Five-year olds choose to 'play nice' based on other kids' reputations

Five-to-six-year olds are more likely to be kind to peers after observing them interacting with other children in positive ways, suggesting that children establish a sense of their peers' 'reputation' early in life. The results are published August 7 in the open access journal PLOS ONE by Kenji Onishi and colleagues from Osaka University, Japan.

The researchers observed kindergarteners' day-to-day behavior and found that bystanders in a playground were more likely to offer an object or help a child whom they had seen being helpful to another child. Children were more likely to behave in pro-social ways when they observed their peers doing so. Observing another child's pro-social behavior also evoked positive emotions towards that child in bystanders.

Cooperating with someone based on their reputation, or observations of their behavior with other people, is crucial to the success of cooperative societies. Though being 'nice' isn't always reciprocated by the recipient, it increases an individual's chances of being helped by others in the network. The results of this study demonstrate children's behavioral tendency toward such social indirect reciprocity, and suggest that this may be mediated by the increase in positive emotions when a child was seen performing a pro-social action.