and john geer is a professor of political science at vanderbilt university and the author of "in defense of negativity: attack ads in presidential campaigns." is welcome. >> you both to the newshour, we're not talking about a massive shift here. >> everybody has got a conscious all of a sudden in this industry. >> that's right. >> i mean it was-- we said it was 2 and 10, now 3 and 10 so far this year but why any more positive ads. >> i think it is a combination of reasons. first of all i do think there was some negative fat agency where people felt there was some of negative ads it didn't work in many cases so there was a tendency let's tripos difficult. >> woodruff: what dow mean, when you said they didn't work in many cases what dow mean. >> people were looking at polling data in a lot of the senate races and so forth where there was this overwhelming negative ads and didn't see allots of polling numbers. so the conclusion that pollsters came up with is evidently negative ads don't work like they used to. in fact i would argue political ads don't work in general like they used to. unin