This color is a little like the famous pipe in René Magritte’s picture: it somehow exists, but still it doesn’t. Makes sense, right?
In the 1980s, a football coach at the University of Iowa had a brilliant idea. He ordered the walls of the visiting team’s locker room to be painted pink. The decor, he must have thought, would be a type of psychological pressure on completely unsuspecting opponents. Pink, a color culturally associated at the time with femininity and delicacy, was meant to undermine visitors’ self-confidence and their feeling of physical superiority. In 2005, the university went one step further during a large renovation project, painting the sinks, toilets and showers pink as well. While this did in fact cause many controversies—critics accused the academic decision-makers of trampling on the principles of equality and social justice—the protests didn’t go anywhere, and the locker rooms stayed pink.
The Iowa football players weren’t the first to try psychological tricks using color-based persuasion. In the 1970s similar attempts—also with pink in the starring role—were made by the American researcher Alexander Schauss. Based on his conviction that color has a key significance in regulating human emotions and temperament, in 1979 Schauss got several cells in a penal institution in Seattle painted in a hue we could describe as flamingo pink. The concept was born out of research indicating a reduction in both muscle tension and the general level of aggression in people exposed to a certain hue of pink. Tests he performed on himself, consisting in staring for a long time at variously colored squares, confirmed his conclusions: after one of these sessions, Schauss observed his pulse and breathing rate slowing specifically when he looked at pink squares. The hue, found by trial and error, was named Baker-Miller pink (from the names of officials at the prison where the color was used for the first time). It was first made by mixing half a liter of the red paint used for the prison walls into 4.5 liters of white paint. Today you can buy Baker-Miller pink in many specialized paint stores. But if you really do want to use its soothing properties, don’t just rush to your nearest hardware store. Experiments in 2015, carried out according to all the rules of scientific research, didn’t confirm the pacifying effect of the pink that Schauss designed. The University of Iowa clearly isn’t bothered by this imprecision: the pink locker rooms are still there, and their color is studiously freshened up during every renovation.
What exactly is it in the color pink that makes it so easy for us to ascribe cultural codes and meanings to it? Schauss fell victim to an overly hasty association of colors with their assumed psychological influence (and, probably also to poorly designed experiments). But it’s hard not to notice that today, pink is rife with meanings, mainly connected with gender identity and gender roles. Barbie dolls are almost a personification of this color, just like many other gadgets associated with toys for girls (ponies, princesses, mini-hairdressing sets). It’s also a fact that you either love pink or you hate it; it’s rare to find indifference to this color. And in fact, from the point of view of physics, it’s actually a color that doesn’t exist! We don’t find it in the multicolored arc of the rainbow, or the streak of colorful light cast on a wall by a prism.
The Mind’s Eye(glasses)
Let’s start with the most basic thing: the way we register color isn’t very different from how digital cameras do it. Our eyes differ from them in the details, such as the material that the light-sensitive elements are made of, or the method of sending the electrical signal that arises in the receptors bombarded by light. But the principle is similar, and based on three-color perception. Microscopic detectors of colored light in our retinas come in three varieties: some register primarily blue light, others green and still others red. The kinship with the RGB (red-green-blue) system used in digital image registration (and reproduction) is no coincidence, though in fact the receptors of “red” light in the human eye should be called something more like “yellow-orange,” if we take into account their actual sensitivity. But one thing matches up: the sensitivity ranges of the “pixels” in our retinas jointly “cover” the rainbow spectrum of visual light, ranging from the short-wave violet to the deep, long-wave red. If the classic rainbow doesn’t include the color pink, then where do our eyes (and minds) get it from?
We usually present the colorful spectrum of visible light linearly: as a perfectly known gradient in which successive colors bleed one into the next, creating all the possible combinations of hues. Let’s imagine that we could wrap such a linear spectrum into a closed ring. The violet-indigo end is then right next to the reds. We perceive intuitively that we can close this circle without hesitation by creating a gentle, tonal transition between the violets at one end and the reds at the other: then we get an infinite variety of lily purples and reddening fuchsia. Just what we need in order to “see” these seemingly physically impossible colors.
The non-spectrality of pink—the fact that seeing it requires the cooperation of two photoreceptors that service opposite ends of the color spectrum—could be one of the reasons that we perceive this color as exceptionally bright and distinctive. Biology teaches us that we’re not at all exceptional when it comes to attributing to non-spectrum colors a unique sensory potential! Ask yourself: which hues predominate in the world of flowers? Leaving aside the quite broadly recognized whites and yellows, the next most dominant color among flowering plants is pink, in all its varieties. So we shouldn’t be surprised that in most languages, the name of the color has a strictly botanical origin (more on that later). But aside from linguistics, in examining pink in nature, particularly among plants, can we perhaps find some deeper meaning? More generally, are the non-spectrum colors some kind of specially privileged (from a biological standpoint) family of colors? The issue is so complicated that the non-spectrality of a given color isn’t something universal, and depends mainly on how the photoreceptors of a particular animal register colored light. Fascinatingly, simple research exploring the spaces of colors that are “impossible” for birds has allowed us to get close to an answer to this question—but it isn’t a simple one. The stars of the experiment were what must be the most colorful organisms to be found in nature: the filigree jewels of the tropics, devilishly fast and fabulously colored hummingbirds.
Undreamt-of Colors
Birds’ color vision isn’t like ours. While we perceive three primary colors in the spectrum, (blue, green and red) and combine them to create all the other hues that the mind perceives, birds go a step further. Beyond the three color receptors known to us, avian eyes are attuned to register light that’s not visible to humans, stretching out in the rainbow spectrum beyond the boundaries delineated by red and violet. That means the hummingbirds, and along with them most other species of bird, see significantly more “nonexistent” colors, including strange and hard-to-imagine shades of pink. So in addition to “human” pink (a consequence of the simultaneous stimulation of the red and blue receptors), birds also see e.g. “ultraviolet pink” (stimulation of the red and UV receptors) and “green pink” (UV and green). Having four photoreceptors rather than three also means they have the ability to see several hues of “hyperpink,” created by stimulation of three receptors (such as red, blue and UV).
For a long time, the non-spectrum colors were fundamentally ignored by biologists. Pink (a non-spectrum color in the visible world of the primates) and its tweaked, hyperintense variants known from the ultraviolet world of birds and butterflies, was silently treated like every other, “normal” spectral color. Researchers seemed not to notice one quite surprising fact. In the plant world—and to be precise, in the reality of its colorful flowers—the non-spectrum colors aren’t a rarity. In fact, they’re almost the rule! Pink, purple, lily and powder pink are some of the most commonly encountered flower colors. That’s primarily because of the ease with which they can be created in plant tissues: all of them are based on anthocyanins, pigments that are present in the cells of almost all land plants. The ubiquity of anthocyanins is a result of their relatively uncomplicated biosynthesis path, while their high concentration in the colorful parts of plants arises from their ideal signaling properties. Anthocynanins can easily produce a whole range of colors: from deep red, through pink, purple and lily, to the violet-pink colors. The colorful versatility of these pigments is caused by their sensitivity to their environment: in acidic conditions they’re red, in base ones, blue or violet. So, steering the reaction of an anthocyanin solution allows plants to create all the imaginable hues of pink or purple. And this isn’t the end of plants’ affinity for “nonexistent” colors. In addition to the colors we humans can see, flowers can also generate the most varied combinations of visible and ultraviolet colors.
American researchers on hummingbirds recently took up the theme of non-spectrum flower colors. These miniature jewels of the bird world, agile as the fastest insects, are colored like the most masterful works of the jeweler’s art. They live on the nectar of flowers, so it would be logical that their vision is particularly good at handling the non-spectrum colors that are so typical for their food source. In building a range of non-spectrum colors to later teach their research subjects to associate them with certain rewards, these scientists demonstrated that hummingbirds do indeed perfectly distinguish even the most subtle variants of pinks and the birds’ “hyperpinks.” What’s more, it turns out that the birds’ feathers, which shimmer with all the colors of the rainbow, also use the non-spectrum richness of the ultraviolet universe. Hummingbirds don’t just live in a world colored by all the surreal, hard-to-imagine hues of pinkness, they’re the personification of this reality, taking the biological possibilities of the sense of sight to the absolute limit.
Subtle Ambiguities
As humans, we’ll never have access to hummingbirds’ hyperpink world. The reality seen by human eyes is a three-color one, and imagining a version expanded to include another dimension, the ultraviolet, is a task just as arduous as trying to broaden out our three-dimensional space to include a fourth one. Here, we can make a clumsy approximation, using various simple assumptions, but we’ll never see this world in its entirety. Still, even the “ordinary” human pink carries a huge symbolic and cultural charge.
Let’s start from the name: it’s hard to say whether because of its fundamental non-spectrality or its unavoidable duality (is it still red, or already violet?), names for the color pink are a relatively late addition in most languages. In many, there’s no such color: the Celtic languages describe pink as “whitish red;” in Danish and Finnish it’s “bright red;” and in Icelandic simply “pale.” The Chinese say “powder red,” and in Japanese, depending on subtle differences of the hue being described, “peach” or “cherry” (both of which come from the color of the trees’ flowers).
Something that evidently goes beyond just the ambiguity of the name is the place that the color pink occupies in our collective cultural consciousness. When I say “our,” of course, I mean the so-called Western cultural space. In it, pink is treated as a synonym for emotionality, delicacy, sensuousness—attributes that are traditionally, stereotypically attributed to the feminine. Few colors have such a strong cultural connotation, which is interesting not only because we’re talking here about a non spectral color. Attempts have been made to demonstrate that the “femininity” of pink is in some way inborn, coded in the primary perception mechanisms of our brains. And insofar as research conducted within that same Western cultural space indicate a certain tendency for women to favor warm colors, and hues of purple that are closer to pink (with a certain preference for cooler colors, blue and blue-green, among men), research that’s broadened out to cultures that aren’t rooted in the Old Continent don’t give such unambiguous results. In fact, research in African hunter-gatherer societies showed that they have no gender divide when it comes to preferred colors and hues.
So it seems that pink and its gender connotations remain one of the most spectacular examples of cultural mutation. Many studies indicate that before the mid-twentieth century, the sexes weren’t so strongly polarized in terms of the colors associated with them. Little children, regardless of gender, were dressed both in pink and blue. There was even a suggestion that at the beginning of the twentieth century, the cultural tendency may have been the opposite, and pink, as more decisive and expressive, was identified as a color that fit better with boys. Still, this concept and the related “reversal of colors’ gender” that supposedly happened around the 1950s aren’t convincingly confirmed in the sociological data. A strong, in fact reflexive, association of pink with femininity is thus almost certainly a cultural distortion, which through a series of feedback loops, has become grounded in our consciousness. There’s a reason why this deep polarization dates to a period in which many feminine personas of the political and cultural world (Mamie Eisenhower, Marilyn Monroe, Brigitte Bardot) were the trendsetters, notoriously appearing in pink stylizations that fully capitalized on the treasury of newly discovered, longer-lasting and brighter pink pigments.
Would the pink fashion revolution of the mid-twentieth century, and the spreading tight association of archetypical femininity with the color pink that followed it, have been possible without the exceptional biology of how it’s seen? The non spectrality of pink and the related nuances concerning the way it’s processed in our brains may lie at the heart of the perceived brightness of this color, and thus, its attractiveness in situations that demand bold, stunning messages. We’ll never know for sure; the thing about such cultural patterns is that over time it’s harder and harder to separate them from frequently subtle biological conditions. So nothing remains for us but to examine this cultural experiment. Who knows? Maybe in a few decades the pink-blue polarization will completely disappear, or be replaced by another, equally mysterious color code? We shall see (literally!)
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