An Electrophysiological Investigation of Linguistic Pitch Processing in Tonal-language-speaking Children with Autism

Abstract

Speech perception is a fundamental skill interfacing sound to meaning; however, systematic characterization of autism in relation to this issue is still lacking, presumably due to insufficient consideration of the language-specific nature of speech processing. Although nearly 70% of world languages are tonal, tonal language users have been significantly under-represented in autism research. An overview of the limited literature reveals that there is a trend of distinct patterns across different language users (i.e., tonal language vs. non-tonal language), indicating potentially disrupted neural specialization for linguistic structures in individuals with autism. This dissertation examined the rapid cortical processing of pitch patterns varying in linguistic status in native Chinese school-age children with autism and age-matched typically developing (TD) peers using electroencephalography (EEG). The auditory stimuli were nonsense speech and nonspeech sounds presented in passive listening conditions. In comparison with the TD group, the autism group displayed neural timing issues at various levels of information processing as indicated by neural response latency. Moreover, the autism group displayed not only hyposensitivity for native vs. nonnative (or prototypical vs. non-prototypical) difference in the early information processing stage but also hypersensitivity in the later processing stage accompanied by diffusive scalp distribution with a rightward dominance. The results collectively support the idea of disrupted neural specialization for linguistic structures in autism. The findings underscore the proposition that autism is bound with auditory and phonological atypicalities in addition to the syndromic social and communication deficits, which have important implications for requiring language-specific considerations in autism research and clinical practice.