Theoretical Model for Lateral Inhibitory Interaction in the Human Retina

Abstract

Several models for lateral inhibitory interaction are available in the literature; however, these models are deficient in providing a systematic account of simultaneous brightness contrast for one or several of the following reasons: (1) no rational basis is presented for phenomenal black; (2) the mediation of lateral inhibitory interaction is generally attributed to the horizontal cells of the human retina, but there is no neuroanatomical evidence that the horizontal cell is present in the central-most fovea, although there is psychophysical evidence that lateral inhibitory interaction occurs in the central-most fovea; (3) the response characteristics of the receptive field have not been conceptually integrated into the models despite general theoretical agreement that the receptive field organization is meaningful for simultaneous brightness contrast. These deficiencies have prompted the development of the theoretical model presented here. In addition to integrating the foregoing empirical aspects of simultaneous brightness contrast, the model predicts that the magnitude of perceived brightness contrast will be greater at a corner than along an edge. Empirical data consistent with this prediction are presented. A further prediction that the perceived magnitude of brightness contrast will increase as the angular size of the corner decreases is tested. In a theoretical analysis, an approximation to the experimental results is obtained when contrast effects due both to the predicted effect of angle size and the well known effect of inducing-field area are considered.