Mental representations of speech and musical pitch contours reveal a diversity of profiles in autism spectrum disorder
Résumé
As an information-bearing auditory attribute of sound, pitch plays a crucial role in the perception of speech and music. Studies examining pitch processing in autism spectrum disorder have produced equivocal results. To understand this discrepancy from a mechanistic perspective, we used a novel data-driven method, the reverse-correlation paradigm, to explore whether the equivocal findings in autism spectrum disorder have high-level origins in top–down comparisons of internal mental representations of pitch contours. Thirty-two Mandarin-speaking autistic individuals and 32 non-autistic individuals undertook three subtasks testing mental representations of pitch contours in speech, complex tone and melody, respectively. The results indicate that while the two groups exhibited similar representations of pitch contours across the three conditions, the autistic group showed a significantly higher intra-group variability than the non-autistic group. In addition, the two groups did not differ significantly in internal noise, a measure of the robustness of participant responses to external variability, suggesting that the present findings translate genuinely qualitative differences and similarities between groups in pitch processing. These findings uncover for the first time that pitch patterns in speech and music are mentally represented in a similar manner in autistic and non-autistic individuals, through domain-general top–down mechanisms. Lay abstract As a key auditory attribute of sounds, pitch is ubiquitous in our everyday listening experience involving language, music and environmental sounds. Given its critical role in auditory processing related to communication, numerous studies have investigated pitch processing in autism spectrum disorder. However, the findings have been mixed, reporting either enhanced, typical or impaired performance among autistic individuals. By investigating top–down comparisons of internal mental representations of pitch contours in speech and music, this study shows for the first time that, while autistic individuals exhibit diverse profiles of pitch processing compared to non-autistic individuals, their mental representations of pitch contours are typical across domains. These findings suggest that pitch-processing mechanisms are shared across domains in autism spectrum disorder and provide theoretical implications for using music to improve speech for those autistic individuals who have language problems.
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