title: Psychophysical evidence for more than two kinds of cone in dichromatic color blindness.
abstract: Psychophysical evidence shows that at least some classically diagnosed dichromats have three cone types rather than two. The anomalous cones, previously thought to be absent, are less sensitive than normal cones to both spectral and temporal variations, and have spectral sensitivities like those of the abnormal cones of anomalous trichromats. These results are not consistent with either loss or replacement models of X-linked recessive color-vision defects, since some dichromats apparently have the same three photopigments as anomalous trichromats.
mesh_terms: D003118:Color Perception / Q000502:physiology*; D003117:Color Vision Defects / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D010786:Photoreceptor Cells / Q000473:pathology / Q000502:physiology*