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404meanings / the dictionary / cognitive biases

38 ways a mind gets it wrong.

Placed by what each one distorts. North is what you notice; south is what you conclude from it. West is the world — numbers, chance, memory — and east is people, including the one in the mirror.

NoticingConcluding The worldPeople Mere Exposure Effect Horn Effect Zeigarnik Effect Negativity Bias Fundamental attribution error Primacy Effect Peak-End Rule Halo Effect Presque Vu Baader-Meinhof Barnum Effect Semantic Satiation Availability heuristic False Consensus Effect Hindsight Bias Recency Bias Actor-Observer Bias Bandwagon Effect Tip of the tongue Jamais Vu IKEA Effect Status Quo Bias Hot Hand Fallacy Gambler's Fallacy Self-Serving Bias Confirmation Bias Dunning-Kruger Effect Sunk Cost Fallacy Anchoring Bias Apophenia Survivorship Bias Framing Effect Overconfidence Effect Loss Aversion Decoy Effect Endowment Effect Spotlight Effect Optimism Bias

I · 13 words

Memory & attention

What sticks, what slips, and what suddenly seems to be everywhere.

II · 7 words

Judging others

How one impression of a person, or of a crowd, bends everything that follows.

III · 12 words

Numbers & chance

Prices, odds and sunk costs: where arithmetic loses to the way a choice is put.

IV · 6 words

Judging yourself

Confidence, credit and blame — the verdicts a mind passes on its owner.

All thirty-eight, by group

Memory & attention13

Judging others7

Numbers & chance12

Judging yourself6

Mirror images

Some of these only make sense as a pair.

Several biases are the same mistake pointed in opposite directions. Read them together and each one gets easier to spot.

Halo and horn

One good impression brightens everything else about a person; one bad one darkens it. The same leak, in both directions.

Primacy and recency

Whatever comes first, and whatever comes last, weighs more than the middle. Which one wins depends on when you are asked.

The gambler’s fallacy and the hot hand

One expects a streak to end; the other expects it to go on. The second may not be an error at all — its own page explains why.

Actor-observer and attribution error

Your own behaviour, you put down to circumstances. Other people’s, you put down to character.

Where each story begins

From 1849 to 2021.

The earliest date on each entry’s own page, for all 38 — sometimes the experiment that named the effect, sometimes an older use of the word it borrowed, like the circus bandwagon of 1849.