When a politician tells a whopper, setting the record straight may not make any difference.

Research suggests that people often cling to misinformation, even when the media point out the facts.

What’s even more surprising – and frightening – is that in some cases correcting misinformation actually makes the misperceptions worse.

Brendan Nyhan, of Duke University, and Jason Reifler, of Georgia State University, write about this “backfire effect” in When Corrections Fail: The Persistence of Political Misperceptions.

Nyhan and Reifler showed test subjects from across the political spectrum a number of mock news articles, including one that described a government report that concluded that Iraq did not possess weapons of mass destruction before the U.S. invasion.

However, after reading the article, conservatives were more likely to believe that Iraq did have WMDs. They may have viewed the information as an example of liberal media bias, the researchers speculate.

Other research also undermines the notion that people will make sound decisions if given factual information.

University of Michigan social psychologist Norbert Schwarz had people read a pamphlet that refuted myths about the flu vaccine. Within half an hour, older people thought that almost a third of the myths they had read were true.

American psychologist George Lakoff, who has written books urging Democrats to understand voter psychology, told the New York Times that trying to correct a politician’s lies often just reinforces the lie.

“In order to say someone is a liar, you have to say what the lie is,” he said.

Tom Barrett is a contributing editor at The Tyee.