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ABSTRACT: A visual stimulus display was created that enabled us to examine how effectively the three depth cues of disparity, motion parallax and shading can be integrated in humans and monkeys. The display was designed to allow us to present these three depth cues separately and in various combinations. Depth was processed most effectively and most rapidly when all three cues were presented together indicating that these separate cues are integrated at yet unknown sites in the brain. Testing in humans and monkeys yielded similar results suggesting that monkeys are a good animal model for the study of the underlying neural mechanisms of depth perception.
Brain research 03/2011; 1377:67-77. · 2.46 Impact Factor
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ABSTRACT: 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.
European Journal of Neuroscience 10/2007; 26(5):1307-21. · 3.63 Impact Factor
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ABSTRACT: A stimulus display was devised that enabled us to examine how effectively monkeys and humans can process shading and disparity cues for depth perception. The display allowed us to present these cues separately, in concert and in conflict with each other. An oddities discrimination task was used. Humans as well as monkeys were able to utilize both shading and disparity cues but shading cues were more effectively processed by humans. Humans and monkeys performed better and faster when the two cues were presented conjointly rather than singly. Performance was significantly degraded when the two cues were presented in conflict with each other suggesting that these cues are processed interactively at higher levels in the visual system. The fact that monkeys can effectively utilize depth information derived from shading and disparity indicates that they are a good animal model for the study of the neural mechanisms that underlie the processing of these two depth cues.
Visual Neuroscience 24(2):207-15. · 2.23 Impact Factor
