Knowing less but presuming more: Dunning-Kruger effects and the endorsement of anti-vaccine policy attitudes.

OBJECTIVE Although the benefits of vaccines are widely recognized by medical experts, public opinion about vaccination policies is mixed. We analyze public opinion about vaccination policies to assess whether Dunning-Kruger effects can help to explain anti-vaccination policy attitudes. RATIONALE People low in autism awareness - that is, the knowledge of basic facts and dismissal of misinformation about autism - should be the most likely to think that they are better informed than medical experts about the causes of autism (a Dunning-Kruger effect). This "overconfidence" should be associated with decreased support for mandatory vaccination policies and skepticism about the role that medical professionals play in the policymaking process. METHOD In an original survey of U.S. adults (N = 1310), we modeled self-reported overconfidence as a function of responses to a knowledge test about the causes of autism, and the endorsement of misinformation about a link between vaccines and autism. We then modeled anti-vaccination policy support and attitudes toward the role that experts play in the policymaking process as a function of overconfidence and the autism awareness indicators while controlling for potential confounding factors. RESULTS More than a third of respondents in our sample thought that they knew as much or more than doctors (36%) and scientists (34%) about the causes of autism. Our analysis indicates that this overconfidence is highest among those with low levels of knowledge about the causes of autism and those with high levels of misinformation endorsement. Further, our results suggest that this overconfidence is associated with opposition to mandatory vaccination policy. Overconfidence is also associated with increased support for the role that non-experts (e.g., celebrities) play in the policymaking process. CONCLUSION Dunning-Kruger effects can help to explain public opposition to vaccination policies and should be carefully considered in future research on anti-vaccine policy attitudes.

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