By the preschool age, children exhibit a diversity of prosocial behaviors that include both sharing resources and helping others. Though recent work has theorized that these prosocial behaviors are differentiated by distinct ages of emergence, developmental trajectories and underlying mechanisms, the experimental evidence in support of the last…

Engaging in prosocial behavior is costly. By selectively directing prosocial behavior toward individuals with a high probability of reciprocating, we are able to offset these potential costs and maintain a sustainable prosocial system. Often, we determine whether an individual will make a good prosocial partner through the observation of their…