Neural representations and behavioral markers of elementary logical processes in preverbal infants

Infants learn by directly experiencing events, but also by drawing logical consequences from experienced events. While such inferential abilities help early knowledge acquisition, their computations and neural bases are not understood. Here, we collect optical brain-imaging and oculomotor data while preverbal infants watch simple scenes requiring disjunctive syllogism to identify an unknown object. These scenes elicited greater hemodynamic activation in bilateral temporoparietal and left-frontal regions, compared to controls. Oculomotor responses signaled higher processing load at two logically relevant moments: when something unknown (x; A or B) can be represented, and when a non-visible object can be identified via inference (not A, therefore B). These responses were similar to those previously described in adults, but the mostly bilateral response differs from the left-lateralized pattern characterizing mature brains, suggesting that the same functional operations are realized in neural circuits which maturation, experience, or language learning modify into a more specialized cortical organization.