How Do Bodies Become Special? Electrophysiological Evidence for the Emergence of Body-Related Cortical Processing in the First 14 Months of Life

There is general consensus that the representation of the human face becomes functionally specialized within the first few months of an infant's life. The literature is divided, however, on the question whether the specialized representation of the remainder of the human body form follows a similarly rapid trajectory or emerges more slowly and in line with domain-general learning mechanisms. Our study investigates visual event-related potentials (ERPs) in adults (P1 and N170) and infants (P1, N290, P400, and Nc) of 3 age groups (3.5, 10, and 14 months) to compare the emergence of face-and body-structural encoding. Our findings show that visual ERPs were absent (P1, N290, P400) or smaller (Nc) for bodies than for faces at 3.5 months. At older ages, P400 was smaller (10 months) and peaked later (14 months) for bodies than for faces. Effects of stimulus orientation were not reliably found until 14 months, where they were more broadly distributed for faces than for bodies. Inverted faces, but not bodies, produced an adult-like pattern for P400 at 14 months, emphasizing the role of P400 as the precursor of the adult N170. Importantly, our findings argue that structural encoding of the human body form emerges later in infancy and is qualitatively different from the structural encoding for faces. This is commensurate with infant motor development and the experience of viewing complete body shapes later than faces.