14-Month-olds anticipate others' actions based on their belief about an object's identity

Past research has accumulated evidence regarding infants' false-belief understanding, measuring their gaze patterns or active helping behaviors. However, the underlying mechanisms are still debated, specifically, whether young infants can compute that others represent the world under a certain aspect. Such performance requires holding in mind two representations about the same object simultaneously and attributing only one to another person. While 14-month-olds can encode an object under different aspects when forming first-person representations, it is unclear whether infants at this very age could also predict others' behavior based on their beliefs about an object's identity. Here, we investigate this question in a novel eye-tracking-based unexpected-identity task. We measured 14-month-olds' anticipatory looks combined with their looking time, using a violation-of-expectation paradigm. Results show that 14-month-olds look longer to an actor's reach that is incongruent with her false belief about the identity of an object compared to a congruent reach. Furthermore, infants correctly anticipated the actor's reach based on her false belief. Thus, as soon as infants represent dual identities they can integrate them in belief attributions and use them for consequent behavioral predictions. Such data provide evidence for the flexibility of false-belief attributions and support proposals arguing for infants' rich theory-of-mind abilities.