title: A theory of the pi1 and pi3 color mechanisms of Stiles.
mesh_terms: D000221:Adaptation, Ocular; D003118:Color Perception / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D010786:Photoreceptor Cells / Q000502:physiology*; D013053:Spectrophotometry; D013997:Time Factors