AP Psych vocab - Units 0-5

critical thinking

thinking that does not automatically accept arguments and conclusions. Rather, it examines assumptions, appraises the source, discerns hidden biases, evaluates evidence, and assesses conclusions.

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.)

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. for example, human intelligence may be operationally defined as what an intelligence test measures.

replication

repeating the essence of a research study, usually with different participants in different situations, 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 in the hope of revealing universal principles.

naturalistic observation

a non-experimental technique of observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation.

survey

a non-experimental technique for obtaining the self-reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample of the group.

social desirability bias

bias from people's responding in ways they presume a researcher expects or wishes.

self-report bias

bias when people report their behavior inaccurately.

sampling bias

bias when people report their behavior inaccurately.

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, from which random samples may be drawn. (Note: Except for national studies, this does not refer to a country's whole population.)

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 variables (from −1.00 to +1.00).

variable

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

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).

illusory correlation

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

regression toward the mean

the tendency for extreme or unusual scores or events to fall back (regress) toward the average.

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.

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.

random assignment

assigning participants to experimental and control groups by chance, thus minimizing preexisting differences between the different groups.

Single-blind procedure

an experimental procedure in which the research participants are ignorant (blind) about whether they have received the treatment or a placebo.

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.

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.

independent variable

in an experiment, the factor that is manipulated; the variable whose effect is being studied.

confounding variable

in an experiment, a factor other than the factor being studied that might influence a study's results.

experimenter bias

bias caused when researchers may unintentionally influence results to confirm their own beliefs.

dependent variable

in an experiment, the outcome that is measured; the variable that may change when the independent variable is manipulated.

Validity

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

Quantitative Research

a research method that relies on quantifiable, numerical data.

Qualitative Research

a research method that relies on in-depth, narrative data that are not translated into numbers.

Informed Consent

giving potential participants enough information about a study to enable them to choose whether they wish to participate.

Debriefing

the postexperimental explanation of a study, including its purpose and any deceptions, to its participants.

descriptive statistics

numerical data used to measure and describe characteristics of groups; include measures of central tendency and measures of variation.

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, 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.

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 score.

normal curve

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 scores lie near the extremes. (Also called a normal distribution.)

inferential statistics

numerical data that allow one to generalize — to infer from sample data the probability of something being true of a population.

meta-analysis

a statistical procedure for analyzing the results of multiple studies to reach an overall conclusion.

Statistical Significance

a statistical statement of how likely it is that a result (such as a difference between samples) occurred by chance, assuming there is no difference between the populations being studied.

Effect Size

the strength of the relationship between two variables. The larger the effect size, the more one variable can be explained by the other.

Nature (heredity)

The influence of genes and biological factors on behavior and traits.

Nurture (environment)

The influence of experiences, upbringing, and surroundings on behavior.

Evolutionary Perspective

The view that behavior and mental processes have developed through natural selection.

Natural Selection

The process where traits that help survival are passed on to future generations.

Eugenics

A discredited movement that aimed to improve the genetic quality of humans by controlling reproduction.

Twin Studies

Research comparing identical and fraternal twins to determine the influence of genes versus environment.

Family Studies

Research examining how traits or disorders run in families.

Adoption Studies

Studies comparing adopted children to biological and adoptive parents to assess heredity vs. environment.

Central Nervous System (CNS)

The brain and spinal cord; controls most body and mind functions.

Peripheral Nervous System (PNS)

All nerves outside the CNS that connect the brain and spinal cord to the body.

Autonomic Nervous System

Controls involuntary actions like heartbeat and digestion.

Somatic Nervous System

Controls voluntary muscle movements.

Sympathetic Nervous System

Activates the body's "fight or flight" response in stressful situations.

Parasympathetic Nervous System

Calms the body and restores energy after stress ("rest and digest").

Neurons

Nerve cells that send and receive electrical and chemical messages.

Glial Cells

Support cells that help nourish and protect neurons.

Reflex Arc

The neural pathway that controls automatic responses like pulling your hand away from heat.

Sensory Neurons

Carry information from senses to the brain.

Motor Neurons

Send messages from the brain to muscles and glands.

Interneurons

Connect sensory and motor neurons within the brain and spinal cord.

All-or-Nothing Principle

A neuron either fires completely or not at all.

Depolarization

The process that allows a neuron to fire by changing its electrical charge.

Refractory Period

A short rest after a neuron fires before it can fire again.

Resting Potential

The electrical charge of a neuron when it's not firing.

Reuptake

When neurotransmitters are reabsorbed by the neuron that released them.

Threshold

The minimum level of stimulation needed for a neuron to fire.

Multiple Sclerosis

A disease where the myelin sheath around neurons is damaged, slowing messages.

Myasthenia Gravis

A disorder causing muscle weakness due to problems in communication between nerves and muscles.

Neurotransmitters

Chemical messengers that send signals across synapses between neurons.

Excitatory Neurotransmitter

Chemicals that make neurons more likely to fire.

Inhibitory Neurotransmitter

Chemicals that make neurons less likely to fire.

Dopamine

Influences movement, learning, attention, and emotion.

Serotonin

Affects mood, sleep, and appetite.

Norepinephrine

Helps control alertness and arousal.

Glutamate

A major excitatory neurotransmitter involved in memory.

GABA

A major inhibitory neurotransmitter that calms neural activity.

Substance P

Involved in sending pain signals.

Endorphins

Natural painkillers that produce pleasure and reduce pain.

Acetylcholine (ACh)

Enables muscle action, learning, and memory.

Hormones

Chemical messengers from glands that travel through the bloodstream.

Adrenaline (Epinephrine)

Increases heart rate and energy in response to stress.

Leptin

Regulates hunger and body fat.

Ghrelin

Triggers hunger.

Melatonin

Regulates sleep and wake cycles.

Oxytocin

Linked to bonding, trust, and social interactions.

Agonists

Drugs that mimic neurotransmitters to activate receptors.

Antagonists

Drugs that block neurotransmitter effects.

Stimulants

Drugs that increase neural activity (e.g., caffeine, cocaine).