December 15, 2022

Peak End Rule: When people judge an experience based on how they felt at its peak and at its end

People judge an experience largely based on how they felt at its peak and at its end, rather than the total sum or average of every moment of the experience. People also recall negative experiences more vividly than positive ones.

A 1993 study titled “When More Pain Is Preferred to Less: Adding a Better End” by Kahneman, Fredrickson, Charles Schreiber, and Donald Redelmeier provided groundbreaking evidence for the peak–end rule.

The first trial had subjects submerge a hand in 14°C water for 60 seconds. The second trial had subjects submerge the other hand in 14°C water for 60 seconds, but then keep their hand submerged for an additional 30 seconds, during which the temperature was raised to 15 °C. Subjects were then offered the option of which trial to repeat. Against the law of temporal monotonicity, subjects were more willing to repeat the second trial, despite a prolonged exposure to uncomfortable temperatures. Kahneman et al. concluded that “subjects chose the long trial simply because they liked the memory of it better than the alternative (or disliked it less)”.

The Peak End Rule makes onboarding and check-out experiences a worthwhile investment for all products and services. In the real world, a lot of positive reviews of applications rave about the onboarding experience. It sets the expectation and gives people a reason to stick around to explore the rest of the app/web-app. Similarly, a good checkout experience determines retention and repeated use.

For example, Flipkart adds a free BYJU's course to the cart that you can't remove. This diminishes the checkout experience which adds to drop-offs and people will think twice before returning to purchase something.