Impaired categorical perception of Mandarin tones and its relationship to language ability in autism spectrum disorders

While enhanced pitch processing appears to be characteristic of many individuals with autism spectrum disorders (ASD), it remains unclear whether enhancement in pitch perception applies to those who speak a tone language. Using a classic paradigm of categorical perception (CP), the present study investigated the perception of Mandarin tones in six-to eight-year-old children with ASD, and compared it with age-matched typically developing children. In stark contrast to controls, the child participants with ASD exhibited a much wider boundary width (i.e., more gentle slope), and showed no improved discrimination for pairs straddling the boundary, indicating impaired CP of Mandarin tones. Moreover, identification skills of different tone categories were positively correlated with language ability among children with ASD. These findings revealed aberrant tone processing in Mandarin-speaking individuals with ASD, especially in those with significant language impairment. Our results are in support of the notion of impaired change detection for the linguistic elements of speech in children with ASD.