Will changing the range of EM that my aliens can see affect how they can relate colors to humans?

Question

We have humans, who can see in the spectrum of 380-740 nm.

Let’s take the aliens, who can see in the spectrum of 500-860 nm. This gives them vision into the infrared. They also cannot see purple as humans would see it, due to them not being able below 500nm. Would this mean that they call 500nm purple? Additionally, they can see between 740-860nm. Would this extend the “reds” that they could perceive?

In a nutshell:

Would shifting where “visible light” falls on the EM Spectrum shift the aliens' perception of different colors compared to us?

Answer 1

Even among humans the naming of different colors doesn't have a 1 to 1 correspondence between languages.

Example: the words corresponding to "green" and "blue" in Japanese are 緑 (midori) and　青い (aoi), yet Japanese uses aoi to describe the color of (young) plants or metaphorically to indicate when one is in their young times.

You can find more info online, for example here

In ancient Japan, only four colors existed — or, at least, acknowledged: 白 shiro (white), 黒 kuro (black), 赤 aka (red) and 青 ao (blue). However, rather than actual colors, these words are used to group particular hues and shades. For example, different shades of blue in the past are now purple, gray and green. As such, 青 has been widely used to describe green and blue; they’re essentially considered the same — not visually, but conceptually.

The Japanese language only got its unique word for green, みどり (緑) during the Heian period, which was between 794 and 1185. However, the term was not widely adopted until after World War II, and its late adoption was partly why we still see あおい used to describe things that are green.

The character 青 is mostly associated with words related to vegetation. Hence, words older than 緑 have remained unchanged. For example, words for “green apples” and “green vegetables” are still あおりんご (青林檎) and あおやさい (青野菜).

Not only does vegetation use the word for blue instead of green, but green traffic lights have been called as 青信号 (あおしんごう) in Japanese. This can be translated to blue traffic light in English. This is because when traffic lights were first introduced in the 1930s, newspapers back then used あお or 青 to describe its color since the word for green had yet to be adopted. The word stayed and much like anything else in society, it refuses to change.

If that happens among specimen of the same species with same spectral sensitivity, you can expect it to happen even more when the sensitivity changes.

Answer 2

The names of colours are partially to do with the photosensitive pigments that the people have, and are partially a function of language. A language may have more or fewer names for colours than we do in English. For example, what we call 'blue', 'green' or 'grey', a gaelic speaker may call 'glas' or 'gorm', depending upon intensity.

For example, people who are red-green colour-blind can't distinguish between red and green, and it affects their entire perception of colour. Consider https://www.colourblindawareness.org/colour-blindness/.

So, you can expect these aliens to have a significantly different perception of colour to humans, as well as a different set of 'words' for colour. We can't even 'see' some of their colours, and they can't 'see' some of ours. It won't be that we can't see some things of certain colours, it'll just be that we or they may not be able to tell the difference between some colours that the other species can distinguish easily.

Answer 3

No... except

First of all, your casual human might point to the leaf of a plant and say, "that's green." Your alien will likely say something along the lines of "Q'riik, naquooba ERK!" Now, we're tempted to assume that something in there, probably the "ERK!" part, means "green." Except when your human mumbles "that dumb alien is a greenhorn" at the same time the alien says, "knwumbbu choomahn D'nkrump" and where are we then?

So, first things first, humans and your aliens can both see 550nm, so they can both see something we call "green," and it's possible (theoretically, depends on declination) that they can convince each other they're seeing the same color. They are, so it can't be too terribly hard — and the same is true for the entire shared spectrum of 500nm–740nm.

Where there's a problem is when we point to our own sky and say "blue" and the alien looks up and sees, well... other than glare from the sun, a black sky full of stars. Or when the alien looks at infrared and we see nothing at all.

How humans and your aliens would react to the realization that one can see something the other cannot and vice-versa is storybuilding.

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Edit: After reading the comments to my answer and the other answers, I need to add to my answer. Regardless the science-based tag, the only viable answer to the question is, "there's a difference if you want one."

Problem: We've never met an alien.¹ All we can work with is the terrestrial life on our own planet. Humans generally see color the same way² (read the footnote before disagreeing) and only particularly disagree about interpretation when the differences are cultural or in relation to fine shades. But would an alien have any problems?

Before answering that question, let's consider some information I gave in an answer to another question.

But, what color does the animal see? Vision, like all of our senses, is processed in the brain. Without being able to get into the head of an animal, it is only possible to know what colors can be detected and not how they "look" to the animal. (source)

This means that we're making assumptions about the aliens when trying to answer the question. Simplistically, we're assuming that their eyesight and color processing capacities are identical to humans other than the shift in the perceptible spectral range. That could be true... but it also might not be true (and this is the gist of @AlexP's comments, below). We can see an example of this on a terrestrial level where humans have only three color receptors in our eyes, some animals have six, and one butterfly has a whopping 15 color receptors (Source). In other words, we could test such animals (testing the butterfly might be problematic...) to see if they "perceive" color the same way humans do.

What we'll learn, of course, is that they won't because they can see more colors than humans can (especially that butterfly). They'll react to colors we can't see (or, more accurately, can't distinguish). At best we'd learn that they can see a wavelength, but we can't know what that wavelength "means" to them. Yes, we could train them (and probably have) to react a specific way to a wavelength (and that's one way to answer the OP's question) but that's not quite my point.

What is my point? We've all done the best we can to provide science-based answers to a question that lacks the details necessary to be a science-based question. And part of it was falling into the temptation of addressing the "Would this mean that they call 500nm purple?" question, which should have got the question closed for Needing More Focus. But it's also an irrelevant question — the aliens will have their way of identifying colors near the 500nm wavelength just as we do, and given enough time to communicate, the two groups would figure out a way of cross-identifying the name(s) and reaction(s) (both scientific and cultural) assigned to the region around that wavelength. What we all should have been focused on was the last question, which can't be answered until the OP explains at least the basic construct of the alien's eyes and neural processing.

Thus, the answer to the OP's question is, "there's a difference if you want one."

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_{¹ <Citation Required>}

_{² In reality, each and every one of us perceives color differently. The case of color blindness is simply the most obvious and most egregious case. Those of us who have worked with graphic design know that color selection is problematic if you're looking for a specific emotional response because (a) different cultures assign different meanings to color and (b) we all see color differently. However, when it comes to "the perception of color," we all recognize common averages without trouble. Why? Because we all know what a plant leaf is, and the colors of tulips, and the colors of the sky. Therefore, arguments that aliens "could" perceive color differently are frankly specious because humanity has already proven that common interpretations between intelligent (meaning: we can communicate specifically with one another) beings can be created. This is why when you say "green" all English speakers know what you're talking about well enough that the small distinctions (chartreuse? celadon? sage?) rarely matter.}

Answer 4

Have a look at Kodak Aerochrome film. This was an infra-red sensitive film stock that more or less matches the wavelengths your aliens are sensitive to.

I make a distinction here between the colours they are sensitive to, and the colours they 'see'. Our vision process has a old blue-sensitive S-cone system, and a younger green-sensitive system which later split into the M-cone (green) and L-cone (red) detectors we have today. There is a lot of overlap between the red and green sensitivity peaks, but we put a lot of emphasis on these small differences.

The Aerochrome colour palette does not seem to be complete. We see very few colours that print as green, meaning they peak in the red wavelengths, and have less on the wavelengths either side. This is true for natural scenes, which have little or no adaption to human vision. We can make red light sources and pigments with a sharp peak at 630nm, but these seem to be rare in nature.

If your aliens came from a planet that orbited a cooler star which gave off very little beneath 500nm, they might have vision that peaks in three equally-spaced bands at 500nm, 650nm and 800nm. They might see colours much as we do (except for deep violets) but with an extended sensitivity to the near infra-red.

Nature has lots of designs for eyes, and it does not always follow common sense. Mantis Shrimps with their 16 bands of vision are completely eclipsed by water-fleas (daphnia) which may have as many as 48 so they can find exactly the yellow of dirty water that they like best.

Answer 5

Humans and aliens will never quite agree on color. Sometimes they will agree that two things have the same color, sometimes they will wildly disagree.

Monochromatic light (such as from a laser) will sort-of work: Given two items, they'll either they agree it's the same color, or one will say it's black (because the color is outside their perception spectrum) and the other will say it is colored.

Disagreement will get rampant with multichromatic light, as is the norm for everyday objects. If something emits red and green, we will see it as yellow, but the alien may not see the green so they'd say it's the same color as a purely-red object, confounding the human to no end. In other words, humans and aliens will likely never quite agree on the colors of things.

Mixed-color disagreement can also happen if the vision range is the same but the photoreceptors have their peak sensitivity at different wavelengths.

Human color vision is a bit weird because red and green receptors have a big overlap, each shade of green also triggers red and vice versa (this is why red and green aren't as easy to distinguish as blue, which always stands out clearly unless the light is too dim for color vision in the first place). I dimly recall having read that human evolution started with a blue and a red receptor, then a mutation doubled the genes for the red receptor, allowing for two receptor types that could and did diverge over time (a lot of time).

So: Color vision is also strongly influenced by where the various cone cells are most sensitive. We never see the "true" color of anything, because for that, we'd need to perceive the full spectrum, but our eyes are sampling just three spectral bands out of a continuum.

Having three kinds of cones is also the reason why red, green, and blue are enough to make a picture. As soon as human technology is supposed to provide images for aliens, we'll need displays that emit light at additional frequencies, and new image formats that have more color channels than the usual three.

Answer 6

Color perception is much more complex than the light wavelength.

It depends on the combination of signals that comes from the sensors in the eyes... Even in the same range of wavelength, if you had 6 different sensors instead of three, the colors you could see would be completely different.

With three sensors, supposing that you can distinguish every possibile shades, the color space you have is formed by $\infty^3$ colors. With 6 sensors, you would have $\infty^6$... A much, much richer palette.

For example, suppose (here I oversimplify) that your alien, Alf, has just two color sensors, Red and Green. So all the colors they can see are plottable in a 2-dimension surface (this is with an arbitrary blue vale for humans):

and suppose that they call the center color "grub". Now, all the following colors:

built by changing the blue component of "grub" are, for Alf, exactly the same.

This happens to us human when comparing our color vision with, say, hummingbirds which have a least 4 cones --- there are full ranges of colors they see that collapse into the same color for us.

If you add a different spectral range, the possibilities really explode. So yes, the color perception will be wildly different. Heck, I can't agree with my wife if a tie I have is blue or green...

See for example https://www.nationalgeographic.com/animals/article/hummingbirds-see-colors-outside-rainbow or https://www.nwf.org/Magazines/National-Wildlife/2012/AugSept/Animals/Bird-Vision.

PS there was a short story from about 1980 about that --- but I can't remember any detail now.

Answer 7

If you show something purple to an alien and say it's "purple", he would see it black (no color) and associate "purple" with that blackness. If you show him something in the 500nm range (blue for us) he would actually see some color rather than black, and wouldn't find it reasonable to call it "purple".

Conversely, suppose he shows you something you recognize as red and say it's "murble". Then he shows you something with a color in the infrared range and say it's "curgle". You would probably infer that "curgle" means black, but one thing is certain: you wouldn't think "curgle" is just another kind of red/"murble".

Perhaps what you mean to wonder is if the alien sees basically the same colors we do, but distributed over a different spectral range (I'll call this option A). One alternative is they see the same colors where the frequencies match, but something wholly different in the infrared (I'll call this option B). Experimentally, it wouldn't be possible to evaluate this question because the results above would be the same regardless. I think a more philosophical approach is required.

Do you believe that you and me see the same red? The arguments in favor hold that the qualia of redness is caused by redness in the "red being" itself. Unless something interferes with this causation (like lacking the proper photoreceptors, as in a color-blind person), the red should be the same. For it to be different, there must be some identifiable causation additional to the redness in the being itself. It will all depend on your aliens' eye structure and how it deals with light in the range we also see. As far as I know, nothing prevents them from having monochromatic vision, for instance. Maybe they're trichromatic like us. Or bichromatic like most other primates. But under this stance option A wouldn't be possible, it's either option B or something else. Feel free to explore the possibilities.