In the idealistic world of U.S. politics, it is tempting to believe that, this time, things will be different. Barack Obama gives a rousing speech at the Democratic convention that dares Americans to dream. In an ad, John McCain acknowledges Mr. Obama's moment. Mr. Obama returns the compliment by praising Mr. McCain's war record. Relatively speaking, the gloves are still on. But they will come off, and the campaign will get personal. In this respect, the future will be like the past.
But here's the thing: Attack ads are good for us. And it's pointless to resist negative political advertising. It's there for a simple reason: It works.
One of the earliest, and most famous, attack ads was used by Lyndon Johnson against Barry Goldwater in the 1964 presidential campaign. The ad portrayed a young girl counting slowly as she picked the petals from a daisy, while an ominous male voice counted down to zero and a mushroom cloud appeared. By implication, a vote for Barry Goldwater was a vote for nuclear war; Mr. Goldwater never did become president.
In 1988, George H. W. Bush launched a negative ad attacking Michael Dukakis's policy on crime: The ad featured convicted murderer Willie Horton, who had kidnapped a young couple while on weekend release under Mr. Dukasis's prison furlough program. In 2004, George W. Bush's campaign benefited from "swift boat" ads that questioned rival John Kerry's Vietnam War record.
Attack ads work in politics because political campaigns are different from advertising soap or shampoo. Voter psychology, timing and competition make it inevitable that one or both sides will use negative ads during a campaign.
Pre-existing beliefs: We are bombarded with thousands of advertising messages each day, so we gloss over those that have little meaning for us and latch on to those that bear some resemblance to what we already believe. So great ads take account of people's existing beliefs and build on them. Because people are cynical about politicians, they are more prepared to believe negative messages than positive ones. Although Mr. Kerry had a distinguished war record, the swift boat ads exploited the belief that, as a politician, he had to be hiding something.
Gains versus losses: Psychological research shows that losses loom larger than gains: We tend to avoid the negative rather than embrace the positive. Negative advertising plays on this bias against potential loss by pointing out the undesirable consequences of voting the wrong way: We worry about how an inexperienced candidate such as Mr. Obama might handle a difficult situation, rather than focus on the fresh thinking that comes with inexperience. Positive advertising, by contrast, has a tougher job to do - so Mr. McCain will find it easier to point out Mr. Obama's lack of experience than to convince voters of his own reliability.
Compressed time: In business, advertising campaigns are designed to build brand equity over time. But election ads are different - everything has to happen within a few weeks. So it's important to have a simple message. Negative ones fit the bill, because all you're doing is bringing existing fears to the surface rather than asking viewers to think about new ideas.
No glass houses: Most businesses avoid targeting their competitors because there is every chance their competitors could retaliate with negative ads of their own. This happens in political campaigns, of course, but political campaigns have an end point: election day. For this reason, you are likely to see more attack ads as the campaign draws to a close.
Inoculation: Negative advertising has a way of neutralizing the other side's positive message by "immunizing" viewers to it. In a way, it shifts your frame: If you've just seen an ad criticizing Mr. McCain's age, you're more likely to be skeptical when Mr. McCain advertises his greater experience.
Winner takes all: No one wants to be second in a presidential election. So winning is often about making the other party lose. Using positive ads can leave you vulnerable to attack by the other side, but negative ads keep the opposition on the defensive.
This may all seem very sad - that politicians cynically exploit psychology to show that, no matter how bad they are, the opposition is worse. But there's a positive side: We're electing public servants, not gods. Negative ads remind us that politicians are flawed, just like the rest of us. If our expectations are low, we can't be disappointed when they turn out to be, well, human. The alternative, of creating idols, is worse - as charismatic dictators have shown for centuries.
Besides, scandals are salaciously interesting: They spice up that bland and boring tofu and make it palatable. Relax, and enjoy the meal. It's good for you.
David Dunne teaches marketing and advertising at the University of Toronto's Rotman School of Management.
