Psychology: The Science of Behaviour
The Nature of Psychology
Psychology is the scientific study of behaviour. The term behaviour refers to actions and responses that can be
observed and measured directly as well as mental processes such as thoughts and feelings that must be
inferred from directly observable responses.
Basic research is the quest for knowledge for its own sake, where as applied research involves the application
of knowledge derived from basic research to solve practical problems.
The primary goals of psychological science are to describe, explain, predict, and influence behaviour and to
apply psychological knowledge to enhance human welfare.
Perspectives on Behaviour: Guides to Understanding and Discovery
Several perspectives have shaped psychology’s scientific growth. Each perspective views human nature
differently and focuses on different causes of behaviour.
With roots in physiology, medicine, and Darwin’s theory of evolution, the biological perspective examines
how bodily functions regulate behaviour. Physiological psychologists study brain processes and other
physiological functions that underlie our behaviour, sensory experiences, emotions, and thoughts.
Behaviour geneticists study how behaviour is influenced by our genetic inheritance. Evolutionary
psychologists examine behaviour in terms of its adaptive functions and seek to explain how evolution has
biologically predisposed modern humans toward certain ways of behaving
Psychology’s intellectual roots lie in philosophy, biology, and medicine. In the late 1800s, Wundt and James
helped found psychology. Structuralism, which examined the basic components of consciousness, and
functionalism, which focused on the purposes of consciousness, were psychology’s two earliest schools of
The cognitive perspective views humans as information processors who think, judge, and solve problems. Its
roots lie in the early schools of structuralism, functionalism, and Gestalt psychology. Piaget’s work on
cognitive development, the study of linguistics, and the advent of computers sparked new interest in mental
processes. Research in artificial intelligence develops computer models of human thought, whereas
cognitive neuroscience studies brain processes that underlie mental activity. Social constructivism
maintains that much of what we call reality is a creation of our own mental processes.
The psychodynamic perspective calls attention to unconscious motives, conflicts, and defence mechanisms
that influence our personality and behaviour. Freud’s psychoanalytic theory emphasized unconscious
sexual and aggressive impulses and early childhood experiences that shape personality.
With roots in 18 -century British empiricism, the behavioural perspective emphasizes how the external
environment and learning shape behaviour. Behaviourists such as Watson and Skinner believed that
psychology should only study observable stimuli and responses, not unobservable mental processes. They
argued that to change behaviour, the key is to modify the environment. Behaviourists discovered basic laws
of learning through controlled research with laboratory animals and successfully applied these principles to
enhance human welfare.
Humanists reject the notion that people are controlled by unconscious forces or merely react to environmental
stimuli. Instead, the humanistic perspective emphasizes personal freedom and choice, psychological
growth, and self-actualization.
The sociocultural perspective examines how the social environment and cultural learning influence our
behaviour and thoughts. Cultural psychologists study how culture is transmitted to its members and examine similarities and differences among people from various cultures. An orientation toward
individualism versus collectivism represents one of many ways in which cultures vary.
Integrating the Perspectives: Three Levels of Analysis
Factors that influence behaviour can be organized into three broad levels of analysis. The biological level of
analysis focuses on brain processes, hormonal and genetic influences, and evolutionary adaptations that
underlie behaviour. The psychological level of analysis examines mental processes and psychological
motives, and how they influence behaviour. The environmental level of analysis calls attention to physical
and social stimuli, including cultural factors, that shape our behaviour and thoughts.
To understand behaviour, we often move back and forth between these levels of analysis. For example, when
as children we are first exposed to cultural norms, those norms reflect a characteristic of our environment.
However, once we adopt norms as our own, they become a part of our worldview and now represent the
psychological level of analysis.
Biological, psychological, and environmental factors contribute to the development of depression. These
factors can also interact to influence a given behaviour. It may take only a mild setback to trigger
depression in a person who has a strong biological predisposition toward depression whereas a person who
does not have such a biological predisposition may become depressed only after suffering a severe setback
Fields within Psychology
Psychologists specialize in numerous subfields and work in many settings. Their professional activities
include teaching, research, clinical work, and application of psychological principles to solve personal and
Psychologists today conduct research and provide services around the globe.
You can use principles derived from psychological science to enhance your learning and increase your
likelihood of performing well on tests. These include time management principles, strategies for studying
more effectively, test-preparation strategies and techniques for taking tests.
Applied Research: research involving the application of scientific knowledge to solve practical problems
Artificial Intelligence: the field within cognitive science that attempts to develop computer simulations of human
Basic Research: research designed to obtain knowledge for its own sake
Behaviour Genetics: the scientific study of the role of genetic inheritance in behaviour
Behaviour Modification: therapeutic procedures based on operant conditioning principles, such as positive
reinforcement, operant extinction, and punishment
Behavioural Perspective: a view that emphasizes the manner in which the environment and the learning
experiences it provides shape and control behaviour
Behaviourism: school of psychology that emphasizes the role of learning and environmental control over
behaviour, and maintains that the proper subject matter of psychology is observable behaviour; Watson and Skinner
were major figures in behaviourism
Biological Perspective: perspective that focuses on the role of biological factors in behaviour, including
biochemical and brain processes as well as genetic and evolutionary factors
British Empiricism: philosophical perspective, all the contents of the mind are gained experientially through the
Cognitive Behaviourism: behavioural approach that incorporates cognitive concepts, suggesting that the
environment influences our behaviour by affecting our thoughts and fiving us information; these cognitive processes
allow us to control our behaviour and the environment
Cognitive Perspective: psychological perspective that views humans as rational information processors and
problem solvers, and focuses on the mental processes that influence behaviour
Collectivism: a cultural factor that emphasizes the achievement of the group rather than individual goals and in
which personal identity is largely defined by ties to the larger social group (see individualism) Culture: the enduring values, beliefs, behaviours, and traditions that are shared by a large group of people and
passed from one generation to the next
Evolutionary Psychology: a field of study that focuses on the role of evolutionary processes (especially natural
selection) in the development of adaptive psychological mechanisms and social behaviour in humans
Functionalism: an early school of American psychology that focused on the functions of consciousness and
behaviour in helping organisms adapt to their environment and satisfy their needs
Gestalt Psychology: a German school of psychology that emphasized the natural organization of perceptual
elements into whiles, or patters, as well as the role of insight in problem solving
Humanistic Perspective: a psychological perspective that emphasizes personal freedom, choice, and self-
Hysteria: a psychological disorder studied and treated by Freud in which physical symptoms appear without any
apparent underlying organic cause
Individualism: a cultural characteristic that favours the achievement of the individual over group goals and which is
characteristic of many Western nations; self-identity is based primarily on one’s own attributes and achievements
Insight: in Gestalt psychology, the sudden perception of a useful relationship or solution to a problem; in
psychoanalysis, the conscious awareness of unconscious dynamics that underlie psychological problems
Interaction: in analyzing causal factors, the influence that the presence or strength of one factor can have on other
Introspection: the method of “looking within” and verbally reporting on immediate experience; used by the
structuralists to study the contents of the mind
Jigsaw Program: an applied research program in which knowledge gained from basic research on factors that
increase and decrease intergroup hostility was translated into a cooperative learning program designed to reduce
interracial hostility in racially integrated schools
Levels of Analysis: an approach to analysing behavioural phenomena and their causal factors in terms of biological,
psychological, and environmental factors
Mind-Body Dualism: the philosophical position that the mind is a non-physical entity that is not subject to physical
laws and cannot be reduced to physical processes; body and mind are separate entities
Monism: the philosophical position that mental events are reducible to physical events in the brain, so that “mind”
and body are one and the same
Natural Selection: the evolutionary process through which characteristics that increase the likelihood of survival
are preserved in the gene pool and thereby become more common in a species over time
Norms: test scores derived from a relevant sample used to evaluate individual’s scores; behavioural “rules”
Perspective: a theoretical vantage point from which to analyze behaviour and its causes
Psychodynamic Perspective: a psychological perspective that focuses on inner personality dynamics, including the
role of unconscious impulses and defences, in understanding behaviour
Psychology: the scientific study of behaviour and its causes
Repression: the basic defence mechanism that actively keeps anxiety-arousing materiel in the unconscious
Self-Actualization: in humanistic theories, an inborn tendency to strive toward the realization of one’s full potential
Social Constructivism: the position that people construct their reality and beliefs through their cognition
Sociobiology: an evolutionary theory of social behaviour that emphasizes the role of adaptive behaviour in
maintaining one’s genes in the species’ gene pool
Sociocultural Perspective: a perspective that emphasizes the role of culture and the social environment in
understanding commonalties and differences in human behaviour
Structuralism: an early German school of psychology established by Wilhelm Wundt that attempted to study the
structure of the mind by breaking it down into its basic components, thought to be sensations
Terror Management Theory: a theory that focuses on the ways people defend against the fear of death
Studying Behaviour Scientifically
Scientific Principles in Psychology
Curiosity, scepticism, and open-mindedness are key scientific attitudes. The scientific process proceeds
through several steps: (1) asking questions based on some type of observation; (2) formulating a tentative
explanation and a testable hypothesis; (3) conducting research to test the hypothesis; (4) analyzing the data and drawing a tentative conclusion; (5) building a theory; and (6) using the theory to generate new
hypotheses, which are tested by more research.
In everyday life we typically use hindsight (after-the-fact understanding) to explain behaviour. This approach
is flawed because there may be countless possible explanations and now way to ascertain which is correct.
Psychologists prefer to test their understanding through prediction, control, and building theories about the
causes of behaviour.
A good theory organizes known facts, fives rise to additional hypotheses that are testable, is supported by the
findings of new research, and is parsimonious.
An operational definition defines a concept or variable in terms of the specific procedures used to produce or
Psychologists assess behaviour by obtaining participants’ self-reports, gathering reports from others who
know the participants, directly observing behaviour, and measuring physiological responses.
Methods of Research
The goal of descriptive research is to identify how organisms behave, particularly in natural settings. Case
studies involve the detailed study of a person, group, or event. Case studies often suggest important ideas
for further research, but they are a poor method for establishing cause-effect relations.
Naturalistic observation gathers information about behaviour in real-life settings. It often yields rich
descriptions of behaviour and allows the examination of relations between variables. Researchers must be
careful to avoid influencing the participants being observed and to interpret their observations objectively.
Surveys involve administering questionnaires or interviews to many people. Most surveys study a subset of
people (a sample) that is randomly drawn from the larger population of people the researcher is interested
in. A major advantage of surveys is that representative samples allow for reasonable accurate estimates of
the opinions or behaviours of the entire population. Unrepresentative samples, however, can lead to
inaccurate estimates. Survey results also can be distorted by interviewer bias or biases in the way
participants report about themselves.
Correlational Research: Measuring Associations between Events
Correlational research measures the association between naturally occurring variables. A positive correlation
means that higher scores on one variable are associated with higher scores on a second variable. A negative
correlation occurs when higher scores on one variable are associated with lower scores on a second variable
Causal conclusions cannot be drawn from correlational data. Variable X may cause Y, Y may cause X, or
some third variable (Z) may be the true cause of both X and Y. Nevertheless, if two variables are
correlated, then knowing the scores of one variable will help predict the scores of the other.
Experiments: Examining Cause and Effect
A well-designed experiment is the best way to examine cause-effect relations. Experiments have three
essential characteristics: (1) one or more variables are manipulated; (2) their effects on other variables are
measured; and (3) extraneous factors are eliminated or reduced so that cause-effect conclusions can be
Each variable manipulated by the experimenter is an independent variable. Variables that are measured are
dependent variables. The independent variable is viewed as the cause, the dependent variable as the effect.
The experimental group receives a treatment or an active level of the independent variable, whereas the
control group does not. The behaviour of the control group sets a standard against which the behaviour of
the experimental group can be compared. In some experiments different participants are randomly assigned to each condition, creating experimental and
control groups that are equivalent at the start of the study. In other experiments the same participants are
exposed to all the conditions, but the order in which the conditions are presented is counterbalanced.
Researchers often examine several causal factors within a single experiment by simultaneously manipulating
two or more independent variables. They examine the separate influence of each variable on behaviour and
determine whether particular combinations of variables produce distinct effects.
Threats to the Validity of Research
An experiment has high internal validity when it is designed well and permits clear causal conclusions.
Confounding occurs when the independent variable becomes mixed up with an uncontrolled variable. This
ruins internal validity because we can no longer tell which variable caused the changes in the dependent
Internal validity is weakened by (1) demand characteristics, which are cues that tip off participants as to how
they should behave; (2) placebo effects, in which the mere expectation of receiving a treatment produces a
change in behaviour; and (3) experimenter expectancy effects, which are the subtle ways a researcher’s
behaviour influence participants to behave in a manner consistent with the hypothesis being tested. The
double-blind procedure prevents placebo effects and experimenter expectancy effects from biasing research
External validity is the degree to which the findings of a study can be generalized to the other people, settings,
and conditions. By replicating (repeating) a study under both similar and dissimilar circumstances,
researchers can examine its external validity.
Ethical Principles in Human and Animal Research
Psychological research follows extensive ethical guidelines. In human research, key issues are the use of
informed consent, the participants’ right to privacy, the degree of risk, and the use of deception.
Ethical guidelines require that animals be treated humanely and that the risks to which they are exposed be
justified by the potential importance of the research. As in human research, before animal research can be
conducted it must be reviewed and approved, often by ethics review boards that include non-scientists.
Critical Thinking in Science and Everyday Life
Critical thinking is an important life skill. However, we should also be open-minded to ideas that are
supported by solid evidence, even when they conflict with our preconceptions.
There is no generally accepted, replicable scientific evidence to support the existence of paranormal
phenomena. Even the ganzfeld procedure, initially supported by several highly controlled experiments, is
controversial because it has often failed to replicate.
Archival Measures: using previously documented results in an experiment or theory.
Case Study: an in-depth analysis of an individual group or event
Confounding of Variables: in an experiment, the intertwining of the independent variable with another,
uncontrolled variable; thus, we cannot tell which variable is responsible for changes in the behaviour of interest (i.e.,
the dependent variable)
Control Group: in an experiment, the group that is not exposed to the treatment, or which receives a zero level of
the independent variable
Correlation Coefficient: a statistic that indicates the direction and strength of a relation between two variables
Correlational Methods: research methods that involve measuring the strength of an association between two or
Correlational Research: research that measures two or more naturally occurring variables, and examines why they
are statistically related
Demand Characteristics: cues used by research participants to guess the purpose or hypothesis of a study, thereby
causing them to alter their behaviour Dependant Variable: in an experiment, the factor that is measured by the researcher and which presumably is
influenced by the independent variable
Descriptive Method: research method that involves recording observations or surveys
Descriptive Research: research in which the main goal is to carefully describe how organisms behave, particularly
in natural settings
Double-Blind Procedure: a procedure in which both the participant and the experimenter are kept unaware of the
research condition to which the participant has been assigned
Experiment: a research method in which the researcher manipulates an independent variable under controlled
conditions and measures whether this produces changes in a dependent variable
Experimental Group: in an experiment, the group that receives a treatment or is exposed to an active level of the
Experimental Methods: research methods that involve manipulations to establish cause and effect relationships
between two or more events
Experimenter Expectancy Effects: subtle and unintentional ways in which an experimenter influences participants
to behave in a way that will confirm the experimenter’s hypothesis
External Validity: the degree to which the results of a study can be generalized to other people, settings, and
Hypothesis: a tentative explanation or prediction about some phenomenon
Independant Variable: in an experiment, the factor that is manipulated by the researcher
Informed Consent: the principle that, prior to agreeing to participate in research, a person should be fully informed
about the procedures, risks involved, and the right to withdraw at any time without penalty
Internal Validity: the degree to which an experiment produces clear causal conclusions; internal validity is high
when there is no confounding of variables
Naturalistic Observation: a method in which the researcher observes behaviour in a natural setting and tries to
avoid influencing the participants being observed
Negative Correlation: as scores on one variable change, scores on a second variable change in the opposite
Operational Definition: defining a concept or variable in terms of the specific procedures used to produce or
Placebo: an inactive or inert substance that has no medicinal value but it is believed by a patient to be helpful
Placebo Effect: a change in behaviour that occurs because of the expectation or belief that one is receiving a
Population: in a survey, the entire set of individuals about whom we wish to draw a conclusion
Positive Correlation: as scores on one variable change, scores on a second variable change in the same direction
Random Sampling: a method of choosing a sample in which each member of the population has an equal
opportunity to be included in the sample
Replication: the process of repeating a study to determine whether the original findings can be duplicated
Representative Sample: a sample that accurately reflects the important characteristics of the population
Sample: in a survey, a subset of individuals drawn from the population
Scatterplot: a graph commonly used to examine correlational data; each pair of scores on variable X and variable Y
is plotted as a single point
Survey Research: a method in which questionnaires or interviews are used to obtain information about many
Theory: a set of formal statements that explain how and why certain events of phenomena are related to one another
Validity: the extent to which a test measures what it is supposed to; the degree to which a diagnostic system’s
categories contain the core features of the behaviour disorders and permit differentiation among the disorders
Variable: any characteristic of an organism or situation that can differ
Learning and Adaptation: The Role of Experience
Adapting to the Environment
Learning is a process by which experience produces a relatively enduring change in an organism’s behaviour
or capabilities. Learning is measured by changes in performance. Learning involves adapting to the environment. Historically, behaviourists focused on the processes by which
organisms learn, and ethologists focused on the adaptive significance of learning. Today these two
perspectives have crossed paths, and more attention is paid also to how mental processes and cultural
environments influence learning.
Habituation is a decrease in the strength of a response to a repeated stimulus. It may be the simplest form of
Habituation allows organisms to attend to other stimuli that are more important.
Classical Conditioning: Associating One Stimulus with Another
Classical conditioning involves pairing a neutral stimulus with an unconditioned stimulus (UCS) that elicits an
unconditioned response (UCR). Through repeated paring, the neutral stimulus becomes a conditioned
stimulus (CS) that evokes a conditioned response (CR) similar to the original UCR.
The acquisition phase involves pairing the CS with the UCS. Extinction, is the disappearance of the CR,
occurs when the CS is presented repeatedly in the absence of the UCS. Sometimes, spontaneous recovery
occurs after a rest period and the CS temporarily will evoke a response even after extinction has taken
Stimulus generalization occurs when a CR is evoked by a stimulus similar to the original CS. Discrimination
occurs when a CR occurs to one stimulus but not another.
Once a stimulus (e.g., a tone) becomes a CS, it can now be used in place of the original UCS (food) to
condition other neutral stimuli. This is called higher-order conditioning.
A wide range of bodily and psychological responses can be classically conditioned, including fears, sexual
attraction, and positive and negative attitudes. Techniques based on classical conditioning are highly
successful in treating fears and phobias.
Cancer patients may develop anticipatory nausea or vomiting (ANV) to stimuli that are paired with their
chemotherapy. ANV is a classically conditioned response. Classical conditioning also can increase or
decrease immune system responses.
Operant Conditioning: Learning Through Consequences
Thorndike’s law of effect states that responses followed by satisfying consequences will be strengthened,
whereas those followed by unsatisfying consequences will be weakened.
B.F. Skinner analyzed operant conditioning in terms of relations between antecedents, behaviours, and
consequences. Antecedents that signal the likely consequences of particular behaviours in a given situation
are called discriminative stimuli.
Operant behaviours are emitted (under voluntary control), whereas classically conditioned responses are
elicited (reflexive). Classically conditioned responses are influenced by what happens before the behaviour
(i.e., by the CS-UCS pairing), whereas operant behaviours are influenced by consequences that occur after
Reinforcement occurs when response is strengthened by an outcome (a reinforcer) that follows it. With
positive reinforcement, a response is followed by the presentation of a positive stimulus, so the response is
followed by the presentation of a positive stimulus, so the response becomes stronger. With negative
reinforcement, a response is followed by the removal of an aversive stimulus, so again, the response
Operant extinction is the weakening and eventual disappearance of a response because it no longer is
reinforced. Punishment occurs when a response is weakened by an outcome (a punisher) that follows it. With positive
punishment, a behaviour is followed by the presentation of an aversive stimulus, and the behaviour
becomes weaker. With negative punishment, a behaviour is followed by the removal of a positive stimulus,
and the behaviour becomes weaker.
Shaping, which uses the method of successive approximations, involves the reinforcement of behaviours that
increasingly resemble the final desired behaviour.
When behaviour changes in one situation due to reinforcement or punishment, and then this new response
carries over to similar situation, this is called operant generalization. In contrast, when an operant response
is made to one discriminative stimulus but not to another, this is called operant discrimination.
On a continuous reinforcement schedule every response is reinforced. Partial reinforcement may occur on a
ratio schedule, in which a certain percentage of responses are reinforced, or on an interval schedule, in
which a certain amount of time must pass before a response gets reinforced. In general, ratio schedules
produce higher rates of performance than interval schedules.
On fixed ratio and interval schedules, reinforcement always occurs after a fixed number of correct responses
or a fixed time i