APA Dictionary of Psychology

n. color blindness marked by the inability to perceive any color whatsoever: Everything is seen in different shades of gray. It is a congenital condition stemming from a lack of retinal cones. When acquired as a result of brain injury, it is called cerebral achromatopsia; the typical site of injury is the ventromedial occipital cortex of the brain (see V4). Also called achromatopsia. See also dichromatism; monochromatism; trichromatism.