Abstract
How does the laminar circuitry in areas V1 and V2 generate 3-D percepts of stratification, transparency, and neon color spreading in response to 2-D pictures and 3-D scenes? Such percepts are sensitive to whether contiguous regions in an image have the same contrast polarity (Adelson, 2000; Anderson, 1997; Watanabe and Cavanagh, 1992, 1993), yet long-range perceptual grouping pools over opposite contrast polarities. In binocular displays that create neon color spreading, like-ocularity of contiguous regions is critical for spreading (Takeichi et al., 1992). Half-visible points in a stereogram can induce near-depth transparency if the contrast relationship favors transparency in the half-visible areas (Nakayama, 1996). The whole contrast relationship must be in the monocular configuration, since splitting it between stereogram images cancels the effect. A recent model of cortical development, grouping, attention, learning, and 3-D planar surface perception by V1 and V2 is extended to show how adding like-polarity competition between V1 simple cells in layer 4 can simulate these data. The model also clarifies how this constraint may arise during development, and is consistent with lateral masking experiments in which two flanking Gabor patches with the same contrast polarity as the target increase the target's detection threshold. In the model, when contrast relationships within an X-junction do not favor transparency, all surface boundaries occur at the same depth plane and no surface appears transparent, because none can fill-in surface brightness or color behind the other. The model also explains how the Metelli (1974) Rules can cause transparent percepts, how bistable transparency can arise, and how transparency reversal can be facilitated by an attention shift.