Four or five years ago, I read something which I remember reporting the following:
It is common to think of the human color perception system as producing sensations of color such that individual colors correspond to freqencies of light.* But some theories indicate that the physiology of the human color perception is such that it is possible for that system to produce sensations of “colors” which do not actually correspond to any frequency of light. And laboratory experiments involving after-images seem to have produced such sensations.
Does this ring a bell with anyone? I was hoping to track this down, or else, to discover that I’m remembering something completely incorrectly.
-FrL-
*Albeit in a complicated way, if you take into account the way perceptions of color are affected by visual context–a patch producing a particular frequency of light can appear to have different colors depending on the colors of surrounding patches.