Model approximations to visual spatio-temporal sine-wave threshold data

Experimental data on visual spatio-temporal sine-wave thresholds obtained by Robson and Kelly are considered. In seeking model approximations to the data it is assumed that the subject's visual threshold to modulation at different spatial and temporal frequencies gives the image of his filter function to within a multiplicative constant. It is further assumed that the data can be approximated by a system with a spatially uniform, isotropic, and temporally invariant response which consists of the difference between an excitatory and an inhibitory term, and that each term is separable into a product of a spatial and a temporal function.