Have you seen the photo of Republican vice presidential nominee Sarah Palin brandishing a rifle while wearing a U.S. flag bikini? Have you read the e-mail saying Democratic presidential nominee Barack Obama was sworn into the U.S. Senate with his hand placed on the Koran? Both are fabricated -- and are among the hottest pieces of misinformation in circulation.

 

As the presidential campaign heats up, intense efforts are underway to debunk rumors and misinformation. Nearly all these efforts rest on the assumption that good information is the antidote to misinformation.

 

But a series of new experiments show that misinformation can exercise a ghostly influence on people's minds after it has been debunked -- even among people who recognize it as misinformation. In some cases, correcting misinformation serves to increase the power of bad information.

 

In experiments conducted by political scientist John Bullock at Yale University, volunteers were given various items of political misinformation from real life. One group of volunteers was shown a transcript of an ad created by NARAL Pro-Choice America that accused John G. Roberts Jr., President Bush's nominee to the Supreme Court at the time, of "supporting violent fringe groups and a convicted clinic bomber."

 

A variety of psychological experiments have shown that political misinformation primarily works by feeding into people's preexisting views. People who did not like Roberts to begin with, then, ought to have been most receptive to the damaging allegation, and this is exactly what Bullock found. Democrats were far more likely than Republicans to disapprove of Roberts after hearing the allegation.

Bullock then showed volunteers a refutation of the ad by abortion-rights supporters. He also told the volunteers that the advocacy group had withdrawn the ad. Although 56 percent of Democrats had originally disapproved of Roberts before hearing the misinformation, 80 percent of Democrats disapproved of the Supreme Court nominee afterward. Upon hearing the refutation, Democratic disapproval of Roberts dropped only to 72 percent.

 

Republican disapproval of Roberts rose after hearing the misinformation but vanished upon hearing the correct information. The damaging charge, in other words, continued to have an effect even after it was debunked among precisely those people predisposed to buy the bad information in the first place.

 

Bullock found a similar effect when it came to misinformation about abuses at the U.S. detention facility at Guantanamo Bay, Cuba. Volunteers were shown a Newsweek report that suggested a Koran had been flushed down a toilet, followed by a retraction by the magazine. Where 56 percent of Democrats had disapproved of detainee treatment before they were misinformed about the Koran incident, 78 percent disapproved afterward. Upon hearing the refutation, Democratic disapproval dropped back only to 68 percent -- showing that misinformation continued to affect the attitudes of Democrats even after they knew the information was false.

 

Bullock and others have also shown that some refutations can strengthen misinformation, especially among conservatives.

Political scientists Brendan Nyhan and Jason Reifler provided two groups of volunteers with the Bush administration's prewar claims that Iraq had weapons of mass destruction. One group was given a refutation -- the comprehensive 2004 Duelfer report that concluded that Iraq did not have weapons of mass destruction before the United States invaded in 2003. Thirty-four percent of conservatives told only about the Bush administration's claims thought Iraq had hidden or destroyed its weapons before the U.S. invasion, but 64 percent of conservatives who heard both claim and refutation thought that Iraq really did have the weapons. The refutation, in other words, made the misinformation worse.

 

A similar "backfire effect" also influenced conservatives told about Bush administration assertions that tax cuts increase federal revenue. One group was offered a refutation by prominent economists that included current and former Bush administration officials. About 35 percent of conservatives told about the Bush claim believed it; 67 percent of those provided with both assertion and refutation believed that tax cuts increase revenue.

 

In a paper approaching publication, Nyhan, a PhD student at Duke University, and Reifler, at Georgia State University, suggest that Republicans might be especially prone to the backfire effect because conservatives may have more rigid views than liberals: Upon hearing a refutation, conservatives might "argue back" against the refutation in their minds, thereby strengthening their belief in the misinformation. Nyhan and Reifler did not see the same "backfire effect" when liberals were given misinformation and a refutation about the Bush administration's stance on stem cell research. Bullock, Nyhan and Reifler are all Democrats.

 

Reifler questioned attempts to debunk rumors and misinformation on the campaign trail, especially among conservatives: "Sarah Palin says she was against the Bridge to Nowhere," he said, referring to the pork-barrel project Palin once supported before she reversed herself. "Sending those corrections to committed Republicans is not going to be effective, and they in fact may come to believe even more strongly that she was always against the Bridge to Nowhere."