| Summary: | This thesis investigated cross-modal selective attention in children and adolescents with Autism Spectrum Disorder (ASD) and typically developing (TD) individuals using the Load Theory of Selective Attention and Cognitive Control (Lavie, 1995). Perceptual load theory states that perception of irrelevant stimuli depends on the perceptual load of the task (the amount of task relevant information). At low levels of perceptual load, when finite perceptual capacity is not reached, remaining resources ‘spill over’ and irrelevant stimuli are automatically processed; when perceptual load exhausts capacity, irrelevant stimuli are no longer processed. In ASD, there is some evidence that on visual attention tasks, individuals with ASD continue to process visual information at higher levels of perceptual load than controls, indicative of an increased perceptual capacity (Remington, Swettenham, & Lavie, 2012; Remington, Swettenham, Campbell, & Coleman, 2009; Swettenham, Remington, Murphy, Feuerstein, Grim, & Lavie, 2014). This thesis tested novel predictions derived from these findings for contexts of cross-modal selective attention. Using behavioural measures, the extent to which participants were able to attend to auditory information was examined as a function of the perceptual demands of a visual task. It was shown that individuals with ASD continued to report awareness of auditory information at higher levels of visual perceptual load than matched typically developing individuals. This was evident on tasks that measured both awareness for an unexpected, as well as expected auditory stimulus. Together, these findings suggest that individuals with ASD are characterised by an increased perceptual capacity that operates across sensory modalities.
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