Infants' representation of asymmetric social influence.

In social groups, some individuals have more influence than others, for example, because they are learned from or because they coordinate collective actions. Identifying these influential individuals is crucial to learn about one's social environment. Here, we tested whether infants represent asymmetric social influence among individuals from observing the imitation of movements in the absence of any observable coercion or order. We defined social influence in terms of Granger causality; that is, if A influences B, then past behaviors of A contain information that predicts the behaviors and mental states of B above and beyond the information contained in the past behaviors and mental states of B alone. Infants (12-, 15-, and 18-month-olds) were familiarized with agents (imitators) influenced by the actions of another one (target). During the test, the infants observed either an imitator who was no longer influenced by the target (incongruent test) or the target who was not influenced by an imitator (neutral test). The participants looked significantly longer at the incongruent test than at the neutral test. This result shows that infants represent and generalize individuals' potential to influence others' actions and that they are sensitive to the asymmetric nature of social influence; upon learning that A influences B, they expect that the influence of A over B will remain stronger than the influence of B over A in a novel context. Because of the pervasiveness of social influence in many social interactions and relationships, its representation during infancy is fundamental to understand and predict others' behaviors.