Using low-level filters to encode spatial displacements of visual stimuli.

Directional responses to visual stimuli were analysed with the aid of a minimal computational model. The model is based upon arrays of motion sensors whose receptive fields are modified versions of those (difference-of-Gaussians) used to describe mechanisms in popular spatial vision models. In the model antagonistic influences on each motion sensor were assumed to: (1) arise from spatially non-aligned areas of the retina; and (2) to follow different time courses. Implications of the model were explored with simulations, and parallel psychophysical data were collected. Visual behaviours chosen for relatively detailed analysis were judgments of the temporal order of onset of two spatially displaced stimuli and motion aftereffects generated with discontinuously moving, sine-wave gratings.