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Jason E. Reiss, James E. Hoffman, Barbara Landau; Motion processing in Williams syndrome: Evidence against a general dorsal stream deficit. Journal of Vision 2003;3(9):288. doi: https://doi.org/10.1167/3.9.288.
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Williams syndrome (WS) is a rare genetic disorder characterized by profound spatial deficits and relatively spared language skills. One attempt to understand the nature of the WS spatial deficit draws on the distinction between ventral and dorsal visual pathways. Findings of intact WS face recognition and object identification suggest preserved ventral stream functioning while other reports are consistent with a dorsal visual processing deficit in WS. For example, Atkinson et al. (1997) reported that WS subjects were impaired in motion coherence tasks, a putative dorsal stream function. In contrast, Jordan et al. (2002) reported that WS individuals were at least as good as mental-age-matched controls (MA) in their ability to discriminate biological motion. Preserved biological motion perception might reflect a general sparing of form-from-motion systems or could be due to the high level of interest in social stimuli associated with WS. We tested this by examining performance of WS individuals on three motion tasks: motion coherence, 2D form-from-motion, and biological motion. Tasks were equated for the size, speed, and contrast of the moving elements. Results indicated that WS individuals performed at normal levels for both motion coherence and biological motion tasks but had slightly elevated thresholds for the 2D form-from-motion task. These findings argue against characterizing WS as including a general motion processing deficit and are considered in the context of the role of dorsal and ventral processing in WS.
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