AP PSYCHOLOGY EXAM REVIEW

Hypothesis

A testable and falsifiable prediction about the relationship between variables.

Examples:

• Students who sleep 8 hours will score higher than those who sleep 4 hours.

• Listening to music while studying will improve memory recall.

Operational Definition

A clear, precise, measurable description of how a variable is defined and measured in a study.

Examples:

• “Stress” = number of hours of sleep lost per night

• “Happiness” = score on a 1–10 survey

• “Exercise” = minutes spent at the gym per day

Population

The entire group a researcher wants to study.

Examples:

• All high school students in the U.S.

• All patients with anxiety

Sample

A subset of the population selected for the study.

Examples:

• 100 students from one school

• 50 patients from a clinic

Qualitative Data

Descriptive, non-numerical data.

Examples:

• Interview responses

• Descriptions like “happy,” “sad,” “angry”

Quantitative Data

Numerical data used for statistical analysis.

Examples:

• Test scores

• Number of hours studied

Correlation

A relationship between two variables where one changes as the other changes (NO cause/effect).

Examples:

• Study finds students who study more have higher grades

• People who exercise more tend to be healthier

Advantage vs Disadvantage of Correlation

Advantage: Useful when experiments are unethical

Disadvantage: Correlation doe not equal/cause causation

Positive Correlation

Both variables increase or decrease together.

Examples:

• More studying → higher grades

• More exercise → better health

Negative Correlation

One variable increases while the other decreases.

Examples:

• More stress → less sleep

• More screen time → lower grades

Directionality Problem

Uncertainty about which variable causes the other.

Examples:

• Does stress cause poor sleep OR poor sleep cause stress?

Third Variable Problem

A hidden variable causes both variables.

Examples:

• Ice cream sales & drowning → caused by hot weather

• Study time & grades → maybe motivation is the third variable

Experiment

A study where the researcher manipulates a variable to determine cause and effect.

Examples:

• Giving one group caffeine and another group none to see effect on focus

Advantage vs Disadvantage of Experiments

Advantage: Only type to establish cause and effect

Disadvantage: Can be unethical or too artificial

Independent Variable

The variable the researcher manipulates/changes.

Examples:

• Amount of sleep

• Type of music played

Dependent Variable

The variable that is measured (depends on IV).

Examples:

• Test scores

• Memory recall

Experimental Group

Group that receives the treatment.

Examples:

• Group given caffeine

• Group given therapy

Control Group

Group that does NOT receive treatment (baseline).

Examples:

• Group given placebo

• Group given no therapy

Random Assignment

Participants are randomly placed into groups to increase chance of equal representation

Examples:

• Assigning participants to control or experimental group by drawing names

Placebo Effect

Participants experience improvement because they expect treatment to work.

Examples:

• Fake pill makes someone feel better

• Sugar pill reduces pain

Double-Blind Procedure

Neither participants nor researchers know who is in which group.

Examples:

• Drug study where both doctor and patient don’t know who gets real drug

Single-Blind Procedure

Participants do not know which group they are in, but researcher knows.

Examples:

• Participants receive either a real drug or a placebo, but only the researcher knows which one they got

• Students take a test after drinking either caffeine or a fake drink, but they don’t know which one they received

Confounding Variable

An uncontrolled variable that affects results (dependent variable).

Examples:

• Noise level affects test performance

Naturalistic Observation

Observing behavior in a natural environment without interference.

Examples:

• Watching children on a playground

• Observing animals in the wild

Case Study

An in-depth study of one individual or small group.

Examples:

• Studying a person with memory loss

• Famous brain injury cases

Meta-Analysis

Combining results from multiple studies to find overall conclusions.

Examples:

• Analyzing 50 studies on depression treatment

Mean

The average of a set of numbers.

Examples:

• (70 + 80 + 90) ÷ 3 = 80

Median

The middle value in a data set when arranged smallest to largest

Examples:

• 10, 20, 30 → median = 20

Mode

The most frequently occurring value.

Examples:

• 2, 2, 3, 4 → mode = 2

In a normal distribution, the mean, median, and mode are:

All equal

In a positively skewed distribution, the order of the measures is:

Mode < median < mean

In a negatively skewed distribution, the order of the measures is:

Mode > median > mean

Bimodal

A distribution that has two modes (two peaks) — meaning two values occur most frequently.

Examples:

• Test scores where most students either scored very high OR very low (two clusters)

• Heights in a group with both children and adults (two common height ranges)

Skews

Created by outliers

Range

Difference between highest and lowest values.

Examples:

• 90 – 60 = 30

Standard Deviation

Measures how spread out data/scores are from the mean.

Examples:

• Small SD → scores close together

• Large SD → scores spread out

Statistical Significance

Results are unlikely due to chance.

Examples:

• p < 0.05 → significant result

Effect Size

Measures strength of relationship or impact.

Examples:

• Strong therapy effect vs weak therapy effect

Informed Consent

Participants must agree to be in the study.

Examples:

• Signing permission form

Confidentiality

Participant information is kept private.

Examples:

• Using ID numbers instead of names

Debriefing

Explaining the study after it ends, especially if deception was used.

Examples:

• Telling participants the real purpose

No Harm

Participants are treated with respect and protected from physical or psychological harm

What is the cost–benefit analysis in research ethics?

Ensuring the benefits to psychology and human welfare outweigh the risks to participants

Deception

Withholding information or misleading participants when necessary for the study’s effectiveness

Survey

Collecting self-reported information by asking people questions

Social Desirability Bias

People responding in ways they think the researcher expects or wishes

Examples:

• Lying about bad habits

Wording Effects

How a question is phrased influences answers.

Examples:

• “Should we ban dangerous driving?” vs “limit freedom?”

Random Sample

Everyone in the population has an equal chance of selection. Increases generalization

Examples:

• Picking names from a hat

Representative Sample

Sample reflects the population’s characteristics.

Examples:

• Same % of genders, ages, etc.

Convenience Sample

Sample based on availability/easy access.

Examples:

• Surveying your classmates

Sampling Bias

Sample is not representative of population.

Examples:

• Only surveying athletes

Experimenter Bias

An researchers action/belief influencing the outcome of the experiment

Examples:

• Giving hints to participants

Participant Bias

Subjects act in ways that they think the experimenter wants them to act

Examples:

• Participants act “nicer” because they think they’re supposed to

Cultural Norms

The shared expectations, values, and behaviors of a specific group or culture that can influence how people think and act in a study.

Examples:

• A study on eye contact may show different results in different cultures (some see it as respectful, others as rude)

• A survey about independence may vary between individualistic cultures (U.S.) vs collectivist cultures (Japan)

Confirmation Bias

Seeking info that supports existing beliefs.

Examples:

• Only reading sources you agree with

Hindsight Bias

Believing you “knew it all along.”

Examples:

• After test, saying “that was obvious”

Overconfidence

Overestimating your abilities.

Examples:

• Thinking you’ll ace a test without studying

Hawthorne Effect

People change behavior because they know they’re being watched.

Examples:

• Workers perform better when observed

Evolutionary Psychology

The study of how natural selection influences behavior and mental processes.

Examples:

• Humans fear snakes/spiders because it helped survival

• Attraction to healthy partners = reproductive advantage

Heredity (Nature)

The genetic transmission of traits from parents to offspring.

Examples:

• Eye color

• Genetic predisposition to anxiety

Environment (Nurture)

External influences like culture, upbringing, and experiences.

Examples:

• Parenting style affects personality

• School environment affects learning

Twin/Adoption Studies

Studies used to separate genetic vs environmental influences.

Examples:

• Identical twins raised apart still have similar personalities → genetics

• Twins raised differently show differences → environment

Central Nervous System (CNS)

The brain and spinal cord — processes information.

Examples:

• Brain interprets pain

• Spinal cord controls reflexes

Peripheral Nervous System (PNS)

All nerves outside the CNS — connects body to brain.

Examples:

• Signals from hand to brain when touching something hot

Somatic Nervous System

Controls voluntary movements and skeletal muscles.

Examples:

• Walking

• Typing

Autonomic Nervous System (ANS)

Controls involuntary functions.

Examples:

• Heart rate

• Digestion

• Breathing

• Blood pressure

Sympathetic Nervous System

Activates “fight or flight” response, arouses body, mobilizing energy

Examples:

• Increased heart rate

• Dilated pupils

Parasympathetic Nervous System

Calms the body, conserving energy (“rest and digest”)

Examples:

• Slows heart rate

• Digestion resumes

Neuron

A nerve cell that sends and receives messages in the nervous system ; basic building block

Examples:

• Brain cells sending signals

Dendrites

Receive incoming signals.

Examples:

• Receive neurotransmitters

Axon

Carries signal away from neuron.

Myelin Sheath

Synapse