Red and Yellow Kills a Fellow

I'll have a danger burger and hazard fries. To glow, please.

Why do we use red and yellow to alert us to fast food and danger? Red/yellow says, "The food's good here and pretty cheap, too," and, out of the other side of its signifying mouth cries, "Watch out! Trouble ahead!"

The National Fire Protection Association uses color-coded warnings in which red indicates flammability, and yellow indicates reactivity. The U.S. Department of Transportation identifies the Pantone colors for its traffic signs, reserving red (187), yellow (116), and orange (152) for the most important cautionary signs. At the same time, hundreds of fast-food joints and cheap eateries rely on the red/yellow/orange combo, their exit-ramp signs blooming from Seattle to Shanghai. If you jumble these signs together, the Toxic Hazards with the Taco Palaces, you'd be unable to distinguish one species from another based on plumage (Figs. 1, 2). You'd need words and context.

So do we instinctively associate danger with these colors? After all, Mother Nature warns us with the red and yellow of the poisonous coral snake (red on yellow kills a fellow/red on black, venom lack). If not by instinct, then perhaps by experience we learn to associate danger with red and yellow. Either way, do fast-food folks bait us with danger colors and then switch to assuring us of the proximity of rice noodles and cheesesteak?

One 1989 theory posits the reverse: that mammals developed the ability to distinguish between red, yellow and orange in order to identify ripe fruit. Fossil evidence suggests early primates lived on a diet of fruit, and a 2002 study showed human vision to be better adapted to perceiving fruit scenes than other random nature scenes. If this is true, then do we glimpse the red of a stop sign and salivate for cherry pie? And why, then, are poisonous snakes and frogs as brightly colored as any still life by Matisse? Fortunately, the brain doesn't encode experience with the binary inflexibility of a machine. We are more than what is dreamt of by primates and professors.

We read signs in context. So maybe red and yellow are popular for just plain standing out against the background. Traffic signs pop against the brown and green of the highway, and burger beacons shine against the cloudy skies above exit ramps. In eye-level clusters, however, they're a mess, mixing with the other colors of the suburban sprawl and urban glut, industrial gray and mini-mall brown. And besides, highway signs are also blue, green and brown; commercial districts feature signage of more hues than seen on the Cartoon Network; and regardless of background, red and yellow show up helter skelter on other kinds of logos-from the Marines to my high school and from DHL to Shell Oil (Fig. 3).

Every culture imbues its colors with positive and negative connotations. Yellow is joy and cowardice, the color of oak-tree ribbons and jaundice, Asian spirituality and Egyptian mourning. Red is love and vengeance, valentines and spilled blood, symbolizing good luck and celebration in China and India and in other countries standing for socialism and slasher films. Everywhere, red and yellow are the fireworks of autumn. While red and yellow can be as beautiful as the robe of a Chinese emperor, they can also be as ugly as the dollops of ketchup and mustard on a cold beef patty.

Still, there's no denying the overwhelming consistency of red/yellow/orange in the realms of danger and food service, which is interesting given that the color with the least universally negative connotations is blue (blue in the realm of food reeks of mold, however, something gone bad). Maybe there's something to the slightly ugly look of red and yellow. It's candy corn and hot sauce but not fine dining, jewelry stores, or anything upscale. If red and yellow stand out, you watch out. If they stand out and look cheap, then it's time to eat. Pick Up Stix, for example, is a Asian restaurant franchise whose reds and golds, according to its executive director of marketing, "reflect spice, flavor and heat."

But this, too, begs the question. Do we glimpse, out of the corners of our eyes, that snatch of red, that blur of yellow, and reflexively look to determine fire or food, hazard or hamburger?

"Colors are constructs of the brain, not physical realities, and the presumption would thus be that whatever color or color combination is most appealing to humans is attractive because of some ecological/evolutionary advantage," explains Dale Purves, M.D., Director of the Center for Cognitive Neuroscience at Duke University.

"While the current evolutionary arguments are interesting, they suffer from being purely correlational," continues R. Beau Lotto, PhD, of University College London. Colleagues Lotto and Purves (with Surajit Nundy) co-authored the general-audience neuroscience book, Why We See What We Do: An Empirical Theory of Vision. "We've no idea whether the pressure that drove the evolution of our receptors was the ability to detect ripe red fruit on green backgrounds, since there are so many other potential correlations one could find. There's even a study suggesting we adapted to detect blushing. The receptors of bees are maximally tuned to detect the "colors" of flowers. However, rather than the eye adapt to flowers, current evidence suggests it was just the reverse: flowers adapted to be detectable by bees and other insects/birds. It is nonetheless true that we can detect some wavelengths better than others, simply because of the physics and physiology of our extant system. Why this is so isn't known."

Purves and Lotto argue that how we see depends as much on experience as on eyeballs. To avoid being tricked by optical illusions, we judge what we see against what we've seen in the past. That is, we interpret visual cues against our experience. Scientists might not yet know why certain colors are such strong visual cues for us, but they do know that we can learn to attach meaning to certain color combinations.

We see color in order to recognize things faster and see them better. So argues Karl R. Gegenfurtner (Department of Psychology, Gießen University in Germany) and Daniel C. Kiper (Institute of Neuroinformatics, University of Zürich in Switzerland) in their article "Color Vision," which surveys past visual experiments. Our ability to detect color helps us see objects, distinguish elements in our environment, and improve our memory of what we've seen. We see color early in our visual process, at the stages of the retina and lateral geniculate nucleus (LGN), where the color signals (in three separate color-opponent channels) are transmitted to the cortex. Gegenfurtner and Kiper argue that many areas of the brain, rather than a single devoted area, work to help us perceive and process color information.

"Concerning early processing," says Professor Gegenfurtner, "it is known that people have vastly different ratios of L- and M-cones (red and green cones), but they all have pretty much the same unique yellow. It seems like the system is self-calibrating." And what about red? "I don't really know why red is such a good warning signal," he says. "It might have to do with the extremely high sensitivity of the red-green system. In fact, Charles Stromeyer and colleagues from Harvard (Chaparro et al, Nature, 1993) have shown that the eye is best suited to detect small red (or green) spots of light."

While scientists continue to explore why we notice certain colors more than others, the explanation for the Jekyll/Hyde symbolism of red and yellow might lie more in our culture than in our craniums. So can we blame McDonald's for linking red and yellow to fast food?

Before McDonald's, red and yellow had a cautionary history in America. Standardizing traffic signs in 1924, highway departments required stop signs to have white letters on red while caution signs had black letters on yellow. The first lone McDonald's opened in 1940 in San Bernadino, California, and catered to drive-up customers. In 1948, it ditched the carhops and delivered the world's first fast-food burgers. In that same year, Nels Garden, one of the heads of the University of California Radiation Laboratory in Berkeley, objected to yellow as a background color for the newly designed radiation symbol because yellow was too commonly used as a warning. Testers cut out the three-bladed radiation symbol (evoking sun rays) in magenta and stuck them to colored cards twenty feet away. A committee chose magenta on yellow as the best combination. Four years later, the first pair of golden arches reflected the rays of the Arizona sun. The golden arches were added as an architectural flourish in 1953, a year before Roy Kroc showed up (Kroc launched the franchise in 1955; other 1954 visitors included the founders of Burger King and Taco Bell). In the 1960s, the arches were removed from the brick and mortar and installed in the logo.

McDonald's grew into a global behemoth, begetting its thousands of red-and-yellow fast-food children all over the world, to the extent that it's possible most people today, when confronted with blank blobs of red and yellow, might think, "Big Mac," before they think "traffic warning" or "radiation" or "fire hazard."

With McDonald's having done the work of spreading the red-and-yellow gospel, maybe fast-food joints decided to ride the golden coattails. And once fast-food joints asserted their red-and-yellow identity, turning red and yellow into the colors of fast food and cheap dining in general, restaurant newcomers might recognize the value to be gained by sticking with the pack, calling all drivers and passersby to the fast-food rows of Denver and New Delhi.

"For those companies that don't have strong brand recognition, the me-too approach is hard to go against," acknowledges Leslie Harrington, principal of LH Color, a consulting and research firm that helps companies better use color in their products and brands. "It would be very hard for the smaller restaurants on Main Street, USA, to challenge the paradigm. It's also difficult for McDonald's to ever change because they created the monster. They're in the same boat as UPS, which owns brown whether they like it or not."

The uniformity of the global McDonald's brand has likely colored the brand of global fast-food. The widespread use of red and yellow may reveal less about the peculiarities of our culture and the neuroscience of our vision than it does about the economics of our habits.

If there's one lesson to be learned, it's this: If fast food endangers our health, we can't say the colors didn't warn us.