Differential neural responses to faces paired with labels versus faces paired with noise at 6- and at 9-months

Labeling objects or faces in the first year of life shapes subsequent attention and perception. Three months of hearing individual-level, unique labels for previously unfamiliar faces promotes face differentiation and impacts neural processing during the first year of life. However, it is currently unclear whether verbal labeling influences visual processing of faces during label learning and whether these effects differ across the first year of life. The current study examined the impact of individual-level labels versus a non-speech noise on neural responses to monkey faces. Event-related potentials (ERPs) were recorded while infants viewed two species of monkey faces: one paired with labels and one paired with a non-speech noise. At 9 months, neural responses differentiated monkey faces paired with labels relative to those paired with noise during both the first and second halves of the experiment. Nine-month-olds exhibited a faster P1 latency, marginally greater N290 amplitude and reduced P400 amplitude to labeled faces relative to a non-speech noise. However, 6-month-olds' neural responses did not differentiate monkey faces paired with labels from those paired with a non-speech noise until the second half of trials and only showed this effect for P1 latency and N290 amplitude. The results of this study suggest that overall, infants differentiate faces labeled with individual-level labels from those paired with a non-speech noise, however, 6-month-olds require more exposure to the label-face pairings than 9-month-olds.