Inhibition of--but not between--orientation detectors: a theoretical note on illusions of direction.

In accounting for illusions of direction, many current models assume lateral inhibition among orientation detectors; however, that assumption is unnecessary. Rather, the illusions can be predicted by a model based on the pattern of inhibition and excitation across orientation detectors as caused by a single stimulus line. From the collective effects of multiple stimulus lines, a pattern of excitation and inhibition results which is perceived as an illusion of direction. This collective effect is predicted by convoluting a function representing physical orientation of stimulus lines with a function representing the pattern of inhibition and excitation elicited by a single line. Both perceived angle-expansion (repulsion) and perceived angle-contraction (attraction) are generated by the model.