Abstract

Recent research demonstrating that the perceived contrast of a small central grating patch can be strongly influenced by the presence of another grating in an annular surround implied the presence of two types of lateral interaction networks, one excitatory and one inhibitory. The present paper describes the development of a model for these networks, under the conditions where both center and surround contain gratings of the same spatial frequency and orientation. Two different interconnection networks were studied. In the feed-forward system, the gain of each member of a 2-D array of contrast sensitive mechanisms is adjusted by the weighted sum of the stimulus inputs to adjacent mechanisms. In the feedback system, the gain of each member of the array of contrast sensitive mechanisms is adjusted by a weighted sum of the outputs of adjacent mechanisms. Simulations indicate that psychophysical data can be accounted for only by the feed-back type network and that individual differences in suppression and enhancement effects can be accounted for by minor differences in the shapes of the spatial weighting functions.

© 1992 Optical Society of America