The peak-end rule explains why we misremember experiences

Psychologist Daniel Kahneman found that people's evaluation of an experience is determined almost entirely by two moments: its most intense point and its end — not by its average quality or duration. In one study, patients subjected to a shorter but more painful colonoscopy actually remembered it as worse than patients who had a longer procedure that ended with a period of milder discomfort. This 'peak-end rule' explains why a good dessert can redeem a mediocre meal, why the last impression an employer has of an interview dominates the overall evaluation, and why holidays feel short but summers feel long in retrospect.

Source: Kahneman et al., Psychological Science (1993)