Peak End Rule

What is the peak-end rule?

The peak-end rule describes a pattern in retrospective evaluation: the most intense part and the ending of an episode can receive disproportionate weight compared with its duration and other moments.

In Kahneman and colleagues’ cold-water experiment (1993), many participants preferred to repeat a longer painful trial when its extra ending was less painful. This helped distinguish remembered experience from the amount of discomfort experienced over time.

The finding is not a universal formula for evaluating every experience. Improving an ending may change a memory, but it does not erase harm earlier in an experience or justify adding pain.