Global motion processing: The effect of spatial scale and eccentricity

Here we examine how global translational motion sensitivity varies with the spatial frequency of the elements in local motion and on the eccentricity of stimulation. Using DC-balanced, spatially narrowband elements (radial log Gabors) matched in terms of multiples above contrast threshold, we show that global translational motion sensitivity is best at mid high spatial frequencies and worst at low spatial frequencies. Furthermore, we show that the lower global motion sensitivity of the periphery is due to differences in spatial scale/contrast that can be attributed to lower reaches of the visual pathway where the local motion signal is transduced. Thus, the efficiency of the global translational motion computation that occurs in extrastriate cortical areas does not vary across the visual field. This may not be directly applicable to global radial motion because there are known visual field anisotropies.