Infants’ anticipation of belief-correcting communication: a theta rhythm investigation

In their second year of life, infants represent others' mental states and understand that agents’ false beliefs can be corrected when relevant information is shared with them. In our false belief correction paradigm, we investigated whether 9-month-olds expect agents to communicate to update a partner's false belief. Infants watched animated videos of two unfamiliar agents. In the familiarization phase, one of the agents aimed to approach a target object hidden in one of two containers. The test phase involved false belief and true belief trials. In false belief trials, the protagonist had incorrect information about the current location of the target object. In true belief trials, the location of the target object was known by both agents. Before the protagonist approached the baited container, the two agents exchanged variable non-speech sound sequences – which allow communicative information transfer – in both conditions. We predicted that infants would expect variable signal exchanges in false belief trials, where correcting the protagonist's false belief was necessary. Since the expectation of relevant information elicits synchronization of EEG theta rhythm, we hypothesized an increase in the theta-band oscillations in the false belief condition in contrast to the true belief condition before communication took place. In a preliminary analysis, we observed an increase in theta oscillations in the left temporal region in the false belief condition only. Our findings indicate that infants attribute mental states to communicative agents and expect the transfer of goal-relevant communicative information between the agents when their mental states need to be updated.