Two and a half-year-old children are prosocial even when their partners are not.

A total of 33 2.5-year-old toddlers were tested for proactive and selective prosocial responding in an iterated Prosocial Game with unfamiliar adult partners who were communicatively neutral and alternated their roles as actors and recipients every other trial. When children were actors, they were required to choose, at no cost to themselves, between a selfish option that delivered a reward to them only (1/0) and a prosocial option that delivered identical rewards to both themselves and their partners (1/1). When adult partners were actors, they consistently behaved prosocially (1/1) or selfishly (1/0) over 10 alternating trials, depending on test condition. An additional 17 children were used as a recipient-absent control group to test for self-oriented versus other-oriented prosocial preferences. This study shows that by 2.5 years of age, and in the particular context of the task administered, toddlers can display proactive, other-oriented prosocial behavior, but their prosocial responding is indiscriminate in that they fail to respond contingently to their partners' prosocial or selfish behavior in the previous trials. These findings lend further support to the view that human prosociality is in place early in development as a basic tendency to be nice to others. This inclination may be so strong that not even partners who are communicatively neutral or repeatedly selfish toward children can erode it. They also suggest that this precocious proactive prosociality may be independent of reciprocity in terms of both its developmental schedule and psychological scaffolding.