UBC Theses and Dissertations
The perception of global motion in typical and atypical visual development Meier, Kimberly
Sensitivity to motion information emerges early in life, but full maturation of motion perception can take many years. Reports on the age at which typically-developing children reach adult-like global motion perception have ranged from 3-14 years. There are also conflicting reports on whether people with amblyopia (a visual disorder that occurs when a young child experiences abnormal visual input to one eye for a prolonged period) show deficits on these tasks. This dissertation examines the spatio-temporal factors underlying immaturities and deficits in motion perception. I tested the hypothesis that perception of motion stimuli created with small spatial displacements would mature later than those created with large displacements; and as a consequence, children with amblyopia would show selective deficits for these small spatial displacements. First, I investigated typical maturation of motion perception across a range of stimulus parameters in people aged 7-30 years (Chapter 3). The youngest children performed similar to adults for large displacements, but mature performance was not reached until middle teenage years for small displacements. Second, I investigated performance for the same stimulus parameters in children with amblyopia (Chapter 4). Deficits were only present for parameters where healthy control children showed late maturation. Finally, I examined two factors that might account for the immaturities and deficits I found: spatial integration and eye stability. I determined that increasing the stimulus area had the same impact on coherence thresholds in 4-6 year-olds and adults (Chapter 5), suggesting children’s immature performance for small displacements was not restricted by spatial integration limitations at stages prior to motion processing. I also determined that eye stability had no relationship with performance in healthy adults (Chapter 6), indicating that poor fixational stability alone could not account for poor performance on a global motion task. This work contributes to a better understanding of how the developing brain is impacted by amblyopia, in turn providing insight into sensitive periods for typical visual development.
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