Category selectivity of the N170 and the role of expertise in deaf signers

Abstract

Deafness is known to affect processing of visual motion and information in the visual periphery, as well as the neural substrates for these domains. This study was designed to characterize the effects of early deafness and lifelong sign language use on visual category sensitivity of the N170 event-related potential. Images from nine categories of visual forms including upright faces, inverted faces, and hands were presented to twelve typically hearing adults and twelve adult congenitally deaf signers. Classic N170 category sensitivity was observed in both participant groups, whereby faces elicited larger amplitudes than all other visual categories, and inverted faces elicited larger amplitudes and slower latencies than upright faces. In hearing adults, hands elicited a right hemispheric asymmetry while in deaf signers this category elicited a left hemispheric asymmetry. Pilot data from five hearing native signers suggests that this effect is due to lifelong use of American Sign Language rather than auditory deprivation itself.