> The first known human tetrachromat, an English social worker identified in 1993, sees 10 distinct colors looking at a rainbow, whereas the rest of us see only five.
What does this even mean? It's setting off my BS detector.
I can see as many colors in the rainbow as I want, since colors are culturally determined. Cyan is prominently there in the rainbow, even though most people don't include it in the traditional "Roy G Biv" -- red, orange, yellow, green, blue, indigo, violet. Speaking of which, where did 5 even come from in that quote? I mean, the fact that we can argue over how many colors the rainbow has just shows how unscientific such a statement is.
If there's anything potentially scientific here, you could say that humans see three primary colors associated with the three cones -- red, green, blue -- and therefore three intermediate colors -- yellow, cyan, magenta. A fourth cone between red and green means that it might be possible to see 8 primary and intermediate colors instead of 6. But it also might not do much of anything at all, if it's then mapped to our existing opponent process [1] that is fundamentally based on red vs. green and blue vs. yellow. In other words, it would just be a redundant or ignored sensory input to our conceptual color processing.
> If there's anything potentially scientific here, you could say that humans see three primary colors associated with the three cones -- red, green, blue -- and therefore three intermediate colors -- yellow, cyan, magenta.
By this measure, a rainbow would be 3 primary colors and 2 intermediate colors: red-green=yellow, green-blue=cyan. That's five. Magenta could be described as "not green" and thus does not appear in a rainbow.
moralestapia 65 days ago [-]
>I can see as many colors in the rainbow as I want, since colors are culturally determined.
Yeah man, tell that to a deuteranopic person.
"You're lacking cuhlshure", mega-lmao, the things one reads here.
tom_ 66 days ago [-]
You're quite right. How could this possibly be worth investigating? There is nothing useful that we could discover here.
crazygringo 66 days ago [-]
What? Nowhere did I say it wasn't worth investigating. How did you come up with that?
I'm complaining about a seemingly non-scientific statement that sounds absurd at first glance.
If you want to do rigorous testing of different combinations of wavelengths to see if anything can be distinguished and how that fits into our current frameworks of color interpretation, then great! But saying someone can see twice as many colors of the rainbow sounds like nonsense unless you have a rigorous scientific framework for that, and the article sure doesn't provide one.
david-gpu 66 days ago [-]
> But it also might not do much of anything at all, if it's then mapped to our existing opponent process [1] that is fundamentally based on red vs. green and blue vs. yellow. In other words, it would just be a redundant or ignored sensory input to our conceptual color processing.
Many flowers have patterns only visible in ultraviolet. Many pollinators can see ultraviolet and these patterns on the flower direct them to the pollination areas.
Kind of the opposite of colorblindness, where people (mostly male) see fewer colors in the rainbow and are often unaware of it.
sublinear 66 days ago [-]
I can't find any consistent estimates on prevalence or whether this is strictly X chromosome related (why it's assumed that only females can have this).
somat 66 days ago [-]
I assume it is the same reason that women have stripey skin.
at ~ 100 cells, if the embryo has 2 X chromosomes the cell shuts one of them off, which one is random, those cells continue to multiply bringing their specific X chromosome with them.
So women have genetically distinct blotches all over their body based on which cell disabled which X chromosome.
I will have to leave this one for the scientists but I assume tetracromats got some of their cone cells from X and the rest from X`
The implication being, I don't think tetracromats have some sort of super vision, they just have what would be considered color blind if all their color cells were defective. But because only some of them are they get an interesting subtle addition to their color sense.
IAmBroom 64 days ago [-]
That's exactly it.
There exists two genes that code for the red-cone-detector. They sense /slightly/ different shades of red (more precisely, their gaussian-like filters are centered differently).
And these are carried on the X chromosome. Either one or the other is in a male fertilized cell, but both are possible in a female fertilized cell.
The measurable end result is that some few women have both kinds of cones (therefore four color detectors, where two majorly overlap in the red region). These tetrachromats can detect finer distinctions between colors on the red end of the spectrum; their color detection in green/blue is identical to ordinary color vision.
oofbey 66 days ago [-]
At some point the world's gonna figure this out and start making tetrachrome cameras and screens and it's gonna be the next big TV upgrade after 8k.
mholm 66 days ago [-]
15 years ago, Sharp released “Quattron” TVs with yellow subpixels. It was effectively indistinguishable, even in person.
_tom_ 66 days ago [-]
But was it distinguishable by tetrachromat?
rini17 65 days ago [-]
IIRC the yellow subpixels did not add any new colors, only increased the yellow beightness.
carlosjobim 66 days ago [-]
Current technology is far more advanced than that, with hyperspectral cameras which can make images to identify different geological materials etc.
They've prototyped displays that can test for it as well.
eesmith 66 days ago [-]
I remember watching a video some years back where the researcher thought he had developed such a test.
As I recall (it's been many years; likely over a decade since I saw it) he tested it with a woman who was believed to have tetrachromatic vision. She could reliably tell the difference.
As a control, he tested it with a man who was trained as a graphic artist.
He too could reliably tell the difference.
That result strongly implied the test did not work as expected.
Do you know anything about this previous work? I tried reading the paper but was immediately out of my depth.
glkindlmann 66 days ago [-]
This is so cool. For your figures, how did you decide the RGB colors of the 4D colorspace? Or did you convince ACM to print your paper with special inks? :)
eesmith 66 days ago [-]
Definitely not the latter as the paper mentions "The digits are faintly visible in this photograph, because the camera’s color response differs from a human’s."
glkindlmann 66 days ago [-]
afaik not based on standard RGB displays. All widespread technology for digital color reproduction is based on RGB primaries, i.e. a 3D space of color, or rather a 3D submanifold of spectra inside the effectively infinite-dimensional space of spectra. It is feasible to test for color deficient vision (deficiency or absence of one or more cones, reducing color perception to a 2D or 1D space) because it is easy to sample 3D RGB space and behaviorally detect if colors that are different in 3D are conflated because in some viewer they project to the same location in their 2D or 1D "color" sub-submanifold.
But we'd need a convenient way to sample a 4D space of colors (perhaps with 4 monochromatic sources?), and thereby generate different spectra that normal trichromats see as the same color (called "metamers"), but that tetrachromats could recognize as distinct. And, how the 4D space is sampled would have to be pretty carefully optimized to generate distinct spectra that have the same response with the M (medium or "green") and L (long or "red") cones (which are actually quite similar already!) while also generating different responses for the putative tetrachromat's additional code between M and L. And that isn't possible with any conventional display device.
carlosjobim 66 days ago [-]
On the contrary, RGB displays should be excellent tools to determine if somebody has vision which differ from normal. Ask the person to adjust the color settings so that real world footage on the display looks like how they experience the real world. Then you will see if there's any divergence in color perception, since display images are direct light while real world vision is reflected light.
glkindlmann 66 days ago [-]
Whether via direct or reflected light, spectra in trichromat's eyes are still projected down to a 3D space (the responses of the S, M, L cones). What you describe would still require a standardized and reliable way to probe an extra degree of freedom in spectra that conventional RGB displays can't access. The paper shared by varunneal explains it better than I can.
carlosjobim 66 days ago [-]
If we assume that digital video/film recording will compress the spectrum to images which are composed of three colors, somewhere in the processes between the light hitting the camera and the light being emitted from a display to the viewer, that means any tetrachromatic person will notice a difference between the images and the real world.
glkindlmann 66 days ago [-]
Sure, but noticing a difference between the images and the real world also happens with us trichromats too, e.g. colors online don't match those in the real world if the illuminant isn't correctly controlled. The intrinsic difficulty of color reproduction is not the same as detecting tetrachromacy. The nuance here is in generating stimuli that reliably and specifically detect the difference between projecting from an infinite-D space of spectra down to 3D (via metamers like the "keef" and "litz" described in the paper linked above), versus projecting down to 4D.
carlosjobim 66 days ago [-]
The difference between display and real world will be at most slight to a trichromat, while it would be extraordinarily obvious to a tetrachromat.
It's not very uncommon for people to be colour blind, dichromats. If media on screens would be dichromatic while the world around me is trichromatic, I would certainly notice at once.
glkindlmann 66 days ago [-]
I suggest trying to quantify "extraordinarily", using the actual spectral response curve for the tetrachromat's fourth cone, called "Q" in the paper shared by varunneal. Most people casually equate the short (S), medium (M), and long (L) cones with blue, green, and red, with the idea that these are all as different as can be, but the M and L cones are very similar to each other, compared to S. The L, M, S curves are independent but far from orthogonal in the way you may be thinking as you say "extraordinarily". The Q curve is just another wide bump, with a peak in between that of M and L, so again, very far from being orthogonal. Whatever 4th dimension of color perception is accessed by the Q curve, it is a relatively cramped dimension, so reliably detecting perception along it requires some carefully designed stimuli.
glkindlmann 66 days ago [-]
(in the awesome paper shared by varunneal, the metamers are named "keef" and
"litz")
colechristensen 66 days ago [-]
Simple? No. My understanding is that the perceptual difference is much less significant than for colorblindness and while visual tests exist they are less reliable and less obvious than the visual tests for colorblindness.
postalrat 66 days ago [-]
Maybe if colors on a monitor or photographs don't match colors in real life? Like how a how black and white displays don't match. This would probably be pretty subtle differences.
See that tiny arrow on the left bottom? You can collapse the container by clicking that.
Really shitty UX.
supermatt 66 days ago [-]
Thanks - I didn’t even notice that. But now you point it out I’ve tried to use it 4 times and each time I go through to the ad :/ really scummy website. Flagged.
IAmBroom 64 days ago [-]
A lot of false assumptions are going on.
Tetrachromats are not seeing four well-separated colors. They are seeing the exact same blue-area and green-area colorrs, with two different cones responding slightly differently to red-area light.
So, instead of a color looking RGB(200,100,100) to them, it might look (200.26,100,100).
The very slight difference is why it's so hard to detect in people, and frankly, doesn't affect much (which is why there's apparently very little evolutionary "pressure" on the color genes).
spondylosaurus 66 days ago [-]
When I learned about tetrachromacy as a kid I remember being devastated for like a week afterwards that I wasn't one too. It felt like discovering that superpowers are real but that you'll never have any :P
chrisco255 66 days ago [-]
No worries, just strap on some infrared night vision goggles. You may not be superman, but you can always be iron man.
What does this even mean? It's setting off my BS detector.
I can see as many colors in the rainbow as I want, since colors are culturally determined. Cyan is prominently there in the rainbow, even though most people don't include it in the traditional "Roy G Biv" -- red, orange, yellow, green, blue, indigo, violet. Speaking of which, where did 5 even come from in that quote? I mean, the fact that we can argue over how many colors the rainbow has just shows how unscientific such a statement is.
If there's anything potentially scientific here, you could say that humans see three primary colors associated with the three cones -- red, green, blue -- and therefore three intermediate colors -- yellow, cyan, magenta. A fourth cone between red and green means that it might be possible to see 8 primary and intermediate colors instead of 6. But it also might not do much of anything at all, if it's then mapped to our existing opponent process [1] that is fundamentally based on red vs. green and blue vs. yellow. In other words, it would just be a redundant or ignored sensory input to our conceptual color processing.
[1] https://en.wikipedia.org/wiki/Opponent_process
By this measure, a rainbow would be 3 primary colors and 2 intermediate colors: red-green=yellow, green-blue=cyan. That's five. Magenta could be described as "not green" and thus does not appear in a rainbow.
Yeah man, tell that to a deuteranopic person.
"You're lacking cuhlshure", mega-lmao, the things one reads here.
I'm complaining about a seemingly non-scientific statement that sounds absurd at first glance.
If you want to do rigorous testing of different combinations of wavelengths to see if anything can be distinguished and how that fits into our current frameworks of color interpretation, then great! But saying someone can see twice as many colors of the rainbow sounds like nonsense unless you have a rigorous scientific framework for that, and the article sure doesn't provide one.
A click away: https://imjal.github.io/theory-of-tetrachromacy/
https://concettaantico.com/
https://www.theguardian.com/society/2022/jan/30/im-really-ju...
https://munsell.com/color-blog/tetrachromat-artist-concetta-...
Many flowers have patterns only visible in ultraviolet. Many pollinators can see ultraviolet and these patterns on the flower direct them to the pollination areas.
https://en.wikipedia.org/wiki/UV_coloration_in_flowers
http://www.naturfotograf.com/UV_ANGE_SYL.html
The lens in our eye filters out a lot of UV.
After Monet had cataract surgery his color perception changed so his later paintings have a different color balance.
https://jamanetwork.com/journals/jamaophthalmology/fullartic...
at ~ 100 cells, if the embryo has 2 X chromosomes the cell shuts one of them off, which one is random, those cells continue to multiply bringing their specific X chromosome with them.
So women have genetically distinct blotches all over their body based on which cell disabled which X chromosome.
I will have to leave this one for the scientists but I assume tetracromats got some of their cone cells from X and the rest from X`
https://www.youtube.com/watch?v=BD6h-wDj7bw (veritasium: Why Women Are Stripey)
The implication being, I don't think tetracromats have some sort of super vision, they just have what would be considered color blind if all their color cells were defective. But because only some of them are they get an interesting subtle addition to their color sense.
There exists two genes that code for the red-cone-detector. They sense /slightly/ different shades of red (more precisely, their gaussian-like filters are centered differently).
And these are carried on the X chromosome. Either one or the other is in a male fertilized cell, but both are possible in a female fertilized cell.
The measurable end result is that some few women have both kinds of cones (therefore four color detectors, where two majorly overlap in the red region). These tetrachromats can detect finer distinctions between colors on the red end of the spectrum; their color detection in green/blue is identical to ordinary color vision.
They've prototyped displays that can test for it as well.
As I recall (it's been many years; likely over a decade since I saw it) he tested it with a woman who was believed to have tetrachromatic vision. She could reliably tell the difference.
As a control, he tested it with a man who was trained as a graphic artist.
He too could reliably tell the difference.
That result strongly implied the test did not work as expected.
Do you know anything about this previous work? I tried reading the paper but was immediately out of my depth.
But we'd need a convenient way to sample a 4D space of colors (perhaps with 4 monochromatic sources?), and thereby generate different spectra that normal trichromats see as the same color (called "metamers"), but that tetrachromats could recognize as distinct. And, how the 4D space is sampled would have to be pretty carefully optimized to generate distinct spectra that have the same response with the M (medium or "green") and L (long or "red") cones (which are actually quite similar already!) while also generating different responses for the putative tetrachromat's additional code between M and L. And that isn't possible with any conventional display device.
It's not very uncommon for people to be colour blind, dichromats. If media on screens would be dichromatic while the world around me is trichromatic, I would certainly notice at once.
Really shitty UX.
Tetrachromats are not seeing four well-separated colors. They are seeing the exact same blue-area and green-area colorrs, with two different cones responding slightly differently to red-area light.
So, instead of a color looking RGB(200,100,100) to them, it might look (200.26,100,100).
The very slight difference is why it's so hard to detect in people, and frankly, doesn't affect much (which is why there's apparently very little evolutionary "pressure" on the color genes).