In the article Twitter Strangers author Jonah Lehrer quotes Why I Stalk a Sexy Black Woman on Twitter (And Why You Should, Too) by Joel Johnson and mentions a study by Charlan Nemeth, a psychologist at UC-Berkeley. Apparently hearing dissenting opinions is all about the power of surprise. It makes us reconsider our preconceived notions, our knee-jerk reactions, it makes us stop, and think.