A psychological heuristic that states that people judge an experience based on how they felt at its peak (emotionally intense periods) and its end, rather than on the average or total of every moment.

The rule applies to both pleasant and unpleasant experiences, and it often leads to duration neglect, meaning that the length of the experience is less important than the peak and the end.

The rule has implications for various fields, such as education, product design, and healthcare.

by Daniel Kahneman and Barbara Frederickson