Despite consensus in the medical community that vaccination prevents the development and spread of disease—it saves lives, in other words—a disturbingly vocal segment of the public believes otherwise. Anti-vaxxers, as they’ve come to be called, often believe that vaccines cause autism, and it can be very hard to change their minds.
That mistaken belief can seriously affect health policy, especially when, say, President Trump tweets support for the debunked connection between vaccines and autism. Research has teased out various influences on anti-vaxxers, from education level to attendance at religious services to political affiliation.
That suggests a complicated array of influences, and a recent study adds a new wrinkle, finding that people who have less knowledge about autism are the most likely to believe they know more than the experts.
The study, published in the August 2018 issue of Social Science & Medicine, surveyed 1,310 US adults. It tested their understanding of the origins of autism and whether they supported the misinformation about links between vaccination and autism.
More from Tonic:
Researchers hypothesized that participants with the least knowledge of autism would be most likely to believe they knew more than the experts. That overconfidence is an example of the Dunning-Kruger effect, which strikes when people are too incompetent within a particular domain to adequately judge their own abilities. They simply don’t know enough about what they’re doing, and profoundly overestimate themselves. (The original paper outlining the effect memorably opened with the story of a bank robber who, when caught by police after his daring daylight raid, revealed that he thought rubbing his face with lemon juice had made him invisible to video cameras.)
The authors suspected something similar might be happening among anti-vaxxers, and the results bore out that hypothesis. More than a third of survey respondents thought they knew more than doctors (36 percent) and scientists (34 percent) about the causes of autism—remarkably high numbers in themselves. Many (42 percent) had high levels of trust in information from non-experts, and 38 percent believed that such non-experts should have a major role in making public health policy.
Those numbers are likely frustrating enough for health authorities. But the authors then examined how overconfidence affected respondents' ideas about vaccination. They found strong correlations: First, overconfidence was highest among people who had less knowledge about autism; it was also highest among those most likely to believe bad science about the disorder.
Overconfidence mapped to ideas about policy as well. On the question of allowing parents to vaccinate their own kids, for example, support was 16 percent among the least overconfident, and 30 percent for the most overconfident.
And while overconfidence didn’t correlate with beliefs about how experts should shape health policy, the more overconfident respondents were more likely to support a role for non-experts in deciding policy. That’s worth reflecting on when considering the influence of celebrity anti-vaxxers such as Robert F. Kennedy, Jr., and Jenny McCarthy.
It’s disturbing to see such a high percentage of people ready to let fringe players influences health policy, but the survey can have a positive effect, too. It gives us a better sense of how anti-vaxxers form their beliefs—and suggest ways to change their minds. The first step will be making them less confident about the things they believe they already know.
Sign up for our newsletter to get the best of Tonic delivered to your inbox.