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Title: Factors underlying attentional abnormalities in autism
Author: Greenaway, R.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2006
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Children with autism can be highly distractible at times, but over-focused and resistant to distraction at others. In this dissertation a series of studies are conducted to explore factors that might underlie this apparent paradox. I start by considering whether the amount of relevant and irrelevant information presented might lead to differences in selection by children with autism compared to typically developing children. However, no differences were found on tasks manipulating perceptual load, indicating that in this respect selection is typical in autism. Next, attentional capture procedures were employed to investigate the interaction between bottom-up and top-down attentional processing in autism. Furthermore, stimulus properties were manipulated to investigate whether these factors interact. Two experiments showed that while children with autism showed typical attentional modulation of static colour stimuli, they did not modulate attentional capture by dynamic onset distractors. There were two potential explanations for this finding: first, that children with autism show selective impairments in modulating the attentional processing of dynamic stimuli; second, that children with autism find dynamic stimuli less salient. In a further experiment, it was demonstrated that children with autism were able to modulate attentional capture of motion to the same degree as typical children, indicating that an abnormality in processing onsets in autism does not generalise to all dynamic stimuli. Thus, it was conjectured that abnormalities might be specific to those stimuli that are processed primarily by the magnocellular visual pathway. This was supported by the results of a psychophysical study that demonstrated that whilst children with autism showed typical parvocellular processing, they showed an impairment in magnocellular processing. It is concluded that a deficit in magnocellular processing could provide a powerful explanation of some of the attentional and perceptual abnormalities previously reported in the literature, and even have an adverse impact on some higher-level abnormalities.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available