This natural human tendency explains why it’s so hard to dislodge false rumors and factual errors. Corrections can even be self-defeating, leading people to stronger commitment to their erroneous beliefs.

A few years ago, for example, both liberals and conservatives were provided with correct and apparently credible information showing that the George W. Bush administration was wrong to think that Iraq had an active unconventional weapons program. After receiving the correct information, conservatives became even more likely to believe that Iraq had such weapons and was seeking to develop more.

The news here is not encouraging. In the face of entrenched social divisions, there’s a risk that presentations that carefully explore both sides will be counterproductive. And when a group, responding to false information, becomes more strident, efforts to correct the record may make things worse.

Can anything be done? There is no simple term for the answer, so let’s make one up: surprising validators.

People tend to dismiss information that would falsify their convictions. But they may reconsider if the information comes from a source they cannot dismiss. People are most likely to find a source credible if they closely identify with it or begin in essential agreement with it. In such cases, their reaction is not, “how predictable and uninformative that someone like that would think something so evil and foolish,” but instead, “if someone like that disagrees with me, maybe I had better rethink.”

Our initial convictions are more apt to be shaken if it’s not easy to dismiss the source as biased, confused, self-interested or simply mistaken. This is one reason that seemingly irrelevant characteristics, like appearance, or taste in food and drink, can have a big impact on credibility. Such characteristics can suggest that the validators are in fact surprising — that they are “like” the people to whom they are speaking.

It follows that turncoats, real or apparent, can be immensely persuasive. If civil rights leaders oppose affirmative action, or if well-known climate change skeptics say that they were wrong, people are more likely to change their views.

Here, then, is a lesson for all those who provide information. What matters most may be not what is said, but who, exactly, is saying it.