"We tend to think of coolness as a pose that you strike with a pair of sunglasses, a nonchalant attitude, and drink in hand. But maybe we didn't choose these social accessories at random. Maybe we've adopted dark glasses, relaxed body language, and alcohol as signifiers precisely because they camouflage signs of a nervous system on overdrive. Sunglasses prevent others from seeing our eyes dilate with surprise or fear; we know from Kagan's work that a relaxed torso is a hallmark of low reactivity; and alcohol removes our inhibitions and lowers our arousal levels. When you go to a football game and someone offers you a beer, says the personality psychologist Brian Little, "they're really saying hi, have a glass of extroversion."