Getting to the Bottom of Anti-Vaccine Attitudes

Overconfidence and Misinformation Help to Explain Opposition to Pro-vaccine Policies

By Kendall Morgan - January 15, 2019  9 mins
Pediatric doctor is vaccinating the child. ©

Each month the Elsevier Atlas Award recognizes research that could significantly ­impact people's lives around the world.

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

Matthew Motta, Timothy Callaghan, Steven Sylvester

Social Science & Medicine, Volume 211, August 2018, Pages 274-281

The life-saving benefits of vaccines are well recognized by medical experts. And, yet, among members of the general public, anti-vaccine attitudes remain widespread with about a third of U.S. adults opposing mandatory vaccines for kids attending public school. All that skepticism about vaccines has come with real consequences, including a resurgence of measles, whooping cough, and other infectious illnesses.

Now, an Atlas-award winning study reported in Social Science & Medicine has evidence to help explain why these attitudes persist despite the evidence. Their findings suggest that Dunning-Kruger effects, in which people who lack expertise fail to recognize their own lack of knowledge, are at play.

“One reason for Dunning-Kruger effects is that people don’t know what they don’t know,” said Matthew Motta from the Annenberg Public Policy Center at the University of Pennsylvania in Philadelphia. “The other may be that they are misinformed, believing something that the experts recognize as being untrue.”

To explore Dunning-Kruger effects and their role in attitudes about vaccines and the causes of autism in the new study, Motta and colleagues including Timothy Callaghan, Texas A & M University, and Steven Sylvester, Utah Valley University, surveyed more than 1,300 U.S. 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 survey results showed that more than a third of study participants believe they knew as much as or more than medical doctors and scientists about the causes of autism. While many respondents indicated trust in experts, they also placed high levels of trust in non-experts and the role of non-experts in setting policy.

The surveys also showed that those with the fewest correct answers on the quiz about autism’s causes showed the highest levels of overconfidence in their own knowledge. As reported in the study, “moving from low to high levels of autism knowledge was associated with a 39% decrease in overconfidence.” Those who know the least are the most confident about their own knowledge.

Motta’s team went on to show that this overconfidence may have consequences when it comes to policy attitudes. Those with the least knowledge about autism and who are the most overconfident are also less likely to support pro-vaccine policies. They are also more likely to elevate the role of non-experts in setting such policies.

The findings “add needed complexity” to understanding what’s behind anti-vaccine attitudes, the researchers say. They may also point to approaches to help encourage greater support for vaccines, with important implications for public health.

Motta says in addition to offering people needed information, it will also be important to combat misinformation about vaccines. “Of course, we need efforts to inform people, but we also need to debunk misinformation,” he said. “Hitting people over the head with facts probably isn’t going to do that.”

Just what that might look like will be the subject of further studies. “That’s the key question,” Motta says, “how can we combat misinformation about vaccines?”


A Conversation with Matthew Motta

Atlas spoke with Matthew Motta from the Annenberg Public Policy Center at the University of Pennsylvania in Philadelphia about his Atlas award-winning study “Knowing less but presuming more: Dunning-Kruger effects and the endorsement of anti-vaccine policy attitudes.”
Listen to the interview now.

Atlas: What are Dunning-Kruger effects?

Matthew Motta: A Dunning-Kruger effect generally refers to observable manifestations of what psychologists call “meta-ignorance.” It’s any of a host of behavioral consequences of people’s ignorance of their own ignorance. It’s what happens when people don’t know the lack of knowledge they have in a particular area. We were interested in studying the application of these effects in public health. We thought there were people who think they know more than medical experts and scientists who actually know quite a bit less. This would be an example of Dunning-Kruger effect because people don’t know how little they know in relation to people who know comparatively more.

Atlas: How is it that people who actually know less find it easier to believe they in fact know more than the experts?

Matthew Motta: There’s a couple ways this can happen. There are two things that go into whether someone exhibits Dunning-Kruger effects. One is having low knowledge and the other is being misinformed. Misinformation doesn’t imply that someone doesn’t know, but rather that they believe information that’s not true.

Atlas: What led you to explore these effects in relation to skepticism around vaccines and ideas about vaccines and autism (that persist despite I should say medical and scientific consensus to the contrary)?

Matthew Motta: There are a couple of reasons why we are interested in studying this. The academic answer is this is something psychologists have asked us to draw attention to for a long time. But really we’re interested in understanding why it is people don’t think vaccines are safe and what political and policy consequences that might have. Attitudes about vaccines can and do have very real public policy and health policy consequences. One example is the Lyme disease vaccine. In the late nineties there was a vaccine for Lyme disease, which public opinion helped pull off the market. The public was skeptical about the safety and effectiveness. Twenty years later, we finally have another vaccine [in clinical trial], but that took a long time. Understanding why the public rejects scientific consensus on things like vaccines and vaccine safety is a tremendously important question.

Atlas: How did you go about exploring this?

Matthew Motta: We gave people a knowledge test about the causes of autism and then we asked people in a national survey: How much do you think you know about the causes of autism? We asked the same question about medical experts like doctors and scientists. We compared people’s perceptions of self to perceptions of experts and looked at that versus how well they scored on the knowledge test. We show there’s a relationship between knowledge and misinformation and what we call overconfidence—the belief that you know more. As we showed, those who are the least knowledgeable and most misinformed were most likely to exhibit overconfidence. Once we did that, we looked at policy implications of overconfidence. We looked at the correlation between attitudes, for example, about whether it should be required to vaccinate kids going to public school. Those who were the most overconfident were less likely to think that was the case.

Atlas: What does this tell us?

Matthew Motta: If we understand where anti-consensus and skepticism comes from, it can help us better alleviate skepticism. We’ll know how to fix it or at least where to look. It’s tempting to think the answer is simple. We just need to educate people. If only people were more educated and less misinformed about autism, they would be less likely overconfident and more willing to support expert opinion. But, it’s not that simple. Informing the public is a monumental task, but knowledge isn’t a panacea. We know from other fields that sometimes those more knowledgeable have stronger cognitive biases. Even though knowledge is a potential path to explore, it’s important to keep in mind that knowledge won’t fix all of our problems.

Atlas: Do you have ideas about other ways to help?

Matthew Motta: Absolutely. A really important path is combatting misinformation about vaccines. Of course, we need efforts to inform people, but we also need to debunk misinformation. Hitting people over the head with facts probably isn’t going to do that. What it might look like is the subject of follow-up studies. That’s the key question: how can we combat misinformation about vaccines?

Atlas: Do your findings suggest that non-experts might actually reach people with doubts about vaccines more effectively than experts can? I’m thinking if some folks prefer to listen to celebrities, why would they not listen to celebrities who support vaccines as well?

Matthew Motta: That is one fascinating path to explore. We recognize that getting some of these folks like celebrities involved and perhaps family and friends might be a effective route because those with high levels of overconfidence tend to trust these non-experts on vaccines. If we can get celebrities or maybe family and friends to communicate support we might have effective way to combat misinformation. But there’s a huge “if” there—you need someone to change his or her mind. What that might look like in practice is hard to say but it could be a fascinating route to explore.

Atlas: Your work here is focused on anti-vaccine attitudes but it would seem to apply to many other areas of science and medicine as well, wouldn’t it?

Matthew Motta: Absolutely. There ought to be more studies on this than there are. We see this as one application and welcome people to look in other areas. We’ve considered looking at climate denial, but really anywhere expert and public opinion doesn’t match up is a great place to look.

Related Resources:

About Social Science & Medicine

Social Science & Medicineprovides an international and interdisciplinary forum for the dissemination of social science research on health. The journal publishes material relevant to any aspect of health from a wide range of social science disciplines (anthropology, economics, epidemiology, geography, policy, psychology, and sociology), and material relevant to the social sciences from any of the professions concerned with physical and mental health, health care, clinical practice, and health policy and organization.

Elsevier Atlas

Science impacts everyone's world. With over 2,500 journals publishing articles from across science, technology and health, our mission is to share some of the stories that matter. Each month Atlas showcases research that could significantly impact people's lives around the world or has already done so. We hope that bringing wider attention to this research will go some way to ensuring its successful implementation.

With so many worthy articles published the tough job of selecting a single article to be awarded "The Atlas" each month comes down to an Advisory Board. The winning research is presented alongside interviews, expert opinions, multimedia and much more on the Atlas website.

We aim to showcase some of the articles that can make a real difference and hope you'll find this to be a valuable resource.


Kendall Morgan, PhD
Written by

Kendall Morgan, PhD

Written by

Kendall Morgan, PhD

Kendall Morgan, PhD, is a scientist turned science writer via the Science Communication Program at the University of California, Santa Cruz. Her work has been featured in publications including Big Science Media's Genome, Cancer Today, The Scientist, Science News, Science Now, and by organizations including Addgene and the Life Sciences Foundation. She lives in Durham, NC.

Applying machine learning and AI to predict patient risk
Enabling patient tracking for physicians out of the feedback loop
Together we created the most advanced 3D female anatomy model


comments powered by Disqus