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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."
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...
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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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