Valentine’s Day is nearly upon us, that sweet Hallmark holiday when you can have anything your heart desires, so long as it’s red. Red roses, red nighties, red shoes and red socks. Red Oreo filling, red bagels, red lox.
As it happens, red is an exquisite ambassador for love, and in more ways than people may realize. Not only is red the color of the blood that flushes the face and swells the pelvis and that one swears one would spill to save the beloved’s prized hide. It is also a fine metaphoric mate for the complexity and contrariness of love. In red we see shades of life, death, fury, shame, courage, anguish, pride and the occasional overuse of exfoliants designed to combat signs of aging. Red is bright and bold and has a big lipsticked mouth, through which it happily speaks out of all sides at once. Yoo-hoo! yodels red, come close, have a look. Stop right there, red amends, one false move and you’re dead.
Such visual semiotics are not limited to the human race. Red is the premier signaling color in the natural world, variously showcasing a fruitful bounty, warning of a fatal poison or boasting of a sturdy constitution and the genes to match. Red, in other words, is the poster child for the poster, for colors that have something important to say. “Our visual system was shaped by colors already in use among many plants and animals, and red in particular stands out against the green backdrop of nature,” said Dr. Nicholas Humphrey, a philosopher at the London School of Economics and the author of “Seeing Red: A Study in Consciousness.” “If you want to make a point, you make it in red.”
What is it, then, to see red, to see any palette at all? Of our famed rods and cones, the two classes of light-sensing cells with which the retina at the back of each eye is supplied, the rods do the basics of vision, of light versus shadow, tracking every passing photon and allowing us to see by even a star’s feeble flicker, though only in gunmetal shades of black, white and grim. It is up to our cone cells to capture color, and they don’t kick in until the dawn’s earylish light or its Edisonian equivalent, which is why we have almost no color vision at night.
Cones manage their magic in computational teams of three types, each tuned to a slightly different slice of the electromagnetic spectrum, the sweeping sum of lightwaves that streams from the sun. As full-spectrum sunlight falls on, say, a ripe apple, the physical and chemical properties of the fruit’s skin allow it to absorb much of the light, save for relatively long, reddish lightwaves, which bounce off the surface and into our greedy eyes. On hitting the retina, those red wavelengths stimulate with greatest fervor the cone cells set to receive them, a sensation that the brain interprets as “healthy, low-hanging snack item ahead.”
In fact, human eyes, like those of other great apes, seem to be all-around fabulous fruit-finding devices, for they are more richly endowed with the two cone types set to red and yellow wavelengths than with those sensitive to short, blue-tinged light. That cone apportionment allows us to discriminate among subtle differences in fruit ruddiness and hence readiness, and may also explain why I have at least 40 lipsticks that I never wear compared with only three blue eye shadows.
Whatever the primary spur to the evolution of our rose-colored retinas, we, like most other animals with multichromatic vision, have learned to treat red with respect. “In the evolution of languages,” Dr. Humphrey writes, “red is without exception the first color word to enter the vocabulary,” and in some languages it’s the only color word apart from black and white. It’s also the first color that most children learn to name, and that most adults will cite when asked to think of a color, any color.
Red savors the spice of victory. Analyzing data from Olympic combat sports like boxing and tae kwon do, in which competitors are randomly assigned to wear red shorts or blue, Dr. Russell Hill and his colleagues at the University of Durham in Britain found that the red-shorted won their matches significantly more often than would be expected by chance alone. What the researchers don’t yet know is whether the reds somehow get an subconscious boost from their garb, or their blue opponents are felled by the view. After all, said Dr. Geoffrey Hill, a biology professor at Auburn University  in Alabama and no relation to Russell Hill, “I’ve seen some of my biggest, toughest students, these tough, athletic guys, faint right to the floor at the sight of one drop of bird’s blood.”
Red refuses to be penned down or pigeonholed. It has long been the color of revolution, of overthrowing the established order. “Left-wing parties in Europe have all been red,” Dr. Humphrey said, “while the conservatives, in Britain and elsewhere, go for blue.” Yet in the United States, the color scheme lately has been flipped, and the red states are said to be the guardians of traditional values, of mom and pop, of guns and red meat.
Context, too, changes red’s meaning. A female bird may be attracted to the bright scarlet sheen of a male’s feathers or of a baby bird’s begging mouth, but will assiduously avoid eating red ladybugs that she knows are packed with poisons.
Given red’s pushy reputation, design experts long thought people felt uncomfortable and worked poorly when confined to red rooms. But when Dr. Nancy Kwallek, a professor of interior design at the University of Texas  at Austin, recently compared the performance of clerical workers randomly assigned for a week to rooms with red, blue-green or white color schemes, she found that red’s story, like the devil, is in the details. Workers who were identified as poor screeners, who have trouble blocking out noise and other distractions during the workday, did indeed prove less productive and more error prone in the red rooms than did their similarly thin-skinned colleagues in the turquoise rooms. For those employees who were rated as good screeners, however, able to focus on their job regardless of any ruckus around them, the results were flipped. Screeners were more productive in the red room than the blue. “The color red stimulated them,” she said, “and they thrived under its effects.”
And the subjects assigned to the plain-vanilla settings, of a style familiar to the vast majority of the corporate labor force? Deprived of any color, any splash of Matisse, they were disgruntled and brokenhearted and did the poorest of all.