Knowing Less but Presuming More: Dunning-Kruger Effects and the Endorsement of Anti-Vaccine Policy Attitudes

Misinformation about the link between vaccines (like measles, mumps, and rubella, or MMR) and autism is one factor that has contributed to the prevalence of anti-vaccine ("anti-vax") policy attitudes in the United States (US). This study is an effort to understand why the public holds anti-vax policy attitudes, despite scientific consensus for vaccines' benefits to public health. In the field of social psychology, the Dunning-Kruger effect is a cognitive bias in which people mistakenly assess their cognitive ability to be greater than it is. This study investigates whether people low in autism awareness are the most likely to think they are better informed than medical experts about the causes of autism. Further: Is this overconfidence associated with decreased support for mandatory vaccination policies and skepticism about the role that medical professionals play in the policymaking process?

The paper begins with an exploration of anti-vax policy attitudes among the American public. The researchers assert that "U.S. adults are generally uninformed or misinformed about the safety of vaccines, particularly concerning their rumored link to autism. A wide range of sources, internet blogs, celebrity activism, and various media point to this link despite no validated scientific evidence supporting [it]." People who endorse misinformation like this have been shown to be more likely to hold anti-vax policy attitudes. Conspiracy theories are described here as a special type of misinformation; research has shown that individuals who exhibit low levels of generalised interpersonal trust and domain-specific knowledge may be especially likely to endorse conspiracy theories about vaccines. In addition, both ideology and education have been shown to influence attitudes towards vaccinations.

Furthermore, as the researchers explain, how people think about medical experts has the potential to influence anti-vaccine attitudes and behaviour. Norms of journalistic balance have led news outlets to give roughly equal coverage to expert-endorsed "pro-vax" stances and non-expert-endorsed anti-vax stances. In addition, experts may face challenges when attempting to communicate pro-vaccine messages with the public: People (e.g., some of those on the ideological right) who hold negative attitudes toward scientific experts tend to be less accepting of scientific consensus on a variety of matters of scientific and political importance.

Continuing to explain the rationale undergirding the study, the researchers introduce autism awareness as a skill criterion, which they conceptualise to include both knowledge and the dismissal of misinformation about autism. People who are misinformed may overestimate their expertise because they believe that experts' knowledge - presumably at odds with misinformation - is deficient in some way.

To explore this Dunning-Kruger effect and its role in anti-vax attitudes towards mandatory vaccination policies, the researchers surveyed 1,310 American adults. Study participants were asked to take a quiz testing their knowledge about the causes of autism. They were also asked to assess their own knowledge and the knowledge of experts.

The results showed that more than one-third of respondents thought they knew as much or more than doctors (36%) and scientists (34%) about the causes of autism. Many respondents also place high levels of trust on information from non-experts (42%) and feel that non-experts should play a major policymaking role (38%). 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. Moving from low to high levels of autism knowledge was associated with a 39% decrease in overconfidence.

Further, the results suggest that this overconfidence could have policy consequences. Even after accounting for the independent effects of autism knowledge, misinformation, and several social, political, and demographic factors, the results indicate that overconfident individuals are less supportive of mandatory vaccination policy and tend to elevate the role that non-experts (e.g., celebrities) should play in the policymaking process. This finding suggests that researchers and policymakers interested in increasing support for mandatory vaccination need to combat not only low levels of knowledge and misinformation, but also the independent effect of overconfidence.

Among the possible objections and limitations the researchers consider is the idea that their conceptualisation of "expert discounting" could imply a normative judgment about the influence of non-experts in the policymaking process. In their words: "We certainly do not wish to shut ordinary people out of the policymaking process entirely, but we do find it reasonable to consider (for example) information from celebrities to be of a generally lower quality than that from communities of medical and scientific professionals."

In conclusion, this study has demonstrated that Dunning-Kruger effects can help to explain public opposition to vaccination policies. Among the directions for future research: investigation of the details of expert discounting in the policy realm. While this analysis was limited to looking at friends/families and celebrities as non-experts, other actors - like community leaders, religious figures, and teachers - might matter as well.