Abstract
It has been demonstrated that amblyopic observers are impaired in the processing of global motion [Simmers, AJ, Ledgeway, T, Hess, RF, and McGraw, PV, Deficits to global motion processing in human amblyopia. Vision Res, 2003. 43(6): p. 729–38]. Whilst the contrast sensitivity deficit in amblyopia shows a clear dependence on spatial scale, being greater at finer scales, the spatial scale dependence of the global motion deficit is not yet known. We used global motion stimuli composed of isotropic log Gabors, each adjusted for their detectability, to determine the spatial scale of the amblyopic global motion deficit. The deficit relative to normal eyes was constant across spatial scale. The relative deficit between the amblyopic and fellow eyes did, however, show a dependence on velocity. Using elements that are a constant factor above the thresholds of the normal and amblyopic eyes, for different spatial scales, ensures that the spatial scale dependence that we measure for global motion reflects the properties of a deficit whose site is likely is likely to be beyond V1.
Research supported by CIHR MOP10818 to RFH.