25. Peak-End Effect
Wireless Philosophy, Cognitive Biases, 5:16. Original title: CRITICAL THINKING - Cognitive Biases: Peak-End Effect [HD]
Summary
Laurie Santos (Yale University) explains the peak-end effect, the finding that we judge an entire experience by only two of its moments: its most extreme point and how it ended.
An easy judgment that should be hard
Asked to rate how a past restaurant meal, film or vacation was, most people answer quickly and easily, even though a full evaluation would seem to require weighing every moment of the experience and deciding how many time points even count. Santos argues our minds solve this by ignoring almost all of it: we judge an experience mainly by its peak (the most extreme point, good or bad) and its end (how it finished).
The cold-water experiment
Daniel Kahneman and colleagues tested this by having participants place a hand in fourteen degree water for sixty seconds, a genuinely painful experience. In a second trial, participants again held their hand in fourteen degree water for sixty seconds, but then kept it in for another thirty seconds while the temperature rose to a still-painful but milder fifteen degrees. Despite the second trial involving more total pain, participants overwhelmingly said they preferred it and would rather repeat it, because averaging its peak and its end gave it a better score than the first, shorter trial.
From the lab to the clinic
Kahneman's team then tested the effect on a painful medical procedure that normally started out mild and grew steadily more painful, ending at its worst moment. They extended the procedure so that patients spent more time in pain overall, but let it end on a slightly less painful note. Patients rated the longer version as less painful and were more willing to come back for repeated procedures.
Duration neglect
Because the peak-end heuristic only registers two moments, it discards all information about how long an experience lasted, a phenomenon Santos calls duration neglect. A wonderful experience stays just as wonderful if you cut it short, and an annoying one can be stretched out without being remembered as worse.
Key takeaway
Since an experience's remembered goodness depends only on its peak and its end, the surest way to make an event feel great is to end it on its best possible point, which is why so many enjoyable events, from a winning goal to a fireworks finale, save their peak for last.