John Tierney in the New York Times Science Blog:
So these five hundred social psychologists walk into a ballroom. They sit through a symposium entitled Cognitive Dissonance Theory Celebrates 50th Birthday. Afterwards there is birthday cake for everyone – two birthday cakes, actually. One is chocolate; one’s white. Neither looks particularly better than the other.
Suppose you’re in line with them for cake. You can have only one piece. You ask a social psychologist for help in choosing. He hasn’t tasted either one, but he says confidently, “Well, one is obviously going to be much, much tastier than the other.”

