The limits of early social evaluation: 9-month-olds fail to generate social evaluations of individuals who behave inconsistently.

Infant studies examining the development of the ability to evaluate others for their pro- and antisocial acts to date have explored how infants evaluate individuals who are either consistently prosocial or consistently antisocial. Yet in the real world, one regularly encounters individuals who behave inconsistently, engaging in multiple different kinds of behaviors that are variably prosocial and antisocial. In order to form accurate social evaluations of these inconsistently helpful and harmful individuals, then, evaluators must be able to aggregate across different types of behaviors and update previously formed evaluations based on new information. The current studies were designed to examine 9-month-old infants' social evaluations of characters who have displayed both prosocial and antisocial acts. Across three experiments using a previously utilized scenario for testing infants' preference for prosocial over antisocial others, infants repeatedly failed to prefer more- versus less-prosocial individuals when one of those individuals had previously acted both prosocially and antisocially, despite various attempts to facilitate responding across experiments. Notably, an additional experiment replicated infants' preference for consistently prosocial over consistently antisocial others. Together, findings from the current studies suggest that incorporating behavioral inconsistency into one's social evaluations may be especially difficult for infants in the first year.