Development of human binocular vision: An electrophysiological perspective

Vision with two eyes confers evolutionary advantages in terms of field of view, binocular summation and the sense of depth from disparity and motion. This review summarizes our current knowledge of the development of binocular vision through the lens of Visual Evoked Potentials (VEPs). The review begins with early studies of binocular summation that compared monocular to binocular VEP amplitude ratios. This is followed by a description of more definitive indices of binocular interaction afforded by studies of dichoptic masking and intermodulation. We then describe a striking immaturity of binocular motion processing - the developmental motion asymmetry - a monocular nasalward/temporalward asymmetry of motion processing that reflects the child's developmental history of normal binocular interaction. We end with a review of the development of sensitivity to the primary cue for depth - horizontal retinal disparity. Together, the available results paint a picture of early competency in some respects, combined with both quantitative and important qualitative differences from the adult that suggest the presence of distinct processing mechanisms with different developmental sequences.