Contrary to what many believe, the central effect of such negative advertising isn’t to move voters from supporting another candidate to backing yours, as Mitt Romney and his allies have discovered during this primary season. The main effect is not even to move undecided voters into your column. No, the real effect of negative advertising is to energize and solidify support among your ideological base while turning everyone else off to the other candidate, the campaign and the entire electoral process. Negative advertising isn’t about changing minds; it’s about altering the composition of the voter pool on Election Day by turning moderate voters into non-voters.The Washington Post’s Stephen Pearlstein • Offering a counterpoint to Ezra Klein’s point from the other night; Pearlstein suggests politicians want people to turn off from the political process, because it helps them stabilize the electoral pool come election time. Which is how we get stuff like Obama eating dog food on an Etch A Sketch with Mitt Romney’s face drawn on it, or something like that.