Hillary Clinton and Donald Trump shake hands during the presidential debate at Hofstra University. (Joe Raedle/Pool photo via the Associated Press)
Alexios Mantzarlis writes about fact-checking and trains fact-checkers in his role as head of the International Fact-Checking Network for Poynter.

The end of facts is nigh. Or so we have been assured by headline after headline declaring the 2016 presidential campaign the dawn of the “post-truth” era.

This storyline resurfaced after the fractious vice-presidential debate Tuesday night. On MSNBC, Chris Matthews suggested that “despite the facts,” Mike Pence had won the debate, in keeping with a campaign that “is not about particular facts, it’s about attitude.” Post-truth was wheeled out matter of factly by outlets as disparate as the New Statesman (“Forget post-truth; we’re past even satire at this point”) and the Sun Sentinel in Florida (“Pence has gone with the logical next step in these post-truth times we live in”).

Politicians have always lied, post-truthers concede: The difference now is that voters don’t care.

Yet a surging appetite for fact-checking and a newly released study of its impact indicate that facts may still have some fight left in them.

In a Monmouth University poll conducted days before the first presidential debate, 60 percent of respondents said that moderators should fact-check the candidates. Only half as many said that task should be left to the candidates themselves, an unfortunate approach endorsed by the chief of the Commission on Presidential Debates. While Democrats favored debate fact-checking more than Republicans, a majority from both sides approved of interventionist moderators.

This stance echoes the responses of an NPR listener panel conducted last year. Asked how interested they would be in different types of stories during the campaign, 96 percent replied that they were “very interested” or “somewhat interested” in fact-checking. That is almost twice as many as said they wanted NPR to cover the latest polls.

It is possible that this enthusiasm is dutiful. Of course respondents told a pollster that they are in favor of fact-checking. Many would no doubt also say that they approve of exercising regularly and eating a balanced diet; that doesn’t mean they will actually do those things. In the same manner, people may profess a preference for fact-checking that they don’t actually express in their everyday media consumption.

And yet, in this election cycle, readers are turning to fact-checking in droves. Unique visitors to The Washington Post’s Fact Checker were up 477 percent year-over-year in July, and up again in August. NPR recorded the highest traffic in the history of its website thanks to its live fact-checking of the first presidential debate. At least 6 million people had checked out the annotated transcript by the next morning. PolitiFact racked up 3.5 million page views in the 24 hours after that debate, drawing more traffic in one day than it did in entire months during the 2012 presidential campaign.

So voters want more fact-checking. But is it making any difference? Do people change their minds when faced with a fact check that surprises them, or do they internalize only fact checks that suit their own biases? Our understanding of basic psychology suggests that fact checks are often read with a partisan eye.

Often, but not always. A new working paper by Brendan Nyhan of Dartmouth College and Jason Reifler of Exeter University, who have studied fact-checking extensively, indicates that readers can learn from fact checks. Nyhan and ­Reifler conducted a survey of a representative panel of 1,000 Americans to gauge their general knowledge, party preferences and attitudes toward fact-checking. They then took participants who accepted a follow-up invitation to be studied further and split them into two groups. One half received nine fact checks; the other half was the control group and received placebo content in the form of PR releases. Lo and behold, participants in the “treatment” group scored far better when asked factual questions related to the content they read than those in the control group. The proportion of accurate answers among individuals who read the fact checks was 47 percent, 14 percentage points higher than the control group. Perhaps most heartening: This increase in accuracy was true even when the fact checks were “belief inconsistent,” that is, when they ran against a participant’s political preferences.

These results ought to be placed in the context of prior research. Nyhan and Reifler themselves have found in the past that corrections sometimes backfire, as people confronted with their false beliefs double down rather than change course.

Even on the Reddit channel Change My View, where users invite others to convince them that their beliefs are wrong using factual evidence, only 30 percent are persuaded to change their minds, a Cornell study found.

Frustration with resistance to facts is understandable. Commentators calling this a “post-fact” era often point to the popularity of a politician like Donald Trump, for whom peddling unverified conspiracy theories is not a bug but a feature of campaigning. Yet politicians appeal to voters in many ways that go beyond facts. Were the millions who voted for “hope” and “change” in 2008 doing so on the back of facts alone or even facts first? Of course not.

Expecting fact checks to neutralize political lies completely is to set expectations higher in politics than in other aspects of life.

For instance, a 2012 survey found that only 75 percent of Americans think the Earth revolves around the sun. That might seem astonishing. It may even lead some to opine that we live in a post-fact galaxy. To me, it is a healthy reminder that no single fact is universally held. That’s just human nature.

Still, a fact doesn’t need to be universally held to matter. If fact-checking has a greater impact on undecided voters than on die-hard partisans, then even a small effect on a key part of the electorate could matter a great deal.

Polling by The Post shows that twice as many independents thought Trump got facts wrong during the first debate as thought the same of Clinton. The Democrat herself called on fact-checkers not once, not twice, but three times during that debate. Clinton isn’t prone to unscripted appeals (“Trumped-up trickle-down,” anyone?), so it is safe to assume that her campaign thinks fact-checking the Trump ticket will yield electoral dividends.

Coverage of the vice-presidential face-off, too, quickly moved on from critiquing the debating style of the candidates to addressing questions of fact. Many major news outlets produced videos pairing Trump quotes with Pence’s denials that his running mate had said precisely those things.

We can expect millions of Americans to turn to fact-checkers once again during Sunday’s presidential debate and for the remainder of this campaign. While fact checks are clearly incapable of eradicating political disinformation, facts may have a far greater effect on this election than critics suggest.

Twitter: @Mantzarlis

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