Trichromacy: Difference between revisions
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The normal explanation of trichromacy is that the organism's [[retina]] contains three types of [[color receptors]] (called [[cone cell]]s in vertebrates) with different [[absorption spectrum|absorption spectra]]. In practice the number of such receptor types may be greater than three, since different types may be active at different light intensities. In vertebrates with three types of cone cells, at low light intensities the [[rod cell]]s may contribute to colour vision, giving a small region of [[tetrachromacy]] in the colour space. |
The normal explanation of trichromacy is that the organism's [[retina]] contains three types of [[color receptors]] (called [[cone cell]]s in vertebrates) with different [[absorption spectrum|absorption spectra]]. In practice the number of such receptor types may be greater than three, since different types may be active at different light intensities. In vertebrates with three types of cone cells, at low light intensities the [[rod cell]]s may contribute to colour vision, giving a small region of [[tetrachromacy]] in the colour space. |
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[[Human]]s and other [[Old World]] [[primate]]s are usually trichromats, as are female [[New World monkey]]s of most species, and both male and female [[howler monkey]]s. [[ |
[[Human]]s and other [[Old World]] [[primate]]s are usually trichromats, as are female [[New World monkey]]s of most species, and both male and female [[howler monkey]]s. Recent research suggests that trichromacy may also be quite general among [[marsupial]]s. Some [[arnivore]]s, especially [[nocturnal]] species, have been claimed to have same kind of colour vision as human anomalous trichromats, possessing three distinct types of color receptors, but which respond to different wavelengths than those of primates. An example is the domestic [[cat]]. However most studies of carnivores, as of other mammals, reveal [[dichromacy]], examples including the domestic [[dog]], the [[ferret]], and the [[Spotted Hyena]]. Such species have color vision similar to humans with [[color blindness|deuteranopia]].) Some species of [[insects]] (such as [[honeybee]]s) are also trichromats, being sensitive to [[ultraviolet]], blue and green instead of blue, green and red. |
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== External links == |
== External links == |
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* Arrese, C. A., Oddy, A. Y., Runham, P. B., Hart, N. S., Shand, J., Hunt, D. M., (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. |
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* Calderone, J. B., & Jacobs, G. H. (2003). Spectral properties and retinal distribution of ferret cones. ''Visual Neuroscience, 20'', 11-17. |
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* Calderone, J. B., Reese, B. E., & Jacobs, G. H. (2003). Topography of photoreceptors and retinal ganglion cells in the spotted hyena (''Crocuta crocuta''). ''Brain Behavior and Evolution, 62'', 182-192. |
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* Rowe, Michael H. "Trichromatic color vision in primates." ''News Physiol Sci.'' 2002 Jun;17:93-8. http://physiologyonline.physiology.org/cgi/content/full/17/3/93 |
* Rowe, Michael H. "Trichromatic color vision in primates." ''News Physiol Sci.'' 2002 Jun;17:93-8. http://physiologyonline.physiology.org/cgi/content/full/17/3/93 |
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* [http://www.straightdope.com/classics/a2_004.html The Straight Dope: Are cats and dogs really color-blind? How do they know?] |
* [http://www.straightdope.com/classics/a2_004.html The Straight Dope: Are cats and dogs really color-blind? How do they know?] |
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Revision as of 11:03, 12 May 2005
A trichromat is an organism for which the perceptual effect of any arbitrarily chosen light from its visible spectrum can be matched by a mixture of no more than three different pure spectral lights. The condition of being a trichromat is called trichromacy.
The normal explanation of trichromacy is that the organism's retina contains three types of color receptors (called cone cells in vertebrates) with different absorption spectra. In practice the number of such receptor types may be greater than three, since different types may be active at different light intensities. In vertebrates with three types of cone cells, at low light intensities the rod cells may contribute to colour vision, giving a small region of tetrachromacy in the colour space.
Humans and other Old World primates are usually trichromats, as are female New World monkeys of most species, and both male and female howler monkeys. Recent research suggests that trichromacy may also be quite general among marsupials. Some arnivores, especially nocturnal species, have been claimed to have same kind of colour vision as human anomalous trichromats, possessing three distinct types of color receptors, but which respond to different wavelengths than those of primates. An example is the domestic cat. However most studies of carnivores, as of other mammals, reveal dichromacy, examples including the domestic dog, the ferret, and the Spotted Hyena. Such species have color vision similar to humans with deuteranopia.) Some species of insects (such as honeybees) are also trichromats, being sensitive to ultraviolet, blue and green instead of blue, green and red.
External links
- Arrese, C. A., Oddy, A. Y., Runham, P. B., Hart, N. S., Shand, J., Hunt, D. M., (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.
- Calderone, J. B., & Jacobs, G. H. (2003). Spectral properties and retinal distribution of ferret cones. Visual Neuroscience, 20, 11-17.
- Calderone, J. B., Reese, B. E., & Jacobs, G. H. (2003). Topography of photoreceptors and retinal ganglion cells in the spotted hyena (Crocuta crocuta). Brain Behavior and Evolution, 62, 182-192.
- Rowe, Michael H. "Trichromatic color vision in primates." News Physiol Sci. 2002 Jun;17:93-8. http://physiologyonline.physiology.org/cgi/content/full/17/3/93
- The Straight Dope: Are cats and dogs really color-blind? How do they know?
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