AP PSYCHOLOGY

critical thinking

Thinking that does not automatically accept arguments and conclusions; examines assumptions and evaluates evidence.

hindsight bias

The tendency to believe, after learning an outcome, that one would have foreseen it.

peer reviewers

Scientific experts who evaluate a research article’s theory, originality, and accuracy.

theory

An explanation using an integrated set of principles that organizes observations and predicts behaviors or events.

hypothesis

A testable prediction, often implied by a theory.

falsifiable

The possibility that an idea, hypothesis, or theory can be disproven by observation or experiment.

operational definition

A carefully worded statement of the exact procedures used in a research study.

replication

Repeating the essence of a research study to see whether the basic finding can be reproduced.

case study

A non-experimental technique in which one individual or group is studied in depth.

naturalistic observation

Observing and recording behavior in naturally occurring situations without manipulation.

survey

A non-experimental technique for obtaining self-reported attitudes or behaviors of a particular group.

social desirability bias

Bias from people's responding in ways they presume a researcher expects.

self-report bias

Bias when people report their behavior inaccurately.

sampling bias

A flawed sampling process that produces an unrepresentative sample.

random sample

A sample that fairly represents a population because each member has an equal chance of inclusion.

population

All those in a group being studied.

correlation

A measure of the extent to which two factors vary together.

correlation coefficient

A statistical index of the relationship between two variables.

variable

Anything that can vary and is feasible and ethical to measure.

scatterplot

A graphed cluster of dots representing the values of two variables.

illusory correlation

Perceiving a relationship where none exists, or perceiving a stronger-than-actual relationship.

regression toward the mean

The tendency for extreme scores to fall back toward the average.

experiment

A research method in which one or more factors are manipulated to observe effects on behavior.

experimental group

In an experiment, the group exposed to the treatment.

control group

In an experiment, the group not exposed to the treatment.

random assignment

Assigning participants to experimental and control groups by chance.

single-blind procedure

An experimental procedure in which the research participants are ignorant of whether they have received the treatment.

double-blind procedure

An experimental procedure in which both participants and researchers are unaware of who has received the treatment.

placebo effect

Experimental results caused by expectations alone.

independent variable

In an experiment, the factor that is manipulated.

confounding variable

A factor other than the factor being studied that may influence results.

experimenter bias

Bias caused when researchers unintentionally influence results.

dependent variable

In an experiment, the outcome that is measured.

validity

The extent to which a test measures or predicts what it is supposed to.

quantitative research

A research method relying on quantifiable, numerical data.

qualitative research

A research method relying on in-depth, narrative data.

informed consent

Giving potential participants enough information about a study.

debriefing

The postexperimental explanation of a study to its participants.

descriptive statistics

Numerical data used to measure and describe characteristics of groups.

histogram

A bar graph depicting a frequency distribution.

mode

The most frequently occurring score(s) in a distribution.

mean

The arithmetic average of a distribution.

median

The middle score in a distribution.

percentile rank

The percentage of scores that are lower than a given score.

skewed distribution

A representation of scores that lack symmetry around their average value.

range

The difference between the highest and lowest scores in a distribution.

standard deviation

A computed measure of how much scores vary around the mean.

normal curve

A symmetrical, bell-shaped curve that describes the distribution of many types of data.

inferential statistics

Numerical data that allow one to generalize — to infer from sample data.

meta-analysis

A statistical procedure for analyzing the results of multiple studies.

statistical significance

A statistical statement of how likely it is that a result occurred by chance.

effect size

The strength of the relationship between two variables.

nature–nurture issue

The controversy over the relative contributions of genes and experience to development.

natural selection

The principle that inherited traits enabling survival will be passed to succeeding generations.

evolutionary psychology

The study of the evolution of behavior and mind using principles of natural selection.

behavior genetics

The study of genetic and environmental influences on behavior.

mutation

A random error in gene replication that leads to a change.

environment

Every nongenetic influence on behavior.

heredity

The genetic transfer of characteristics from parents to offspring.

genes

The biochemical units of heredity.

genome

The complete instructions for making an organism.

identical twins

Twins developed from a single fertilized egg split into two.

fraternal twins

Twins developed from separate fertilized eggs.

interaction

The interplay that occurs when the effect of one factor depends on another factor.

epigenetics

The study of how environments influence genetic expression.

nervous system

The body's electrochemical communication network.

central nervous system (CNS)

The brain and spinal cord.

peripheral nervous system (PNS)

The sensory and motor neurons connecting CNS to the body.

nerves

Bundled axons connecting the CNS with muscles and glands.

sensory neurons

Neurons that carry incoming information to the CNS.

motor neurons

Neurons that carry outgoing information from the CNS to muscles.

interneurons

Neurons within the CNS that communicate internally.

somatic nervous system

The division of the PNS that controls skeletal muscles.

autonomic nervous system (ANS)

The part of the PNS that controls internal organs.

sympathetic nervous system

The division of the ANS that arouses the body.

parasympathetic nervous system

The division of the ANS that calms the body.

reflex

A simple, automatic response to a sensory stimulus.

neuron

A nerve cell; the basic building block of the nervous system.

cell body

The part of a neuron that contains the nucleus.

dendrites

Neuron extensions that receive messages and conduct impulses.

axon

The neuron extension that passes messages to other neurons or muscles.

myelin sheath

A fatty tissue layer encasing axons, enabling faster transmission.

glial cells

Cells that support and protect neurons.

action potential

A neural impulse; a brief electrical charge that travels down an axon.

threshold

The level of stimulation necessary to trigger a neural impulse.

refractory period

A resting pause that occurs after a neuron has fired.

all-or-none response

A neuron's reaction of either firing or not firing.

synapse

The junction between neurons where communication occurs.

neurotransmitters

Chemical messengers that cross synaptic gaps between neurons.

reuptake

The reabsorption of neurotransmitters by the sending neuron.

endorphins

Natural, opioid-like neurotransmitters linked to pain control and pleasure.

agonist

A molecule that increases a neurotransmitter’s action.

antagonist

A molecule that inhibits or blocks a neurotransmitter’s action.

endocrine system

The body’s chemical communication system using hormones.

hormones

Chemical messengers produced by the endocrine glands.

psychoactive drug

A chemical substance that alters the brain and affects perceptions.

substance use disorder

A disorder characterized by continued substance use despite disruption.

depressants

Drugs that reduce neural activity and slow body functions.

tolerance

The diminishing effect with regular use of the same dose of a drug.

addiction

Compulsive substance use despite harmful consequences.