Perception of forbidden colors in retinally stabilized equiluminant images: an indication of softwired cortical color opponency?

In color theory and perceptual practice, two color naming combinations are forbidden-reddish greens and bluish yellows-however, when multicolored imag es are stabilized on the retina, their borders fade and filling-in mechanis ms can create forbidden colors. The sole report of such events found that o nly some observers saw forbidden colors, while others saw illusory multicol ored patterns. We found that when colors were equiluminant, subjects saw re ddish greens, bluish yellows, or a multistable spatial color exchange (an e ntirely novel perceptual phenomena); when the colors were nonequiluminant, subjects saw spurious pattern formation. To make sense of color opponency v iolations, we created a soft-wired model of cortical color opponency (based on winner-take-all competition) whose opponency can be disabled. (C) 2001 Optical Society of America.