The eyes of man as a photic bisensor system

Abstract

Non-patterned photic stimulation of the eyes of human subjects was obtained by homogeneous illumination of the closed eyes. The subjects perceived a difference between the stimulation intensity of the left and of the right eye as a field of view consisting of a bright and a dark half, adjoined across an indeterminate vertical midline. It is not clear which parts of the visual system mediate the residual perceptual functions that survive this stimulatory reduction of man's eyes to a photic bisensor system. It is argued that animals with side-set eyes might use this perceptual ability for photic orientation in an anisotropic light field.