Peak-End Rule

The peak-end rule is a heuristic when people judge an experience based on how they felt at its peak, the intense point, and at its end, rather than based on the average of every moment of the experience. Regardless of whether or not the experience is pleasant or unpleasant, apart from the peak and end of the experience, the other parts of the experience are ignored and not used in a judgment.

Kahnemann et al (1993) is a study that looked at the phenomenon of peak-end rule in people. The study asked participants to hold their hand up to the wrist in painfully cold water until they were told to remove it. After this, the participants recorded how strong the pain was from 1 to 5. This was repeated in two conditions: condition 1, where participants put their hands in the cold water for 60 seconds, and condition 2, where participants put their hands in for 90 seconds while also putting their hands in warm water after the 60 seconds.

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When participants had a choice to choose between the two conditions, 80% of the participants chose the second condition. This shows the peak-end rule as the second condition was longer, but the participants ignored that fact and focused on how the condition ended, rather than the overall experiment.

To avoid this heuristic, we must consider the entire experience and take time to make a judgment rather than making immediate decisions.