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Tetrachromats: people who see colors invisible to most of us (2014)

249 points| jakub_g | 6 years ago |bbc.com | reply

221 comments

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[+] andrewl-hn|6 years ago|reply
My spouse is a tetrachromat, and it's fascinating. Sometimes she sees patterns on leafs or bird feathers that other people don't see. Sometimes she can detect a very minor difference in colors of clothing items that other people see as identical. If a person wears those two items of clothing together she finds it really irritating.

She also sometimes see colors in her dreams that are outside of a pallet humans see in real life, but after she wakes up she can't describe them. It's not one color or one hue, there are several colors that she can only experience in her dreams.

[+] raphlinus|6 years ago|reply
There's actually a way for us to experience something similar: wear eyeglasses where the two lenses have different spectra. Then these "extra colors" show up as a shimmering sensation.

I have such a pair, but have to say it's not very exciting; there's not that much metamerism in the real world.

[+] OscarCunningham|6 years ago|reply
This is a really good idea. In fact it should be able to promote trichromats to hexachromats, since we have two eyes. I wonder if we could calculate optimal filters, sort of like EnChroma (enchroma.com) for trichromats.

Where did you get your pair? What filters did they have?

[+] triclops200|6 years ago|reply
What are they called? I'm interested in buying a pair.
[+] bhauer|6 years ago|reply
Maybe if this group grows over time we can finally move past the 24-bit color space that the mainstream has been stuck with for decades. I'm not a tetrachromat nor a woman, but I do routinely find myself bothered by the banding of gradients in the 24-bit color space. I went as far as asking Mozilla to consider adding a dithering algorithm to their gradients [1].

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=627771 (note the linked example is from 9 years ago and the -moz-linear-gradient CSS attributes no longer work.)

[+] neilwilson|6 years ago|reply
My daughter has something like this. She can see colours nobody else can, but pays for it a little by not being able to see as much out of the corner of her eyes than most people.

One optician panicked so much at what she said they referred her to the hospital in case she was having a stroke! And that's when we discovered what she can do. I just thought she was good at picking clothes that went together well.

[+] goto11|6 years ago|reply
> I just thought she was good at picking clothes that went together well.

Good for her, but I doubt this is because she can "see colors nobody else can". If that was the case, she would most likely be worse at picking colors which (to the average eye) goes together well. Maybe she just have good taste?

[+] OscarCunningham|6 years ago|reply
Are Antico's colourful paintings really a result of her tetrachromacy, rather than artistic flair? If she's painting such that the colours of the paint match what she sees, then trichromats should also think the paints match what they see, since they're less discriminating than she is.
[+] TheOtherHobbes|6 years ago|reply
Distorting colour is a standard post-Impressionist painterly technique.

But the moonlight painting gives it away. Most people don't see any colours under low light, and being able to see and paint a colourful scene under those conditions is a unique ability.

Of course it could be imagination, but it doesn't look like it. The tree and the moonlight paintings have similar colours to the ones you'd see if you took a photo of a scene and turned up the saturation in Photoshop, with a few extra shades. It's a surprisingly literal and unimaginative form of exaggeration, and it's not how most painters distort colour for effect. So I'm more inclined to think it's a perceptual feature, not a creative choice.

[+] cryptica|6 years ago|reply
Agreed, if the artist saw more range of colors than a normal person, I would think that they would paint using a smaller range of colors because they would find it sufficiently stimulating.

- It should be easier for them to paint highly photo-realistic scenes.

- They should struggle to find the right colors to buy in the shop.

- They should be frustrated with mixing colors because they could never get the color right as they see it.

[+] wizzard|6 years ago|reply
It sounds like she doesn’t necessarily see new colors, she just can distinguish far more colors in things that look monochromatic to the rest of us. It’s not that the rest of us can’t see lime green, but we don’t see it in a pebble or tree bark.
[+] rebuilder|6 years ago|reply
I'm pretty sceptical, personally. I'm male, therefore not tetrachromatic, and long ago I had this idea of representing high contrasts as pure rgb values.

For example, if you hold up your hand to shield your eyes from the sun, that's a pretty challenging situation to paint. But the way the after images of the sunlight interact with the silhouette of the hand suggested to me that the idea could be conveyed by painting a shimmering primary colour halo around the hand. And sure enough, Antico's paintings look much like what I had in mind.

[+] crazygringo|6 years ago|reply
I find tetrachromaticity fascinating -- particularly, I wish there were a way to scientifically prove whether tetrachromatics actually perceive colors as qualia that the rest of us don't, because that is absolutely not clear.

Let me explain: our eyes perceive RGB, but we don't in consciousness -- the RGB is mapped somewhere, long before consciousness, further in the brain to more of a perceptual RYGB -- a two-dimensional space of warm/cold (RY/GB) against "lighter/darker" for lack of a better term (YG/RB). See [1] for more info. Psychologically yellow functions as a primary color even though we don't have a rod for it. (In reality it's much more complicated than this, since we perceive saturation, brightness, etc. but this is a valid simplification for current purposes.)

So it's entirely possible that tetrachromats map their four rods to the same RYGB box the rest of us perceive as qualia, only with a different mapping. Then, they can still distinguish between colors everyone else sees as the same (because different spectra), but they'll still perceive them as the same color qualia the rest of us perceive -- colors in the world will just be mapped slightly differently. The closest (but imperfect) analogy I can think of is wearing polarized glasses -- same color gamut, but certain things "compare" differently now.

Or, does tetrachromacy somehow also change the perceived-qualia RYGB model itself? So there's, say, a 3rd axis beyond warm/cold and "lighter/darker"? Or the span of the two axes somehow becomes wider to accomodate more information? Or something else?

Hope this is clear. Perhaps it could be tested psychologically, though -- simply by asking participants to describe the colors they see qualitatively, to see if the words they use in color comparisons (e.g. warmer/colder) are the same as those used by the rest of us... or if there's any new "feeling" component involved.

[1] https://en.wikipedia.org/wiki/Opponent_process - "...the cells were widely called opponent colour cells, Red-Green and Yellow-Blue. Over the next three decades, spectrally opposed cells continued to be reported in primate retina and LGN."

[+] EventH-|6 years ago|reply
Not sure what the justification is for saying Y functions 'psychologically' as a primary color. It would be a secondary color (R + G) in terms of the light spectrum, and (as you noted) our cones are directly most sensitive to RGB.

To answer the question, as qualia cannot be compared from person to person, there is in principle no way to show that they differ (or are the same) objectively. A sort of relative comparison of qualia within an individual (as you propose) will also not get you there, as it may be that the individual is simply more sensitive to changes along the gradient, not that they are experiencing a new color, and that's assuming we are able to use an objective comparison scale which we aren't.

[+] proverbialbunny|6 years ago|reply
>I find tetrachromaticity fascinating -- particularly, I wish there were a way to scientifically prove whether tetrachromatics actually perceive colors as qualia that the rest of us don't, because that is absolutely not clear.

There is an African tribe that can see more greens and browns, due to their genetics and it has been proven for them.

Don't quote me on this, but I believe as a whole qualia has been proven. That is, we all do experience the world differently, but we can both point at the same thing and give it a same name. Words like 'red' are just pointers to the colors we see, and everyone sees it differently. This, ofc, doesn't guarentee we can see more or less levels of detail, just that we what we do see can be different.

[+] OscarCunningham|6 years ago|reply
> So it's entirely possible that tetrachromats map their four rods to the same RYGB box the rest of us perceive as qualia, only with a different mapping.

If they did this then wouldn't they necessarily also confuse some colours that trichromats can distinguish?

[+] rtkwe|6 years ago|reply
I don't see where there's much question about them perceiving differently. The ability of people to distinguish different colors is limited by the peaks of sensitivity of the rods in our eyes. By adding a fourth it's a new where they can distinguish better between colors that fall in the valley between the red and green cones.
[+] peter303|6 years ago|reply
I saw a six color channel video system at SIGGRAPH some years ago in their emerging technology exhibition. I believe the developer may have been Sony, but could not find an online reference. The additional colors were approximately midway the R-B-G colors conventional used. They claim they could display more of the color that people normally are sensitive to. And they had a 6-color monitor side-by-side with conventional showing how nature scenes were more vivid in their system. Of course every part of the system had to double up: video camera, transmission, storage, display.

I do not know if subsequent technologies like OLED, Quantum dots, HDF capture much of the color increase of the six channel system.

I do not know if the six color system could be used to quantify tetrachromacy.

[+] WrtCdEvrydy|6 years ago|reply
Quattron TVs tried this with a dedicated yellow pixel and weren't that good... I highly doubt we'll see something beyond RGB (unless it's a first class citizen from camera to TV)
[+] nitrogen|6 years ago|reply
Sharp had a four primary display on the market (added yellow), not sure if it's still around. They hired George Takei to do some of the marketing at the time.
[+] goto11|6 years ago|reply
I wonder how such people experience pictures, movies etc.? All color reproducing technology is based on the the three-color system.

I'm skeptical of the articles claim that the painting gives us any insight in how a tetrachromat perceive the world. This is just like claiming a color blind person would be able to perceive full-color vision by looking at a painting. Never mind that tetrachromat painters would have real difficulty finding the necessary color pigments to reproduce what they see.

[+] BurningFrog|6 years ago|reply
Yeah, image reproduction tech that reduces pictures to the three colors us "normals" see, will not contain anything extra for tetrachromats.

Only the real world does.

[+] gatherhunterer|6 years ago|reply
The title is misleading. The extra cone allows tetrachromats to appreciate individual colors that the normal optic system would “average” into a single hue. The visible spectrum is the same for tetrachromats: they cannot see infrared or ultraviolet wavelengths. These individuals see more color detail, not more colors.
[+] masklinn|6 years ago|reply
> These individuals see more color detail, not more colors.

If you're not able to differentiate between colors you're not able to see those colors.

Hell, your argument can be stretched to stating that there's no difference between monochromatic and trichromatic vision as long as the covered light spectrum is the same.

[+] goto11|6 years ago|reply
Disagree. They are not be able to perceive a larger spectrum of wavelengths but they may perceive more colors. Just like a person without green cones would be able to perceive fewer colors.
[+] BurningFrog|6 years ago|reply
By that logic, color blind people can see as many colors as us three-color seers, just in less "detail".
[+] jryb|6 years ago|reply
Would you also say that normal-sighted people "see more color detail" than those with deuteranopia? Sure, there's an experience of perceiving color when deuteranopes look at something green, but they still don't know what green is.
[+] anon946|6 years ago|reply
Depends on what you mean by more "color detail". Assuming that the activation curve of the 4th cone is sufficiently different, it's definitely possible to create two different spectra that a trichromat would be unable to distinguish between (regardless of how close they were or how long they stared at it) that a tetrachromat could easily distinguish between.
[+] zachrose|6 years ago|reply
Can dogs just not distinguish between colors that we can, or are they actually missing out on parts of our visual spectrum?
[+] sugerman|6 years ago|reply
If colorblindness is due to a lack of cones it seems the title isn't all that misleading.
[+] Aardwolf|6 years ago|reply
I'd love to see a tetrachromat who also knows about scientific color theory (tristimulus curves, CIE XYZ color, chromaticity and whitepoints, ...) explain how the color science would looks for them (do they have 2-dimensional hue, and 3-dimensional chromaticity diagram?)
[+] tzs|6 years ago|reply
I wonder if commonly available color changing smart bulbs, such as Philips Hue bulbs, have fine enough color control to be able to produce color changes that only a tetrachromat can see?

If so, that would be an interesting way for a tetrachomatic magician with a mentalism act to have their assistant pass them information. In particular, it would almost certainly work to fool Penn & Teller on their show "Fool Us" [1], where it often comes down to whether or not the mentalist can find a way to pass information that Penn & Teller can't spot.

[1] https://en.wikipedia.org/wiki/Penn_%26_Teller:_Fool_Us

[+] BurningFrog|6 years ago|reply
I'd be really surprised if the Hue internally doesn't just have three lights (R, G & B) that combines to produce all colors a human "trichromat" can distinguish.

To my mild surprise, 10 minutes googling did not find any description of how it works.

[+] Waterluvian|6 years ago|reply
Does finding advantageous mutations like this give us a sort of blueprint if one day we wanted to artifically modify genes for these traits?
[+] Merrill|6 years ago|reply
Adding genes for more opsins is interesting. However, the regulatory mechanisms for developing the retina and differentiating cone types appear to be quite complex.
[+] eeZah7Ux|6 years ago|reply
12% of women is not exactly "rare"! The fact that it did not come out before is telling.

It's interesting to notice how designing screens to use the RGB colors is very limiting for those people.

Imagine living in a world where 94% of people have the same form of color blindness and you don't.

People would randomly mix e.g. blue and green in every place and ignore your comments with a smirk.

[+] OscarCunningham|6 years ago|reply
Most of that 6% don't have the useful form of tetrachromacy. Their response curve of their extra cone is almost identical to one of their existing ones. This is like deuteranomaly (the most common form of colourblindness), in which people can't distinguish red and green because their L and M cones are too similar.
[+] masklinn|6 years ago|reply
12% of women are tetrachromats in the sense that they have 4 pigments, but only a small minority of those are functional tetrachromat, where the 4th pigment is sufficiently shifted from L or M that it can actually pick up relevant information.

As the article notes, Jordan & al spent 20 years researching tetrachromacy before they found a functionally tetrachromat individual.

[+] zozbot234|6 years ago|reply
12% per cent of women is roughly 6% overall, that's quite rare. 94% of the population can't perceive this.
[+] k_sze|6 years ago|reply
Is it possible that tetrachromat people may have a lot of trouble shopping for painting supplies? Since the dye or pigment used on the packaging may not be the same as the dye or pigment in the actual pastel/watercolour/whatever.

Wouldn't it be really confusing?

Are there lines of painting and art supplies specifically for tetrachromats?

[+] gameguy43|6 years ago|reply
Super interesting. My notes as a colorblind man (might be misunderstanding some stuff though):

(Being a little sloppy with sex stuff here. Not all women have two x’s, women can be colorblind too, etc.)

• Two of our usually-three cones are specified on the X chromosome

• When one of a woman’s X’s specifies an anomalous cone she ends up with a 4th, anomalous type of cone.

• This happens ~14% of the time for women.

• That’s about the same percent as color blindness in men.

• That’s not a coincidence. Because color blindness comes from one of these women’s sons getting that anomalous 4th come instead of a typical 3rd cone. This anomalous cone tends to overlap more with one of the other cones in its range of perceived frequencies, which is what causes color blindness.

• But only a small percentage (not sure what percent yet?) of these women with 4 different cones actually seem to be able to perceive more colors

• that’s because the 4th, anomalous cone might basically fully overlap with one of the typical ones in its perceived frequency range, so it doesn’t really give the brain any additional info

• one question I have: so it seems like not all these anomalous cones are the same. Is there a fixed number of types? Or is it more of a spectrum? Further, are /all/ cones on a variable spectrum? Or is almost everyone’s blue cone exactly the same?

• this was interesting: colorblind men actually have a set of colors they can distinguish that people with normal color vision can’t (the article explains why)

• in this study they found colorblind men (but by looking at unusual things they /could/ see, not things they couldn’t? Not sure) and then tested their mothers to see if they could see extra colors.

• Most of them couldn’t. One of them could. The study was only like 9 people? Safe to say /all/ of these women had 4 types of cones, even though only one of them had a sufficiently non-overlapping fourth one to get some benefit?

• As a colorblind man, I’ve never noticed an ability to distinguish colors others can’t. Only the opposite.

• it’s intellectually neat to know that’s possible, even if it doesn’t tend to “come up” in everyday life.

• It souuuunnndssss like the amount of extra color vision that these tetrachromats get is only the same as the extra color vision /I/ get—that same “theoretically there, but doesn’t seem to come up in everyday life” thing. That’s a little disappointing—I though tetrachromacy was more kooky.

[+] 3pt14159|6 years ago|reply
> Or is almost everyone’s blue cone exactly the same?

I get a stronger blue channel from one eye than the other. So I'm quite sure that there is variability, it's a matter of degree. Also, research into language and culture shows that the brain is heavily influenced by colour as well. Some cultures have difficulty seeing differing shades of blue or green that westerners think are trivial.

[+] azth|6 years ago|reply

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[+] pilooch|6 years ago|reply
What would be a good source of tetrachromat images ? Would love to train a model and "see" what these women see !
[+] zeristor|6 years ago|reply
At what point would it be worth accommodating to these tetrachromats?

Sensors, displays, software.

Unicode encompasses vast numbers of characters, wouldn’t an update to colour science and displays be in order?

[+] exabrial|6 years ago|reply
One on my buddies wives can see ultraviolet. It's sort of incredible, she describes it as a very dark blue to white with brighter sources
[+] mirimir|6 years ago|reply
I vaguely recall an SF short story about a genetic or nanotech hack for becoming a tetrochromat. Either by Greg Egan or Hannu Rajaniemi.