Linguistic and Musical Information-Processing in Children with Autism

This thesis focuses upon investigating the relationship between linguistic and musical information-processing in children with autism. The framework for the experiments presented herein derives from three main sources: first, studies highlighting enhanced musical pitch processing abilities in individuals with autism; second, findings from neurological and cognitive studies showing that social stimuli have substantially reduced salience for those with the disorder; and third, investigations reporting higher level language processing deficits in such individuals. Theories of autism that variously account for the featurally-biased information-processing style (weak central coherence hypothesis) (Frith, 1989a; Happe, 1999), atypical perceptual processing (theory of enhanced perceptual processing) (Mottron & Burack, 2001), as well as the social and communicative abnormalities in the disorder, are outlined and discussed within the context of the experimental findings.

The experiments presented in this thesis examined the relationship between perceptual processing of pitch information in speech stimuli, and musical stimuli, and higher-level linguistic abilities, in children with autism. Additionally, a pilot study into rhythmic processing was conducted. The main findings showed that whilst children with autism exhibited enhanced perceptual processing of pitch in speech stimuli, marked deficits in the understanding of the linguistic function of prosodic cues were in evidence. Furthermore, children with autism failed to consistently outperform their controls in experimental conditions comprising non-social stimuli. These findings suggest that the enhanced perceptual processing in autism is a consequence of atypical social development. Evidence suggesting reduced neural specialisation in the speech domain was explained by an atypical modularisation hypothesis. Taken together, the findings suggest that many aspects of speech processing, as well as more general auditory processing, are down-stream effects of an early reduction in the salience of social information in autism. Consequently, these children develop finely-tuned appreciation of the physical features of stimuli, and show difficulties in interpreting socially relevant information meaningfully.