Abstract
Although we understand that a trichromatic color match is a match for the cones, we have no idea how the appearance of the matched colors relates to their neural representation. For instance, proposals about the colors seen by the red/green color blind require highly suspect assumptions about the relation between neural events and color experience. The limited evidence available does not support a simple view of that relation: in particular, color blindness cannot be explained by a cone pigment swap with normal postreceptoral organization.
In anomalous trichromats, the reduced separation between the long-wave and mid-spectral cone absorption spectra will lead to a commensurate reduction in red/green differentiation if the pigment swap is the only difference between anomalous and normal trichromatic systems. But here again the pigment swap model seems to be incomplete. Anomalous observers differentiate red from green more strongly than the pigment swap model predicts. And they display exaggerated orientation-contingent color aftereffects, that are explainable only if the cortical representation of color benefits from a compensatory post-receptoral gain enhancement that compensates for the effects of the pigment swap.