This is a Lexicon entry: the mechanism, when it shows up, and the countermeasure. The full correction, with real-world cases and the audit prompt, hasn't been written yet.
Definition
The finding that the length of an experience has almost no effect on how we remember or evaluate it - only the peak intensity and the final moments matter.
When it shows up
Retrospective evaluation of experiences: vacations, medical procedures, workouts, relationships. Any judgment about 'how good/bad was that?' made after the experience is over.
Failure mode
Total duration is ignored. The remembered quality is determined almost entirely by the peak intensity and the final moment. A short intense bad experience is remembered as worse than a long mild bad one.
Countermeasure
Separate 'how was it?' into peak, end and duration. When designing experiences for others (or planning your own), invest disproportionately in the ending; it will dominate memory.
Related concepts
Also connected in the mapDistinction Bias·Scope Insensitivity·The Peak-End Rule·The Well-Travelled Road Effect·The Impact Bias·Tachypsychia
Origin
Discovered by, 1996Donald RedelmeierMedicine · Decision scienceWith Kahneman, showed we judge episodes by their peak and end, not their duration.See in Origins →
Discovered byDaniel KahnemanPsychology · Nobel laureate · 1934–2024Proved judgement runs on fast, biased heuristics - the foundation the whole field stands on.See in Origins →Also revealed
Entry #62 of 631 in The Lexicon · see the full Lexicon