Abstract
It is commonly held that filling-in phenomena stop at luminance edges (e.g. Troxler Fading). Previously, we reported a counter-example where edges facilitated color-spreading. Subjects fixating on a color gradient containing dark gaps perceived the central color to spread and replace the peripheral colors, ‘jumping’ over the gaps (Shimojo, Wu & Kanai, 2002, Perception 31, suppl).
Here, we show that the configuration of multi-colored patches present near the fixation point can spread into the periphery, as can multiple color-shape pairings.
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Subjects fixate on a dark field containing an array of color patches. Each patch consists of a “square” surrounded by a “frame”. Squares vary from red to green in a graded fashion: they are red near fixation, green in the periphery. Frames are all green (so peripheral patches are homogeneous). Subjects perceive the configuration present at the fovea to spread, until all patches appear as red squares surrounded by green frames.
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Color-spreading persists when both squares and frames vary in color. It is fastest when they are given opposite color gradients (center = red squares & green frames, periphery = green squares & red frames). Often, the extreme periphery quickly takes on the foveal pattern, even as areas of intermediate eccentricity retain their actual color (homogeneous yellow) for a time. This suggests that color-shape misbinding can facilitate the process of color-spreading.
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For the above stimuli, color-spreading is weaker when patches are not colinear. However, for stimuli consisting only of frames (or squares), spreading is independent of colinearity. In a third condition, if squares and frames are both present — but as separate objects — color-spreading is again independent of colinearity; the percept is of red squares and green frames lying on separate surfaces. We propose that interference between different elements on the same perceptual surface is alleviated by segregation onto different surfaces.