Why Can’t We Say What Color Our Skin Is?

I had to explain to my two dark-skinned black girls (foster and adopted) what it meant that the Snork Maiden’s skin was getting pale when she was upset, because this was not a phenomenon they’d noticed before, though the elder has a lot to say about when my pale white skin is unusually red or splotchy. I know skin shade matters a lot to them, but I’m not sure how it will be meaningful compared to how it would have been within their families.

Corey’s post was indeed interesting, as was Ta-Nahesi-Coates’. What a whirlwind all this Jefferson (not to mention Lincoln) stuff has been, as this post promises to be.
I will need much more time to absorb it all. In the meantime, in between time, I can’t help but think of many years ago, 80’s some time, teaching a J-term course on rhetoric and presidential elections (you know, Perikles, Sojourner Truth, Lincoln, and MLK — lus presidential candidates), I eagerly shared with a totally sympathetic group of students my experience of Geraldine Ferraro’s apparel/self-presentation as she accepted nomination as VP: V-neck! (in contrast to the then-favored Repub flouncy-stuffings at neck) and winter-white, which only accentuated the lovely shade of white in her skin (a translucence I associate with a certain Italian skin-tone, but that’s me). All these students, who really liked me, were nervously hissing or groaning or otherwise registering disapproval or discomfort, all of a sudden! I tried to explain, there are many shades and tones of white, as of black, brown, whatever — that’s not the point! She was out there, as a woman! As a person in the flesh! Flesh nice! A lot of them got it. Not all, I would guess.

For the record, it sounds to me like Changizi is pitching utter hokum. With that said, I’m sort of morbidly curious as to how his just-so story weaves in the following:

1. 7-10% of men in a typical population are color blind

2. Color blindness is nearly nonexistent in women, and

3. The most common form of color blindness, by far, is the one which causes great difficulty in distinguishing that “blood” color from what I imagine Changizi would sagely regard as the “leafs” color.

I’d rather leave it to someone who knows a little bit more about the subject, but I feel compelled to note that the ancestors of mammals may well have been trichromats or tetrachromats, like birds or fish, and according to Wikipedia some marsupials may be trichromatic as well. Early mammals may have become dichromats because color sensitivity wasn’t essential or even particularly useful in their nocturnal lifestyle, and the same condition is probably no more a problem for human hunters than it is for carnivores.

I have two friends who are trichromats but will still argue with the rest of us whether a given shade is yellow or green.

As for skin color, a field trip to any well-supplied drugstore or cosmetics establishment will reveal a wide range of precisely defined variations on skin color. My aged mother, a Southern Californian of Scandinavian descent, is Neutrogena’s idea of “neutral beige.”

Forgive me, but I just remembered something about the American color television standard, NTSC. The idea was that you would tweak the color balance to achieve a realistic “skin tone”, for which of course you would need a pale face on the screen for reference, instead of an apples to oranges comparison.

@12

Thank you so much, that’s far, far more amusing than I’d hoped for.

Other primates (think mandrills and guenons) have virtually the same color vision we do, but have far more strikingly colorful markings, so I don’t think an evolutionary argument for skin color is viable; our color vision evolved long before our peculiar naked skin. The sensitively to fine differences is certainly real, but that gets readjusted as one’s surroundings change.

As for Jefferson, it’s important to remember that he grew up and living amongst a diverse range of skin colors, from lily-white planter’s daughter to sunburnt redneck, high-yellow to field hand. Plenty of room for discrimination and hierarchy, but hardly a sense of normal self vs. exotic other. It’s not about having a baseline and deviations, but rather having a structured set of categories. People might be bad at drawing fruit, but they’ll always make sure to use different colors for the oranges and bananas.

As for names for skin colors, that might be an artifact of contemporary culture; Shakespeare wasn’t shy about about calling folks rosy, ruddy, dun, tawny, or fair.

Holbo @8 has managed to make me orders of magnitude more confused. Two things. First:

He does an experiment, showing people a bunch of folks standing together in a Target ad

What skin color(s) are the people? Because if the people are various skin colors and if the people being asked the question include people with skin color that differs from those in the photographs, and if in the question “colors” is supposed to include skin colors, then the fact that people only say “red” and “white” surely undermines the thesis. Because: Isn’t the thesis supposed to be that what’s colorless, or “uncolored”, is precisely only one’s own skin color?

Secondly, and relatedly:

We are aware – even if not consciously, so we’re still lousy painters – of the variety of color we are really seeing.

But this won’t do, will it? The idea is supposed to be something like: I don’t see my own skin color, I take it to be an uncolored baseline, etc., but I do see “others” as having relatively uniform skin colors, where the “others” in question will also manage to fall into independently identifiable racial/ethnic categories (as far as I can see, this is the only way you get the explanatory payoff you want—and let’s note that this seems fairly suspicious). In any case, at this point, I have no idea what this “unconscious seeing” is supposed to be, or what explanatory work it’s supposed to do.

@15

People have a lower success rate recognizing/reidentifying individuals not of their own race/ethnic group. This is hardly to be explained in terms of skin and blood”

Or even of colors at all, no?

Perhaps that color-sameness is quite a bit after the fact? Take, for example, those people with ranges of skin color not notably different from those of latino or pacific islander populations, who anglophones nonetheless referred to as “yellow” not so long ago?

I suspect you* are rather deliberately misreading the well-established “those people all look the same to me” as “to me, those people all appear to have exactly the same skin color”

 * or perhaps the fellow you’ve decided to champion for our amusement, and again, thank you for that

…in other words, is this about you, or the people around you?

This Wikipedia entry doesn’t support the claim that only female New World primates have three-color vision. The usual model for humans is that the trait is carried on the X chromosome and is missing on the Y, which is why males are at the mercy of their maternal inheritance. Either things are much differently arranged for New World monkeys or Changizi is full of it.

As for the specifics of skin color, and diagnosis through its minutest variations, I really don’t think the opinions of assorted men who rarely use make-up could be reasonably considered definitive.

“Oh, sorry, clearly it’s about you. Clearly a European raised by ethnically Chinese people is going to be good at identifying ethnically Chinese people and worse at identifying European people.”

Then it’s all about the people around you. Then, it’s trivial. You observe some phenomenon all your life, you learn to recognize the nuances of it.

@30

Oh drat, I thought you were going to stand by your man. This will be a lot less fun to watch now :(

I, too, wish you could fish up some citations; particularly, the results of the same research protocol run with black witnesses identifying white suspects. Or maybe even exactly the same study, except done in various parts of Not America.

Um.

“our color vision evolved long before our peculiar naked skin.”

If we know that, then Changizi is obviously sunk. Do we know that?

Although few of our primate relatives dress up even for special occasions, nearly all of them have more fur than we do and also have three-color vision.

How much skin could our fur covered ancestor who developed color vision have seen to “read?”

Also, too:

@41

Well, you could go at him for trying to slither past the fact that homo sapiens have got tetrachromatic vision, not trichromatic. Which is probably what your guy was on about to begin with.

Come on, man, get back in there and fight! Jim’s just reading wikipedia, it won’t take you more than 20 minutes to draw even with him.

I haven’t read the book, but silly speculation about women evolving better colour vision than men isn’t selling me on it. As bad Jim said, this is simple genetics. Men have only one copy of each cone pigment gene, whereas women have two. It’s quite common for a pigment gene to mutate, so the pigment’s response curve is a little closer to the other pigment. In men, this makes the overall colour vision less efficient. Women with the same mutation have a back-up copy of the normal gene, so they get all three versions and their colour vision is actually better, with four “primary colours”. It’s important to note that this is only demonstrated in the laboratory, it’s not clear whether there are any real-world advantages from this. The only way selection might play a role is the racial pattern – colour blindness is much more common in white people. I’m not sure how this fits with Changizi’s theory. I think the standard explanation is that colour blindness is lethal for hunter-gatherers of both sexes, and white people have been farming for longer than other races.

My nephew used to date a girl whose mother is African-American, and one time we went to meet them at a taco stand where he used to work. Looking west toward the setting sun, the slender girl I spotted wasn’t dark enough to match my mental model, since her hair wasn’t actually black and her skin wasn’t particularly dark by local standards. I didn’t identify her until she was jerked forward by what could only be two small dogs I knew quite well on a leash she held.

Just the other day I was nonplussed by a Latina at my local coffee shop who had dyed her hair black. I would previously have described her as black-haired, but whatever she did (there was a haircut involved as well, and who knows what makeup) made me hesitate for a second or two before saying “Rebecca?” (She was probably already making my double espresso, so I don’t get points for perceptiveness.)

@45

I think the standard explanation is that colour blindness is lethal for hunter-gatherers of both sexes, and white people have been farming for longer than other races.

Erm, I’m not sure which circles that explanation would be “standard” in, but it’s definitely not standard, or even particularly credible, with geneticists or molecular biologists. The default explanation for undesirable conditions caused by any recessive gene is “there’s a benefit* from having having a single copy of that gene, but an adverse effect when it’s on both chromosomes”

And the default explanation for a given gene being more prevalent in one population than another is not “there has been an astonishingly long-running cultural difference between those populations”** but rather “eh, that’s about how you’d expect a relatively recent mutation to disperse in a world without internal combustion”

  * and what with it being early days yet, Big Science is still pretty sanguine about usually not having any clue as to what the beneficial effect might be.

  ** keep in mind that if we believe what the archeologists tell us, agriculture spread throughout the globe within less than 5,000 years; pretty much all of the “primitive hunter gatherer” cultures which were “discovered” in the 1950s relied heavily on planting and harvesting.

Wikipedia’s not very good on the subject of color vision. I’m mostly using it as a check on things I thought I knew but may be out of date or weren’t true to begin with.

It’s news to me, and probably to everyone, that humans have four-color vision. Birds do, and it’s not out of the question that crows and ravens, to our eyes as puritanically clad as priests or nun, are actually as iridescently arrayed as an emperor to eyes sensitive in the near ultraviolet, though I’d bet against it.

Most mammals are dichromats. Like fellow “color-blind” humans, they see a more limited range of colors than we do, but they still distinguish colors. Cetaceans, I think, are monochromats, and only distinguish luminance. If you think this is horrible I have a cabinet full of gorgeous black-and-white photographs and movies to show you.

How color vision works is a surprisingly interesting, not to say maddening subject. Edwin Land did some interesting work which he published about the time his Polaroid patents expired (the “Retinex” theory) which Oliver Sacks thought notable. I’m pretty sure I’m out of date on this subject, if only because it never seems to come up any more.

@52

That’s the Spirit, John! Your critics, they haven’t got A Life, like you do!

I knew you still had a bit of the old piss-n-vinegar in you!

Okay, we have three cones plus rods, which is sorta four, but birds and at least some reptiles and presumably dinosaurs have/had four cones. (Look, my first comment asked for someone who knew something. I’m still waiting for someone to weigh in with experience in matching pores and freckles with powders and paint.)

If hunters were severely disadvantaged by poor color vision then fewer of our ancestors would have been eaten by lions and tigers and bears.

@55

I’m still waiting for someone to weigh in with experience in matching pores and freckles with powders and paint.)

I think Chris Mealy got you there, with the link to the pantone/skin-color art project. Some of the women in it are even wearing lipstick, foundation, blush, eyeshadow, and pencilled eyebrows.

And if you want to find a skin-tone vocabulary without the, er, somewhat oblique marketing language of over-the-counter cosmetics for women, I have a suggestion:

Two words: theatrical makeup.

The names don’t change nearly as often, and the product is shamelessly designed (and named!) to project specific ethnic and racial stereotypes.

Okay, we have three cones plus rods, which is sorta four

And most primates (and also nocturnal mammals like hyenas) have two cones plus rods, which is “sorta” three.

On primate color vision, Changizi’s got it covered. Some primates have color vision, some don’t. Those that do have patches on their faces where there is no fur. Text on p. 27, color plate as Fig. 9 btw pp. 40 & 41 in Changizi, The Vision Revolution.

* * * * *

@JE McKellar: “The sensitively to fine differences is certainly real, but that gets readjusted as one’s surroundings change.”

Yes, as Changizi knows well. Here’s a post where he talks about being in Japan for a week and how is visual sensitivities adjusted to a baseline of Japanese people:

And so about my trip to Japan. I was there only one mere week, and yet by its end some sort of averaged Japanese face had become my new baseline (or at least my perceptual baseline had shifted significantly toward it).

The first-person experience for me was fascinating—exhilarating even. Japanese people no longer looked Japanese at all. They had become baseline.

In fact, to my eyes, the best description I can give is that everyone there seemed…Caucasian. As a Caucasian in a Caucasian-majority society, Caucasian has been my perceptual baseline all my life. Although I had never quite noticed, just as my own accent doesn’t sound accented to me, Caucasian faces (especially those I regularly experience) don’t seem ethnic. But now the Japanese face had lost its perceptual feel of ethnicity, and it thereby seemed strangely like Caucasian faces seem in my life at home! Furthermore, when I did occasionally stumble upon an actual Caucasian face, it now seemed strangely ethnic, because of their obvious differences from the norm.

These baseline shifts gave the perceptual results for which they’re designed: I could much better distinguish among Japanese faces.

But, to my surprise, Japanese faces hadn’t simply become the norm. The faces in my temporary Japanese world now fell into the sorts of higher-resolution categorizations I already automatically carry out among Caucasians: the horsey faced, rugged-cowboy, lawyer-gray, big-necked bruiser, Robert-Deniro-looking, British-looking, and thousands of other tiny perceptual characters I have for Caucasians.

* * * * *

And keep in mind that Changizi is primarily interested in visual perception, but in making that argument he must also deal with linguistically encoded color categories. His point is that perceptual discrimination is most senstive in the region of color space where the category system is weakest.

I think there is some truth to it, people using their own looks and those the closest to them as a natural reference / heuristic for how emotional reactions “should look”. On the other hand I think it’s silly to say that this is the way it is forever, Changizi doesn’t, the more time you spend with other people and experience their emotional reactions the broader your heuristic becomes.

The differences in visual perception and the subsequent reaction are seen between communities of the same color as well. In highly polarized areas of the world where people are (seemingly to me at least) the same color, other visual and audial cues are used to differentiate between “us” and “them”. Even if the polarization reduces, animosity drains away, and populations mix, it takes generations if not centuries for the cues to be forgotten.

Skin color is the easiest thing to generalize over (along with hair color and eye color) because it is so apparent, but that doesn’t mean you’re racist for talking about it, something I think needs to be the “baseline” so that people can start hating each other for less obvious things!

“Because our skin color cannot be categorized,we are better able to see very minor deviations in skin color, and therefore register minor changes in others’ skin color as they occur.”

And “If our skin color is so uncolored, why do we use color terms so often to refer to race?”

Huh?

I am not an academic, and thus, I struggle with these rather bold statements from the Changizi book. Are there really people who see no color at all in their skin? That seems a rather interesting assumption; not clear if the book provides data to support that claim.

That we do not have the right name (or Pantone color) for a particular shade of skin does not mean we do not categorize. I think we look at skin color as we do the orange – we lump it into a highly categorized shade, and ignore the shadings and subtle differences. We like to categorize. Does that make us all racists? No. Can such categorization enable a racist? Yes.

LOVE that tumbr link! Thanks to the Chris Mealy @ #12 for posting it!

“people get more worked up, and driven apart, over skin color than they do about other possible characteristics that might be possible markers of ‘race’”

Well, modern “people” do, I guess. But it seems very unlikely to me that this is a universal human characteristic, rather than a historical development a few centuries old. Ancient Greek and Roman authors weren’t very interested in skin color as a marker of ancestry at all (it gets mentioned occasionally; I think Lucretius talks somewhere about faraway people to the south whose skin is burned black by the sun), and they definitely don’t use it as a shorthand for different races the way we do. Is skin-color-as-race a more widespread way of seeing things than I’m aware?

Perhaps people of Jefferson’s time and social class really did see more gradations of color. In their consumer goods (available only to the aristocracy), the libertine eighteenth century made a big deal out of the color we call “pink” — or “rose” in French. Xavier de Maistre wrote an ode to it in his book, “A Journey Round My Room” (1794). And, as is widely known by fans of old roses, the French technical color terms for dye-stuff were also naughtily suggestive: there was “Cuisse de nymphe” — a pale blush or dawn pink, and the slightly darker, “Cuisse de nymphe emue”, “thigh of sexually excited nymph”. I understand that the English word for the color “pink” only came into use at this time, named for the serrated edges if the dianthus flower, which resembled the cut “pinked” edges of textiles. http://www.flowerspictures.org/flowers/dianthus/pink-dianthus.htm

robotslave @60:

The Nagel paper is *way* better (“What is it like to be a bat?”). You probably need a JSTOR subscription to access a digital copy though.

The Nagel paper is *way* better (“What is it like to be a bat?”). You probably need a JSTOR subscription to access a digital copy though.

Don’t know if this is the whole thing….?

καδδ’ ἱδρως ψυχρος χεεται, τρομος δε
πασαν ἀγρει, χλωροτερα δε ποιας
ἐμμι· τεθνακην δ’ ὀλιγω ‘πιδευσα
φαινομαι ἀπνους.

– Sappho.

The ancient Greeks would describe someone as green with fear, which seems somewhat strange to us. (We might describe someone who was sea-sick as green, though).

My base skin colour is a “00” in most of the cosmetics I use, which is a yellow (reasonably close in hue to yellow ochre pigment) at very low staturation (00 being the least saturated yellow in the range). My blusher is a cool red, more saturated than the foundation, and is blended into the foundation to pull it in a red direction where you would expect the blood flow to be. At the moment I’ve just come indoors, and it’s below zero celcius outside . The blood flow over my knuckles and the bones in the back of my hands is a warm, medium staturated red, more saturated than the base colour. My arteries are a bluish-grey, more saturated than the base colour but less saturated than the blood flow. As my hands warm up, their colour decreases in saturation and becomes more yellow.

Part of the reason we have difficulty using colour words for human skin is that basically everyone is in a fairly small region of the colour space, even including people of Asian or African ancestry. Nobody is bright blue, it is sometimes said. (Though at the moment I’m managing a quite good approximation of a low saturation blue-grey, close to Payne’s Grey, above the arteries).

Also, people may have difficulty distinguishing hues at low saturation

I was on the fringes of automated face recognition for a time. I recall that tests showed that East Asians (Chinese, Japanese and others with epicanthic folds and padded cheekbones) were less good at recognising faces of their own type than European faces. So it’s not just practice – some physical differences do actually count.

@69: Sorry, I don’t think I made my point clear. The thing is, Greeks and Romans did have quite a bit to say about people being of different races (or at least, physically distinct ancestry-groups or something; obviously not exactly the same as what modern people mean by race). And some of these groups did, I think, have different skin colors — this isn’t something I’m an expert in, but surely Persians and Britons and Indians didn’t have the exact same range of skin color as Romans or Greeks. Yet in distinguishing those and other groups, skin color doesn’t seem to have been the difference that got picked out as the most important one, in any text that I’m aware of. (In mentions of Africans from farther south, as I mentioned, it at least sometimes does — though I don’t know of any claims that their skin is less variable in color.) There are definitely a few places where particular barbarian tribes and such are identified as having a particular *hair* color, but I can’t think of any about skin color. So at least the claim that that’s the physical difference that people get particularly “worked up” about seems weak.

The Nagel references are terrific. The post points to the Hard Problem and I’d suggest Jackson’s knowledge argument as another lens through which one could unpack Changizi.

““…doesn’t a Nigerian mother get less information from her baby’s skin than an Irish mother gets from hers?”

Changizi says, no, she doesn’t get less information.”

The idea that a flushed skin tone is the key signifier is new info to me. Non-verbal communication includes so much more than flushed skin. And babies are QUITE good at signifying in ways that go far beyond skin tone changes.

To amplify the point about being able to distinguish subtle differences of common things that are important to you versus the opposite. Early arctic explorers were flabbergasted that Eskimos had something like a hundred different words for snow. To the Europeans snow was snow, but to the Eskimos, knowing the many subtle variations probably contributed to survival. But, this is mainly about the environment, ones own skin color (if you are embedded in a culture with other “colors”) is only marginally more noticeable to you.

Probably everyone here knows this already, but in the Homeric cycle, Memnon, a black warrior prince from Ethiopia, is said to have been the handsomest man who ever lived.

http://en.wikipedia.org/wiki/File:Picart_-_Memnon.jpg

His mother was Eos, the goddess of the dawn.

The Ethiopian Queen of Sheba was likewise renowned for her beauty. Ethiopia during the Bronze Age was evidently a wealthy and prestigious place.

The entry in wikipedia states (I don’t know how reliably) that according to the Prose Edda of Icelandic chronicler Snorri Sturluson, Memnon married a daughter of king Priam of Troy and their son, Tror (Thor), with hair “fairer than gold”, became king of Thrace and the ancestor of all the Germanic kings.

JanieM @75: That does seem to be the full text — footnotes and all. Thanks! (Here’s also endorsing your 88.)

JH @44:

Maybe the conversation has moved on, but I did want to make the following point. Yes, I got the argument in the OP (helpfully restated in 44). Thing is, though, once you admit both that, objectively speaking, there’s very little variation across all the different race-identified or race-associated skin colors, and you concede the point in #40 about black people not having as much difficulty identifying whites as white people have identifying blacks, similarity vs. differences in skin color as a sort of “natural” explanans of racial mistrust becomes really quite difficult to defend.

The first thing makes this sort of point difficult to defend:

if you can tell whether people who have similar skin tones to your own (because that’s what you grew up around) are sick, well, blushing, excited, etc.

Skin colors aren’t objectively supposed to fall into easily categorizable categories, right? All sorts of non-discrete variation, etc. So, what’s “similar” picking out here? Why is it exactly, if it is the case, that I can “read” people from South Asia, or some part of South Asia, but not, or not so easily people from Scandinavia or Sub-Saharan Africa? This is anyway utterly bizarre to me. (Also, Argentinians I’m presumably totally down with? Even though I didn’t grow up around a single one of them?) Put this another way: if it is true that objectively speaking the skin tone of a white person can be closer to that of some brown, yellow, or black person than to that of another white person, it’s extremely difficult to see how the “information” provided by “similar skin tones” is going to map onto familiar racial divisions.

But the second point is really damning. If black people can in fact pick out white people better than vice versa, then this pretty easily suggests that it really is all about power and privilege. Presumably, a bunch of peasants all looked the same to a feudal lord as well, and not inexplicably, but also not necessarily because they were of a different race or ethnicity.

Meredith, I was referring back to Jefferson’s remarks about gradations of blushing (“suffusions of color”) in the OP as possibly a reflection of the licentiousness of the age. Looking back on what I wrote, I failed to make myself very clear. They saw more blushing and savored it in a way that doesn’t happen now. It certainly occurs a lot in 19th c. novels.

There was a podcast on WNYC’s Radiolab about color perception that had as its starting point Gladstone’s contention that the ancient Greeks couldn’t see the color blue, because of Homer’s “wine-dark”, etc. They talked about the possible existence of female “super-color perceivers” (color perception is on the x part of the chromosome and women have 2 full x’s) , but came to no definite conclusion. I myself suspect that a lot of color names and possibly even color consciousness come from manufacturing trades such as dyeing and jewelry and are rather recent in origin.

This has been an interesting thread, though John’s unwillingness to engage in partisan mud-slinging has been disappointing, to say the least.

I am notoriously bad at judging faces, to the extent that I can’t pick friends in old photographs, can’t recognize movie stars in photos and am confused by people I know wearing sunglasses. When I first moved to Japan I was embarrassed that “they all look the same to me” but after a few months I adapted and now I see faces here in the same (muted) technicolor I was used to in my own country. My understanding is that facial recognition is a mathematical problem, and our brains are very good at PCA – it’s not about skin color at all.

One point in defense of Changizi: I read of an old racist theory from the USA that holds that black people are morally inferior because they have no sense of shame, since it is not possible to detect “Blood in the face” of a black person. I once read a history of the US nativist/white christian movement with this title, and it was the first I’d ever heard of this ludicrous racial theory. It’s interesting to suppose that an entire racial theory of this kind can be sparked by a simple problem in colour perception. But then it could be that hte people who composed this silly idea were perfectly capable of recognizing a blushing black person, they just thought the theory apt.

@Holbo: “If Changizi is right, you would expect skin color to be a more consistently salient consideration than hair color. So if it’s the other way, that weighs in the other scale.”

Keep in mind that we’ve got two more or less independent things going on here. On the one hand there’s the ability to perceive fine-grained differences in skin color. On the other hand, there’s the categorizing process that lumps things into bins that have names on them. That process seems to work, in part, by ignoring subtle differences. When that process goes to work on color it’s going to insert lots or more or less arbitrary boundaries and lose lots of perceptual distinctions. Hence, as Harold points out, there’s the problem of Homer’s “wine-dark” sea. What range of the color spectrum typically fell under term? (And notice, for fans of the color-term literature, that we’re not dealing with a primary color term. We’re dealing with a phrase.)

So, you were respondeing to a remark about what shows up in texts, right? If the color term system falls apart in the region of skin tones, because we don’t want to mess with fine perceptual discrimination) then it might be less likely to show up in descriptions. On the other hand, as far as I know, hair color isn’t used as a diagnostic indicator and so we’re free to slap color terms on it and that’s what texts mention.

Now, there is, in fact, a third thing. If you mess around a bit with digital photography you’re likely to run into something called white balance. What’s that? White isn’t given in the world on the surface of things. It’s a funciton of the interaction between things, light, and the perceiving system. In effect, you tell the system (whether its the camera or your processing software) “this is WHITE.” It then adjusts all the other pixels so that they have the appropriate difference from the white point.

Changizi is arguing that the visual system has evolved treat the skin tone region of color as something like the white balance point. When the categorizing system goes to work on color it avoids the skin tone region. It’s not going to put any boundaries in the region nor is it going to attempt to put boundaries around the region. Now, just what THAT means is tricky, tricky enough so I don’t really know what I’m talking about.

One aspect of the trickiness: There’s this conventional notion of the spectrum as a mapping between colors (violet through yellow to red) and electromagnetic wavelength. Simple, easy, but not how we see. We, that is, most of us, have three kinds of color receptor (cones) and one intensity receptor (rods). So, we’re getting four independent streams of information about any given patch of stuff out there in the world. I have no idea what the most sophisticated thinking is concerning just how those streams get mapped into perceptual color space, but it’s surely NOT 1-dimensional, like that conventional notion of the spectrum.

@Meredith: “…what does neuroscience at this point (a science in its infancy, after all) have to say about the way shape and color, among other things, relate to one another in our busy brains? I understand that in early analysis we (as conscious, rigorous analyzers) must isolate, but our brains, finally, don’t isolate but for a nano-second. Each part/activity almost immediately is interacting with others.”

You mean, for example, what happens perceptually when some shape is colored a brilliant orange vs. a dull medium-gray, are the shapes perceived differently? Don’t know off-hand if such things have been investigated, but my reaction is that it’s an interesting question. I do recall having read, years about and in a classic little book that is, alas, in storage (by R E L Gregory, Eye and Brain), having read about a person who’d been blind from birth but had vision surgically restored in adulthood. But it never really worked. For one thing, there’d be colored patches “over here” and visual forms “over there” and they never really got synched up.

@js.: “Skin colors aren’t objectively supposed to fall into easily distinguishable categories, right?”

Note that it’s one thing, when given a paint chip of some color, to be able to identify other chips of the same color. This ability is very fine-grained. Naming those colors, that’s a whole different ball game.

Also, skin tones aren’t given in the structure of the perceptual system. Rather, the system has to learn them.

“Put this another way: if it is true that objectively speaking the skin tone of a white person can be closer to that of some brown, yellow, or black person than to that of another white person, it’s extremely difficult to see how the “information” provided by “similar skin tones” is going to map onto familiar racial divisions.”

I’m not quite sure what you’re getting at, but one has to learn just what region of color space is the skin tone region.

“But the second point is really damning. If black people can in fact pick out white people better than vice versa, then this pretty easily suggests that it really is all about power and privilege.”

Well, in the USA black people are more likely to spend time around white people than vice versa and so they’re more likely to have experience in reading white people’s skin tones. Now, the population distribution that brings this about is certainly one influenced by power and privilege.

That a color-blind mother who can’t see flushed skin wouldn’t notice a choking child seems (to me) an absurd claim.

It is. As you say, it’s “an oversimplification required to fit an example into a hypothesis.” Does the fact that Changizi made that absurd claim mean that we should toss out the entire argument? Does the fact that many factors are involved in our perception of others imply that an argument about the value of skin color is of no interest? His argument does not rest on that one example. It’s just an example, one of 10, 30, 50 or more in long discussion.

Changizi is trying to figure out why we have color perception. He figures, not unreasonably, that we have it because it is useful. So, what makes it useful. He’s arguing that it’s useful because it provides valuable clues about a person’s state of mind and about their health. He’s not arguing that it’s the only source of such information, just that it’s a source.

And one aspect of his argument is that it’s something that can’t be faked. It can be masked with make-up, but that’s different. One can’t blush or un-blush at will, to use your own example. One can’t turn cyanotic at will. If one could turn cyanotic at will then one could elicit help and resources from others when it’s not needed. That’s cheating; it allows one person to benefit at the expense of others. But verbal cries are relatively easy to fake, as is physical destress (a limp, falling down).

I still don’t understand the idea that “we cannot say what color our skin is.”

Here’s an example of what it means: “…two young women [their color being shades of white, pink, peach, whatever]…”

One thing it’s important to realize about color is that it’s not a direct read-off from wavelength such that 400 nm (nanometers) gets automatically mapped to color X, 401 nm gets mapped to color Y, and so forth up to 700 nm. Rather, color is constructed from the outputs of three independent sensors. Just how that construction process goes is not at all simple.

Now, why did I suggest bracketing the discourse on race (up there at 76) when that’s why Holbo got into the discussion in the first place and when Changizi himself brings it up? Consider the Jefferson statement that Hoblo quoted:

Are not the fine mixtures of red and white, the expressions of every passion by greater or less suffusions of colour in the one, preferable to that eternal monotony, which reigns in the countenances, that immoveable veil of black which covers all the emotions of the other race?

Why did Jefferson say that? I’ll offer three possibilities. (1) One possibility, one that I don’t think anyone here believes, nor does Changizi, is that it’s true. If it’s not true, then why’s he saying it? (2) The obvious reason is that he’s a racist and that he ignores expressive variation in black people as an expression of his power an privilege. He notices them, but pays no attention and never ever articulates such variation.

Changizi gives us a third option: (3) he does not in fact see the expressive variation. It’s genuinely invisible to him. Why? Well, that’s a complicated story, really complicated and Changizi devotes 45 or so pages to telling it.

But if it’s a possibility, then we ought to know about it, no? And, of course, this possibility is not in the least incompatible with power and privilege. On the contrary, it makes it easier for power and privilege to justify its ways.

@Harold: It is interesting, as someone pointed out here, how the lumping and splitting systems of categorizing in the brain operate in fact as separate systems.

That might have been me, in 97, were I observed that we have “two more or less independent things going on here. On the one hand there’s the ability to perceive fine-grained differences in skin color. On the other hand, there’s the categorizing process that lumps things into bins that have names on them.” If so, then what you’re saying has little to do with the distinction I made, which is not between lumping and splitting systems (that’s a different kind of discussion), but between perception and cognition. If that’s not what you’re referring to, then just forget this comment.

The lumping appears to be more primal – in the sense of flight or fight. But the human brain has a sometimes inordinately developed capacity for splitting as well.

That’s all yours.

Harold, Aulus: Wherever Homer thought Ethiopia was, Herodotus firmly identifies Ethiopians as black Africans (he thought they had black semen), and as the most beautiful race on earth. Ethiopia, by Herodotus’ time, usually meant the Cushite empire of Meroe, a city near modern Khartoum, which was certainly powerful and prosperous and became more so as time went on.

I knew that the Memnon myth came from other poems not by Homer about Troy.

About the blush, it seems to me that it was used to diagnose, or rather admire from an aesthetic point of view — not health, but extreme youth and its concomitant virginity, shame, and arousal at a time when brides (and prostitutes) were often in their teens and Europeans covered up most of their non-facial skin with clothing.

The eighteenth century invented the color pink and was also under the mistaken impression that Greek temples and statues had been white.

“…doesn’t a Nigerian mother get less information from her baby’s skin than an Irish mother gets from hers?”

Changizi says, no, she doesn’t get less information.

He says that, but does he present evidence of it? What if the kind of minor differences in skin tone Changizi is talking about really are more evident in low-melanin people, not just to the experienced observer, but to anyone with human color vision? I mean, obviously some of Jefferson’s ultimate conclusions are pretty unjustified — whether melanin makes it harder to read Africans’ emotions or not, it’s not something they’re doing on purpose and so it’s unfair to assign blame for it — but what if he had a point on the brute facts?

Then the people who display their emotions by their changing skin color and the people who don’t would probably *both* consider the other group abnormal because of the difference (relative to their respective previous life experiences), but because some cultures lacked written language at the time of first contact (or at least their writings haven’t survived to the present), we can’t really know what they said about the people who changed color when they were angry.

Or maybe there actually is a surviving Ethiopian account of an early encounter of the people who, while normally the color of (some object familiar to other Ethiopians), turned as red as a baboon’s butt when they got angry/excited/etc. (hard as that might be to believe for an audience of “normal” people without color-changing skin). Boy, wouldn’t Changizi’s face be red when he found out… unless of course it’s very dark brown regardless of his emotional state, I dunno. (How many African or Australian Aborigine languages have a similar figure of speech that isn’t a recent borrowing? That might give some indication of how familiar they are with visible moment-to-moment changes in skin color as a signal of emotion or health.)

Of course, if some ethnic group actually does refer to Caucasians as “color-changing people” rather than “white”, that would pretty much clinch it.

Seems more a justification for racism (which any slaveholder needs)

A bit of a side issue, but this is not really true — plenty of societies in history have allowed holding slaves of the same race as the owner (even after accounting for different ways of classifying and lumping/splitting). Probably even most of slaveholding societies haven’t had anything like a race distinction between owner and property. Many have allowed freeborn people to be reduced to slavery, e.g. as a criminal punishment or even for debt. The society just has to come up with some other way of justifying its social structures — if you can’t think of anything else, the will of the gods will do fine.

Re: colorblindness, here is what he has to say.

From a colour scientist’s point of view, there is so much wrongness in that paragraph that I don’t know where to start.

Main Street Muse @98: “Yes, the blue shade she was turning was alarming (we are of the Celtic family of skin tones); however the blue-ish tint was but one of the signals – others being a look of panic in her eyes, an inability to talk, to make noise, her hands moving toward her throat. So the assumption that a mother who cannot see changes in skin color would not notice a choking child is a bit of a stretch – and seems to be an oversimplification required to fit an example into a hypothesis.”

Call it over-determination. Or think Sign Theory 101, as I like to think of it. (I wish I could see what the Sign Corps folks in the military study, how they are taught. We all have a lot to learn from them, I’m damned certain.)

You want to get a message through for sure? Send it multiple times in multiple ways. (And ensure mechanisms for registering receipt of message — another part of the story.) Skin-color changes (btw, even very black-skinned people’s blushing is visible, easily if you’re attuned to very black skin), choking, eyes opening wide, and so forth.

The more important the message, the more mechanisms for its expressions. (Hello, Darwin.)

He says that, but does he present evidence of it?

Yes.

And, to the extent not subtle, do not require precise discrimination.

Let me walk out on a limb and suggest that we don’t know why people have the skin color they do. Light skin is clearly a necessity at high latitudes to permit Vitamin D production, but black skin has only evolved in three places (Africa, South Asia, Australia) and its necessity isn’t a settled issue.

The very pale skin of many Northern Europeans may, like blue eyes and blond hair, be the result of selection for sexual appeal rather than survival advantage. It’s not out of the question that black skin rapidly became the norm in equatorial regions for the same reason.

It’s a bit puzzling to claim that human color vision has such a specifically human-oriented and human-derived purpose, when lots of animals have color vision — some of it even more sensitive (e.g., more than trichromatic) than human vision. What on earth are birds doing with color vision, when most of them don’t have visible skin? (Now, if vultures were the only birds with color vision, you might be on to something…)

There are more specific problems with some of the text John quotes. E.g., on the one hand Changizi’s arguing that “… there is no mystery as to why all primates have such similar color vision. Although skin colors vary across primates, we all have the same kind of blood.” And on the other hand, he seems to imply that human skin is uniquely variable, unlike even the skins of, say, chameleons or squid: “The skins of these animals do not, however, appear able to display a continuum of hues, nor can they return to baseline or ‘turn off’ like human skin, at least not to human eyes (e.g., squids at baseline appear gray, and chameleons at baseline appear green). An object capable of dynamically displaying all possible hues and also appearing uncolored is, then, a rarity in the natural world.”

(So, I’m confused — if squid skin can’t return to “baseline”, how is that “squids at baseline appear gray”? And is the “baseline” color of squid really “gray”? Well, squid that have been dead for several days are, I suppose:
http://ca-seafood.ucdavis.edu/squid/squidcol.htm )

This level of nitpicking doesn’t necessarily bear on the overall argument, but the sloppiness and inconsistency don’t give me confidence.

And I also have trouble with the Changizi’s claims that nothing in the world has the variety of colors that human skin does. I mean, even oranges can display other colors than “orange” — you can get some interesting variations on gray, green, blue, brown, and black when oranges get moldy or rotten. (Possibly there might be some evolutionary advantage to identifying fruit that has gone rotten, I don’t know.) It amounts to arguing that the entire rest of the (natural) world doesn’t have the color range of the skin of your local hunter-gatherer band.

Meredith @113 “You want to get a message through for sure? Send it multiple times in multiple ways.”

Yes. Tell that to Changizi. He’s the one who said a color-blind mother would not notice her child was choking because she couldn’t see the flush.

and were practicing human sacrifice until the 10th or 11th c. A.D. (someone will probably correct me, here).

I won’t correct you, although it sounds odd that the Celts in particular would do human sacrifice some 500 years after converting to Christianity.

A more pretinent question would be why you think it would be relevant either way.

Anyway, skin is one of those things (along with marble and milk) that computers really couldn’t render realistically until we developed good models for subsurface scattering. So it’s absolutely special color-wise, it’s no wonder people can’t describe skin colors accurately.

“This rings alarm bells, because it defines “uncoloured” as “uncoloured to human eyes”. Possibly a non-displaying squid is uncoloured to other squid.”

No. Squids at “baseline” (in some neutral state where nothing much is going on) appear gray to human eyes. Gray IS a color. But they may well appear colored to other squids.

According to radiolab, certain insects and shellfish (the mantis shrimp) can see many more colors on the spectrum than mammals, many of whom lack the cones necessary to distinguish red, like some male humans. Tribal and peasant languages typically have a very limited vocabulary for color.

No. Squids at “baseline” (in some neutral state where nothing much is going on) appear gray to human eyes. Gray IS a color. But they may well appear colored to other squids.

Exactly. This guy is arguing, as I read it, “human skin is weird and special because it can display lots of different colours and then go back to uncoloured. Squid skin can’t go back to uncoloured; it goes back to grey.” But maybe grey is uncoloured, and human skin tone is coloured – to a squid.

129: What colour is snow? “Tout sauf blanc”.

This rings alarm bells, because it defines “uncoloured” as “uncoloured to human eyes”. Possibly a non-displaying squid is uncoloured to other squid.

Cephalopods are monochromatic.

This may be of interest:
http://freethoughtblogs.com/pharyngula/2012/12/10/ep-the-fundamental-failure-of-the-evolutionary-psychology-premise/#more-8381

Chingizi from comment 13:

I have wondered on occasion whether this could be one reason color blindness is more common among men than women.

— That seems to be a good example of why people become so anti-EvoPsych. I mean, colour-vision deficiencies are more common in men because (a) it is a recessive problem and (b) it is X-linked. No more reason is necessary. To speculate about *adaptionist* reasons is flatly absurd. It would be analogous to looking for a function of haemophilia that has selected for a greater prevalence of haemophilia among men.

The standard line on primate color vision has been, for a long time, that it evolved to help us find fruit (by making it pop out of the background, visually.) The problem with this hypothesis is that different sorts of primates have very different diets but they seem to have similar similar visual capacities.

It has to be that way. Look at it like this: the basic mammalian colour-vision system is a blue / yellow opponency, S-cones versus LM-cones. Among some primates, duplication of the gene for the LM opsin — followed by a small shift of the sensitivity spectra of what were now separate L and M opsins — allowed that to turn into trichromatic vision.

Once you have got that far, there is only one way to do it. The additional visual information is provided by the difference between the signal from L-cones and the signal from M-cones. There is simply no room for providing this additional colour discrimination in alternative forms.

Main Street Muse @122: yes. I meant to be supporting your earlier comment. Sorry if I came across otherwise.

One more thing. The reason it’s going to be hard to explain the sense of similarity re skin color is the following. The information is all supposed to be conveyed in perceptual experience. So, linguistically, I might classify some people as white, others as black, etc. But this is all wrong! Sheer nonsense! So says Changizi. What matters is that I get information from skin colors that are like mine and not from ones that are not like mine. But again, the “like” in the previous sentence is not supposed to map onto the linguistically articulated categories from the one before. (On pain of defeating the whole hypothesis in fact: if the two match, then our linguistic categorizations will accurately track our perception of color. Which is exactly what’s supposed to be denied.)

So the people whose faces that TJ can read vs. the ones he can’t read can’t have anything to do with the people TJ calls “black” vs. “white” vs. “red” vs. “aquamarine”. Because, again, what he calls them is supposed to have nothing to do with what he sees in them.

@herr doktor bimler: check out the reflectance spectra in:

http://www.changizi.com/colorface.pdf

@js. # 139: “Because, again, what he calls them is supposed to have nothing to do with what he sees in them.”

No one said anything about “nothing to do.”

More generally, just forget about Jefferson. I know, that’s the example Holbo hung Changizi on but, really, we don’t know what Jefferson could and could not see. We do know he was a racist. That gives him a reason for “not seeing” that’s stronger than the one Holbo saw in Changizi’s work.

As far as I can tell from reading his book and glancing through the two papers Holbo linked is that the bulk of Changizi’s thinking and writing is about discriminating modulations in skin tone as indices of mental and physical state. The observation about how we see people of other races is something of a side issue, though an interesting one. But it needs more work.

How much time do you spend interacting with these or those people, how early in life, and in what kind of relationship? Immediate family members probably weigh more heavily in perceptual tuning than people you pass while walking on the street. People you talk with probably count more than people you don’t. And so forth. Just how you would sort all this out experimentally would be tricky. As far as I know Changizi hasn’t attempted that nor has anyone else. So we don’t know.

But we do know alot about the physiology and perceptual characteristics of color vision. We know about the reflectance spectra of lots of things, including human skin, and we know about use of skin tone as diagnostic criteria in clinical situations. We know about primate and mammalian vision. Changizi has looked at all of that and put together an interesting story.

If you don’t buy the story, then you don’t buy it. But with all respect to Holbo’s expository abilities, what he’s said taken together with what I’ve said doesn’t present Changizi’s argument in full. Many details and lines of inference are missing from this discussion. If, at this point, you still think Changizi’s hypothesis is somewhere between really dodgy and nonsense, well then that’s what you think. If you don’t care to read him for yourself, well, you’re busy, I’m busy, we’re all busy. Can’t do everything.

js. @ 139:

As a very speculative hypothesis: it’s possible that when one (as a child) learns to read expressions (including variations in skin tone due to blood flow), there could be a focus on people perceived as “important” or “significant” to the child: e.g., parents and siblings, as opposed to others who have less direct importance in the child’s life[*]. If you as a young child are doing something that makes your parents or siblings upset or happy, it’s quite useful to know this, because they have lots of influence and power over you; depending on the household, the reactions of the servants may not matter as much. I don’t know anything about Jefferson’s childhood other than what’s in Wikipedia, which mentions nine siblings, including some older sisters he was apparently quite close to, and that he attended a local school (which we can probably assume didn’t have any black students) from the age of nine onwards.

Thus it might be that, despite the presence of black slaves in the household, Jefferson could have grown up learning to pay more attention to white faces, especially those of close relatives.

(This ignores the additional possibility — likelihood, even — that household slaves would school their expressions to give away as little as possible, since open displays of emotion would be likely to get them punished.)

[*] Of course, if young Jefferson had been raised by a slave acting as a nanny, or allowed to play frequently with slave children, then the nanny and slave children would qualify as “significant” in this respect.

Of course, in “wine-dark” the wine is a modifier of dark; Homer didn’t say “wine-red”. Colour depth/density is independent of hue.

Is wine red? I mean red wine? I think red wine is purple and white wine is yellow. It seems sometimes colors restricted to specific things (red wine, white skin) refers to color that is consistent across the category but different than the color associates with the term when it’s used a general descriptor. I’m not sure if there are other things besides wine and skin where this is true.

The race and colour-vocabulary parts of the argument are perhaps the least convincing bits.

The claim that Old World primates (including humans) evolved tri-chromatic vision in order to better read the emotional state of other members of their species seems at least plausible (if not exactly proven).

Going beyond there, we encounter the difficulty that (a) humans of all races have basically the same colour receptors (there are different alleles of opsin LW and opsin MW, but if I recall correctly the allele frequencies don’t vary much geographically – you could check this with e.g. the hapmap database). (b) The genetic variants that led to light skin pigmentation in Asians and Europeans evolved later than trichromatic vision.

.. which would leads us to expect that (a) dark-skinned people can read each other’s variation in skin colouration (b) light-skinned people have at least the colour receptors needed to see the variation in dark-skinned people, if not the training to make use of the sensory information.

I suppose it’s imaginable that improved readability is one of the factors that led to light skin being selected for in the northerly lattitudes of Europe and Asia (while in Africa, the need to protect the skin against harsh sunlight won out over improved readability).

====

Colour perception is more relative (comparison of adjacent colour) than absolute. Coloured objects look subjectively more or less the same colour even when the colour of the ambient light changes (shifting the actual R, G, B values of everything in the scene). In painting, you can use almost any colour for the human body and still have a comprehensible image, if you keep the relative changes the same. For example, a blue nude is a completely understandable image, even if clearly unrealistic. … All of which would tend to suggest that shifting the base skin colour in the red/yellow or light/dark directions won’t have much effect on our perception of the differences between high blood flow/low blood flow regions of skin.

@51, 55, 56
The existance of vision into the UV range is well documented among birds, as are UV reflective color patterns that humans cannot see. Blue Tits (Parus caeruleus), for example, have sexually differentiated plumage in the UV spectrum while appearing completely sexually monochromatic to humans. Females of the species appear most attracted to males with the “brightest” (in the UV spectrum) crests.

This is also true with insects and flowers – a number of flowers have UV reflective patterns that are likewise invisible to humans and other mammals.

(and I do believe there are corvid researchers working with jays – there is just a cluster of corvid researchers doing crows and ravens at the University of Washington, and crows have proven more useful for the corvid intellegence research – sort of the same reason that Cotton-top Tamarinds have been heavily used in language research).

@Harold, #152: For one thing, I am not sure it is true that “all races” refer to people of other race by color.

Quite possible. I have no idea whether or not he did a reasonable cross-linguistic search.

Many pre-literate people refer to other *tribes* — often ones living quite close proximity and belonging to what we would think of the same “race” — as “other” in some way, even non-human. The Ancient Greeks referred to non-Greeks as “babblers” (barbarians).

Unlike your Chinese example, these aren’t (necessarily) about race. They’re just about foreigners.

But even when calling other people “black” they may not be referring to a precise color you could reproduce with paint.

Which is what Changizi argues.

I mean, if you and others have taken a dislike to Chagnizi’s argument for whatever reason, fine. But at least do him the courtesy of offering coherent counter-arguments and counter-cases. This is … well, there’s no charitable word for it, so I won’t say.

… he seems (at first blush) not to refer to what well known people have said about the subject of color over the millennia…

Color theory is a huge territory. As far as I can tell, he knows it way better than you do.

Not quite, Harold, but moving in that direction:

http://www.technologyreview.com/view/428264/i-see-right-through-you-glasses-to-read-peoples-skin/

Bad Jim:
This Wikipedia entry doesn’t support the claim that only female New World primates have three-color vision. The usual model for humans is that the trait is carried on the X chromosome and is missing on the Y, which is why males are at the mercy of their maternal inheritance. Either things are much differently arranged for New World monkeys or Changizi is full of it.

Changizi is right.
Several clades of New World monkeys have re-invented a version of trichromacy where there are more than one version of the gene for the LM photopigment floating around in the gene pool, with the photopigments themselves differing enough in their absorption spectra that we might as well call them L and M. Depending on which version they inherit on their X chromosome, the males have either L-cells or M-cells in their retinas, which (combined with their S-cones) gives them dichromatic vision.

Some females inherit the L version on one X chromosome, and the M version on the other. Remember that only one X-chromosome is working in a given cell, and the other is switched off (Lyonisation). So in in the retina for these females, some cells are expressing the L pigment and others the M pigment, and their retinal circuitry extracts the difference between the two, providing trichromacy. Other females inherit two L versions (or two M versions) and are dichromats.

One lineage of New World primates (the howler monkeys) has independently evolved full trichromacy, with a duplicated version of the gene, as in Old World primates.

It’s news to me, and probably to everyone, that humans have four-color vision.

We don’t. The fourth class of photoreceptors (the rods) work at night when the three classes of rod cells are insensitive. Conversely, the rods are switched off during the day. There may be some input from rod cells into cone vision during twilight lighting levels (“rod intrusion”), but we don’t get an additional dimension of colour space from it, because we don’t have the neural circuitry to *compare* the signal from rod cells against the signals from the rod cells and process any differences.

If we’re going to be pedantic, we also have also a *fifth* class of photosensitive cells, the melanopsin ganglion cells.

Vielen dank, herr doktor bimler. I especially liked your comments at 137 and 142. Land et al. have made it very clear that our color perception is not simply a matter of registering the frequency of incoming light. I’m definitely looking forward to getting down to details with my dichromatic brother-in-law the next time we uncork a third bottle.

A funny thing, though. I blush easily, it doesn’t take much to make me tear up, but I don’t recall ever noticing someone blushing. I’m shy, I’ve never married, but I also live in Southern California, where complexions converge on caramel. When I wanted to know if a red-headed and luxuriantly pale employee had a fever I touched my knuckles to her forehead to take her temperature. (Most mothers know how to do this, I think. The lady in question was rather hot, did see a doctor, and recovered.)

If we assume a social species desirous of or dependent on fresh fruit, the occasional defect might not be subject to selection if there are redundant tests of palatability. Consider a tribe of monkeys, some of whom can by sight descry ripe fruit at a distance. Once they near the trees where the good stuff can be found, smell and taste allow those less visually endowed to share the bounty, even if they can only discard the inedible.

A funny thing, though. I blush easily, it doesn’t take much to make me tear up, but I don’t recall ever noticing someone blushing.

Blushing puzzles me. Everyone talks about blushing as if it were an accidental escape of mood-state information that we would prefer to keep concealed… providing an evolutionary advantage for anyone who has evolved the ability to detect this information channel. And I can see the temptation of this way of thinking because it fits into the common metaphor of the face as a window into the soul.

But presumably the tendency to blush has evolved/b>. It is a signal we broadcast, purposefully, because it was advantageous for our ancestors to blush under similar situations (as well as for their companions who noticed the social signal). Same as any other emotional signal. But what is the message?

Seems to me that there is an interesting evo-psych story waiting to be told about the blushing phenomenon (and apologies to Chingizi if he does in fact tell that story).

harold:
he seems (at first blush) not to refer to what well known people have said about the subject of color over the millennia
I see what you do there.

@162. There has been a fair amount of nature photography in the near IR and UV as it’s well known that some plants are brightly patterned at frequencies invisible to humans, but visible to their pollinating insects. See for example http://www.naturfotograf.com/.

(Glass tends to be opaque to UV, so you need special lenses for UV. Also, many modern cameras use IR LEDs to sense the film, and so can be used with a very near IR film like Ilford SFX, but won’t work with a film that goes further into the IR, like one from Kodak … I’ve only ever done IR photograph with a film SLR, and the methods for digital cameras are probably different).

As for blushing as a deliberate (if by the genes, not the will of the individual) signal, seems likely. But signals are useless unless the target has the means to pick them up. And Changizi is arguing that, yes, human color vision evolved to give us the means.

If you keep this up you’re going to re-create his theory, all by way of proving him wrong.

Well, my lewd mind tells me that one clear use of being able to see blushing is “hey, seems that he/she has the hots for me”.

That it gets triggered by a ton of other things apart from omg the guy/girl I like is talking to me may be part of our messy unintelligent design :-P

“Well, my lewd mind tells me that one clear use of being able to see blushing is “hey, seems that he/she has the hots for me”.”

Of course in the social context any hint can be useful, but it seems unlikely that evolution anticipated that some of the apes are going to be wearing pants and analyzing each other’s faces to ascertain their chances of mating – instead of looking directly at the genitalia.

To caricature this a little bit: I hear that people tend to cover their mouths with their hands when lying. So, that must be why nature gave them hands.

The color chip test appears to show that people have the ability to make fine discriminations but they don’t use it to the fullest in their daily lives, clearly. Or rather some groups do and some do not, and some individuals do and some do not. Which we knew before.

As Mao Cheng Li and many others have pointed out in this thread, evolution is not purposive and to suggest that it is is fallacious. You might as well say that people evolved for the purpose of playing video games, going to the moon, or buying Dr. Changizi’s pink-tinted glasses.

There was a recently published study about blushing in the news, as I recall. I seem to remember that it maintained that people who blushed on confessing a fault were looked upon more kindly by onlookers than those who didn’t. Which suggests off hand that (in the society studied) as social communication, blushing signals submission, which may be why so it titillated 18th c. libertines like Jefferson. But, as others have remarked, also on this thread, human communications systems necessarily contain multiple redundancies. Human societies employ multiple levels (mostly culturally determined) of redundant signals, as Birdwhistle pointed out years ago, that overwhelmingly serve to convey non-aggressive intent (“I am a friend, don’t kill me”) — absolutely vital in cooperative social communities.

Presumably, the default setting of each person’s “normal” perceived skin colour would be based on the faces of the people they grew up around. This offers a possible way to test the hypothesis by measuring where that “normal” setting is and relating it to childhood ethnic background where that is different from the child’s own ethnicity. One problem here is that you’re going to find far more, say, black people who were bought as kids adopted among whites than you would the other way around. perhaps more urban backgrounds – with a wide exposure to different ethnicities as children – might yield adults with a wider perceptual range.