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Kimberly Meier, Farnaz Javadian, Kevin Chang, Deborah Giaschi; The effect of stimulus area on global motion thresholds in children and adults. Journal of Vision 2017;17(10):435. doi: 10.1167/17.10.435.
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Introduction: Coherence thresholds on a global motion task vary as a function of spatial and temporal stimulus parameters. This is of particular interest when studying visual development, because these parameters can have a larger impact on the performance of young children compared to adults. For example, children perform better when presented with a denser dot array while adult performance is unaffected (Narasimhan & Giaschi, 2012). We have shown that coherence thresholds for global motion direction discrimination are immature in 4-6 year olds when smaller spatial displacement (∆x) values are used to create stimulus motion, but adult-like when larger values are used (Meier & Giaschi, 2014). The current study was designed to investigate whether the apparent immaturity in motion perception for small displacements is due to immaturity in spatial integration mechanisms. To this end, we assessed the effect of stimulus area on global motion coherence thresholds in young children. Methods: Coherence thresholds were assessed in children (4.5 – 6.5 years, M = 5.5) and adults (18.6 – 29.9 years, M = 21.3) using a two-alternative forced choice direction discrimination task with a staircase paradigm. Nine conditions were assessed: spatial displacement was 1, 5, or 30 arcmin; stimulus area was 9, 36, or 82 deg2. Participants were assessed monocularly, and conducted one staircase per condition, for a total of 9 measurements. For each participant, we calculated the change in coherence threshold as a function of stimulus area at each spatial displacement. Results: There was a significant effect of spatial displacement, such that an increase in coherence threshold with decreasing area was present for large displacements (∆x = 30 arcmin) only. There was no effect of age group, and no age group by displacement interaction. Conclusion: Immaturities in global motion perception are unlikely to be accounted for by limitations in spatial integration area.
Meeting abstract presented at VSS 2017
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