Abstract

We investigated 21-month-olds' ability to help others and share some resources with them on the basis of their past behavior. Infants were presented with real-life events in which a fair actress distributed her resources equally among two puppets, while an unfair actress allocated her resources only to one of the puppets. Then, the actresses played together with a ball that accidentally fell to the floor and asked infants to help them to retrieve it. Infants preferred to help and share resources with the fair actress, suggesting that their prosocial behaviors are modulated by an emerging sense of fairness.