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Mutant Tetrachromat Females Found
Hydrophobe writes "Red Herring reports that
at least one living human female has
four-color (tetrachromat) vision. Apparently, genetics dictates that all such tetrachromat mutants would be female. Compared to them, the rest of us are partly colorblind - they would be able to see colors beyond the standard three-axis RGB scale."
So none of the guys' clothes will match in the eyes of women--great. If we don't get female assistance, every woman around will know what losers we are. We'll have to hire women to help us shop, so we can pretend we had girlfriends sometime in the recent past.
A lot of comments here reflect a somewhat, uh, uninformed view of color vision. I was going to write up a little summary, but then decided to try my Google skills out.
I came up with this definitive article on Color Vision by Peter Gouras. It's very deep, with a special focus on the neurology of color vision.
Another potentially interesting link is the Color Vision Q&A from Rochester Institute of Technology.
What's especially fascinating to me about color vision is that it still isn't fully understood. The low level parts, such as rods and cones, and even some of the "early vision" parts of the brain, have been studied for a while now. However, there are lots of higher level brain activities that are still quite mysterious. As such, making color photographs "match" across computer screen, print, video, etc., is still a subjective art, claims of rigor in "color management solutions" notwithstanding.
LILO boot: linux init=/usr/bin/emacs
The trick is to use a pair of my patented spectral shifting eyeglasses. The extra colors are visible as discrepancies between the two eyes, a somewhat glittery effect.
I have a prototype pair here. I haven't done an experiment along the lines of Dr. Jordan's, but my intuition is that you'd be able to pass the tetrachromat test.
In theory, this technique can give you up to hexachromic vision. In practice, the color shifts in the yellow area are by far the most pronounced.
The prototypes cost me about $1000. The optical coating technology is pretty straightforward, and it should be possible to manufacture these in quantity for $20-$30. Anyone interested in going into production?
LILO boot: linux init=/usr/bin/emacs
> Evolution makes no claim about traits being "good" or "bad", there are simply those that become common and those that don't.
I'm not sure how you think that some traits will get passed on, though. It's not through magic. If the traits in one type of mutant wind up being passed on, great. It's only going to GET passed on if that creature reproduces, which it won't do, or won't do ANY MORE THAN THE NON-MUTATED ONES, unless there's that mutant is in some way 'superior' as far as getting their genes propogated. Otherwise, those genes would wind up staying in approximately the same projected percentage as they are currently. Unless the progeny of the mutant becomes statistically more-numerous than the non-mutants, it won't become commonplace.
Slightly-improved colour detection in this day and age will do little to nothing to make those people able to reproduce more than a non-mutant. _Maybe_ the ability to detect one's progeny being ill _slightly_ faster than another might help, but with modern medicine - I find it highly unlikely.
My private theory has always been that colours are analogous to musical tones. Under this theory, while there may be an infinite number of frequencies and hence an infinite number of distinct "colours", they actually sort themselves out into a limited number of hues analogous to the tones of the musical scale. The reason we are unaware of this phenomenon is that the human visual range extends approximately from 700nm to 400nm. Since the top (violet) end of our visual range is less than twice the frequency (more than half the wavelength) of the bottom (red) end, we perceive less than one full visual "octave".
Of course, the only way to test this theory, as far as I can tell, would be to engineer some lucky (or unlucky) child with the genes for extended-range pigments, let them grow up, and then ask them if 400nm light looks somehow the same or different than 800nm light.
"The deep-fried Mars bar is a symptom of a wider crisis." -- Nutritionist Ann Ralph, on the Scottish diet
Most of this post was essentially correct, but I just wanted to amplify this part of the message. Yes, if you look at the spectral sensitivities of red, green and blue cones (or, strictly, their dyes), blue is many nanometers shorter in wavelength than the difference between red and green. But to test your understanding of how color "works" at the retinal level, the key question should be: where does "yellow" come from?
The answer, of course, is from the additive contributions of both red and green cones; indeed, when you look at the sensitivity curves, you can see that the response to "yellow" should be larger than either green or red. And, it is. Visual acuity is actually slighly better for yellow than for any of the primaries (think shooter's glasses). Now, having said that, I should point out that blue is a special weird case, since the blue cones have a much more limited distribution on the retina than do red and/or green cones.
And, having said all of this, the most amazing thing about color vision (in my opinion) is not what happens at the retina, but what happens in the cortex, apparently in area V4. That's where the very hard problem of color constancy (aka "discounting the illuminant") is solved in a manner studied at great length by Edwin Land, who really would be every geek's hero if only he were better known.
Babar
Yes. This is exactly right. Consider it this way:
The color receptors in the eye are not monochromatic, that is, they don't react to just one frequency of light. Instead, they react in a curve, with a peak at the frequency of greatest sensitivity of that particular color receptor. What goes into the visual channel, then, is the output from each kind of receptor. Their curves overlap, so all three of them would react (at very different levels) to a monochromatic light.
Now, let's say we have four monochromatic light sources, one at the peak frequency of each of the receptors in "Mrs. M's" eyes. To further simplify matters, let's pretend that a "normal" eye's color receptors have peaks at the same frequencies of three of Mrs. M's four receptor types. Call them R, G, B and Q, where Q is the color receptor that the normal eye doesn't have.
Shine equal intensities of R, G, and B into the normal person's eye. The three color receptors will respond with a particular color, probably white. Now, add in color Q, and at the same time, decrease R, G and B so that the response from each of the normal receptors for R, G, and B remains the same. The normal person will see no difference. They can't, we've made sure of that: their color receptors are putting out just the levels they did before.
Now, shine these two different combinations into Mrs. M's eyes. She'll see two VERY different colors. Her R, G and B receptors will be putting out the same levels in both cases, but her Q receptor will jump way up on the second combination. Result: the "white" light suddenly looks Q-colored. What color that actually corresponds to in normal vision depends on where the peak of the Q receptors lies in the spectrum. Could be aqua, cyan, anything.
Anybody can read by a blacklight, at least on most paper. Chances are the paper will flouresce slightly, basically turning invisible UV into visible light. Some paper will flouresce more than others-- depends on how it was made, depending on the brand, etc.
What you see coming from a blacklight (violet) is only a fraction of what's actually there because it's mostly in the invisible part of the spectrum.
Now maybe our corneas also filter out some violet light that we would otherwise be able to see, but I don't know anything about that.
Incidentally, in a dark room with a blacklight on, you can see every single spot on the carpet where your cat has ever barfed, pissed, crapped or where somebody spilled something-- no matter how clean the carpet looks in normal light!
It's quite a hideous sight, although pretty useful for determining where you're supposed to pour the cleaning fluid.
-CausticPuppy "Of all the people I know, you're certainly one of them." -Somebody I don't know
Neitz Color Vision Lab
"This message is composed of 100% recycled electrons."
but does this mean she's losing resolution to gain color, or does the resoltion stay the same?
:)
:-)
No, the resolution is really the department of the rods - that's where you get most of the image defintiion, the extra cones just means the colours are painted into that image with a cruder brush, which, if you've mess around with image channels, you'll find makes virtually no perceptual difference. (It's quite weird actually - we can't define by colour to save our lives
An example that is probably due to the same phenomina - put green text on a red background, and adjust the tone such that there is no tone-difference between the colours (ie your rods see a flat grey - no text at all) then try to read the text using just your cones. You can do it, but your eyes will totally bug out
"People will think things match, but I can see they don't."
Does this mean that all of my girlfriends have been tetrachromatic? I often hear this about my clothing...
sulli
RTFJ.
I don't think you see the value of having an alpha channel, or transparency channel.
As you point out, it does no good in the framebuffer.
But just think of all the many, many places ahead of the framebuffer where graphics are manipulated? If non-Mac software would universally support alpha channels in graphics formats then think of now naturally graphics would appear to work to end users?
You paste two pictures into your word processor. The two pictures partly overlap. The degree of transparency of each picture (indeed each pixel) is determined by data within the picture itself. Both pictures might be partially transparent so that you could still see the text underneath the two pictures. Bring one of the graphics into the GIMP, crank the alpha channel to fully opaque, now copy&paste the pic back to the word processor, and it obscures everything behind it.
By the time it gets to the framebuffer all you care about is RGB, no alpha.
Another cool thing about this is that you no longer tend to think of pictures as "rectangular". Pictures are arbitrary shaped. Of course, they're rectangular, but just some of the pixels are fully transparent.
I'll see your senator, and I'll raise you two judges.
Sorry, the article states that the extra photoreceptor cones are sensitive to a wavelength in between red and green, directly on the range of visible wavelengths. At the most extreme, they would be receptive to a yellow-orange colour, although most of them hover around slightly different shades of green or red. No UV vision for you. (PS - aren't most remotes IR nowadays? Less harmful if you aim it at your eye).
It may look like I'm doing nothing, but I'm actively waiting for my problems to go away.
--Scott Adams
Tumbleweed writes: Unfortunately, it almost certainly won't spred into the general population unless it's done on purpose. Tetrachromat vision doesn't give any measurable survival advantage in the modern world, therefore it won't be in a majority of the 'surviving' population.
If you read the article, you could have avoided shooting yourself in the foot.
From the article: Would there be any practical advantages to tetrachromacy? Dr. Jordan notes that a mother could more easily spot when her children were pale or flushed, and therefore ill. Mrs. M reports that she has always been able to match even subtle colors from memory -- buying a bag, for example, to match shoes she hasn't laid eyes on for months. And computers, color monitors, and the Internet raise a whole raft of possibilities. Just as someone with normal three-color vision surfs rings around a dichromat on the Internet, 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.
So, Tetrachromatics have an increased chance of catching diseases in their children (improving offspring's chance of survival), can match outfits better (improving attractiveness and desirability), and might be able to intake more data.
Not sure how this sounded to you, but I'd say that the genes for Tetrachromatics are beneficial (at least to the female half of our population).
Get cataract surgery, and you'll be able to see UV light. Apparently, it's been noticed that people who've had their corneas removed can read by a black light. I'm not sure what the practicle applications of this would be, but I suppose you could read War and Peace at a rave.
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there aren't any superheros flying around in the real world
That's what you think. Guess you're a trichomat, right?
People replying to my sig annoy me. That's why I change it all the time.
By the same token, how do you know that we both perceive colors the same way? Perhaps the way I perceive blue in my mind looks just like the red that you perceive in your mind. We all kind of assume that we see the colors the same way. But, it could easily be the case that they we all see them differently.
Sure, things like the color wheel dictate a certain amount of consistency in each individuals perception. But the color wheel could be rotated to a different angle for each person. Or perhaps the world to me looks like an inverted negative to you. The fun part is that there is absolutely no way to tell.
Does this mean that the web safe palette drops from 22 to 2? Just black and white now...
-- toolie
If the human brain can adapt to 4-color sight, then I wonder how much longer before someone tries to engineer extra infra-red cones. Infrared-sensitive eyes have long been a part of the cyberpunk genre of fiction, but the idea of growing up with "natural" infrared vision in addition to normal color vision would be wonderful.
If we ever moved that way, though, would we have to come up with new color words -- words that most of the population couldn't understand?
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
There might be colors (shades of blue and violet) that can be distinguished at twilight but not in bright sunlight because of the importance of rods to vision in the reduced light. I keep meaning to go check, but haven't.
A mutant is the term you would use because the scientific term for what this woman has is a genetic mutation.
It is actually such things as the X-Men that gives the term a misunderstood meaning. A mutation doenst have to be anything as drastic as in the movie "The Fly" for example, and certainly, there arent any superheros flying around in the real world. Im sure if you looked closely enough, most of us have some sort of genetic mutation in our DNA, but they just arent significant enough to manifest themselves in any noticeable way.
If the 4 color vision is a good mutation, it will hopefully propogate into the general population eventually (well, half of it anyway :)
The ivory tower has never had to reach so h
Rods see intensity (ie B&W). A couple more interesting facts: rods react to changes more quickly, and to smaller changes as well. Cones are concentrated around the centre of your eye, whereas there are relatively many more rods in your peripheral vision. This is why it is easier to see movement out of your peripheral vision, and easier to spot something that is a different colour by looking directly at it. Pretty cool if you ask me. Peripheral vision sensitive to movement to spot attacking predators, and central vision sensitive to colour differences to spot hiding prey...
It may look like I'm doing nothing, but I'm actively waiting for my problems to go away.
--Scott Adams
A better question might be "Can living beings perceive an infinite amount of colors?" Color is just a function of wavelength, and there is obviously an infinite number of discreet wavelengths within the visible color spectrum.
Scientists have come up with some finite number of colors that can be percieved by humans. (I can't remember the exact count off the top of my head - check any perception textbook.) However, a machine with high quality photon sensors can distinguish between a much higher number of wavelengths, even though it doesn't have the perception of color. If we wanted it to describe that color for us as a perceptual experience, it would simply map that wavelength to a human-defined color table.
It is fair to say that there are an infinite number of colors out there, just that we can't see them all.
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--
"How many six year olds does it take to design software?"
dinner: it's what's for beer
Forget an extra receptor, when I was growing up I could have sworn that my mom had a whole extra eye in the back of her head.
The slashdot headline is premature in stating that a tetrachromat had actually been found.
"Nevertheless, Dr. Jordan declines to say that she has finally found a tetrachromat, partly because her testing is still a work in progress."
Sure, the dyes each represent vectors in the full infinite-dimensional spectral space, and not simply particular wavelengths -- but so long as they're linearly independent (i.e. you can't generate the spectrum of any one dye out of a weighted sum of the other dyes' spectra), they're useful for distinguishing color.
The primary additive colors (R, G, and B) are determined by the spectra of the dyes. You can't pick any set of primary colors you want -- the color wheel was discovered experimentally long before we knew the cellular biology to do direct experiments on the human eye. The primary subtractive colors (C, M, Y) are made by subtracting the corresponding (R, G, or B) from white light -- cyan light has G and B components, but no R.
When you get into detailed color vision, things (as always) get more complex. It turns out that there are no precise primary colors that everyone can agree on, because not everyone uses the same dyes in his cones! There are slight variations across the population, so that the R, G, and B primary colors correspond to different pieces of spectrum depending on who's looking.
Because of the overlap of (for example) the R and G spectra, it's not normal possible to generate a pure R signal in the human retina with any single wavelength of visible light. But we're wired to do the linear decomposition ourselves: in effect, the differential gain is really high between the R and G "raw" channels coming out of our retinas. Cool, eh? As laser pointing becomes more accurate, we ought to be able to stimulate directly our individual cones -- one day somone could perceive "superred" by directly stimulating only the red cones in his fovea. I wonder how different it would look than the more common red?
There's a really interesting overview article on color vision in the Feynman Lectures, volume I. It includes typical spectra for R, G, and B dyes. If I recall right, R and G are actually rather similar spectrally, with somewhat broad humps in the long end of the spectrum, while the B dye has a very different spectrum with a sharp peak near the short end of blue.
HER: Honey, can you find my red shirt for me?
HIM: Yeah, here it is.
HER: No, dear, that's the magenta one. I wanted the red one.
HIM: Is this it?
HER: No, that's burgundy. Forget it. Just give me my cream sweater instead.
HIM: Cream? Is that white?
HER: It's almost white but has a little yellow in it.
HIM: Here it is!
HER: You moron! That's a khaki colored sweater. I wanted the cream one! MEN!
>they just have extra reception
Er, I don't thinks so. They have a different *distribution* of receptors - four kinds (instead of three) with relatively tight color-bands, and one type which responds to the full visible light spectrum. This is why you can see B/W in very low light - still enough to trigger enough of the broad-spectrum receptors, but not enough for the tight-spectrum color recievers. This is why animals with very good night vision usually can't see color - they punt the color entirely for extra broad-spectrum receptors.
The space for those extra receptors in a tetrachromat came from somewhere, presumably other color receptors. I would *guess* that means they need more light to see in color than we do, but see finer color gradients....??
Pigeons have tetrachromat vision as well. My question though, is do they see a fourth and different color?, OR are the colors we see spread out a larger spectrum for them?? I know the frequencies are higher (or lower), Im talking about what shade it looks like in their brain, the whole how do you know when I look at grass I dont see red and call it green? According to a theory, this is similar as the difference between the vision of a dichromat (a color-blind) and a normal trichromat, like most of us. It means that a tetrachromat can have a novel pair of colors similar to our yellow-blue and red-green pairs. I would really really like to have the sensory output from her eyes fed into my brain, dont you think they could hook that up? Does that mean that there are an infinite amount of colors, because a pentachromat (some animals have five color receptors) would see even more colors.
Roses are red,
violets are blue,
trichromats can't see
the other amazing hues
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