Abstract

A pulse model is described to account for the neural interaction involved in simultaneous brightness contrast. It is assumed that the response of a neural unit depends rather on the responses of its neighboring units through the process of recurrent inhibition than on its excitation by the external stimulus. A digraph of rosette form is designed to model the phenomenon of the Herman grid illusion based on the assumption of recurrent inhibition. Unlike the existing one-dimensional mathematical models of simultaneous brightness contrast, the pulse model includes the topographical aspects of neural interaction and successfully predicts the Hermann grid illusion.