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tetrochromatic women among us?

By wolfie in MLP
Sat Dec 02, 2000 at 09:42:23 PM EST
Tags: Science (all tags)


Preliminary evidence suggests that women with tetrochromatic (4-channel colour) vision may exist. Supposedly, this could only exist in women, due to how it is genetically inherited, interesting read.


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tetrochromatic women among us? | 40 comments (12 topical, 28 editorial, 0 hidden)
Interesting, but not very useful yet... (2.88 / 9) (#6)
by pb on Tue Nov 28, 2000 at 09:40:18 PM EST

Even if this did enhance color perception of some sort, I really doubt it would help on the Internet. Most of that article is in plain old black-and-white, as are most books you'll ever find. This would have more applications for fashion designers than for website designers IMHO...

Besides, I find that I don't need much more than the 8 original crayola crayon colors to describe most things; the 64-color pack is just overkill. :)
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That's SOOO twentieth century! [OT] (3.28 / 7) (#7)
by qslack on Tue Nov 28, 2000 at 10:14:34 PM EST

Wow, someone who doesn't like using "Heinz (r) Ketchup Kool Red," "Jolly Rancher (r) Razz-tazz Purple," "Coca-Cola (r) Radical Brown," "Kuro5hin (r) Commently-Awesome Blue," and "Heinz (r) Kool-Ketchup (r) Green?"

Looks like Crayola has taken advantage of young kids by pushing brand names into their faces starting at age 3 (since crayons are not meant to be kept in reach of children under 3).
(Note: for those of you who are humor-disabled, this was a joke. Thanks.)

[ Parent ]
Yeah, well... (2.50 / 6) (#9)
by pb on Tue Nov 28, 2000 at 10:53:31 PM EST

Since they call <A HREF="http://kids.infoplease.lycos.com/ipka/A0872797.html">their colors</A> stuff like black, blue, brown, green, orange, red, violet, yellow, etc., etc., I'm not too worried.

It didn't start getting wack until 1972, with the introduction of colors like "razzmatazz", which probably needs an extra color receptor (or chunk of right brain) to connect the color with the naming scheme...

Basically, as long as you don't get past the 64-color box, and you don't get what's up with "green-yellow" and "yellow-green" (I thought color names were commutative) you should be fine. Otherwise, I'm sorry, but you're a mutant color freak. :)
"See what the drooling, ravening, flesh-eating hordes^W^W^W^WKuro5hin.org readers have to say."
-- pwhysall
[ Parent ]
Wouldn't help at all on current tech anyway (4.33 / 3) (#18)
by fluffy grue on Wed Nov 29, 2000 at 11:01:55 AM EST

The way that computers display color is that they display pigments which are close to the three receptors in normal peoples' eyes. It's not a perfect match (and it couldn't be a perfect match with everyone anyway, since some peoples' reds and/or greens are different than others, as the linked article stated), but it's close enough to display a reasonably-large subset of the color gamut the human eye can perceive. All that this tetrachromaticness would do with a computer monitor is shift a bit of the perception in the existing red and green - since the fourth wavelength isn't being used/displayed anyway, perception on a monitor won't be improved at all.

Really, all that a tetrochromatic person would have to show for her variation with respect to computers is monitor colors being even LESS vivid compared to real life than it is for normal people.

Here's a simple experiment to perform. Get a spectroscope or diffraction grating or the like and look at the sun or a lit lightbulb or any other incandescent white light source with it. Notice how the brightness of the colors is pretty much consistent across the entire spectrum. This is what makes a reference 'white'. Now point it at a computer monitor displaying white. Notice how it only shows a few peaks of color. Change the color of the screen to display different colors. Notice how rather than the peaks shifting around through the spectrum, they just change in brightness according to the RGB values used to create the color.

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[ Parent ]

The Fourth Pigment (3.13 / 15) (#8)
by the Epopt on Tue Nov 28, 2000 at 10:25:44 PM EST

The fourth pigment, between red and green, the color that men cannot see, is obviously the puce pigment.
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Emphasis on women (2.50 / 4) (#22)
by driptray on Thu Nov 30, 2000 at 12:13:52 AM EST

I'm interested why, in both Slashdot and here, this story was written up with an emphasis on the fact that it is only women who may be tetrachromatic. The women-only bit is a very minor part of the story that in no way deserves the emphasis given to it here.

If it was only men that could be tetrachromatic, do you think that fact would be trumpeted so loudly?

Is it envy on the part of the (presumably) men who are submitting the stories? Or is it just an attempt to create opportunities for a bunch of questionable jokes?

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Gene expression - differences between the sexes (3.40 / 5) (#26)
by red on Thu Nov 30, 2000 at 09:31:32 AM EST

Part of the emphasis may be due to the fact that in the article discusses the difference in the way that the relevant genes are expressed differently in men and women due to women having 2 X chromosomes.

Thus, with 1 X chromosome, men are more prone to having deficiences expressed (colour blindness).

Women with 2 X chromosomes can have other fun things happening (like four colour vision genes expressing themselves instead of three)

What I found particularly interesting was the fact that, even if these women exist, they probably don't realise that their vision is different. They explain the difficultly of even proving the existence of tetrachromacy in the article.

BTW just because it's on Slashdot, doesn't mean we can't talk about it here. Not ALL of us read /. you know :)

[ Parent ]
Women-only (3.00 / 3) (#27)
by royh on Thu Nov 30, 2000 at 01:11:48 PM EST

I noticed that it was women only because it means that I could not possibly be tetrachromatic (darn). On the other hand, any women reading this article from kuro5hin or slashdot might actually be tetrachromatic, and have never known. It's not important, as the chances of being one are small anyways, but there's still that wishful thinking involved.

[ Parent ]
A hypothesis (3.75 / 4) (#31)
by SIGFPE on Fri Dec 01, 2000 at 01:05:22 PM EST

I've always wondered whether or not colour space might be four dimensional for most people. We usually have receptors sensitive to 4 different colour bands in the eye, not 3. There are the three different 'colour' receptors and the 'luminosity' receptors. Now unless the response function for the luminosity receptor is precisely a linear combination of the other 3 receptor types we have a 4 dimensional space of colours, not 3. I wonder if very sensitive testing could identify subtle colour discrimination in subjects subconsciously using this. In particular you might be able to construct colours with peaks between the humps of the 3 'colour' receptors. This would register with high 'luminosity' even though the sums of the inputs from the 'colour' receptors would be comparatively low. Might that be perceptible - maybe under special conditions?

BTW - I recently experimented with a filter that approximately removes wavelengths between the humps. It's a fascinating filter that seems to do some counterintuitive things. For example it looks superficially like a neutral filter - hold it up to most things and it makes little difference - just reducing brightness by a fraction of a stop. But hold it up to a human face and it looks redder - presumably because the colour of blood lies confined to the middle of the red hump. It's pretty weird seeing something apparently colourless making such a difference.
simple answer (3.00 / 1) (#34)
by Potatoswatter on Fri Dec 01, 2000 at 11:09:24 PM EST

Yeah, it's a rather pronounced effect of black-and-white vision in any dark room, visible with your RDA of vitamin A. I think that being very awake (read: epinephrine) helps it too. The luminosity sensors are geared towards more sensitivity at the expense of less selectivity.

As for "seeing things in a different light", the effects of removing important wavelengths can be seen by viewing your sweetheart under any cheap yellowish streetlamp.

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[ Parent ]

A good reference on color vision... (4.50 / 2) (#38)
by egnor on Sat Dec 02, 2000 at 11:06:06 PM EST

Handprint's articles on color are by far the best resource I've found on the Web for explaining color vision. (If you think you have some clue about human color vision, or know what "primary colors" are, you're probably quite mistaken. There are a lot of very interesting details.)

This article on color vision in blue-code monochromats discusses SIGFPE's slightly ill-stated conjecture. Specifically, it's true that our "rods" have a different color sensitivity than any of the three kinds of "cones". In theory, that makes us all tetrachromats, except that during the "photopic" conditions (ordinary fairly bright light) when our cones work well, the rods shut down; conversely, under "scotopic" conditions (dim light, "night vision") when the rods are active, the cones don't have enough light to function. There is a narrow "mesopic" range in between, when both rods and cones are active, but even then it appears that the rods simply reuse some of the cones' visual circuitry, so we're still trichromatic (though our color sense tends to skew because of the way the rods' input is mixed in; specifically, everything tends to look blue). The first link above (from Handprint) talks in more detail about the stages of color processing and how inputs get "mixed".

All in all, the important part is not that the hypothesized tetrachromatic women have four kinds of cones, but that they may have the neural circuitry to make sense of all that input. The psychology of color is a complex and fascinating subject; I wonder how they see the world (if they do indeed exist).

Ahem.. (1.00 / 1) (#40)
by Chiron on Tue Dec 05, 2000 at 01:56:53 AM EST

That's low signal to noise, and apply commas where necessary, it's been a long shift.

tetrochromatic women among us? | 40 comments (12 topical, 28 editorial, 0 hidden)
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