Mentally vaccinating people against fake news goes back to the 1960s, when psychologist William McGuire proposed making people resistant to propaganda using a strategy he called a “vaccine for brainwash.” Much as weakened viruses can teach the immune system to recognize and fight off disease, alerting people to false arguments — and refuting those arguments — might keep them from succumbing to deception, McGuire reasoned.
Take, for example, the public-health recommendation that everyone visit a doctor every year. In an experiment, McGuire gave people counterarguments against going to the doctor annually (say, that regular visits promote health anxiety and actually lead people to avoid the doctor). Then he poked holes in those counterarguments (in reality, regular doctor visits reduce undue health anxiety). In McGuire’s studies, people became better at resisting false arguments after their beliefs were challenged.
The inoculation messages warned people of impending attempts to persuade them, causing them to recognize that they might be vulnerable. The brain is wired to mount a defense against apparent threats, even cognitive ones; when challenged, people therefore seek fresh ways to protect their beliefs, much as they’d fight back if someone attacked them in a bar. Threat is a critical component of inoculation, says Josh Compton, a Dartmouth speech professor who specializes in inoculation theory. “Once we experience threat, we are motivated to think up counterarguments folks might raise and how we’ll respond,” he says.
In the 1980s and 90s, experts put inoculation theory into practice with fairly limited goals, like preventing teenage smoking, and limited but promising outcomes. It wasn’t until the mid-2010s, as fake news gained traction online, that Cambridge’s Van der Linden was inspired to take the inoculation concept to a higher level. Like McGuire, he was convinced that “prebunking,” or sensitizing people to falsehoods before they encountered them, was better than debunking fake stories after the fact. Multiple studies show that once someone has internalized a nugget of false information, it’s very hard to get that person to disavow it, even if the original creator posts a correction.
Van der Linden found that focusing on a single issue, as McGuire had done, has its limits. Warning people about lies on a particular subject like smoking may help them fend off falsehoods about that one topic, but it doesn’t help them resist fake news more broadly. So Van der Linden started focusing on building people’s general immunity by cluing them in to the persuasion techniques in every fake-news creator’s toolbox.
In a series of mostly online studies, Van der Linden gave people general warnings about bad actors’ methods. For instance, he told them that politically motivated groups were using misleading tactics, like circulating a petition signed by fake scientists, to convince the public that there was lots of scientific disagreement about climate change. When Van der Linden revealed such fake-news tactics, people readily understood the threat and, as a result, got better at sniffing out and resisting disinformation.
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