Sarah: I think there are two arguments for political yard signs. One is that friends or neighbors who respect you might think, "Huh. If Sarah supports Kerry, there must be something good about him because Sarah is so nice." The other, more compelling argument, is that it's a form of "brand recognition," just like when Coke advertises even though everyone has opinions already about Coke vs. Pepsi. Various studies have shown that this type of advertising does, in fact, make a difference in attracting customers/voters.