. In this way, scientists use the
case history in much the same way that a therapist or
physician might when trying to formulate a diagnosis and
treatment for a particular individual.
Literature reviews
One final way in which psychological research is done is
by conducting literature reviews. A literature review is a
scholarly summary of the existing body of research on
a given topic. Because the field of psychology grows at a
fast pace, an up-to-date literature review is an indis-
pensable tool for assessing patterns within the accumu-
lating scientific evidence for a particular psychological
hypothesis or theory.
Literature reviews come in two forms. One form is a
narrative review, in which authors use words to describe
Field studies can often tell us more about social behavior than
experimental studies can. Professor Shirley Strum has been
observing the same troop of baboons in Kenya for more than
20 years, identifying individual animals, and making daily
recordings of their behaviors and social interactions. Her data
have provided remarkable information about the mental
abilities of baboons and the role of friendships in their social
system.

studies previously conducted and discuss the strength of
the available psychological evidence. College students
enrolled in upper-level psychology courses often write
narrative reviews of a chosen topic for term papers.
Another type of review, which has become increasingly
popular, is a meta-analysis, in which authors use statisti-
cal techniques to combine and draw conclusions about
studies previously conducted. In any given experiment, as
we have seen, participants are treated as ‘cases’, with each
participant contributing his or her own unique
data, which are then summarized statistically. In a meta-
analysis, by contrast, individual studies are treated as
‘cases’, with each study contributing its own unique
summary data, which are then further summarized at a
higher – or meta – level of analysis. As you might imag-
ine, meta-analyses have the potential to be more system-
atic and evenhanded than narrative reviews. Throughout
this book, we often rely on meta-analyses to describe the
state of the evidence for psychological theories and
hypotheses.
Ethics of psychological research
Because psychologists study living beings, they need to be
sensitive to ethical issues that can arise in the conduct of
research. Accordingly, the American Psychological Asso-
ciation (APA) and its counterparts in Canada and Great
Britain have established guidelines for the treatment of
both human participants and animal subjects (American
Psychological Association, 1990). In the United States,
federal regulations require any institution that conducts
federally funded research to establish an internal review
board, which reviews proposed studies to ensure that
participants will be treated properly.
Research with humans
The first principle governing the ethical treatment of
human participants is minimal risk. In most cases, the risks
anticipated in the research should be no greater than
those ordinarily encountered in daily life. Obviously, a
person should not be exposed to physical harm or injury,
but deciding how much psychological stress is ethically
justified in a research project is not always so clear-cut. In
everyday life, of course, people may be impolite, lie, or
make other people anxious. Under what circumstances is
it ethically justifiable for a researcher to treat a participant
in such ways to meet the goals of a research project?
These are the kinds of questions that review boards
consider on a case-by-case basis.
The second principle governing the ethical treatment of
human participants is informed consent. Participants must
be told ahead of time about any aspects of the study that
could influence their willingness to cooperate and, after
this disclosure, they must enter the study voluntarily and
be permitted to withdraw from it at any time they desire
without penalty. Like the principle of minimal risk,
informed consent is not always easy to implement. In
particular, informed consent is sometimes at odds with
another common requirement of research: that partic-
ipants be unaware of the hypotheses being tested in a
study. If a researcher plans to compare participants who
learn lists of familiar words with participants who learn
lists of unfamiliar words, no ethical problem arises by
simply telling participants ahead of time that they will be
learning lists of words: They do not need to know how the
words vary from one participant to another. Nor are any
serious ethical issues raised if participants are given a
surprise quiz they did not expect. But what if the
researcher wants to compare participants who learn
words while in a neutral mood with participants who
learn words while they are angry or embarrassed? Clearly
the research would not yield valid conclusions if partic-
ipants had to be told ahead of time that they would be
intentionally angered (by being treated rudely) or embar-
rassed (by being led to believe that they had accidentally
broken a piece of equipment). Accordingly, the guidelines
specify that if such a study is permitted to proceed at all,
participants must be debriefed about it as soon as possible
afterwards. During debriefing, the reasons for keeping
them in ignorance – or deceiving them – about the pro-
cedures must be explained, and any residual emotional
reactions must be dealt with so that participants leave with
their dignity intact and their appreciation for the research
enhanced. The review board must be convinced that the
debriefing procedures are adequate to this task.
A third principle of ethical research is the right to
privacy. Information about a person acquired during a
study must be kept confidential and not made available to
others without the research participant’s consent. A
common practice is to separate the names and other
information used to identify participants from the data
collected in the study. The data are then identified only by
ª
MICHAEL
NEWMAN/PHOTOEDIT/PICTUREQUEST
Survey researchers ask individuals or, as in this case, a mother
and son about their attitudes and behavior. For survey results to
be valid, the respondents must be representative of the larger
population being studied.

SEEING BOTH SIDES
ARE WE NATURALLY SELFISH?
We are naturally selfish
George C. Williams, State University of New York,
Stony Brook
Yes we are selfish, in a special biological sense, but an important
one that should be borne in mind in discussing human affairs,
ethical philosophy, and related topics (Williams, 1996: Chs. 3
9). We are selfish in the special way that our genes demand.
They are maximally selfish because, if they were not, they would
not exist. The genes that get passed on through many gen-
erations are those that are best at getting themselves passed on.
To do this they must be better than any alternatives at making
bodies, human or otherwise, that transmit genes more profusely
than other members of their population. Individuals can win this
genetic contest mainly by surviving to maturity and then com-
peting successfully for the resources (food, nest sites, mates,
etc.) needed for their own reproduction.
In this sense we are necessarily selfish, but this need not
imply that we are never expected to be unselfish in the sense in
which this term is normally understood. Individuals can and often
do assist others in gaining resources and avoiding losses or
dangers. For a biological understanding of such behavior, the
important observations lie in the circumstances in which the
apparent benevolence occurs. The most obvious example of
helpful behavior is that performed by parents for their own off-
spring. Its obvious explanation is that parents would not suc-
cessfully transmit their genes if they did not help their own young
in special ways: mammalian mothers must nurse their babies;
birds must bring food to their nestlings; a plant must pack an
optimum quantity of nutrients into each of its seeds. Yet this kind
of provisioning is never a generalized helpfulness of adults
toward young. There are always mechanisms at work by which
parents can usually identify their own offspring and confine their
helpfulness to them alone.
If all reproduction is sexual and mates are seldom closely
related to each other, each offspring has half of each parent’s
genes. From a parent’s perspective, a son or daughter is
genetically half as important as itself, and an offspring’s repro-
duction is half as important as its own, for getting genes trans-
mitted. Yet the same kind of partial genetic identity is true of all
relatives, not just offspring. It may serve the genetic selfishness of
an individual to behave helpfully toward relatives in general, not
merely offspring. Such behavior arises from what is termed kin
selection, natural selection for the adaptive use of cues that
indicate degrees and probabilities of relationship. To whatever
extent there is evidence of genealogical connections, an indi-
vidual is expected to favor relatives over nonrelatives and close
relatives (parents, offspring, siblings) over more distant ones.
A male bird whose mate laid eggs in his nest can be favored
in evolution if he incubates the eggs and feeds the later hatch-
lings. But what about possible cuckoldry? Can he really be sure
that his mate was not inseminated by a neighboring male so that
one or more of those eggs are not actually his own offspring?
Extra-pair mating by female birds, with or without consent, does
happen in many species. Males in such species are especially
watchful of their mates’ behavior and diligent in chasing rival
males from their territories. It is expected that males, in species in
which an average of 10 percent of the eggs are fertilized by rivals,
will be less conscientious toward their nestlings than in species in
which cuckoldry never happens. Kin selection is one factor that
causes what looks like unselfish behavior. Reciprocation
between unrelated individuals, with immediate or likely future
profit to each participant, is another. So is that which is caused
by the selfish deception or manipulation of another’s kin-selected
or other altruistic or cooperative instincts. Female birds, like
males, cannot be certain that nestlings are their own, because
egg dumping (Sayler, 1992), the laying of an egg in another
bird’s nest while its owner is briefly away feeding, happens in
many species. One female gains genetically by exploiting the
parental instincts of another. The
species in which deception and
manipulation are most extensively
developed is our own, by virtue of our
language capability. Henry V, accord-
ing to Shakespeare, addressed his
army as ‘We band of brothers’. Fem-
inist leaders speak of the ‘sisterhood’.
Deception and manipulation of others’
emotions can, of course, be for either
a worthy or an unworthy cause.
George C. Williams

SEEING BOTH SIDES
ARE WE NATURALLY SELFISH?
We are not naturally selfish
Frans B. M. de Waal, Emory University
‘How selfish soever man may be supposed, there are
evidently some principles in his nature, which interest him
in the fortune of others, and render their happiness necessary
to him, though he derives nothing from it, except the pleasure
of seeing it.’
Adam Smith, 1759
When Lenny Skutnik dove into the icy Potomac in Washington,
DC, in 1982, to rescue a plane-crash victim, or when Dutch
civilians sheltered Jewish families during World War II, life-
threatening risks were taken on behalf of complete strangers.
Similarly, Binti Jua, a lowland gorilla at Chicago’s Brookfield Zoo,
rescued an unconscious boy who had fallen into her enclosure,
following a chain of actions no one had taught her.
Such examples make a deep impression mainly because they
benefit members of our own species. But in my work on the
evolution of empathy and morality, I have found evidence so rich
of animals caring for one another and responding to each other’s
distress that I am convinced that survival depends not only on
strength in combat but also at times on cooperation and kind-
ness (de Waal, 1996). For example, it is common among chim-
panzees that a bystander approaches the victim of an attack to
gently wrap an arm around his or her shoulder.
Despite these caring tendencies, humans and other animals
are routinely depicted by biologists as complete egoists. The
reason is theoretical: all behavior is supposed to have evolved to
serve the actor’s own interests. It is logical to assume that genes
that fail to benefit their carrier are at a disadvantage in the pro-
cess of natural selection. But is it correct to call an animal selfish
simply because its behavior evolved for its own good?
The process by which a behavior came to exist over millions
of years of evolution is irrelevant when considering why an animal
here and now acts in a particular way. Animals only see the
immediate consequences of their actions, and even those are
not always clear to them. We may think that a spider builds a
web to catch flies, but this is true only at the functional level.
There is no evidence that spiders have any idea what webs are
for. In other words, a behavior’s purpose says nothing about its
underlying motives.
Only recently has the concept of ‘selfishness’ been robbed of
its vernacular meaning and applied outside the psychological
domain. Even though the term is now seen by some as synon-
ymous with self-serving, selfishness implies the intention to serve
oneself, hence knowledge of what one stands to gain from a
particular behavior. A vine may serve its own interests by over-
growing a tree, but since plants lack intentions and knowledge,
they cannot be selfish except in a meaningless, metaphorical
sense. For the same reason, it is impossible for genes to be
selfish.
Charles Darwin never confused adaptation with individual
goals, and endorsed altruistic motives. In this he was inspired
by Adam Smith, the moral philosopher and father of eco-
nomics. It says a great deal about the distinction between self-
serving actions and selfish motives that Smith, known for his
emphasis on self-interest as the guiding principle of econom-
ics, also wrote about the universal human capacity of
sympathy.
The origins of this inclination are no mystery. All species that
rely on cooperation show group loyalty and helping tendencies.
These tendencies evolved in the context of a close-knit social life
in which they benefited relatives and companions able to repay
the favor. The impulse to help was, therefore, never totally
without survival value to the ones showing the impulse. But the
impulse became divorced from the consequences that shaped
its evolution, permitting its
expression even when pay-
offs were unlikely, such as
when strangers were the
beneficiaries.
To call all behavior selfish
is like describing all life on
earth as converted sun
energy. Both statements
have some general value but
offer little help in explaining
the diversity we see around
us. Some animals survive
through ruthless competition,
others through mutual aid. A
framework that fails to dis-
tinguish the contrasting
mind-sets involved may be of
use to the evolutionary biol-
ogist: It has no place in
psychology.
An adult male chimpanzee,
defeated in a fight with a rival,
screams while being comforted
by a juvenile with an embrace.
Such ‘consolations’ have as yet
not been reported for other
animals. The behavior seems a
form of empathy without tangi-
ble benefit to the performer.

code or case numbers. In that way, no one other than the
experimenter has access to how any particular participant
responded. Another common practice is to report only
aggregated data – for example, data averaged across all
participants in the same group or condition. This further
protects the privacy of individual research participants.
Even if all of these ethical conditions are met, the
researcher must still weigh the costs of the study – not the
economic costs but the costs in human terms – against
the potential benefits. Is it really necessary to conduct a
study in which participants will be deceived or embar-
rassed? Only if the researcher and the review board
are reasonably certain that the study can uncover
worthwhile information – either practical or theoretical –
can the research proceed.
Research with animals
Another area in which ethical standards must be observed
is research with animals. About 7 percent of psychologi-
cal studies employ animals, 95 percent of which are rats,
mice, and birds. Psychologists conduct research with
animals for two main reasons. One is that animal
behavior can itself be interesting and worthy of study. A
second is that animal systems can provide models for
human systems, and so research on animals can produce
knowledge that might be impossible or unethical to
obtain from humans. Animal research has in fact played a
pivotal role in understanding and treating psychological
problems such as anxiety, stress, aggression, depression,
drug abuse, eating disorders, hypertension, and Alz-
heimer’s disease (Carroll Overmier, 2001). Although
debate continues about whether and what kind of
research with animals is ethical, in the United States most
psychologists (80%) and most psychology majors (72%)
support the use of animals in research (Plous, 1996a,
1996b). Amid this wide support, concerns remain about
the small subset of animal studies that involve painful or
harmful procedures. To address these concerns, both
federal and APA guidelines require that any painful or
harmful procedures imposed on animals must be thor-
oughly justified in terms of the knowledge to be gained
from the study. APA guidelines also underscore that
researchers have a moral obligation to treat animals
humanely and to minimize their pain and suffering. Spe-
cific rules about the living conditions and maintenance of
laboratory animals govern how this moral obligation is to
be met.
Aside from these specific guidelines, a central principle
of research ethics is that those who participate in psy-
chology studies should be considered full partners in the
research enterprise. Some of the research discussed in this
text was conducted before the ethical guidelines just
described were formulated and would not be permitted by
most review boards today.
INTERIM SUMMARY
l Doing psychological research involves generating a
hypothesis and then testing it by using a scientific
method. Core concepts necessary for understanding
psychology experiments include independent and
dependent variables, experimental and control
groups, random assignment, and measurement and
statistics.
l When experiments are not feasible, the correlational
method may be used to determine whether one
naturally occurring variable is associated with another.
The degree of association between two variables is
measured by the correlation coefficient, r, which can be
positive (up to +1.00) or negative (down to 1.00),
depending on whether one variable increases with
another (+) or one variable decreases as the other
increases ().
l Another way of conducting research is to use the
observational method, either through direct observation,
indirect survey methods, or case histories.
l A final way of conducting research is by literature review,
either narrative reviews or statistical meta-analyses.
l The basic ethical principles governing the ethical
treatment of human participants are minimal risk,
informed consent, and the right to privacy. Any painful
or harmful procedures imposed upon animals must be
thoroughly justified in terms of the knowledge to be
gained from the study.
1 Figure 1.3 displays the results of a classic study
showing that preference for viewing violent TV programs
by boys at age 9 is related to aggressive behavior at age
19. Why does this study fail to demonstrate that
watching violence on TV makes boys more aggressive?
What kind of evidence would be needed to make such
an argument?
2 Suppose a researcher finds a correlation of .50
between symptoms of disordered eating and a
preoccupation with physical appearance. What can
the researcher conclude? What might explain the
observed relationship? Can you formulate a hypothesis
about cause and effect? How could you test that
hypothesis?

CHAPTER SUMMARY
1 Psychology is the scientific study of behavior and
mental processes.
2 The roots of psychology can be traced to the 4th
and 5th centuries B.C. The Greek philosophers
Socrates, Plato, and Aristotle posed fundamental
questions about the mind, and Hippocrates, the
‘father of medicine’, made many important
observations about how the brain controlled other
organs. One of the earliest debates about human
psychology focused on the question of whether
human capabilities are inborn (the nature view) or
acquired through experience (the nurture view).
3 Scientific psychology was born in the late nine-
teenth century with the idea that mind and
behavior could be the subject of scientific analysis.
The first experimental laboratory in psychology
was established by Wilhelm Wundt at the Uni-
versity of Leipzig in 1879.
4 Among the early ‘schools’ of psychology in the
twentieth century were structuralism (the analysis
of mental structures), functionalism (studying how
the mind works so that an organism can adapt to
and function in its environment), behaviorism (the
study of behavior without reference to conscious-
ness), Gestalt psychology (which focuses on the
patterns formed by stimuli and on the organization
of experience), and psychoanalysis (which empha-
sizes the role of unconscious processes in person-
ality development and motivation).
5 Later developments in twentieth-century psychol-
ogy included information-processing theory, psy-
cholinguistics, and neuropsychology.
6 The study of psychology can be approached from
several perspectives. The biological perspective
relates actions to events taking place inside the
body, particularly the brain and nervous system.
The behavioral perspective considers only external
activities that can be observed and measured. The
cognitive perspective is concerned with mental
processes, such as perceiving, remembering, rea-
soning, deciding, and problem solving, and with
relating these processes to behavior. The psycho-
analytic perspective emphasizes unconscious
motives stemming from sexual and aggressive
impulses. The subjectivist perspective focuses on
how people actively construct and interpret their
social worlds, which is expected to vary by culture,
personal history, and current motivational state. A
particular topic often can be analyzed from more
than one of these perspectives.
7 The biological perspective differs from the other
viewpoints in that its principles are partly drawn
from biology. Often, biological researchers
attempt to explain psychological principles in
terms of biological ones; this is known as reduc-
tionism. Behavioral phenomena are increasingly
being understood at both the biological and psy-
chological levels.
8 Among the major subfields of psychology are
biological psychology, experimental psychology,
developmental psychology, social and personality
psychology, clinical and counseling psychology,
school and educational psychology, and industrial
and engineering psychology. Many new areas of
inquiry gaining momentum in twenty-first-century
psychology span traditional subfields and dis-
ciplines. These new areas include cognitive neu-
roscience (as well as affective and social cognitive
neuroscience), evolutionary psychology, cultural
psychology, and positive psychology.
9 Doing psychological research involves generating
a hypothesis and then testing it by using a scien-
tific method. When applicable, the experimental
method is preferred because it seeks to control all
variables except the ones being studied and can
thus test hypotheses about cause and effect. The
independent variable is the one that is manipu-
lated by the experimenter; the dependent variable
(usually some measure of the participant’s
behavior) is the one being studied to determine
whether it is affected by changes in the indepen-
dent variable. In a simple experimental design, the
experimenter manipulates one independent vari-
able and observes its effect on one dependent
variable. An essential element of experimental
design is the random assignment of participants to
experimental and control groups.
10 In many experiments the independent variable is
something that is either present or absent. The
simplest experimental design includes an experi-
mental group (with the hypothesized cause pres-
ent for one group of participants) and a control
group (with the hypothesized cause absent for
another group of participants). If the manipula-
tion of the independent variable results in a sta-
tistically significant difference in the dependent
variable between the experimental and control
groups, we know that the experimental condition
had a reliable effect, and the difference is not due
to chance factors or a few extreme cases.
CHAPTER SUMMARY 29

CORE CONCEPTS
law of effect
overjustification effect
psychology
prosopagnosia
fundamental attribution error
childhood amnesia
obese
cathartic effect
physiology
nature–nurture debate
nature view
nurture view
tabula rasa
associationist psychology
introspection
structuralism
functionalism
behaviorism
gestalt
psychoanalysis
unconscious
free association
information-processing models
psychological perspective
eclectic approach
biological perspective
behavioral perspective
cognitive perspective
psychoanalytic perspective
subjectivist perspective
naïve realism
reductionism
biological psychologists
cognitive psychologists
developmental psychologists
social psychologists
personality psychologists
clinical psychologists
counseling psychologists
school psychologists
educational psychologists
organizational psychologists
engineering psychologists
cognitive neuroscience
affective neuroscience
social neuroscience
evolutionary psychology
cultural psychology
positive psychology
hypothesis
theory
scientific
experiments
variable
independent variable
dependent variable
experimental groups
control group
random assignment
multivariate experiment
measurement
statistics
mean
statistical significance
correlation coefficient
positively correlated
negatively correlated
test
direct observation
survey method
social desirability effects
case history
literature review
narrative review
meta-analysis
minimal risk
informed consent
debriefing
right to privacy
11 In situations in which experiments are not feasi-
ble, the correlational method may be used. This
method determines whether a naturally occurring
difference is associated with another difference of
interest. The degree of correlation between two
variables is measured by the correlation coeffi-
cient, r, a number between þ1.00 and 1.00. The
absence of any relationship is indicated by 0; a
perfect relationship is indicated by 1. As r goes
from 0 to 1, the strength of the relationship
increases. The correlation coefficient can be posi-
tive or negative, depending on whether one vari-
able increases with another (þ) or one variable
decreases as the other increases ().
12 Another way of conducting research is to use the
observational method, in which one observes the
phenomenon of interest. Researchers must be
trained to observe and record behavior accurately.
Phenomena that are difficult to observe directly
may be observed indirectly by means of surveys
(questionnaires and interviews) or by recon-
structing a case history.
13 The basic ethical principles governing the ethical
treatment of human participants are minimal risk,
informed consent, and the right to privacy. Any
painful or harmful procedures imposed upon
animals must be thoroughly justified in terms of
the knowledge to be gained from the study.

WEB RESOURCES
http://www.atkinsonhilgard.com/
Take a quiz, try the activities and exercises, and explore web links.
http://academic.udayton.edu/gregelvers/hop/welcome.asp
This History of Psychology website gives you access to information about important psychologists throughout
history, provides a host of web links, and even has a trivia section. Do you know who left human bone dust in the
drill presses in the mechanical workshops of the Hungarian Post Office while doing research on the inner ear? Find
out here!
http://www.apa.org/science/infostu.html
This site – provided by the American Psychological Association – offers you access to the wide variety of oppor-
tunities available for psychology students.
http://www.apa.org/ethics/code.html
http://www.bps.org.uk/the-society/code-of-conduct/code-of-conduct_home.cfm
If you are concerned about the ethics of psychology, search through these detailed sites to learn more about the
principles of psychologists and their code of conduct, from US and UK perspectives.
CD-ROM LINKS
Psyk.Trek 3.0
Check out CD Unit 1, History and Methods
1a Psychology’s timeline
1b The experimental method
1d Statistics: Correlation
1e Searching for research articles in psychology
CD-ROM LINKS 31

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