Rf. Hess et Lr. Ziegler, What limits the contribution of second-order motion to the perception of surface shape?, VISION RES, 40(16), 2000, pp. 2125-2133
Both motion and stereopsis can be derived from contrast as well as luminanc
e defined stimuli. It is currently assumed that these two different sources
of information about objects feed into one common stage. Thus it would not
be expected that their role in visual perception would be different. Here
we show that although motion can be carried by contrast-defined elements, s
uch motion is not used to define three-dimensional (3D) surfaces. A similar
effect has been reported in stereopsis; although such contrast-defined ele
ments can give signed disparity signals they nevertheless do not contribute
to the percept of shape. We show that the reason for this lies in the inab
ility of the second order signals to cohere or bind across space/spatial sc
ales rather than a characteristic of the elementary motion signals per se.
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