Consonant differentiation mediates the discrepancy between non-verbal and verbal abilities in children with ASD.

Abstract

Many children with autism spectrum disorder (ASD) demonstrate verbal communication disorders reflected in lower verbal than non-verbal abilities. The present study examined the extent to which this discrepancy is associated with atypical speech sound differentiation. Differences in the amplitude of auditory event-related potentials elicited by contrasting consonant-vowel syllables during a passive listening paradigm were used to assess speech sound differentiation in 24 children with ASD and 18 chronological age-matched children with typical development (TD), M age 6.90 years (SD = 1.39). Results revealed that compared with TD peers, children with ASD showed reduced consonant differentiation in the 84- to 308-ms period. Brain responses indexing consonant differentiation were negatively related to the degree of discrepancy in non-verbal and verbal abilities and mediated the relationship between diagnostic group membership and the greater discrepancy. We discuss the theoretical and clinical implications of the brain's response to speech sound contrasts possibly explaining the greater non-verbal versus language ability in children with ASD compared with that in typically developing children.