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Topic: Tetrachromat

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Colour blindness

Color vision

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Optical spectrum

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Visual perception

Pohnpei

	[No title]
		Nevertheless, Dr. Jordan declines to say that she has finally found a tetrachromat, partly because her testing is still a work in progress.
		Nathans also believes, however, that for full-blown tetrachromacy, the fourth photopigment must not have a peak in sensitivity that is too close to the peaks of either the red or the green photopigments.
		That's the rub, as far as he's concerned -- he suspects that most female tetrachromats would have only mildly superior color vision, because the genetics indicates that the fourth photopigment would almost always be very close to either the red or the green.
	www.cs.utk.edu /~evers/documents/tetraChromat.txt (1878 words)

	Tetrachromat - Wikipedia, the free encyclopedia
		A tetrachromat 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 four different pure spectral lights.
		The normal explanation of tetrachromacy is that the organism's retina contains four types of higher-intensity light receptors (called cone cells in vertebrates as opposed to rod cells which are lower intensity light receptors) with different absorption spectra.
		It has also been suggested that women who are carriers for certain kinds of color blindness (protanomaly or deuteranomaly) may be born as full tetrachromats, having four different simultaneously functioning kinds of cones.
	en.wikipedia.org /wiki/Tetrachromat (329 words)

	Some women may see 100 million colors, thanks to their genes (Site not responding. Last check: 2007-10-22)
		A tetrachromat is a woman who can see four distinct ranges of color, instead of the three that most of us live with.
		A true tetrachromat has another type of cone in between the red and green -- somewhere in the orange range -- and its 100 shades theoretically would allow her to see 100 million different colors.
		She knew that the mothers of those boys would have either two red or two green cones, and she is now in the process of testing those women to see which of them might be "strong tetrachromats," as she put it.
	www.post-gazette.com /pg/06256/721190-114.stm (1033 words)

	Guardian Unlimited \| Archive Search
		For normal trichromats there should be a whole range of matches, but for a tetrachromat the added dimension means there would only be one combination that matched exactly.
		The experiment showed that the potential tetrachromats were much more finicky about declaring a match to be exact, and made different matches to others.
		If tetrachromats exist, it would prove that the brain, which normally only handles three colour channels, is capable of handling input from a fourth channel.
	www.guardianunlimited.co.uk /Archive/Article/0,4273,4128183,00.html (1111 words)

	Color - Wikipedia, the free encyclopedia
		If these four types are sufficiently distinct in spectral sensitivity and the neural processing of the input from the four types is developed, a person may be a tetrachromat (tetra=four).
		For many species, tetrachromacy is the normal case, although the cone cells of animal tetrachromats have a very different (more evenly-spaced) spectral sensitivity distribution than those of possible human tetrachromats.
		There is an interesting phenomenon which occurs when an artist uses a limited color palette: the eye tends to compensate by seeing any grey or neutral color as the color which is missing from the color wheel.
	en.wikipedia.org /wiki/Color (3604 words)

	The Daily Telegraph and Bayer Science Writer Awards
		Up to 50 per cent of women are tetrachromatic and can use their extra pigments in "contextually rich viewing circumstances".
		For example when looking at a rainbow, tetrachromat females can segment it into, on average, 10 different colours, whereas their trichromat brothers and sisters can see only seven, much as Isaac Newton's red, orange, yellow, green, blue, indigo and violet.
		Consequently for those special tetrachromat women, this island that they inhabit may be seen in emerald, jade, verdant, olive, lime, bottle and 34 other shades of green.
	www.science-writer.co.uk /award_winners/16-19_years/2004/winner.html (730 words)

	Tetrachromat at AllExperts
		A tetrachromat 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 four different pure spectral lights.
		The normal explanation of tetrachromacy is that the organism's retina contains four types of higher-intensity light receptors (called cone cells in vertebrates as opposed to rod cells which are lower intensity light receptors) with different absorption spectra.
		It has been suggested that women who are carriers for certain kinds of color blindness (protanomaly or deuteranomaly) may be born as full tetrachromats, having four different simultaneously functioning kinds of cones.
	en.allexperts.com /e/t/te/tetrachromat.htm (417 words)

	Tetrachromat (Site not responding. Last check: 2007-10-22)
		A tetrachromat is an organism for which the effect of any arbitrarily chosen light from visible spectrum can be matched by a of no more than four different pure lights.
		The normal explanation of tetrachromacy is that organism's retina contains four types of color receptors (called cones in vertebrates) with different spectra.
		Humans and other Old World primates normally have three types of cone cells and are therefore trichromats.
	www.freeglossary.com /Tetrachromat (128 words)

	Tetrachromat: Encyclopedia topic (Site not responding. Last check: 2007-10-22)
		In practice the number of such receptor types may be greater than four, since different types may be active at different light intensities.
		However, at low light intensities the rod cell (rod cell: Visual receptor cell sensitive to dim light) s may contribute to colour vision, giving a small region of tetrachromacy in the colour space.
		It has also been suggested that women who are carriers for certain kinds of color blindness (color blindness: Genetic inability to distinguish differences in hue) (protanomaly or deuteranomaly) may be born as full tetrachromats, having four different simultaneously functioning kinds of cones.
	www.absoluteastronomy.com /reference/tetrachromat (190 words)

	Color - ExampleProblems.com
		If these four types are sufficiently distinct in spectral sensitivity and the neural processing of the input from the four types is developed, a person may be a tetrachromat (tetra=four).
		For many species, tetrachromacy is the normal case, although the cone cells of animal tetrachromats have a very different (more evenly-spaced) spectral sensitivity distribution than those of possible human tetrachromats.
		There is an interesting phenomenon which occurs when an artist uses a limited color palette: the eye tends to compensate by seeing any grey or neutral color as the color which is missing from the color wheel.
	www.exampleproblems.com /wiki/index.php?title=Color&printable=yes (3556 words)

	Color - the free encyclopedia (Site not responding. Last check: 2007-10-22)
		Some animals may have more than three different types of color receptor (most marsupials, birds, reptiles,and fish; see tetrachromat, below) or fewer (most mammals; these are called dichromats and monochromats).
		In theory it may be possible for a person to have four,rather than three, distinct types of cone cell.
		Such a person might, depending on the neural processing of the input from thesefour types, be a tetrachromat (tetra=four).
	www.free-web-encyclopedia.com /?t=Color (4349 words)

	taa_tez (Site not responding. Last check: 2007-10-22)
		Tetrachromat - A person with colour vision based on four channels.
		About 8 percent of caucasian men who are colour blind has the blue cone photopigments but are usually lacking one of the other two types of cone photopigments.
		A tetrachromat has a fourth cone photopigment, for a colour between red and green.
	www.etscience.co.za /taa_tez.htm (1523 words)

	[Psych3120] Tetrachromats (Site not responding. Last check: 2007-10-22)
		This is what I found about tetrachromats: There have been many attempts to find individuals with 4 cones.
		Most female tetrachromats would have only mildly superior color vision, because the genetics indicates that the fourth photopigment would almost always be very close to either the red or the green.
		I found it interesting that a tetrachromat, looking at a special computer screen based on four primary colors rather than the standard three, could theoretically dump data into her head faster than the rest of us.
	lists.csbs.utah.edu /pipermail/psych3120/2002-January/003522.html (215 words)

	The real reason women can distinguish lavender and periwinkle (reddit.com)
		Actually, the bigger problem wouldn't be that the tetrochromats can see colors that monitors don't show, it would be that monitors rely on two differing sets of frequencies looking like the same color to trichromats (there's a name for this in color theory-- metamers, maybe).
		Well, the ability of some females in a species to see with greater color depth is a trait that goes back at least as far as the new world monkeys, and I don't believe gendered division of labor is consistent in all those hundreds of species.
		It's not about "women," it's about tetrachromats, who happen to necessarily be women but not vice versa.
	reddit.com /info/ic3t/comments (1044 words)

	Encyclopedia: Tetrachromat (Site not responding. Last check: 2007-10-22)
		They also have the fourth-fewest main phone lines.
		The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye.
		A pentachromat 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 five different pure spectral lights.
	www.nationmaster.com /encyclopedia/Tetrachromat (1092 words)

	Tetrachromacy - Disenchanted Dictionary
		If one of those X chromosomes has just the right kind of mutation (green and off-green, rather than green and red photopigments), then the cells which chose to grow from that chromosome rather than the other will be sensitive to the magic fourth color.
		Men have only one X chromosome, however, and that often results in tetrachromat women giving birth to colorblind boys because their unfortunate sons inherit the mutated X chromosome and don't have a spare “good” one.
		Tetrachromacy interests neurophysiologists because, if these women truly can see colors that mere trichromats cannot, then it means the human brain can adapt to make good use of new senses without having to translate them into approximations of others.
	www.disenchanted.com /dis/lookup.html?node=1831&context=1572 (431 words)

	Artblog.net - Roundup
		I was not aware of the existence of abilities possessed by the tetrachromat.
		Buried in the geek links I posted on shooting images post was this article by Bruce Fraser on how we see color and how it is scientifically defined.
		The tetrachromat phenomena is essentially an extension of this, but rather than having a different illuminant, the tetrachromat has the extra receptor.
	www.artblog.net /?name=2006-09-15-09-11-roundup (439 words)

	Advanced Light And Vision Concepts
		Fulton suggests that all normal humans are indeed tetrachromats, having a photopigment that responds in the UV range.
		The researchers interviewed in the article think that they have found two tetrachromats, but haven't gone so far as to actually state it for a fact.
		We don't need to speculate that a tetrachromat would need more nerve fibers to carry the new color; it is far more likely that the new color information would be encoded for transmisison along existing pathways.
	wolfstone.halloweenhost.com /Lighting/litadv_AdvancedLightingConcept.html (5959 words)

	ECVP2006 Abstract - Do tetrachromatic women exist?
		We ask whether she can become a functional tetrachromat and exhibit enhanced colour discrimination.
		Our subjects perform a three-alternative temporal forced-choice task, in which two of the stimuli are monochromatic (590 nm) while the third is a mixture of two monochromatic lights (550 nm plus 670 nm).
		For the normal, there is a combination of (a) and (b), equivalent to the Rayleigh match, where performance is at chance.
	www.conferencesoft.com /ECVP/Program/Abstract.aspx?ag=1933fa27-dc24-4fbf-b58c-398e1514c1d5 (283 words)

	Looking for Madam Tetrachromat [Free Republic]
		Because the tetrachromats had the use of only two receptors, they found a whole slew of mixes that produced a matching color.
		In this case, I agree, the survival advantages of tetrachromaticity are probably insufficient to offset the penalty paid by heterozygous males.
		Once the tetrachromaticity gene is established on both chromosomes and becomes common in the gene pool, the chromosomes that carry trichromaticity become the de facto cause of color blindness: people homozygous for tetrachromaticity have 4-color vision, while heterozygous people have the problem.
	www.freerepublic.com /forum/a3a24199b1ef8.htm (3763 words)

	CYBER-MIND - Redherring.com - Looking for Madam Tetrachromat- From the (Site not responding. Last check: 2007-10-22)
		Dr. Jordan reports that of the fourteen test subjects in her study, two showed "exactly" the behavior that would be expected of tetrachromats.
		Because the tetrachromats had the use of only two receptors, they found a whole slew of mixes that produced a matching color.
		Dr. Nathans also believes, however, that for full-blown tetrachromacy, the fourth photopigment must not have a peak in sensitivity that is too close to the peaks of either the red or the green photopigments.
	mailarchivers.ncsa.uiuc.edu /cgi-bin/mailarchivers/viewmsg.pl?type=MAIL&&archive=CYBERMIND&&username=ANONYMOUS&&msgid=1215 (2085 words)

	Genes may let some women see 100 millions Colors! - Body of Wealth
		A tetrachromat can be a woman who can see four distinct ranges of color rather than three, normally seen by most of the people.
		A real tetrachromat woman found to have red and green type of cone like orange in appearance providing her to see 100 million varied colors.
		This superior color vision is only found in woman and not in man. It is due to the presence of two X chromosomes in woman, on which the genes for the pigments in green and red cones lies.
	www.bodyofwealth.com /entry/genes-may-let-a-woman-to-see-100-millions-colors (528 words)

	Plurp: A Weblog
		Tetrachromats, if they exist in the population, have a third kind of color receptor, for some other color blend.
		But tetrachromats would be able to see lots of colors that can't be made from three base colors.
		Your orange ink and my orange ink may be, to a tetrachromat, entirely different colors, so "standard" colors and "standard" inks would have to be completely revised.
	www.stevewhite.org /log/archive/20001210.htm (5510 words)

	[No title] (Site not responding. Last check: 2007-10-22)
		Thanks to Annie for telling me I ought to write it, no thanks to GigaNews for server reliability.] Tetrachromat women One of the many things I hate about direct marketing is the way marketers share their lists.
		But also we could find the people who are carrying the right genes to create more tetrachromats, and encourage them to have children with each other.
		I'm not sure it's even fair to deliberately go out of your way to conceive children where you know the male ones are probably going to end up having a reduced quality of life on account of being color blind.
	www.nothings.org /usenet/fts/2000/news0042.html (2726 words)

	ON TETRACHROMACY
		But then 1) a researcher (say, trichromat) cannot discuss the extra dimension of tetrachromats with another researcher without the danger of misunderstanding; and 2) misunderstanding is almost inevitable between a trichromat researcher and a tetrachromat subject.
		One of these tetrachromats permitted to report her all observations while nothing personal except that she is female and well past her teens.
		Now, in the first situation both parents are trichromats, so the genetically tetrachromat girl cannot learn her extra degree of freedom from the parents.
	www.rmki.kfki.hu /~lukacs/TETRACH.htm (7067 words)

	Tetra Chromat (Site not responding. Last check: 2007-10-22)
		Tetrachromats have colour vision based on four channels.
		Most humans have three channels (from the red, green and blue receptors in their eyes), while some colour-blind humans have only two channels.
		Conversely, TetraChromats are exclusively female, since one requires both a color-blind and non-color-blind X-chromosome to be susceptible to tetrachromacy, and males usually have only one X-chromosome.
	www.c2.com /cgi-bin/wiki?TetraChromat (319 words)

	Brand new colors
		A tetrachromat would have a fourth cone photopigment, for a
		showed "exactly" the behavior that would be expected of tetrachromats.
		tetrachromat, partly because her testing is still a work in progress.
	www.vocaboly.com /forums/ftopic1584-15.html (2970 words)

	PSYCHE-B Archives -- February 2001 (#1)
		THE GUARDIAN A gleam in the eye The tetrachromat sees a vivid world unavailable to most of us, writes David Hambling David Hambling Guardian Thursday February 1, 2001 There is more to colour than meets the eye.
		We learn at school that there are three primary colours, and the rest of the rainbow can be made by mixing these.
		Colour television uses three colour guns, and colour printers need three inks to cater for the full range of our trichromatic colour perception.
	listserv.uh.edu /cgi-bin/wa?A2=ind0102&L=psyche-b&F=&S=&P=58 (251 words)

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