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Psychology glossary
125 key psychology terms, each with a plain-English definition and one real example. Search it, skim it, or work through a full unit at a time — it's free and there's nothing to sign up for.
Study by AP Psychology unit
Unit 1
Biological Bases
22 terms · definitions + examples
Unit 2
Cognition
20 terms · definitions + examples
Unit 3
Development & Learning
22 terms · definitions + examples
Unit 4
Social & Personality
20 terms · definitions + examples
Unit 5
Mental & Physical Health
20 terms · definitions + examples
Foundations
Perspectives & Foundations
9 terms · definitions + examples
Research Methods
Research Methods
12 terms · definitions + examples
Every term, A–Z
Absolute threshold
The minimum stimulation needed to detect a stimulus half the time.
Example: The quietest volume at which you can still just barely hear a tone.
Acetylcholine
A neurotransmitter involved in muscle movement, learning, and memory.
Example: Blocking it at the muscle produces paralysis; losing it in the brain is linked to memory loss.
Acquisition
The initial stage of learning, when the association between two stimuli (or a behavior and a consequence) is first formed.
Example: The first several bell-then-food pairings, before the dog reliably salivates.
Action potential
The brief electrical charge that travels down an axon once the neuron reaches its firing threshold.
Example: The all-or-nothing spike that either happens fully or does not happen at all.
Amygdala
A structure involved in processing fear, threat, and other strong emotional reactions.
Example: The jolt you feel before you consciously identify the shape in the dark as a coat.
Anxiety disorder
A category of disorders defined by persistent, excessive fear or worry that disrupts daily functioning.
Example: Avoiding classes for weeks because of the possibility of being called on.
Availability heuristic
Judging how likely something is by how easily examples come to mind.
Example: Fearing plane crashes more than car accidents because crashes dominate the news.
Axon
The long fiber that carries the neuron's signal away from the cell body toward other cells.
Example: A single axon running from your spinal cord all the way down to a muscle in your toe.
Behavioral perspective
Explains behavior as learned responses shaped by rewards, punishments, and associations in the environment.
Example: A student studying harder because good grades have consistently earned praise.
Big Five
The five broad personality dimensions used in most modern research: openness, conscientiousness, extraversion, agreeableness, and neuroticism.
Example: Describing someone as high in conscientiousness rather than simply 'organized.'
Biological perspective
Explains behavior through genetics, brain structures, neurotransmitters, and hormones.
Example: Attributing depression partly to low serotonin activity rather than only to life events.
Biomedical therapy
Treatment that changes the body's functioning directly, most often through medication.
Example: Prescribed medication used alongside talk therapy.
Bipolar disorder
A disorder involving alternating periods of depressed mood and mania or hypomania.
Example: A period of little need for sleep and rapid, expansive plans following a depressive stretch.
Bystander effect
Being less likely to help when other people are present, as responsibility feels shared.
Example: A crowded street where everyone assumes someone else has already called for help.
Cannon-Bard theory
The theory that physiological arousal and the emotional experience happen at the same time.
Example: Feeling fear and feeling your heart race as one simultaneous event.
Central nervous system
The brain and the spinal cord — the body's processing center.
Example: The spinal cord handling a knee-jerk reflex before the brain is even informed.
Cerebral cortex
The wrinkled outer layer of the brain responsible for higher-order thinking and processing.
Example: Where the language you're reading right now is being interpreted.
Chunking
Grouping items into meaningful units to expand how much working memory can hold.
Example: Remembering 1-4-9-2 as the year 1492 instead of four separate digits.
Circadian rhythm
The roughly 24-hour biological cycle that governs sleep, alertness, and body temperature.
Example: The mid-afternoon slump that arrives on schedule whether or not you slept well.
Classical conditioning
Learning by association: a neutral stimulus becomes linked to a stimulus that already triggers an automatic response.
Example: Feeling hungry the instant you hear a microwave beep.
Cognitive behavioral therapy
A treatment approach that targets unhelpful thought patterns and the behaviors that maintain them.
Example: Testing the belief 'I'll fail no matter what' against actual recorded outcomes.
Cognitive dissonance
The discomfort of holding conflicting beliefs or acting against a belief, which pushes us to change one of them.
Example: Deciding a job you settled for was 'what you wanted anyway.'
Cognitive perspective
Explains behavior through how people take in, store, interpret, and retrieve information.
Example: Two people leaving the same meeting with different memories because they focused on different details.
Conditioned response (CR)
The learned reaction to a conditioned stimulus.
Example: The dog salivating at the bell alone, with no food present.
Conditioned stimulus (CS)
A previously neutral stimulus that, after pairing, comes to trigger a learned response.
Example: The bell Pavlov rang before feeding the dogs.
Confirmation bias
Seeking and favoring information that supports what you already believe.
Example: Reading only the reviews that agree with the purchase you already want to make.
Conformity
Adjusting behavior or thinking to match a group standard.
Example: Going quiet in a meeting once you notice nobody else is objecting.
Confounding variable
An uncontrolled third factor that could explain the results instead of the independent variable.
Example: If the 8-hour sleep group also happened to be the honors class, ability is confounded with sleep.
Correlation coefficient
A number from -1.00 to +1.00 describing the strength and direction of a relationship between two variables. It never proves causation.
Example: Ice cream sales and drowning deaths correlate at about +.70 — because both rise with summer heat.
Debriefing
Fully explaining a study's true purpose, including any deception, after participation ends.
Example: Telling participants the 'other student' who criticized them was actually a confederate.
Defense mechanism
In psychoanalytic theory, an unconscious strategy for reducing anxiety.
Example: Insisting you 'never wanted the position anyway' after being turned down.
Dendrite
The branching ends of a neuron that receive incoming messages from other neurons.
Example: The 'inbox' side of the cell, collecting signals from dozens of neighbors at once.
Dependent variable
The outcome the researcher measures — it depends on the independent variable.
Example: The number of words recalled on the memory test.
Diathesis-stress model
The view that disorders emerge when a predisposition is combined with significant environmental stress.
Example: A genetic vulnerability appearing only after a period of prolonged hardship.
Discrimination
Learning to respond only to the specific conditioned stimulus and not to similar ones.
Example: The dog salivating at Pavlov's bell but not at a doorbell.
Dopamine
A neurotransmitter involved in reward, motivation, movement, and learning what to repeat.
Example: The surge that makes you want to check your phone again after one interesting notification.
Double-blind procedure
A design in which neither participants nor the researchers interacting with them know who is in which condition.
Example: A drug trial where the nurse handing out pills doesn't know which are active.
Drive-reduction theory
The idea that biological needs create drives we act to reduce, restoring balance.
Example: Thirst pushing you to drink until the need is met.
Emotion-focused coping
Reducing stress by managing your emotional reaction rather than the stressor itself.
Example: Going for a walk when a situation genuinely cannot be changed today.
Encoding
Getting information into memory by converting it into a usable mental form.
Example: Turning a spoken phone number into a mental image of the keypad.
Explicit (declarative) memory
Consciously recalled facts and personal experiences.
Example: Naming the capital of France, or recalling your first day of school.
Extinction
The weakening and eventual disappearance of a learned response when the association is no longer reinforced.
Example: The bell ringing repeatedly with no food until the dog stops salivating.
Extrinsic motivation
Doing something for an external reward or to avoid a penalty.
Example: Studying only because the quiz is graded.
Fixed-interval schedule
Reinforcement for the first response after a set amount of time. Produces a scalloped pattern of responding.
Example: Studying hard right before each scheduled Friday quiz and barely at all after it.
Fixed-ratio schedule
Reinforcement delivered after a set number of responses. Produces a high, steady rate of responding.
Example: A coffee shop card that gives a free drink after every 10 purchases.
Framing
How a choice is worded changing the decision people make, even when the options are identical.
Example: '90% survival rate' feeling much better than '10% mortality rate.'
Functional fixedness
The inability to see an object being used in a way other than its usual one.
Example: Not realizing a coin can work as a screwdriver.
Functionalism
An early school of thought focused on the purpose of mental processes — what behaviors and thoughts do for survival — rather than their parts.
Example: William James asking why fear is useful instead of what fear is made of.
Fundamental attribution error
Overestimating personality and underestimating the situation when explaining someone else's behavior.
Example: Assuming the driver who cut you off is rude, rather than rushing to an emergency.
General adaptation syndrome
Selye's three-stage response to prolonged stress: alarm, resistance, and exhaustion.
Example: The crash that arrives the weekend after finals rather than during them.
Generalization
Responding the same way to stimuli that resemble the original conditioned stimulus.
Example: A child afraid of one barking dog becoming afraid of all dogs.
Groupthink
A group prioritizing harmony and agreement over realistic evaluation of options.
Example: A team approving a plan nobody privately believes in because nobody wants to break consensus.
Hippocampus
A brain structure central to forming new explicit, long-term memories.
Example: Damage here can leave old memories intact while making new ones impossible to form.
Homeostasis
The body's tendency to maintain a stable internal state.
Example: Shivering to bring body temperature back up.
Humanistic perspective
Emphasizes free will, personal growth, and the drive to reach one's full potential.
Example: A therapist offering unconditional positive regard so a client can explore who they want to become.
Hypothalamus
A small brain structure regulating hunger, thirst, body temperature, and hormone release.
Example: The reason you start feeling cold and hungry at the same time on a long study night.
Hypothesis
A testable, falsifiable prediction about the relationship between two variables.
Example: 'Students who sleep 8 hours score higher on a memory test than students who sleep 4 hours.'
Implicit (procedural) memory
Memories expressed through skills and conditioned responses without conscious recall.
Example: Typing quickly without being able to name the key positions.
In-group bias
Favoring the group you belong to over groups you don't.
Example: Rating your own school's students as friendlier without any evidence.
Independent variable
The variable the researcher deliberately manipulates to see what effect it has.
Example: The amount of sleep participants are assigned to get.
Informational social influence
Going along with a group because you believe they have better information.
Example: Following the crowd toward an exit you can't see during a fire alarm.
Informed consent
Participants must be told enough about a study to freely decide whether to take part.
Example: Signing a form describing the tasks, time commitment, and right to withdraw at any point.
Intrinsic motivation
Doing something because it is satisfying in itself.
Example: Reading psychology articles no one assigned.
Introspection
Looking inward and reporting on your own conscious thoughts, feelings, and sensations — psychology's earliest research method.
Example: Wundt's participants sipping coffee and describing the exact sequence of sensations they noticed.
James-Lange theory
The theory that emotion follows from noticing our own physiological reaction.
Example: 'My hands are shaking, so I must be afraid.'
Latent learning
Learning that occurs but isn't demonstrated until there's a reason to show it.
Example: Rats that wandered a maze with no reward suddenly running it perfectly once food appeared.
Locus of control
Whether you believe outcomes come mostly from your own actions (internal) or from outside forces (external).
Example: 'I didn't study enough' versus 'that professor grades unfairly.'
Long-term memory
The relatively permanent, effectively unlimited store of knowledge, skills, and experiences.
Example: Remembering how to ride a bike after ten years off one.
Major depressive disorder
A disorder marked by at least two weeks of depressed mood or loss of interest, along with other significant changes in functioning.
Example: Persistent loss of interest in activities that were previously enjoyable.
Misinformation effect
Memory becoming distorted after exposure to misleading information following an event.
Example: Witnesses estimating faster speeds when asked how fast cars 'smashed' rather than 'hit.'
Mnemonic device
A memory aid that uses vivid imagery, acronyms, or organization to make material easier to retrieve.
Example: ROY G. BIV for the colors of the visible spectrum.
Myelin sheath
The fatty insulation wrapped around many axons that speeds up signal transmission.
Example: The reason a reflex arrives in milliseconds rather than crawling along the nerve.
Negative punishment
Removing something desirable to decrease a behavior.
Example: Taking away phone privileges for a week.
Negative reinforcement
Removing an unpleasant condition to increase a behavior. Still increases behavior — it is not punishment.
Example: Buckling your seatbelt to stop the car's beeping, so you buckle up faster next time.
Neuron
The basic cell of the nervous system, built to receive, carry, and pass along signals.
Example: The cell that fires when you touch something hot, before you have consciously decided anything.
Neurotransmitter
A chemical messenger released at the synapse that influences whether the next neuron fires.
Example: Serotonin, dopamine, and GABA all doing very different jobs in the same gap.
Normative social influence
Going along with a group to be liked or accepted, not because you believe they're right.
Example: Laughing at a joke you didn't find funny.
Obedience
Following the direct instruction of a perceived authority figure.
Example: Continuing a task you're uncomfortable with because someone in charge said to keep going.
Observational learning
Learning by watching and imitating others rather than through direct consequences.
Example: Children in Bandura's Bobo doll study hitting the doll after seeing an adult do it.
Obsessive-compulsive disorder
A disorder involving intrusive, unwanted thoughts and repetitive behaviors performed to reduce distress.
Example: Rechecking a lock many times despite knowing it is locked.
Operant conditioning
Learning in which behavior is strengthened or weakened by its consequences.
Example: Taking the same route to work because it has consistently been fastest.
Operational definition
A precise statement of how a variable is measured or manipulated in a specific study.
Example: Defining 'stress' as a score above 20 on the Perceived Stress Scale, not just 'feeling overwhelmed.'
Parasympathetic nervous system
The branch that calms the body back down and conserves energy — 'rest and digest.'
Example: The slow settling you feel a few minutes after a near-miss in traffic.
Peripheral nervous system
All the nerves outside the brain and spinal cord that connect it to the rest of the body.
Example: The nerves carrying the message from your fingertip to your spinal cord.
Placebo effect
Improvement caused by a participant's expectations rather than the treatment itself.
Example: Feeling more alert after a sugar pill you were told was caffeine.
Plasticity
The brain's ability to reorganize and form new connections in response to experience or injury.
Example: Nearby regions gradually taking over some functions after a stroke.
Positive punishment
Adding an unpleasant consequence to decrease a behavior.
Example: Assigning extra chores after a curfew violation.
Positive reinforcement
Adding a desirable consequence to increase a behavior.
Example: Giving a dog a treat after it sits.
Prejudice
An unjustified attitude — usually negative — toward a group and its members.
Example: Disliking a candidate before hearing anything they've said.
Proactive interference
Older learning disrupting recall of new information.
Example: Typing your old password out of habit after changing it.
Problem-focused coping
Reducing stress by acting directly on the source of the problem.
Example: Building a study schedule instead of avoiding the syllabus.
Psychodynamic perspective
Explains behavior through unconscious motives, internal conflict, and early childhood experience.
Example: Interpreting a persistent fear of commitment as rooted in an early loss.
Random assignment
Placing participants into experimental groups by chance so pre-existing differences spread out evenly.
Example: Drawing names to decide who gets the 8-hour and who gets the 4-hour sleep condition.
Random sample
A sample in which every member of the population has an equal chance of being selected, making results generalizable.
Example: Pulling 200 student ID numbers at random from the full enrollment list.
Reciprocal determinism
Bandura's idea that behavior, personal factors, and environment continuously influence one another.
Example: A shy person choosing quiet settings, which then reinforces the shyness.
REM sleep
The sleep stage marked by rapid eye movement, vivid dreaming, and near-paralyzed muscles.
Example: Waking mid-dream and being briefly unable to move.
Representativeness heuristic
Judging likelihood by how well something matches a mental prototype, ignoring base rates.
Example: Assuming a quiet, bookish stranger is a librarian rather than a salesperson — though salespeople vastly outnumber librarians.
Retrieval
Pulling stored information back into conscious awareness.
Example: Recalling a definition mid-exam without any prompt on the page.
Retroactive interference
New learning disrupting recall of older information.
Example: Learning Spanish and then struggling to recall French vocabulary.
Schachter-Singer two-factor theory
The theory that emotion requires both physical arousal and a cognitive label for it.
Example: Racing heart plus 'this is a first date' being read as excitement rather than fear.
Schizophrenia
A disorder involving disturbances in thought, perception, and behavior, which may include hallucinations or delusions.
Example: Speech that moves between loosely connected ideas.
Self-efficacy
Your belief in your own ability to succeed at a specific task.
Example: Feeling confident about a chemistry exam but not a public speech.
Self-serving bias
Crediting our successes to ourselves and blaming our failures on circumstances.
Example: 'I aced it because I'm good at this' versus 'I failed because the test was unfair.'
Sensory memory
A very brief, high-capacity record of sensory input lasting well under a second for vision.
Example: The trail a sparkler seems to leave in the dark.
Serial position effect
The tendency to best recall the first (primacy) and last (recency) items in a list.
Example: Remembering the first and last people introduced at a party, but not the middle five.
Serotonin
A neurotransmitter involved in mood, sleep, appetite, and arousal.
Example: Frequently discussed in research on depression and commonly targeted by SSRI medications.
Shaping
Reinforcing successive approximations — steps that get closer and closer to the target behavior.
Example: Rewarding a rat first for facing the lever, then touching it, then pressing it.
Social facilitation
Performing better on simple or well-practiced tasks when other people are watching.
Example: Running your fastest mile at a race rather than alone on a track.
Social loafing
Putting in less effort when working in a group than when working alone.
Example: The group project member whose contribution arrives at 11:58 p.m.
Sociocultural perspective
Explains behavior through the influence of culture, social norms, and group membership.
Example: Why direct eye contact reads as confident in one culture and disrespectful in another.
Spacing effect
Information studied in spread-out sessions is retained far better than the same time spent cramming.
Example: Reviewing flashcards 15 minutes a day for a week rather than two hours the night before.
Spontaneous recovery
The sudden reappearance of an extinguished response after a rest period.
Example: A week after extinction, the dog salivates at the bell again — briefly.
Stereotype
A generalized belief about the characteristics of members of a group.
Example: Assuming an engineering student must be bad at writing.
Storage
Retaining encoded information over time.
Example: Still knowing your childhood address decades later.
Stressor
Any event or condition that a person perceives as threatening or demanding.
Example: Three deadlines landing in the same 24 hours.
Structuralism
An early school of thought that tried to break consciousness down into its most basic elements, the way chemistry breaks matter into atoms.
Example: Titchener asking participants to describe an apple purely as color, weight, and texture — never as 'an apple.'
Sympathetic nervous system
The branch that mobilizes the body for action — the 'fight or flight' response.
Example: Heart pounding and palms sweating the second you realize you're being called on.
Synapse
The tiny gap between two neurons where chemical messages cross.
Example: The space a neurotransmitter floats across after it is released from the sending neuron.
Systematic desensitization
Gradually pairing relaxation with increasingly close contact with a feared stimulus.
Example: Working from photos of dogs up to standing near a calm dog.
Trait
A relatively stable pattern of behavior, thought, or emotion that describes a person.
Example: Being consistently punctual across jobs, classes, and friendships.
Unconditioned response (UCR)
The unlearned, automatic reaction to an unconditioned stimulus.
Example: Salivating at the taste of food.
Unconditioned stimulus (UCS)
A stimulus that naturally and automatically triggers a response without any learning.
Example: Food in the mouth causing salivation.
Variable-interval schedule
Reinforcement for the first response after unpredictable time intervals. Produces slow, steady responding.
Example: Checking your phone for a text that could arrive at any moment.
Variable-ratio schedule
Reinforcement after an unpredictable number of responses. Produces the highest response rate and is the hardest to extinguish.
Example: Slot machines — which is exactly why they're so hard to walk away from.
Working memory
The limited-capacity system that actively holds and manipulates information right now — an update to the older 'short-term memory' idea.
Example: Holding three numbers in mind while adding them without writing anything down.
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