| Revision as of 21:19, 22 November 2006 edit65.121.30.30 (talk) →Dichromacy in mammals← Previous edit | Revision as of 21:20, 22 November 2006 edit undo65.121.30.30 (talk) →Human dichromats and color blindnessNext edit → | ||
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| It is currently believed that most ]s are dichromats. The straightforward exceptions are ]s, including ]s, which are usually trichromats, and sea mammals (both ]s and ]s) which are ]s. ]s are a partial exception: in most species, males are dichromats, and about 60% of females are trichromats, but the ]s are monochromats, and both sexes of ]s are trichromats. Recent research (e.g. Arrese et al, 2005) suggests that trichromacy may be widespread among ]s. hi pplz!!!! | It is currently believed that most ]s are dichromats. The straightforward exceptions are ]s, including ]s, which are usually trichromats, and sea mammals (both ]s and ]s) which are ]s. ]s are a partial exception: in most species, males are dichromats, and about 60% of females are trichromats, but the ]s are monochromats, and both sexes of ]s are trichromats. Recent research (e.g. Arrese et al, 2005) suggests that trichromacy may be widespread among ]s. hi pplz!!!! | ||
| yo yo yo wat is with it home dog? | |||
| ==Human dichromats and color blindness== | |||
| The two best-known forms of ] in human is the result of 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== | ==External links== | ||
Revision as of 21:20, 22 November 2006
Dichromacy is a moderately severe color vision defect in which one of the three basic color mechanisms is absent or not functioning. It is hereditary and sex-linked, affecting predominantly males. Dichromacy occurs when one of the cone pigments is missing and color is reduced to two dimensions.
Organisms with dichromacy are called dichromats. Dichromats can match any color they see with a mixture of no more than two pure spectral lights. By comparison, a trichromat requires three pure spectral lights to match all colors in their visual spectrum.
Dichromacy in mammals
It is currently believed that most mammals are dichromats. The straightforward exceptions are Old World primates, including humans, which are usually trichromats, and sea mammals (both pinnipeds and cetaceans) which are monochromats. New World monkeys are a partial exception: in most species, males are dichromats, and about 60% of females are trichromats, but the owl monkeys are monochromats, and both sexes of howler monkeys are trichromats. Recent research (e.g. Arrese et al, 2005) suggests that trichromacy may be widespread among marsupials. hi pplz!!!!
yo yo yo wat is with it home dog?
External links
- Visual comparisons of various types of color vision impairments by Cal Henderson
- Color Vision, Color Deficiency at Firelily Designs
References
- Cassin, B. and Solomon, S. Dictionary of Eye Terminology. Gainsville, Florida: Triad Publishing Company, 1990.
- "Guidelines: Color Blindness." Tiresias.org. Accessed September 29, 2006.
- Color blindness at Absolute Astronomy Reference
- Arrese, C. A., Oddy, A. Y., Runham, P. B., Hart, N. S., Shand, J., Hunt, D. M., * Beazley, L. D. (2005). Cone topography and spectral sensitivity in two potentially trichromatic marsupials, the quokka (Setonix brachyurus) and quenda (Isoodon obesulus). Proceedings of the Royal Society of London Series B, 272, 791-796.
- Jacobs, G. H., & Deegan, J. F. (2001). Photopigments and colour vision in New World monkeys from the family Atelidae. Proceedings of the Royal Society of London, Series B, 268, 695-702.
- Jacobs, G. H., Deegan, J. F., Neitz, J., Crognale, M. A., & Neitz, (1993). Photopigments and colour vision in the nocturnal monkey, Aotus. Vision Research, 33, 1773-1783.
- Mollon, J. D., Bowmaker, J. K., & Jacobs, G. H. (1984). Variations of colour vision in a New World primate can be explained by polymorphism of retinal photopigments. Proceedings of the Royal Society of London, Series B, 222, 373-399.
| Physiology of the visual system | |
|---|---|
| Vision | |
| Color vision | |