| Summary: | It has often been reported that individuals with autism process visual motion information atypically. This thesis uses psychophysical methods and a parent-report questionnaire to characterise better the nature of atypical motion processing in children with autism. In Chapter 1, I review the evidence for atypical sensory perception in autism, focusing on the processing of dynamic information. In Chapter 2, I show that children with autism are just as sensitive to speed information as typically developing (TD) children, but have elevated motion coherence thresholds specifically for slow stimuli. In Chapter 3, I analyse questionnaire results which suggest that children with autism have difficulties processing speed-related information in everyday life. In Chapters 4 and 5 I use an equivalent noise direction integration task alongside a standard motion coherence paradigm to determine whether local and/or global factors limit sensitivity to coherent motion information in TD children and children with autism. In Chapter 4, I show that the ability to average motion information drives age-related increases in coherent motion sensitivity in TD children. In Chapter 5, I present the unexpected finding that children with autism have enhanced integration of motion information compared to TD children. In an attempt to resolve discrepant motion coherence findings, I reveal that children with autism are equally susceptible to correspondence noise as TD children in Chapter 6. In Chapter 7, I discuss the importance of these findings within the context of current theoretical accounts, and suggest that we need a more nuanced account of motion processing abilities in autism. In particular, I argue that motion processing in autism may be characterised by increased integration and reduced segregation of signal from noise.
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