Information AboutDichromat |
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PHYSICAL CAUSES OF DICHROMACY The normal explanation of dichromacy is that the organism's Retina contains two types of Color Receptors (called Cone Cell s in Vertebrate s) with different Absorption Spectra . In practice the number of such receptor types may be greater than two, since different types may be active at different light intensities (in other words, the absorption spectra of different types of color receptors may overlap). In vertebrates with two types of Cone Cell s, at low light intensities the Rod Cell s may contribute to color vision, giving a small region of Trichromacy in the color space. DICHROMACY IN MAMMALS It is currently believed that most s are monochromats, and both sexes of Howler Monkey s are trichromats. Recent research (e.g. Arrese et al, 2005) suggests that trichromacy may be widespread among Marsupial s. HUMAN DICHROMATS AND COLOR BLINDNESS The two best-known forms of Color Blindness in humans result in dichromacy, since one of the three cone systems is non-functional in these conditions. However, many people who are described as color blind are in fact anomalous trichromats; in this condition, there are three functional cone systems but one of them has an unusual absorption spectrum so the person does not make the same color matches as the rest of the population. EXTERNAL LINKS
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