9-month-olds expect goal-relevant movements and communicative information transfer during false belief correction

Infants represent others' mental states and can retrospectively infer whether communication served to update an agent's false belief in third-party contexts. In this study, we investigated whether 9-month-olds make anticipatory inferences about the aim of communication — specifically, whether they expect agents to communicate in order to correct a partner’s false belief. Infants were familiarized with videos of two non-human agents, one of which aimed to retrieve a target object hidden in one of two containers. At test, the protagonist held either a false belief (FB) or a true belief (TB) about the object's location, while the other agent always had the correct information. Before the protagonist approached the baited container, the agents oriented toward each other and exchanged variable non-speech sound sequences, allowing communicative information transfer. Based on prior findings, we hypothesized increased theta-band oscillations in the FB condition before communication took place, indexing the expectation of relevant information exchange, as well as sensory-motor alpha desynchronization in central channels, reflecting the prediction of goal-directed movement. Our preliminary results (N = 9) support our hypotheses. First, we found an increased left temporal theta-band activity, suggesting that infants expected variable signal exchanges only when necessary to update the protagonist's FB. Second, we observed central sensory-motor alpha desynchronization, which may indicate that infants expected the agents to turn toward each other only when goal-relevant information was needed. Together, these results suggest that 9-month-olds not only attribute mental states but also form anticipatory inferences about the aim of communication when mental states require updating.