Abstract
Stereopsis depends on matched inputs from the two eyes. The role of contrast and spatial frequency have been well studied but we know little about the effects of a mismatch in mean luminance between the two eyes. If stereo depends on a matched luminance between the two eyes there are three possible reasons why. First, even though the physical contrast is unaltered, the neural contrast sensitivity will eventually change and this could result in reduced stereo via its contrast dependence. Second, mean luminance is known to be associated with a slower visual response and this could reduce stereo due to temporal asynchrony. Thirdly, optimal stereo may require a matched interocular mean luminance per se. We thus tested the effects of different neutral density (ND) filters in a disparity detection task using a spatially filtered and unfiltered fractal noise stimulus. We first determined whether the reduction in stereo with mean luminance reduction in one eye was spatial scale dependent. We then determined whether any reduction in stereo performance could be accounted by the expected luminance-dependent temporal asynchrony. The results suggest that stereo does depend on a match mean luminance in the two eyes, it is scale dependent with greater reduction occurring at the lowest scale and that while temporal asynchrony is a factor resulting from reducing the mean luminance, it is not the sole cause of the reduced stereo performance. We conclude that there is a mean luminance per se constraint to stereo matching. Supported by an NSERC grant (# 46528) to RFH
Meeting abstract presented at VSS 2013