Check this out: a 1996 study of placebo pills published in the British Medical Journal shows that red placebos are more effective as stimulants and blue placebos are more effective as sleep aids. Another one: a study of Greco-Roman wrestling at the 2004 Olympics shows that wrestlers randomly assigned red rather than blue uniforms won 55 percent of the matches. More? There’s evidence that blue outdoor lighting may reduce crime.
You’ve heard it before, and science bears it out: color influences your mood. Heck, color influences you even when you aren’t aware that you’ve seen the color. For example, in a study reported in Psychological Science, when green, blue, or white discs were flashed, even when subjects weren’t aware of the color they had seen, it affected their later perceptions of other colors. In this experiment at least, it’s not as if the unconscious perception of color turned pussycats into tigers, but it shows that you don’t have to be aware of color for it to affect you.
If you believe the traditional view that our ability to see color evolved so that we could figure out which fruit is ripe, the effect of color on our emotions doesn’t make much sense. Why should an unripe fruit make us calm and a ripe fruit make us agitated? But what if the human ability to sense colors with our eyes evolved not to gauge the color of fruit but to help us read emotions? See, it turns out that the color-sensing cones in our eyes are exactly optimized to detect changes in color due to blood oxygenation—the red of oxygenated blood and the blue of blood carrying less oxygen through the bloodstream. And the primates who have evolved the ability to see color are also the primates whose hairless faces and/or rumps let us display emotions through our blood-rich skins.
While it’s important to know which fruit is best to eat, it may be even more important to know the emotions of those around you while you’re eating. And once millions of years of evolution trained the human brain to see red as aggressive and blue as calming, it’s not as though a puny little thing like your cognitive mind can just override it. Now when a wrestler sees his or her opponent in a red one-piece, it seems as if that opponent is aggressive and angry. Maybe wearing a red one-piece even makes that opponent slightly more aggressive and angry. Because the basic biology of your eyes is optimized to recognize these colors and your brain has evolved to interpret them, you may feel just a touch meeker standing there in your blue suit. Or you might expect that a blue pill will make you feel as if your blood is deoxygenated and a red pill will make you feel full of pepped-up hemoglobin.
Or you might find yourself stressed and steaming in a red office, whereas you could find yourself calm (and sleepy?) in a blue office. The question of what color you should paint your office comes down to how you need to feel while at work. Paint it red if you need aggression. Paint it blue if you need to chillax.