Psychology terms, defined plainly
The 55 terms that carry most of psychology — grouped by learning and behaviour, memory, thinking and judgement, emotion, personality and motivation, social life, brain and body, and the research-method words that let you judge a claim for yourself. Each one is defined in a sentence or two, without jargon.
Psychology’s vocabulary is doing a lot of quiet work. Half the confusion around the subject comes from words that sound like their everyday meaning but are not — negative reinforcement does not mean punishment, significant does not mean important, and bias is not an insult. Here are the terms that matter, grouped by what they are for.
Every definition is plain-language and self-contained. Where we have a full page on the idea, it is linked.
Learning & behaviour
A neutral cue comes to trigger a response after repeated pairing with something that already triggers it. Pavlov’s bell. A great deal of fear is learned this way.
Behaviour is shaped by consequences: reinforcement makes it more likely, punishment less. The engine under most habits.Go deeper →
Anything that makes a behaviour more likely to recur. Positive adds something wanted; negative removes something unwanted. Both increase behaviour — the common mix-up is thinking negative reinforcement means punishment.
A learned response fades once the cue stops predicting the outcome. The mechanism behind exposure therapy, and the reason avoidance keeps fear alive.Go deeper →
Responding less to a stimulus after repeated harmless exposure. Why you stop hearing the fridge.
Rewards that arrive unpredictably produce the most persistent behaviour. This is the design principle behind slot machines and infinite feeds.
Memory
The small, temporary workspace holding what you are actively using. Its limits explain most of what people call poor concentration.Go deeper →
The process turning fresh, fragile memories into stable ones — much of it during sleep.Go deeper →
Remembering is rebuilding, not replaying. Each recall can alter the trace, which is why confident memories can be wrong.Go deeper →
Information encountered after an event contaminates the memory of it — including the wording of a question.Go deeper →
Most forgetting is not erasure but an inability to find the memory. The right cue can restore it.Go deeper →
Retrieving information strengthens memory far more than rereading it. The single highest-value study technique.Go deeper →
Learning distributed over time beats the same total time crammed together.Go deeper →
Partial retrieval — you can access the word’s first letter or rhythm but not the word.Go deeper →
Thinking & judgement
A systematic, predictable departure from accurate judgement produced by mental shortcuts.Go deeper →
The shortcut itself — a fast rule that is usually good enough. Biases are the price of speed.Go deeper →
Noticing, seeking and remembering what fits what you already believe, and discounting what does not.Go deeper →
The first number you see drags every subsequent estimate toward it, even when it is arbitrary.Go deeper →
Judging how likely something is by how easily examples come to mind — which is why vivid rare events feel common.
Explaining other people’s behaviour by their character and your own by your circumstances.
The discomfort of holding conflicting beliefs, or acting against one. People usually resolve it by changing the belief, not the behaviour.
Losses feel larger than equivalent gains. Real, though the classic 2-to-1 ratio is debated.Go deeper →
Continuing because of what you have already spent, rather than what remains worth doing.Go deeper →
A mental template built from experience that organises knowledge and quietly fills gaps with what “should” be there.
Emotion & stress
The body’s activation level. Because arousal is ambiguous, the same racing heart can be labelled fear or excitement depending on context.Go deeper →
The strategies used to influence which emotions you have and how you express them. Procrastination is often a regulation strategy, not a time-management failure.Go deeper →
Repetitive, passive dwelling on distress and its causes. Distinct from problem-solving, and reliably makes mood worse.Go deeper →
An unwanted thought that arrives unbidden. Near-universal, and not a statement about character.Go deeper →
A persistently elevated state of physiological activation. Central to how insomnia is maintained.Go deeper →
Difficulty identifying and describing one’s own emotions.
Self, personality & motivation
The best-evidenced personality model: openness, conscientiousness, extraversion, agreeableness, neuroticism. Dimensions, not types.Go deeper →
Belief in your capacity to perform a specific action. Predicts persistence better than general confidence.
Whether you attribute outcomes mainly to your own actions or to outside forces.
Doing something because it is inherently rewarding. Adding external rewards to it can reduce interest — the overjustification effect.Go deeper →
Durable motivation rests on autonomy, competence and relatedness rather than external pressure.Go deeper →
Attributing your success to luck or overwork while treating failure as proof of real inability. Not a diagnosis.Go deeper →
The tendency to return toward a baseline level of wellbeing after good or bad events. Real, but not total.Go deeper →
Social & relational
The enduring bond between child and caregiver, and the adult patterns of closeness, anxiety and avoidance that follow.Go deeper →
Repeated exposure to something increases liking for it, even without interaction.Go deeper →
Using other people’s behaviour as evidence for what is correct, especially under uncertainty.Go deeper →
The strong pull to return a favour — including unrequested ones, which is why free samples work.Go deeper →
A pattern of largely non-physical tactics — isolation, financial control, monitoring, micro-regulation — producing entrapment. The pattern is the harm.Go deeper →
Feeling understood, validated and cared for. A core ingredient of intimacy.Go deeper →
Brain & body
The brain’s capacity to reorganise structure and connections in response to experience. A mechanism, not a miracle.Go deeper →
A neurotransmitter central to wanting and prediction, not liking. You cannot “detox” from it.Go deeper →
The molecule that accumulates while you are awake to build sleep pressure. Caffeine works by blocking its receptors.Go deeper →
The roughly 24-hour internal clock, entrained by light, that sets sleep timing and much else.Go deeper →
A sudden drop in heart rate and blood pressure causing fainting — the mechanism that makes blood and needle phobia unique.Go deeper →
Method — the words that protect you
Two things moving together does not mean one causes the other. The most useful sentence in the field.
How big a finding is, as distinct from whether it reached statistical significance. Real can still be too small to matter.
A measure of how unlikely a result is under the assumption of no effect. It says nothing about importance.
Independently repeating a study to see whether the finding holds. Outranks fame, every time.Go deeper →
Publishing your hypotheses and analysis plan before collecting data, so you cannot quietly change them afterwards.
Statistically combining many studies to estimate an overall effect. Usually more trustworthy than any single study.
The tendency for significant, surprising results to get published while null results sit in drawers — which inflates the apparent strength of everything.
If you take only four terms from this page, take correlation is not causation, effect size, replication and publication bias. Together they let you read any psychology headline and ask the right question: not “is this true?” but “how big, how repeated, and compared to what?”
Looking for a term that isn’t here? The full dictionary is searchable and considerably longer.
Frequently asked
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Sources & further reading
- Open Science Collaboration (2015), Estimating the reproducibility of psychological science, Science. Science, 2015 ↗
- Gilbert, King, Pettigrew & Wilson (2016), Comment on the above — the counter-argument. Science, 2016 ↗
- Studies named on this page are attributed inline by author, year and journal. Full linked citations live on the topic pages in each wing, and every debunked claim is sourced on our myths page.