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

Abstract

In color theory and perceptual practice, two color naming combinations are forbidden-reddish greens and bluish yellows-however, when multicolored images are stabilized on the retina, their borders fade and filling-in mechanisms can create forbidden colors. The sole report of such events found that only some observers saw forbidden colors, while others saw illusory multicolored patterns. We found that when colors were equiluminant, subjects saw reddish greens, bluish yellows, or a multistable spatial color exchange (an entirely novel perceptual phenomena); when the colors were nonequiluminant, subjects saw spurious pattern formation. To make sense of color opponency violations, we created a soft-wired model of cortical color opponency (based on winner-take-all competition) whose opponency can be disabled.

Higher-order awareness, misrepresentation and function

“…Surprisingly, something like that conscious experience seems actually to occur; in a striking study, Billock et al [81] found that when multi-coloured, equiluminant images are stabilized on the retina, some subjects report seeing reddish greens or bluish yellows, presumably owing to filling-in mechanisms. But higher-order theories are in any case not committed to such predictions.…”

‘Reddish Green’ – Wittgenstein on Concepts and the Limits of the Empirical

“…Ordinary human beings are said to have colour perceptions that require a description which contradicts our ordinary colour concepts (cf. Billock et al 2001Billock et al , p. 2398. It is claimed that it is possible to perceive reddish green and bluish yellow under the following special conditions.…”

“…Billock, Gleason, and Tsou write: "Our subjects (...) were tongue-tied in their descriptions of these colors, using terms like 'green with a red sheen,' or 'red with green highlights'." (Billock et al 2001(Billock et al , p. 2398) Using these terms for what; answering which question? Apparently, they did not use the term "reddish green".…”

“…To reply that this is because they know it from having seen the two-coloured display at the beginning of the experiment would, of course, be self-refuting; to reply that at least some of them are tongue-tied shows nothing. The subjects perceive red and green in the apparent mixture colour "as clear and as compelling as the red and blue components of a purple" (Billock et al 2001(Billock et al , p. 2399. I suggest that it is even more compelling than red and blue in a purple, since in fact two colours are seen.…”

The Self-Locating Property Theory of Color

“…The stimulus was adjacent red and green stripes (or blue and yellow stripes); when the stimulus was held in the same position relative to the participants' eyes, some of the subjects experienced reddish-green or bluishyellow. The study was successfully repeated by Vincent Billock et al (2001), who also adjusted for variation in luminance. Despite the fact that some subjects can experience reddish-green and bluish-yellow, these shades of color have no instantiated physical color correlates.…”