The Intriguingly Social N400 of Preverbal Infants

ABSTRACT Recent investigations have shown that the neural processing of linguistic content may interact with social cognition. Specifically, semantic processing, as reflected by the N400 event-related potential, appears to be sensitive to manipulations of Theory of Mind (ToM), the ability to attribute mental content to social partners. In this study, we labeled objects for 14-month-old infants either correctly or incorrectly (an N400 manipulation), ehiter in the presence or absence of an observer. We found that the N400 response was enhanced in the presence (relative to the absence) of the social partner, but only for the incongruent labels. ToM's role in language comprehension has long been proposed, but the outcome that ToM may impact not solely pragmatic but also semantic level computations—already at the developmental onset of the N400 response—may warrant a reevaluation of the functional organization of the language system. Although a large body of developmental research suggests that language may be a prerequisite for ToM, our findings raise the possibility that ToM may play a fundamental role in language acquisition. Linguistic content may be processed by a semantic system functioning mentalistically, recovering meaning as intended by communicative partners, which could hold the key to the rapid word learning of infants.