Thesis (Ph. D.)--University of Rochester. Department of Brain and Cognitive Sciences, 2017.
A growing number of studies suggest atypical visual processing in autism spectrum
disorder (ASD). Given that human behavior heavily relies on visual information,
impairments in visual processing may have cascading effects on many other brain
functions. Recent proposals in ASD, both domain-specific and -general, hypothesize
different mechanisms that may impact visual abilities in this population. However,
empirical support for such accounts has been lacking, and it is unclear whether and how
these mechanisms can influence visual perception in ASD. The series of studies in this
dissertation examine atypical visual processing mechanisms in ASD under three
frameworks: larger receptive field size, elevated internal noise, and impaired prediction
abilities. We examine each of these hypotheses in children and adolescents with ASD,
using a combination of psychophysics, computational modeling, and eye-tracking. In
Chapter 2, we tested the integrity of receptive field size using a visual motion
discrimination task. The results showed that individuals with ASD have impaired motion
sensitivity at smaller stimulus size, which was best explained by the larger receptive field
size account. In Chapter 3, we investigated whether internal noise is elevated in ASD, and
found evidence that supports this account. Importantly, we found that higher internal noise
was associated with more severe behavioral symptoms of ASD. Lastly, in Chapter 4, we
examined the prediction abilities in ASD in the context of visual motion extrapolation. The
results demonstrate impaired motion prediction in ASD, which was also accompanied by their atypical eye-movement patterns during the task. Taken together, these studies reveal
deficits in visual processing in ASD across a wide range of processing stages. The findings
not only provide empirical support for existing proposals of ASD, but also shed lights on
the specific mechanisms associated with atypical visual abilities in this population.
