How the parallel channels of the retina contribute to depth processing.

Reconstructing the third dimension in the visual scene from the two dimensional images that impinge on the retinal surface is one of the major tasks of the visual system. We have devised a visual display that makes it possible to study stereoscopic depth cues and motion parallax cues separately or in concert using rhesus macaques. By varying the spatial frequency of the display and its luminance and chrominance, it is possible to selectively activate channels that originate in the primate retina. Our results show that (i) the parasol system plays a central role in processing motion parallax cues; (ii) the midget system plays a central role in stereoscopic depth perception at high spatial frequencies, and (iii) red/green colour selective neurons can effectively process both cues but blue/yellow neurons cannot do so.