Attack ads can work or flop

If John McCain and Barack Obama think their ads blasting each other are persuading undecided voters, they're probably wrong. But negative ads do have an impact, an AP-Knowledge Networks poll suggests, even if it's just to neutralize the other guy's attacks.

They can also solidify support – or turn voters off to both candidates.

In a new survey, voters were asked to watch two of the presidential candidates' negative ads, an Obama spot that says McCain would tax health benefits and a McCain ad that claims Obama wants “massive government.” The campaigns have spent millions of dollars on such ads with millions more committed for the last two weeks before Election Day.

On the whole, ad watchers who went into the experiment undecided were unmoved. About 60 percent of so-called “persuadable” voters said the ads made them no more or less likely to vote for McCain or Obama. And about a third appeared to throw up their hands, saying they were less likely to vote for either candidate after watching the ads.

Are this year's ads fair?

More than half the voters polled believe presidential campaign commercials have been unfair or somewhat unfair. And the more ads they said they had watched, the less fair they found them. As for poll respondents' views about what they see on TV, about four of 10 said Obama's ads mostly attack, while about seven of 10 said that of McCain's.

The Associated Press-Knowledge Networks poll was conducted Oct. 10-12, a time when McCain was drawing particular attention for questioning Obama's relationship with 1960's militant William Ayers.

“It's not just McCain's negative ads, it's also the news media's coverage,” said John Geer, a political scientist at Vanderbilt University and author of “In Defense of Negativity: Attack Ads in Presidential Campaigns.” “The news media have given McCain a bit of a hard time for running negative ads, and I think that's also shaping the public's perception.”