Teenagers often act dumber around other teenagers. Steinberg, a psychologist at Temple University, put people of various ages in a simulated driving game with streets and stoplights. Adults drove the same, whether or not they had an audience. But teenagers took twice as many “chances”—like running a yellow light—when their friends were watching. Teenagers are exquisitely sensitive to the influence of their peers. The precise definition of coolness may change over time, from cigarettes to Snaps, but the deep animal need to possess it does not.
