AP Psychology Cheat Sheet 2026

Key terms and concepts by unit · Updated for 2026 exam

Unit 1 — Biological Bases of Behavior

Term	Definition
Neuron	Basic unit of the nervous system; receives and transmits signals
Action potential	All-or-nothing electrical signal that travels down the axon
Synapse	Gap between terminal buttons of one neuron and dendrites of the next
Reuptake	Reabsorption of neurotransmitters back into the sending neuron
Acetylcholine (ACh)	Muscle movement, memory; deficit → Alzheimer's
Dopamine	Reward, movement; deficit → Parkinson's; excess → schizophrenia
Serotonin	Mood, sleep, appetite; deficit → depression
GABA	Main inhibitory NT; deficit → anxiety
Endorphins	Natural pain relief; released during exercise
Hippocampus	Forms new explicit (declarative) memories
Amygdala	Fear, aggression, emotional memory
Hypothalamus	Hunger, thirst, body temp, controls pituitary gland
Frontal lobe	Planning, impulse control, voluntary movement, Broca's area
Broca's area	Speech production (left frontal); damage → can't speak fluently
Wernicke's area	Speech comprehension (left temporal); damage → fluent but meaningless speech
Sympathetic NS	Fight-or-flight; increases heart rate, dilates pupils
Parasympathetic NS	Rest-and-digest; slows heart rate, aids digestion

Unit 2 — Research Methods & Statistics

Term	Definition
Independent variable (IV)	Variable manipulated by the researcher
Dependent variable (DV)	Variable measured as the outcome
Control group	Group not exposed to the IV; baseline for comparison
Random assignment	Each participant equally likely to be in any condition; controls confounds
Placebo effect	Improvement due to belief in treatment, not the treatment itself
Double-blind study	Neither participants nor researchers know who got the real treatment
Correlation coefficient (r)	Measures strength/direction of a relationship; ranges from −1 to +1
Correlation ≠ causation	Two variables can be related without one causing the other
Normal distribution	Bell curve; mean = median = mode
Standard deviation	Measure of how spread out scores are around the mean

Unit 3 — Sensation & Perception

Term	Definition
Absolute threshold	Minimum stimulation needed to detect a stimulus 50% of the time
Difference threshold (JND)	Minimum difference needed to detect a change
Weber's law	JND is a constant proportion of the original stimulus intensity
Signal detection theory	Detecting a stimulus depends on sensitivity AND decision criteria
Sensory adaptation	Decreased sensitivity after constant exposure to a stimulus
Perceptual set	Tendency to perceive stimuli based on expectations
Figure-ground	Organizing perception into a focal object (figure) against a background
Depth cues	Binocular: retinal disparity, convergence. Monocular: relative size, linear perspective, interposition

Unit 4 — Learning

Term	Definition
Classical conditioning	Associating a neutral stimulus with an unconditioned stimulus (Pavlov)
Unconditioned stimulus (US)	Naturally triggers a response (food)
Conditioned stimulus (CS)	Previously neutral; now triggers response after pairing
Extinction	Conditioned response disappears when CS no longer paired with US
Operant conditioning	Behavior strengthened or weakened by its consequences (Skinner)
Positive reinforcement	Adding something pleasant to increase behavior
Negative reinforcement	Removing something unpleasant to increase behavior
Punishment	Consequence that decreases a behavior
Fixed ratio schedule	Reward after set number of responses; highest response rate
Variable ratio schedule	Reward after unpredictable number; most resistant to extinction (slot machines)
Observational learning	Learning by watching others (Bandura; Bobo doll experiment)
Latent learning	Learning that occurs without reinforcement; shown when motivation appears

Unit 5 — Cognition & Memory

Term	Definition
Encoding	Getting information into memory
Storage	Retaining encoded information
Retrieval	Getting information out of memory
Sensory memory	Very brief storage of sensory information (iconic: visual; echoic: auditory)
Short-term memory	Limited capacity (~7 items); holds info for ~20 seconds without rehearsal
Long-term memory	Relatively permanent and unlimited storage
Working memory	Active processing of information; includes phonological loop, visuospatial sketchpad, central executive
Explicit memory	Conscious recall: episodic (events) and semantic (facts)
Implicit memory	Unconscious memory: procedural skills, classical conditioning
Proactive interference	Old memories interfere with new ones
Retroactive interference	New memories interfere with old ones
Confirmation bias	Tendency to search for information that confirms existing beliefs
Availability heuristic	Judging likelihood by how easily examples come to mind

Unit 6 — Developmental Psychology

Term	Definition
Piaget's stages	Sensorimotor (0–2), Preoperational (2–7), Concrete operational (7–11), Formal operational (12+)
Object permanence	Understanding objects exist when out of sight (sensorimotor stage)
Conservation	Understanding quantity stays same despite appearance changes (concrete operational)
Egocentrism	Difficulty seeing things from another's perspective (preoperational)
Secure attachment	Healthy bond; child explores freely with caregiver as safe base (Ainsworth)
Authoritative parenting	High warmth + high control; best outcomes
Authoritarian parenting	Low warmth + high control; children may be obedient but less happy
Erikson's stages	8 psychosocial stages from infancy to old age; each has a conflict to resolve

Unit 7 — Social Psychology

Term	Definition
Fundamental attribution error	Overestimating personality, underestimating situation when explaining others' behavior
Self-serving bias	Attributing success to self, failure to external factors
Conformity	Adjusting behavior to match group norms (Asch line studies)
Obedience	Following authority figures' orders (Milgram shock studies)
Bystander effect	Less likely to help in an emergency when others are present
Diffusion of responsibility	Each bystander feels less personally responsible as group size increases
Social facilitation	Performing better on simple/well-learned tasks in front of others
Social loafing	Exerting less effort in a group than alone
Groupthink	Group prioritizes harmony over critical thinking; leads to bad decisions
Cognitive dissonance	Discomfort from holding conflicting beliefs; resolved by changing beliefs or behavior
In-group bias	Favoring members of one's own group over out-group members

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