It’s a social scientist’s curse—what you most want to get at is exactly what your subjects are most eager to hide. This tendency is called social desirability bias, and it’s well documented: the world over, respondents answer questions in ways that make them look good. The most famous case was the so-called Bradley effect: in 1982, California voters told exit pollsters they had elected a black governor, Tom Bradley, by a significant margin, but in the privacy of the ballot box they had actually given his white opponent a narrow victory.
