Seventy percent of presidential ads have been negative so far this year. Why?
Negative ads don't affect voter turnout and they don't change minds of voters who are already decided.
Negative ads do inspire people to seek out more information about the issues.
We are emotionally wired to pay attention to negative information.
In a new political ad Mitt Romney is portrayed as a job-destroyer who is out of touch with the American working class. With the message, Barack Obama's campaign takes part in an age-old political tradition -- the attack ad.
And even though voters overwhelmingly say they hate negative political advertising, attack ads are becoming more common -- presumably because they sway voters.
Why do negative political ads work?
Reasons, experts say, are emotional and psychological -- and partly up for debate. Studies show that negativity doesn't affect voter turnout. Nor does it sway those who are already convinced one way or the other.
Instead, the power of negativity may lie in its ability to compel people to seek out more information about candidates, in turn influencing the undecided.
"Advertising matters at the margins," said political scientist Erika Franklin Fowler, director of the Wesleyan Media Project, which tracks political advertising at Wesleyan University in Conn. "We never see ads that take a candidate from 20 percent to 70 percent of the vote. But when you have a country that is divided 50/50, every percentage point counts. That's where advertising makes a difference."
Negativity has been around as long as elections have, Fowler said, but the practice has recently become more prevalent than ever. In a 2008 study, Fowler's research group looked at hundreds of thousands of presidential ads from the year before and found negativity in nine percent of those ads.
A more recent study found that 70 percent of presidential ads were negative through April 22 of this year. The huge jump is partly because of a rise in activity by interest groups, but more than half of this year's candidate-sponsored ads have focused on negative details about opponents.
One reason that negative messages are so compelling is that we are emotional creatures, wired to pay attention to harmful information, said Joel Weinberger, a psychologist at Adelphi University in New York and owner of Implicit Strategies, a consulting firm that investigates unconscious influences on behavior.
"Think of our ancestors on the African savannah," he said. "If you miss a leopard, it's over for you. If you miss a deer, oh well, you're hungry. People are more focused on negative information. People stop for a car wreck, but there are no traffic jams for beautiful flowers. "
"In negative ads, they make a narrative for you that is supposed to brand the person," he added. "People say, 'I hate negative ads, they do nothing for me,' while unconsciously processing them. Emotion trumps cognition."
In a study for a 2008 appearance on Good Morning America, Weinberger and colleague Drew Westen found that undecided voters became subliminally hung up on words used in negative political ads, even though they insisted that the ads had no effect on them.
The test that the researchers used asked people to name the colors of various words. And even though participants are not supposed to pay attention to the actual words, it takes them longer to respond if the words hold emotional resonance for them.
Six months later, the researchers found, adjectives used to describe candidates in ads still held power over viewers.
The best way for a candidate to combat negative ads, Weinberger said, is to immediately fire back. Doing nothing allows his opponent's message to sink in, whether true or not.
As grating as they can be, negative ads aren't all bad, Fowler said. Studies show that negative ads contain more information, and they inspire people to seek out even more knowledge about the issues.
"Negativity has informational benefits, especially for citizens that don't necessarily tune into politics," she said. "It's more beneficial for democracy if citizens show up for polls better informed as a consequence."