Consciousness: Confessions of a Romantic Reductionist (The MIT Press)

by Christof Koch

A pure loss of color perception is called achromatopsia. This is quite different from everyday, hereditary color blindness that mainly afflicts men. Because they miss the gene for one of the color pigments in the eye, these dichromats don’t perceive as rich a color palette as normal sighted people (trichromats) with three retinal photopigments. Achromatopsia, in contrast, follows destruction of the color center in the visual cortex. In its wake, all hues are leached from the world. No more glorious violet- and purple-tinted Alpenglow in the setting sun. Instead, the world is experienced in chiaroscuro, like a color television that has reverted to shades of black and white. Notably, colors words and associations with colors (e.g., “red” with “fire truck”) remain.