Psychological science: the study of mind, brain, and behavior.
Mind: refers to mental activity.
Behavior: describes a wide variety of observable actions.
Critical thinking: systematically evaluating information to reach reasonable conclusions.
Amiable skepticism: remaining open to new ideas.
Culture: the beliefs, values, riles, norms, and customs existing within a group of people who
share a common language and environment.
Nature/nurture debate: has taken one form or another throughout psychology’s history.
Mind/body problem: a fundamental psychological issue: are mind and body separate and distinct,
or is the mind simply the physical brain’s subjective experience?
Introspection: a systematic examination of subjective mental experiences that requires people to
inspect and report on the content of their thoughts.
Structuralism: an approach to psychology based on the idea that conscious experience can be
broken down into its basic underlying components.
Stream of consciousness: a phrase coined by William James to describe each person’s continuous
series of ever-changing thoughts.
Functionalism: an approach to psychology concerned with the adaptive purpose, or function, of
mind and behavior.
Evolutionary theory: a theory presented by the naturalist Charles Darwin; it views the history of
a species in terms of the inherited, adaptive value of physical characteristics of mental activity,
and of behavior.
Adaptations: in evolutionary theory, the physical characteristics, skills, or abilities that increase
the chances of reproduction or survival and are therefore likely to be passed along to future
Natural selection: in evolutionary theory, the idea that those who inherit characteristics that help
them adapt to their particular environments have a selective advantage over those who do not. Gestalt theory: a theory based on the idea that the whole or personal experience is different from
simply the sum of its constituent elements.
Unconscious: the mental processes that operate below the level of conscious awareness.
Psychoanalysis: a method developed by Sigmund Freud that attempts to bring the contents of the
unconscious into conscious awareness so that conflicts can be revealed.
Behaviorism: a psychological approach that emphasizes the role of environmental forces in
Cognitive psychology: the study of how people think, learn, and remember.
Cognitive neuroscience: the study of the neural mechanisms (involving the brain, nerves, and
nervous tissue) that underlie thought, learning, and memory.
Social psychology: the study of how people are influenced by their interactions with others.
Scientific method: a systematic procedure of observing and measuring phenomena (observable
things) to answer questions about what happens, when it happens, what causes it, and why;
involves a dynamic interaction between theories, hypotheses, and research.
Theory: a model of interconnected ideas or concepts that explains what is observed and makes
predictions about future events.
Hypothesis: a specific prediction of what should be observed if a theory is correct.
Research: a scientific process that involves the systematic and careful collection of data.
Data: objective observations or measurements.
Replication: repetition of an experiment to confirm the results.
Descriptive studies: a research method that involves observing and noting the behavior of people
or other animals to provide a systematic and objective analysis of the behavior.
Naturalistic observation: a type of descriptive study in which the researcher is a passive observer,
making to attempt to change or alter ongoing behavior.
Participant observation: a type of descriptive study in which the researcher is actively involved in
Longitudinal studies: a research method that studies the same participants multiple times over a
period of time. Cross-sectional studies: a research method that compares participants in different groups (young
and old) at the same time.
Observer bias: systematic errors in observation that occur because of an observer’s expectations.
Correlational studies: a research method that examines how variables are naturally related in the
real world, without any attempt by the researcher to alter them or assign causation between them.
Directionality problem: a problem encountered in correlational studies; the researchers find a
relationship between two variables, but they cannot determine which variable may have caused
changes in the other variable.
Third variable problem: a problem that occurs when the researcher cannot directly manipulate
variables; as a result, the researcher cannot be confident that another, unmeasured variable is not
the actual cause of differences in the variables of interest.
Experiment: a study that tests causal hypotheses by measuring and manipulating variables.
Control group: a comparison group; the participants in a study that receive no intervention or
receive an intervention that is unrelated to the independent variable being investigated.
Experimental groups: treatment groups; the participants in a study that receive the intervention.
Independent variable: in an experiment, the variable that is manipulated by the experimenter to
examine its impact on the dependent variable.
Dependent variable: in an experiment, the variable that is affected by the manipulation of the
Confound: anything that affects a dependent variable and may unintentionally vary between the
experimental conditions of a study.
Population: everyone in the group the experimenter is interested in.
Sample: a subset of a population.
External validity: the degree to which the findings of an experiment can be generalized outside
Selection bias: in an experiment, unintended differences between the participants in different
Random assignment: placing research participants into the conditions of an experiment in such a
way that each participant has an equal chance of being assigned to any level of the independent
variable. Culturally sensitive research: studies that take into account the role that culture plays in
determining thoughts, feelings, and actions.
Observational techniques: a research method of careful and systematic assessment and coding of
Reactivity: when the knowledge that one is being observed alters the behavior being observed.
Case studies: a research method that involves the intensive examination of unusual people or
Self-report methods: methods of data collection in which people are asked to provide
information about themselves, such as in questionnaires or surveys.
Response performance: a research method in which researchers quantify perceptual or cognitive
processes in response to a specific stimulus.
Electroencephalograph (EEG): a device that measures electrical activity in the brain.
Positron emission topography (PET): a method of brain imaging that assesses metabolic activity
by using a radioactive substance injected into the bloodstream.
Magnetic resonance imaging (MRI): a method of brain imaging that produces high-quality
images of the brain.
Functional magnetic resonance imaging (fMRI): an imaging technique used to examine changes
in the activity of the working human brain.
Transcranial magnetic stimulation (TMS): the use of strong magnets to briefly interrupt normal
brain activity as a way to study brain regions.
Institutional review boards (IBRs): groups of people responsible for reviewing proposed research
to ensure that it meets the accepted standards of science and provides for the physical and
emotional well-being of research participants.
Internal validity: the extent to which the data collected in a study address the research hypothesis
in the way intended.
Reliability: the extent to which a measure is stable and consistent over time in similar conditions.
Accuracy: the extent to which an experimental measure is free from error.
Descriptive statistics: statistics that summarize the data collected in a study. Central tendency: a measure that represents the typical response or the behavior of a group as a
Mean: a measure of central tendency that is the arithmetic average of a set of numbers.
Median: a measure of central tendency that is the value in a set of numbers that falls exactly
halfway between the lowest and highest value.
Mode: a measure of central tendency that is the most frequent score or value in a set of numbers.
Variability: in a set of numbers, how widely dispersed the values are from each other and from
Standard deviation: a statistical measure of how far away each value is, on average, from the
Scatterplot: a graphical depiction of the relationship between two variables.
Inferential statistics: a set of procedures used to make judgements about whether differences
actually exist between sets of numbers.
Meta-analysis: a “study of studies” that combines the findings of multiple studies to arrive at a
Neurons: the basic units of the nervous system; cells that receive, integrate, and transmit
information in the nervous system. They operate through electrical impulses, communication
with other neurons through chemical signals, and form neural networks.
Central nervous system (CNS): the brain and the spinal cord.
Peripheral nervous system (PNS): all nerve cells in the body that are not part of the central
nervous system. The peripheral nervous system includes the somatic and autonomic nervous
Sensory neurons: one of the three types of neurons; these afferent neurons detect information
from the physical world and pass that information to the brain.
Motor neurons: one of the three types of neurons; these efferent neurons direct muscles to
contract or relax, thereby producing movement.
Interneurons: one of the three types of neurons; these neurons communica