The Evolution and Development of Peak-End Effects for Past and Prospective Experiences

When people assess the pleasure or pain associated with past episodes, they tend to evaluate these episodes in terms of their peak-intensity and endpoint, ignoring other salient parts of the events. Although this tendency-known as the peak-end rule-is well studied in adult humans, little work has addressed the origins of this tendency, both developmentally and evolutionarily. Here we explore whether 3 populations-human adults, human children, and capuchin monkeys (Cebus apella)-structure events in order to maximize their experience through picking sequences with the best endpoint. Experiment 1 first demonstrates that peak-end effects can be observed in phylogenetically close species; we found that capuchins preferred to receive a food reward with the tastiest part delivered at the end of the event rather than the beginning, and showed a marginal preference for a reward with a short but high peak to a reward with a longer but less intense peak. We then tested whether these 3 populations structure their sequences using high peaks and ends to maximize pleasure. We found that all 3 populations fail to construct their experiences in ways that maximize hedonic gains. These results are discussed in terms of their implications for the evolutionary and developmental origins of the peak-end effect.