Brendan Nyhan · Journal of Economic Perspectives, 2020 · ~6–7 min read

False beliefs are a real problem. So is the panic about them.

Nyhan reviews the research on political misperceptions: what they are, why people hold them, where they come from and what reduces them. His verdict: the problem is serious, but the “post-truth” era is not supported by evidence.

Misperceptions can reshape real policy.

In 2009, Sarah Palin claimed Obama’s health reform would create “death panels” deciding who deserved care. It was false, yet within weeks three in ten Americans believed it. The myth changed the law: a once-bipartisan provision paying doctors to discuss end-of-life care with patients was dropped from the bill to avoid fuelling the controversy.

Surveys can make misperceptions look more common than they are.

Most evidence comes from surveys, which have blind spots. People answer on the spot, so some “beliefs” are really guesses. Some are partisan cheerleading: shown labelled photos of the 2009 and 2017 inauguration crowds, some Trump supporters insisted his visibly smaller crowd was bigger. A few respondents simply troll. Paying for correct answers narrows partisan gaps, so not every answer is sincere.

Fixing a false belief often doesn’t change anyone’s opinion.

Myths and matching policy views go together, but often the belief is just a rationalization of a preference held anyway. When experiments correct the facts, beliefs improve but opinions often stay put: a 2016 fact-check of Trump’s claims about rising crime corrected readers’ beliefs without reducing their support for him. And a myth’s effect on a whole debate can’t be measured: we can’t rerun history without it.

We rarely stop to check, and we trust our own side’s messengers.

Misperceptions also spread when we skip scrutiny. People who go with their gut rather than reasoning things through are worse at telling false headlines from real ones. A simple reminder to think about accuracy reduces sharing of false news. We also use the source as a shortcut: a claim becomes more believable to a leader’s supporters, and less to his opponents, just by being attributed to him.

Many myths start at the top. Elites supply them, and followers adopt them.

The most prominent misperceptions often begin with politicians, pundits and partisan media. Climate change shows how. In the 1990s, conservatives were actually more likely than liberals to accept the science; as Republican leaders voiced denial, belief split along party lines. The gap isn’t ignorance, since both parties know similar amounts of science. It comes from following elite cues, and it’s widest among the most politically engaged.

Echo chambers are overstated, but falsehood spreads fast to a small, intense audience.

Most people aren’t sealed in filter bubbles: they consume little political news, or a fairly balanced mix. Still, on Twitter false claims spread farther and faster than true ones, probably because they’re novel. But exposure is highly concentrated: before the 2016 election, about 80% of fake-news exposures on Twitter reached just 1% of users.

Truth wins slowly, so fixes matter. They differ by target and timing.

People do update when shown accurate information, and over decades opinion converged on smoking and cancer, or evolution. But updating is slow and incomplete, as with climate change, and sometimes partisans drift further apart. Nyhan sorts interventions by timing (before or after people meet a false claim) and target (the public, political elites or platforms):

Correcting the public helps a little, but misses the people who need it, and fades.

Better information in advance faces two problems: there’s no consensus on which institutions to trust, and those most exposed to misinformation rarely seek out reliable sources. Media-literacy tips look promising but untested at scale. Fact-checks do improve accuracy, and the feared “backfire effect” (Nyhan’s own early finding) proved rare, but they reach few of the people who saw the myth, and their effects decay over time.

The “post-truth” panic is itself misinformation.

Some cures threaten free speech, like banning “false” political ads or criminalizing false information, as Kenya did. They feed on a moral panic about a lost golden age of truth. But conspiracy thinking is old, from JFK theories to the “paranoid style” Hofstadter traced to America’s founding, and there’s no evidence misperceptions are worse today. Even warnings about “fake news” backfire, making people distrust real news too. Responses must be proportionate, starting with correcting misinformation about the problem itself.