Empiricism
the idea that knowledge comes from experience, and that observation and experimentation enable scientific knowledge
Structuralism
an early school of thought promoted by Wundt and Titchener; used introspection to reveal the structure of the human mind.
Functionalism
an early school of thought promoted by James and influenced by Darwin; explored how mental and behavioral processes function—how they enable the organism to adapt, survive, and flourish.
Experimental Psychology
A branch of psychology that focuses on conducting scientific research to study human behavior and mental processes. It involves designing experiments, collecting data, and analyzing results to gain insights into various psychological phenomena.
Behaviorism
the view that psychology (1) should be an objective science that (2) studies behavior without reference to mental processes. Most psychologists today agree with (1) but not with (2).
Humanistic Psychology
a historically significant perspective that emphasized human growth potential.
Cognitive Neuroscience
the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language).
Psychology
the science of behavior and mental processes.
Natural Selection
the principle that inherited traits that better enable an organism to survive and reproduce in a particular environment will (in competition with other trait variations) most likely be passed on to succeeding generations.
Biopsychosocial Approach
an integrated approach that incorporates biological, psychological, and social-cultural viewpoints.
Behavioral Psychology
the scientific study of observable behavior, and its explanation by principles of learning.
Biological Psychology
the scientific study of the links between biological (genetic, neural, hormonal) and psychological processes. (Some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists.)
Cognitive Psychology
the study of mental processes, such as occur when we perceive, learn, remember, think, communicate, and solve problems.
Evolutionary Psychology
the study of the evolution of behavior and the mind, using principles of natural selection.
Psychodynamic Psychology
a branch of psychology that studies how unconscious drives and conflicts influence behavior and uses that information to treat people with psychological disorders.
Social-cultural Psychology
the study of how situations and cultures affect our behavior and thinking.
Industrial-Organizational (I/O) Psychology
the application of psychological concepts and methods to optimizing human behavior in workplaces.
Human Factors Psychology
a field of psychology allied with I/O psychology that explores how people and machines interact and how machines and physical environments can be made safe and easy to use.
Counseling Psychology
a branch of psychology that assists people with problems in living (often related to school, work, or marriage) and in achieving greater well-being.
Clinical Psychology
a branch of psychology that studies, assesses, and treats people with psychological disorders.
Psychiatry
a branch of medicine dealing with psychological disorders; practiced by physicians who are licensed to provide medical (for example, drug) treatments as well as psychological therapy.
Case Study
a descriptive technique in which one individual or group is studied in depth in the hope of revealing universal principles.
Control Group
in an experiment, the group not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.
Correlation
a measure of the extent to which two factors vary together, and thus of how well either factor predicts the other.
Correlation Coefficient
a statistical index of the relationship between two things (from −1.00 to +1.00).
Critical thinking
thinking that does not blindly accept arguments and conclusions. Rather, it examines assumptions, appraises the source, discerns hidden biases, evaluates evidence, and assesses conclusions.
Culture
the enduring behaviors, ideas, attitudes, values, and traditions shared by a group of people and transmitted from one generation to the next.
Debriefing
The postexperimental explanation of a study, including its purpose and any deceptions, to its participants.
Dependent variable
in an experiment, the outcome that is measured; the variable that may change when the independent variable is manipulated.
Descriptive Statistics
numerical data used to measure and describe characteristics of groups. Includes measures of central tendency and measures of variation.
Double-Blind Procedure
an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies.
Experiment
a research method in which an investigator manipulates one or more factors (independent variables) to observe the effect on some behavior or mental process (the dependent variable). By random assignment of participants, the experimenter aims to control other relevant factors.
Experimental Group
in an experiment, the group exposed to the treatment, that is, to one version of the independent variable.
Hindsight Bias
the tendency to believe, after learning an outcome, that one would have foreseen it. (Also known as the I-knew-it-all-along phenomenon.)
Hypothesis
a testable prediction, often implied by a theory.
Illusory Correlation
perceiving a relationship where none exists, or perceiving a stronger-than-actual relationship.
Independent Variable
in an experiment, the factor that is manipulated; the variable whose effect is being studied.
Inferential Statistics
numerical data that allow one to generalize—to infer from sample data the probability of something being true of a population.
Informed Consent
giving potential participants enough information about a study to enable them to choose whether they wish to participate.
Mean
the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores.
Median
the middle score in a distribution; half the scores are above it and half are below it.
Mode
the most frequently occurring score(s) in a distribution.
Naturalistic Observation
a descriptive technique of observing and recording behavior in naturally occurring situations without trying to manipulate or control the situation.
Normal Curve
(normal distribution) a symmetrical, bell-shaped curve that describes the distribution of many types of data; most scores fall near the mean (about 68 percent fall within one standard deviation of it) and fewer and fewer near the extremes.
Operational Definition
a carefully worded statement of the exact procedures (operations) used in a research study. For example, human intelligence may be operationally defined as what an intelligence test measures.
Placebo Effect
experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent.
Population
all those in a group being studied, from which samples may be drawn. (Note: Except for national studies, this does not refer to a country's whole population.)
Random Assignment
assigning participants to experimental and control groups by chance, thus minimizing preexisting differences between the different groups.
Random Sample
a sample that fairly represents a population because each member has an equal chance of inclusion.
Range
the difference between the highest and lowest scores in a distribution.
Replication
repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding can be reproduced.
Sampling Bias
a flawed sampling process that produces an unrepresentative sample.
Scatterplot
a graphed cluster of dots, each of which represents the values of two variables. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation (little scatter indicates high correlation).
Skewed Distribution
a representation of scores that lack symmetry around their average value.
Standard Deviation
a computed measure of how much scores vary around the mean score.
Statistical Significance
a statistical statement of how likely it is that an obtained result occurred by chance.
Survey
a descriptive technique for obtaining the self-reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample of the group.
Theory
an explanation using an integrated set of principles that organizes observations and predicts behaviors or events.
Validity
the extent to which a test or experiment measures or predicts what it is supposed to. (See also content validity and predictive validity.)