Auditory global-local processing in typical development and autism spectrum disorder

by Tia Ouimet

Institution: McGill University
Department: Department of Educational and Counselling Psychology
Degree: PhD
Year: 2014
Keywords: Education - Psychology
Record ID: 2029699
Full text PDF: http://digitool.library.mcgill.ca/thesisfile126908.pdf


To perceive our sensory world, we parse whole or “global” features of visual and auditory information into smaller “local” details. In vision, typically developing (TD) individuals first process global features before the local details, or see the “forest before the trees” (“global precedence effect”) (Navon, 1977). In contrast, a more locally-based visual processing style hasbeen found in individuals with autism spectrum disorder (ASD). Relative to vision, however, the distinction between global and local processing in the auditory domain remains unclear, due in large part to methodological limitations. How we process global and local auditory information at a behavioural level affects what we hear and how we hear it, and accordingly, how we interact with our environment. This dissertation includes three articles that aim to better characterize auditory global-local processing in TD and ASD. In Article 1, a new set of auditory global-local stimuli (adapted from Justus & List, 2005) was validated in TD adults, and the effects of attention and musical expertise on auditory global-local processing were examined. The results showed that although the global precedence effect persisted across attention tasks, this effect wasrelated to musical experience, wherein a more pronounced global precedence effect was observed in non-musicians versus musicians. Next, to elucidate basic sensory processing differences in ASD, Article 2 reviewed and critically evaluated current literature on auditory processing in this population. Overall, auditory global-local findings were consistent withfindings from the visual domain of enhanced local processing and intact global processing. Article 3 then tested for group differences in auditory global-local processing between TD children and children with ASD, specifically in terms of the effects of attention and age. The results showed a more pronounced global precedence effect in TD relative to ASD,driven by enhanced local (but intact global) processing in ASD. The type of attention task affected global-local processing in children, wherein enhanced local processing was found specifically in the divided and not the directed task, and most predominantly in ASD. Finally, a more globally-based processing style was found at older ages in both groups, but withsignificantly protracted development in ASD compared to TD. The findings from these three articles contribute to an improved understanding of basic auditory processing in TD and ASD by providing new evidence for an auditory global precedence effect in both groups, as well as evidence for differences in global-local processing associated with musical experience, attention, and age. This research contributes to a better understanding of the ASD phenotype, stimulatesfuture research directions (e.g., studies on the brain-behavioral correlates of auditory global-local processing), and may guide future auditory-based interventions in ASD. Pour percevoir notre environnement, nous divisons le tout ou la forme "globale" des informations visuelles et…