Young children police group members at personal cost.

Humans' evolutionary success has depended in part on their willingness to punish, at personal cost, bad actors who have not harmed them directly-a behavior known as costly third-party punishment. The present studies examined the psychological processes underlying this behavior from a developmental perspective, using a novel, naturalistic method. In these studies (ages 3-6, total N = 225), participants of all ages enacted costly punishment, and rates of punishment increased with age. In addition, younger children (ages 3-4), when in a position of authority, were more likely to punish members of their own group, whereas older children (ages 5-6) showed no group- or authority-based differences. These findings demonstrate the developmental emergence of costly punishment, and show how a sense of authority can foster the kind of group-regulatory behavior that costly punishment may have evolved to serve. (PsycINFO Database Record (c) 2019 APA, all rights reserved).