Invisible Colors Revisited

For a demonstration of response priming by color, it is not critical whether or not the primes are consciously perceived. However, it is fascinating that color processing can be dissociated from visual awareness. Although this is consistent with Milner and Goodale's (1995) framework, which allows for dissociations within the streams, I think it is counterintuitive that a ventral-stream feature like color should be isolated from other ventral-stream processing but easily accessible by the dorsal stream. One might expect visual awareness, compared with visuomotor transformations, to have more direct access to color information.

So, what if there really are "invisible colors"? Many areas of visual psychophysics depend on what observers express about their subjective experience (e.g., whether or not a stimulus was present, whether it was red or green, and similar judgments about phenomenal qualities). On the basis of these experiential data, theories about quite early perceptual processes can be formed. Although this is obviously valid in many areas of vision (like color matching; see Wandell 1995), functional dissociations in our cognitive architecture set limits to what is accessible for conscious report. This is why we cannot expect to get uniform answers when posing our questions to different parts of the system.

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