Infants understand that only in social interaction language updates an agent's false belief
Correcting a person’s false belief verbally seems to affect infants’ predictions of this person’s belief-based actions. However, the role of the context in which this verbal correction takes place has not been investigated. That is, it is not yet clear whether it is the social interaction between interlocutors that makes children interpret an utterance as a communicative act that alters the recipient’s mental states. Using a violation-of-expectation paradigm, we tested whether 18-month-olds (n=84) understood that for a communicative act to be successful in repairing an agent’s false belief, the agent had to discern the verbal statement. Participants saw how an agent put a toy into a box and left. An assistant then moved the toy into a cup. Before the agent reached into either the box or the cup, an intervention phase varied the social context within which communication took place. In a social context without any statement, infants expected the agent to search the toy at the original location. In a non-social context with a statement, infants had no clear expectations. However, in a social context with a statement, infants updated their predictions about the agent’s action, expecting her to search the toy at the actual location. Thus, 18-month-olds infer that a social interaction is required for a communicative act to be successful and to repair an agent’s false belief.