Peak-end rule
We remember an experience by its most intense moment and by how it ends, not by how long it lasted.
What problem it addresses
It explains why a longer experience with a good ending can be remembered more fondly, and why a single bad moment shapes how we judge a service.
An example
In an experiment, each person put their hand in very cold water twice. Then they had to choose which of the two trials to repeat.
B has more cold in total, but most people preferred to repeat it.
Why it happens
Memory does not keep every second of an experience.
It keeps two moments: the most intense and the last.
Duration barely counts. More time is not remembered as worse.
Applications in design
Use it like this
Take care of the ending: the goodbye, the bill, the cancellation. And reduce the worst moment before polishing the rest.
Avoid
Dressing up the ending to cover a service that is bad from start to finish.
Don’t fall for it
When judging something, also remember how long it lasted and how the middle went, not just the ending.
Memory ≈ (peak + end) ÷ 2
What the research says
What we report after an experience looks more like the average of the peak and the end than the sum of all its moments. This was shown with cold water (Kahneman et al., 1993) and with real colonoscopies (Redelmeier and Kahneman, 1996).
Solid evidence. The formula is an approximation, not an exact rule.
Connections
Authors and works
- 1993
Daniel Kahneman et al.
Showed it with the cold water experiment.
- 1996
Donald Redelmeier and Daniel Kahneman
Confirmed it with real patients during a colonoscopy.
Sources
Original sources
- Kahneman, D., Fredrickson, B. L., Schreiber, C. A., & Redelmeier, D. A. (1993). When more pain is preferred to less: Adding a better end. Psychological Science, 4(6), 401–405. View source: Kahneman, D., Fredrickson, B. L., Schreiber, C. A., & Redelmeier, D. A. (1993)
- Redelmeier, D. A., & Kahneman, D. (1996). Patients' memories of painful medical treatments: Real-time and retrospective evaluations of two minimally invasive procedures. Pain, 66(1), 3–8. View source: Redelmeier, D. A., & Kahneman, D. (1996)
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