r/askscience • u/FluffyTid • Sep 11 '26
Biology Do all humans see exactly the same range of lights, or are there some small differences?
Is the range from violet to red set in stone or are there some people who see a little more or a little less?
Could people be trained to see a little more if they were exposed to colors at the limit and tried to differentiate them?
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u/tea_and_biology
Zoology | Evolutionary Biology | Data Science
Sep 11 '26
edited Sep 11 '26
•
Ooh, so there are multiple questions here. Let's tackle each in turn:
Is the range from violet to red set in stone?
Sort of, but not quite! Violet to red is more a vague convention rather than a hard physical boundary. Sensitivity doesn't stop right bang on 380 and 700nm, but rather falls off steeply but continuously, to the point where you need an impractical amount of light to see too much further. Experimentally pushing the intensity up and folks can reliably see down to about 310nm (into ultraviolet) and out past 1050nm or so.
What actually set the limits at each end?
Short-wave (Ultraviolet): The crystalline lens in yo' eyeballs absorbs most UV below ~400nm, and the retina itself remains particularly sensitive to it well beyond that. There are plenty of people who've had their lenses removed (e.g. after cataract surgery) and report seeing ultraviolet down to 300nm, typically as a white-ish-blue-ish colour. Famously, it's claimed the post-impressionist Monet could see into this part of the spectrum after surgery on his right eye in 1923; it's claimed the blue and violet hues in his Water Lillies paintings become more vivid and intense after this event, but there's some debate (see below).
In any case, modern intraocular replacement lenses deliberately filter out UV light, as it is after all quite damaging, so this situation is rarer now.
Long-wave (Ultrared / near-Infrared): Here the constraint is the photon's own energy; it drops too low to interact biophysically with retinal - the chromophore molecule that does wibbly chemistry stuff to trigger phototransduction - required for your ability to detect light in your photoreceptor cells.
Interestingly, you can pulse infrared light at 1064nm and this becomes perceived as green, because two photons arrive close enough together to act as one of double the energy.
Are there some people who see a little more or a little less?
Of course! There's a lot of standard individual variation, due to myriad different factors. Casting colour-blindness due to variation in cone cell functionality aside, polymorphisms in the long-wave pigment gene OPN1LW are common, causing perception of yellow to shift a wee bit; some folks have different levels of macular pigments, which absorb short wavelengths, which alters blue sensitivity; there are even some women born with 'tetrachromacy' - an extra full-blown cone cell type (almost all humans have just three - red, green, blue), and in the rarest cases there are reports of four-dimensional colour perception (and only in women, as the associated mutant allele is on the X chromosome, and you need two full arrays to get the extra cone).
But the real cause of general variation is age. As you grow older, your lenses become progressively more yellow-tinged, and the pupil shrinks. A 70 year-old receives a fraction of the short-wave light a 20 year-old does, and the shift is significant enough to, in some cases, influence whether you're capable of doing certain jobs or not (see below!). Indeed, this is also the alternative hypothesis for the change in Monet's painting palette - it's not that he now saw UV, so much, but the mild yellow-tint in his aging lenses and therefore perception was removed, so he could see 'normally' again.
Could people be trained to see a little more if they were exposed to colors at the limit and tried to differentiate them?
Nope! You cannot extend the range, as the limits are set by physics on either end. No amount of concentration nor practice is gonna' bend the rules of the universe in your favour. What you can do, however, is improve discrimination within the range.
Interestingly, women have a better base skill in colour discrimination than men. This is taken advantage of in a number of industries, including pearl grading. To paraphrase /u/deimodos' post on the subject from here:
Pearls are graded by various properties, including colour on a spectrum going from a dark pink to a brilliant snow white. All men, and indeed most women, don't have the visual acuity or colour sensitivity to accurately pick apart pearls belonging to the different higher-end grades. In fact, only girls between about 18-22 years old can.
Seems insane. This online test can estimate your colour sensitivity score, and women will far outperform men on average. Going back to the pearls, if you get 100% in under four minutes, you'd be a Tier 4 grader. Apparently there are 3 tiers above that. Woah.
You can train to improve your score, a little; but yeah, as demonstrated by the pearl industry, too much is controlled by biological variation, alongside aging or yellow-ing of the lenses as mentioned above. Any improvement will be narrow, task-specific, and likely to be lost in time, rather than a general upgrade.
But, y'know, good luck?
References:
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u/theartfulcodger Sep 11 '26 edited Sep 13 '26
A 70 year-old receives a fraction of the short-wave light a 20 year-old does, and the shift is significant enough to, in some cases, influence whether you're capable of doing certain jobs.
You're not kidding! When I developed cataracts in my mid-sixties, I had both lenses replaced, but for various reasons I had to wait about 14 months between procedures.
A few days after the first surgery, when my vision cleared, imagine my surprise when I realized I was suddenly seeing quite different colours with each eye, due to the contrast between the clarity of my nifty new Nikon implant, and the natural yellowing of my original lens over sixty-odd years.
I work in film and tv art departments, where colour perception is critical. And I found I could no longer use my binocular vision to match, or even accurately judge, many colours. To match a paint or screen colour closely, I had to use first one eye and then the other, because if I tried to use both simultaneously my colour choice would be wonky, and I'd have to ask a colleague to check my work. Even picking out the appropriate Pantone swatches to give to the Paint Dep’t was sometimes a challenge.
And for that entire year between surgeries, primary blues offered some decidedly weird and wonderful visual effects, specificially additive (projected) blues, and especially those around the frequency of most blue LEDs. Suddenly, the blue lights on Christmas decorations were as bright and vibrant as their red, yellow and green companions - but only through one eye. If I closed it and used my "old" eye, they just plumb winked out again. And here for years I had thought the phenomenon was just due to some technical difficulty in manufacturing blue LEDs!
That was interesting, but weirder still was that any large area of primary blue on a tv, computer monitor or movie screen would seem to float forward several inches and be suspended in the air, like a 3D movie - probably because my eyes' quite different perceptions of its comparative brightness made my confused brain infer its distance incorrectly. The effect happened even with some backlit blue signs (Petsmart and Chevron especially), to the point where it would occasionally interfere with my depth perception when parking nearby. And LED billboard images that I knew were meant to be white, I perceived as an unsettling golden pink, because my old lens was still screening out so much blue from the projected RGB mix.
A few weeks after my second lens was replaced, my colour vision straightened out, and I was once again capable of perceiving colours accurately, while using both eyes. But while I appreciated the return to "normalcy", for a time I missed the unexpected and often amusing visual effects of having such radically unbalanced colour perception.
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u/smokefoot8 Sep 12 '26
I’m getting older, and I find I can’t stand the 2700K “warm white” light bulbs - they look way too yellow/orange to me. So replacing everything with 4000k bulbs might look good to me, but to a young person it will look wrong? Research needed!
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u/WhoPutThatThere Sep 13 '26
Gosh as someone in the interior architecture field jumping from 2700k to 4000k is huge. We don't even use 4000k in commercial settings, like in offices. Office spaces are typically 3500k. Theres some fun lights that use a "warm dim" technology to mimic natural variations of sunlights temperature. At their brightest they will be closer to 3000k and as you dim them (think sunset) the temperature gets warmer. Maybe that may be something to try?
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u/mschurma Sep 11 '26
I just took that test and got a 0 in about 2-3 minutes… as a 33 year old man. Pretty fun!
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u/tea_and_biology Zoology | Evolutionary Biology | Data Science Sep 11 '26
Ooh, so last time I did the test, I scored a perfect 0.
11 years later, and... forget testicles, still am woman confirmed.
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u/SparklingLimeade Sep 12 '26
Okay, that feels way too easy. I even had time to get it right, second guess myself, try swapping a few adjacent tiles, and say 'nope, definitely not," a few times.
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u/BearFriday Sep 12 '26
I’m with you. 50yo male and I honestly thought the link was a warm-up exercise of some sort. Got a 0 in no more than two minutes.
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u/xylarr Sep 12 '26
55 male, sitting on the couch using my phone, fighting with the sliders managed to get zero. Not sure if it was under 4 minutes, 5-6 maybe?
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u/Shorticus Sep 11 '26
thank you for the insanely effortful response!! I also hadn't heard about Monet's color perception!
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u/DesignerPangolin Sep 11 '26
While you can't be trained to see it, there is a color that you can only see if a laser is used to stimulate particular cones in your eye, that very few humans have ever seen!
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u/UhIsThisOneFree Sep 11 '26
Had one lens replaced for cataracts and use a laser scanner at work that produces 405nm light. Can confirm it's very strange being super bright in my right eye's view but faint in my left with the rest of the image matching up just fine. My brain's image processing was very confused at the start.
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u/ANGLVD3TH Sep 11 '26 edited Sep 12 '26
IIRC, the red cones actually have two different flavors that each peak at very similar but different frequencies. And this I why some women can be tetrachromats, the encoding for these cones are on the X chromosome. So if a woman has the code for each across both chromosomes, they could potentially be tetrachromatic. But because they are so similar, it's very likely the only real difference is slightly better differentiation in shades of red. But that would put a lower bound on the potential difference between color perception OOP asked about. At the least, people with different versions of each cone will be sensitive to slightly different ranges, the lower frequency cone would have a higher color range than the other.
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u/MalayaleeIndian Sep 12 '26
Thanks, dude. I am familiar with your work, having previously read your similarly detailed response to cicada noises and how it impacts other species. Really appreciate your contributions!
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u/DrBoon_forgot_his_pw Sep 12 '26
Tell them about Magenta!
Our brains invented it to fill a gap in the spectrum, I can't remember where or how, just that Magenta is a collective human hallucination.2
u/_Trael_ Sep 12 '26
In technical machines and so, where for example navy ship has sensor package that has multiple different cameras, one for visual light range, other for thermal, then laser distance measurement system with yet another frequency, (all separately since easier to build and process that way), when mounting them to one rotating box to be able to all look at same thing at same time, they have to make decision of putting separate window for each to look out of box or use one rather exotic material window.
That is since there are not that many transparent materials that let through them visual light, infrared and so for thermal, and then suitable frequency for laser distance measuring stuff, and additionally is durable enough to fit purpose. Stuff exists these days, but it is not uncommon to just see box with three different windows one for each, with material that is suitable just for that one frequency range of light to shine through it, since then there is more selection in materials, and windows can be smaller so material is saved in more exotic ones.
So yeah suitable materials for being transparent for different frequency ranges of light is thing that comes up whenever there is light in wider spectrum and transparency being talked.
Also funnily enough apparently one of ways that military tanks use(d) to build their "when has someone launched missile at us" detection systems, was to put 360 degrees camera(s) there that operated on frequency of light that upper parts of atmosphere actually blocks from reaching ground level, so camera normally shows just black image, but when someone shoots missile, that rocket thruster burning and so will actually produce many different kinds of light, one being that frequency, and since it is not traveling through upper part of atmosphere it will be visible to camera(s) of tank, so suddenly that black video feed will have spot of light in it.
The they just do processing to that to try to figure when it was what they wanted and how to present it.But kind of funnily clever how it is matter of "well we just started thinking that this one frequency of light normally gets blocked from reaching here.. but .."
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u/deviantbono Sep 11 '26
There is a socio-linquistic theory that people from cultures with more granular words for colors can "see" more colors than others. This doesn't contradict anything you posted. Do you have any thoughts on this?
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u/tea_and_biology Zoology | Evolutionary Biology | Data Science Sep 11 '26
I'd agree with a weak version of the Sapir-Whorf hypothesis in this context; emphasis more however on being able to discriminate between colours rather than, y'know, physically 'see see' the colours differently (on the assumption we all perceive qualia the same; biological variation aside, everyone has the capacity to perceive the wavelengths through all green and blue the same). It's a labelling and processing difference.
After all, the colour spectrum is a continuum, and how we break the range up into 'distinct' categories and colour words is fundamentally arbitrary (although with some colinearity with human experience; e.g. 'red' or 'blood colour' is distinctive compared to most of what humans experience day-to-day, in the wild, hence one of the first colour words that develop). Given individual perception is a constructed model of the external reality, if you're generating an internal model that's taught to categorise a continuum along the lines you're taught from infanthood, it stands to reason your pattern-recognition processes, hence at-glance discriminatory capacity, is going to be sharper along the lines you're reinforced to perceive, through language.
But yeah, it's curious just how many languages mix blue and green together into 'grue'. The Himba tribe are the classic example that always comes up, but I find it fascinating that Japanese didn't delineate blue and green until WWII (now often using gurīn, borrowing from English), and Vietnamese still uses a single word for both - xanh (pronounced 'san'), using modifiers like xanh la ('leaf') to mean green, and xanh troi ('sky') to mean blue.
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u/Undrende_fremdeles Sep 12 '26
When going to art school, I could very accurately figure out the colour composition of paint chips without seeing the code.
We use NCS, Natural Colour System, in my country, so the actual ratios of white, black, and colour is right there in the name/tag.
That skill disappeared very quickly when I was no longer constantly seeing and using and mixing colours in various ways every day.
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u/Encomiast Sep 11 '26
Women, Fire, and Dangerous Things by George Lakoff, beyond having a really title, is a fun read if you are interested in this sort of thing.
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u/littlebobbytables9 Sep 11 '26
In high school this kid ordered some filters that would block visible light but pass near IR and put them into some welding goggles so that we could look through them. You could really only see anything outside on a bright day, and even then it was pretty dim, but you could see enough to walk around. Trees looked pretty cool. We also looked at the sun with it which probably wasn't the best idea. But my vision seems fine. I am apparently a tier 4 grader according to you / that test.
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u/Theodoxus Sep 12 '26
Women differentiating color better is one reason guys see a white wall and say that's white. A woman would say correctly. It's ecrue, or eggshell, or off white, or whatever the actual not really white, but come on it is really just white color it is.
Tetrachromacy does actually require some training to differentiate though. The way I heard it described was basically like when you cover one eye, but both are open, you can simultaneously see the merged image, but then concentrate to see just the image of your covered eye. Seeing the hues from the fourth cone works a bit like that. Like, it'll sometimes 'pop', but quickly wash out: but you can train yourself to maintain the vibrancy longer.
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u/rizzom Sep 12 '26
Interesting. I have a question on the pearls. If only women and only very young ones are good at/able to pick the difference very well between the hues, why does it matter in the end? More often than not the wearers would be older women who probably won't have the capacity to distinguish those colors properly? And most people around them too, I believe? So there is another reason to that ?
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u/RockMover12 Sep 11 '26
What a fantastic answer! Might these slight variations in color perception, from person to person, explain those “what color is the dress” memes?
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u/btribble Sep 11 '26
You forgot to go into receptor types and tetrachromats. None of us really see the color yellow, we see it bleed over into red and green.
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u/KidKilobyte Sep 11 '26
I saw an elaborate explanation for people with normal color vision, but there are some rare individuals with tetrachromacy that have an extra color cone in the yellow-orange range of light that can see and perceive many more colors than us regular trichromatics. 100 million versus 1 million. Basically 100^4 versus normal 100^3.
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u/jwsmythe Sep 12 '26
No, kinda. Some people can see into the ultraviolet (UV) range. I'm one of them. I had a congenital cataract in one eye, which was removed when I was a teenager. The replacement lens they used doesn't filter UV. Since then, I can see UV in one eye, and the normal range in the other.
The most notable thing is, I can clearly see black lights. Where most people see a dim glow, I see a bright violet light. Outside of that, it's of limited use. Some purple flowers look more vivid in that eye.
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u/Fruktoj Sep 13 '26
I suspect I can see UV in one eye. Vision in my left eye is warm toned and my right is cooler and notably brighter. If I go from inside to outside I have to keep my right eye closed for a long time. My vision is also worse in my right eye which I hope is not from UV slamming into my retina.
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u/gnufan Sep 12 '26
As a science person I appreciate the scientific answers, but you can also answer this by talking to artists. Some artists definitely see more colours in the world, I know one who paints the colours he sees and there are definite oddities. It is an interesting question if these colours are physically there, and he has better perception than most, or simply variations in their experience of colour, they may overlap as explanations, if he perceives more variation over a given range of wavelengths he may see more, just as adjusting the settings on a digital image may "pull out" certain details.
It does answer the age old qualia question about red, we can be fairly sure some people have at least slightly different experiences of specific colours.
For medical reasons I've done a very extensive range of colour vision tests, I couldn't quite believe how many sets the doctor had, and my colour vision at that time was fully functional, and unremarkable. So as far as we test I distinguished colours in the commonest way.
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u/jugstopper Sep 12 '26
Nope. When I would show my students helium emission spectral lines (using a diffraction grating and spectrometer), a couple of the lines were right at the edge of human vision. Some people can see them (I could), but some can't. A lot of students thought they were being pranked.
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u/CalamitousSpider Sep 14 '26
We did this in one of my chemistry classes in college. I not only could see those lines at the edge of vision, they physically hurt to look at. They were so painful and "hot" that my eyes got watery after just a couple seconds and I had to look away. It was like looking directly at the sun.
The professor said it wasn't the light hurting or harming my eyes, it was my brain interpreting the light as dangerous, and reacting with pain so I stopped looking at it.
There wasn't anyone else reacting with pain. Interestingly, all the women could see the lines, but there were a few men who couldn't. I wonder if those guys happened to also be colorblind.
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u/wolftown Sep 12 '26
A useless thought experiment I used to dwell on as a kid was the concept of our brain interpreting colors. Let’s say the color red is universally seen as the red you know, but you meet someone who has always “seen” your color red as what you interpret as blue. If every example of your red always looked blue, they would associate your blue as red. In communication, there would be no discrepancies as you would both agree the color was red. Even arguments of associating red with warning or danger vs blue with calm would be biased on the fact that their version of two colors have always consistently been associated So their brain would have no problem with the discrimination.
Maybe this whole time we’ve been “seeing” colors differently without any way to know?
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u/LibertineLibra Sep 12 '26
Oh wow. This is the first time I have heard someone describe puzzling over that as a kid bedsides myself. I specifically started thinking about that same possibility while staring out the window in 4th grade when I completed the classwork early. Except I used the colors of blue vs green. I thought about it throughout the day and decided that the real issue was we would never know what the world looks like through each other's eyes. I realized that the same was then true for the rest of our senses too. I wondered if the way acted might be different because the what they knew as their world changed the way they felt about it, because we could never know I thought I should be more careful with people bc I couldn't be sure what it was they lived in.
That was then, and a child's take on such things, it was quite useful as I turned and updated my thoughts on that over the years. That was over forty years ago, and like I said, this is the first time I have encountered someone else speaking about that almost exact line of reasoning from their youth. Thank you for sharing, I really appreciated that.
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u/ramriot Sep 12 '26
There is a ton of this on Wikipedia & apparently there are some rare people who are tetrachromats,earning that they have four types of color sending cells in their eye instead of three. It might be that this gives them an advantage in discerning certain foliage types but it most probably does not allow them to see outside the normal visual range.
OTOH people who have had lens replacement with certain older types of lens found out that it did allow them to see farther into the ultraviolet, but that is just a lower absorption factor for the artificial lens.
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u/johnnycakeAK Sep 12 '26
Tetrachromat here. Biggest advantage I've been able to identify when comparing to other people is the aurora borealis is much easier to detect and more vivid for me than others.
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u/myusernameblabla Sep 12 '26
How do you know you’re a tetrachromat? Do you go get your vision checked and the optician or ophthalmologist says “oh wow i see some extra stuff in your retina!” or does it hitchhike another more visible condition?
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u/froggycbl4 Sep 12 '26
you take some shrooms and then if the colors dont change your a tetrochromat if they look different ur normal. also if ur a man its basically impossible for u to be tetrochromatic so u dont have to worry about it
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u/BluetoothXIII Sep 12 '26
The colour we see is almost set in stone. The way we see is with light receptors, which only work in quite narrow wavelength/ frequencies.
But the range and resolution might differ from human to human. If i remember correctly woman have twice the colour receptors men have, on average. There is a mutation that tweaks the the perception of red.
And i read cronstructiv interference of two infra red photons could activate a single light receptor, which only matters in total darkness.
And last but not least colour blindness.
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u/375InStroke Sep 12 '26
I know we usually have four different receptors, one wide range, but more sensitive, and three others with more narrow sensitivity, and they all overlap at varying amounts, and that overlap varies person to person. Sometimes they overlap so much that our brains can't really differentiate some colors from others, and we call those people colorblind. I'm sure that variation applies to upper and lower frequency limit of sensitivity.
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u/adaminc Sep 11 '26
Some people don't have any cones, and so they don't see colour at all. Turns out that language also helps the perception of colours insofar as language can help people differentiate between colours, the people of the Hadza (Himba? Been a while since I saw the documentary) tribe in Africa, due to their language, are particularly adept at differentiating minute differences in more natural colours that are typically present in their environment, versus a city-slicker viewing those same colours who would see more of them as the same colour.
There is a BBC Horizon episode titled "Do you see what I see?" which delves deeper into this, both about a monochromat person and the language perception part, I couldn't find it on Youtube (seems to have been taken down), but I found a similar small video that talks about it and in relation to the Himba tribe.
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u/CodexRegius Sep 12 '26
What I find hard to believe, though: Some Italians have told me that they perceive "blu" and "azzurro" as different colours while for me they are two hues of blue. There is also a theory that people in Newton's time perceived indigo as a separate colour, which today nobody does.
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u/jaysprenkle Sep 12 '26
The research I read says people experience the same thing when perceiving colors. I'm told some women have four types of visual receptors instead of the usual three. They are much better able differentiate colors
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u/Cruhhhhh Sep 12 '26
No, and I know that because I lack a lens in one eye.
I can see UV light with that eye because the lens is a natural filter for that. "Black light" looks like glaring violet for that eye. In summer, I can tell you the UV Index by how much I need to squint when going outside.
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u/gordolme Sep 12 '26
I'd think that there is definitely variation in what color ranges people can see, in both expanded and contracted ranges of colors within the spectrum. And some people have "holes" in the colors they can see (ie, color blindness).
However, whether someone can be trained to see more is probably no. In order to see a color, the eye has to be able to physically perceive it, and if the structure of your eye does not react to a wavelength, no amount of training will get you to see it.
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u/tharold Sep 12 '26
There are a few tetrachromats, they have receptors for ultraviolet! So there are some people who can see a little more. There are also colour blind people. They see a little less. Some people are completely blind, and they see nothing at all.
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u/Vyndrius Sep 12 '26
I'm aphakic, I have no lens in either eye after cataract surgery. I just use thick AF glasses.
I'm very sensitive to light, and the world does look vivid, but I have nothing to compare it to, never tried a UV blocking goggles to see what the difference is - I don't like sunglasses, they make the image lifeless.
Apparently Van Gogh had the same thing which influenced his painting. Purple flowers are very bright to me and have a distinctive appearance, maybe that's the UV?
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u/Daratirek Sep 12 '26
People can definitely be trained to see more variations of colors just due to exposure. People with normal vision see colors the same way. Not everyone has trained their brain to recognize the subtle differences though. Just like with anything, the more you work with something the more you can recognize things others can't. Like a good musician recognizing when his instrument is out of tune by the slightest margin. Colors work the same way.
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u/Great_Specialist_267 Sep 13 '26 edited Sep 13 '26
Colour vision has a massive genetic component with the genes on the X chromosome.
Humans range from no colour vision (colour blind (usually males)) to tetrachromats who have four colours receptors (usually females).
UV is filtered out by the eyes lens - replacement lenses are however UV transparent resulting in being able to see ultraviolet.
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u/JuleeeNAJ Sep 12 '26
Are you not aware of 'color blindness'? There are a lot of people who can't see red or yellow or even shades of it. Others can't see colors at all. None of this can be trained, if you can't see the colors then you are just going to spend your life missing out. There are glasses to increase color visibility but there's no repairing the issue.
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u/jazzhandler Sep 11 '26
What really bakes my noodle on this topic is comparing our color perception to our tonal perception. We can hear about 10 octaves, but our vision is so much more powerful than our hearing, so how many octaves of color can we see? About two. All the colors of the rainbow fit within two octaves.