Audiovisual speech integration in autism spectrum disorder: ERP evidence for atypicalities in lexical-semantic processing

摘要

Lay AbstractLanguage and communicative impairments are among the primary characteristics of autism spectrum disorders (ASD). Previous studies have examined auditory language processing in ASD. However, during face-to-face conversation, auditory and visual speech inputs provide complementary information, and little is known about audiovisual (AV) speech processing in ASD. It is possible to elucidate the neural correlates of AV integration by examining the effects of seeing the lip movements accompanying the speech (visual speech) on electrophysiological event-related potentials (ERP) to spoken words. Moreover, electrophysiological techniques have a high temporal resolution and thus enable us to track the time-course of spoken word processing in ASD and typical development (TD). The present study examined the ERP correlates of AV effects in three time windows that are indicative of hierarchical stages of word processing. We studied a group of TD adolescent boys (n=14) and a group of high-functioning boys with ASD (n=14). Significant group differences were found in AV integration of spoken words in the 200–300ms time window when spoken words start to be processed for meaning. These results suggest that the neural facilitation by visual speech of spoken word processing is reduced in individuals with ASD.