Cite as:
Maloney L T, Boyaci H, 2002, "Observers correct perceived albedo for perceived orientation when stereo disparity cues are available" Perception 31 ECVP Abstract Supplement

Observers correct perceived albedo for perceived orientation when stereo disparity cues are available

L T Maloney, H Boyaci

When a scene contains a punctate source, the amount of light that reaches the eye from a patch on a matte gray surface depends on both patch albedo and patch orientation. We examined whether the human visual system actively discounts perceived orientation in estimating perceived albedo. Seven scenes were rendered with identical punctate + diffuse lighting models from two slightly different viewpoints, creating a stereo pair. Each contained a collection of specular and matte objects chosen to allow the observer to determine the direction from a test patch to a distant punctate source. The scenes differed in the orientation of a test patch to light rays radiating from the punctate source. The observer viewed the scenes in a Wheatstone stereoscope and, on each trial, performed two tasks. He or she first estimated the orientation of a gray rectangle by adjusting a superimposed gradient probe, and then matched the lightness of the patch to a standard gray scale. Three naïve observers made these two judgments 20 times for each of the scenes in random order. Observers' estimates of orientation and lightness were found to be highly reliable and covaried as would be expected if the observers were discounting perceived albedo for perceived orientation.

[Supported by NIH/NEI grant EY08266; HFSP grant RG0109/1999-B.]

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