Home > Cognitive Bias, Metacognition > Are You Smarter Than A Doctor? The Dunning-Kruger Effect and Vaccine Misinformation

Are You Smarter Than A Doctor? The Dunning-Kruger Effect and Vaccine Misinformation

Picture this: it’s a beautiful fall day in elementary school, and one day after you get home from school, your parents tell you to get in the car because you have a doctor’s appointment. You’re not very excited, but you have no choice but to go along with them. When you arrive, you receive some dreadful news from the doctor: it’s time for you to get your seasonal flu shot! You’re terrified, but your parents tell you to close your eyes and that it will be over quickly, and that getting a shot isn’t nearly as bad as getting the flu later on. You hold your breath, and before you know it, you’re out the door with a Pokémon band-aid on your arm and a lollipop in your mouth.

For most Americans, receiving vaccinations against diseases such as the seasonal flu or measles is a common and expected practice. In fact, vaccines are often considered to be one of the greatest medical achievements of the 20thcentury. Although vaccines have been heralded as a medical breakthrough, anti-vaccination sentiments are by no means a new phenomenon. In the past decade or so, this anti-vaccination movement has grown tremendously on the internet. The public’s attitude towards vaccines is shaped by multiple factors, such as scientific, political, and psychological factors, as well as people’s levels of knowledge and exposure to misinformation. Despite overwhelming clinical evidence that vaccinations are safe and effective, there is still a community that stands strong in their beliefs in misconceptions about vaccines. People who hold these beliefs are generally known as “anti-vaxxers“.

Anti-vaxxer’s lack of metacognitive awareness leads often leads them to disregard science in favor of their own opinions.

Some basic beliefs anti-vaxxers tend to hold are that vaccines cause illness, inject toxins into children, or that they are ineffective. Some of the more wild beliefs are found in this community are that vaccines are part of a conspiracy between the government and the pharmaceutical industry (Kata, 2012), and one of the most famous anti-vaxxer statements: vaccines cause autism. Thanks to a now-retracted 1998 study that claimed that the MMR (measles, mumps, rubella) vaccine causes autism, the anti-vaccine seeds were planted and continue to grow to this day, even though the study was exposed as a complete fraud about a year later. It has been around 22 years since then, and the link between vaccines and autism has been discredited and disproven again and again by scientific communities including, but not limited to, countless peer-reviewed scientific studies and the CDC. Regardless, there are still anti-vax parents who refuse to vaccinate their school-age children. When asked why they do this, many of these people will tell you that because of all of their online ‘research’, they have a deeper knowledge of vaccines and their dangers than their children’s pediatrician. Some even claim to know more about vaccines than scientists.

POV: You’re an anti-vaxxer but there’s no clinical evidence to support your argument.

Assuming you understand and believe in science, you are probably wondering how it is that a person could believe that watching a few YouTube videos and reading a few anti-vaccine blogs could make a person think that they know more about vaccines than the doctors and scientists who developed them. Well, we’ve all met someone who thinks they know a lot more about a topic than they actually do, regardless of any evidence to the contrary. This phenomenon is known as the Dunning-Kruger Effect. The Dunning-Kruger effect is a type of cognitive bias where people believe they are smarter and more knowledgeable than they actually are. This is caused by their inability to recognize their own lack of skill due to a lack of metacognition, or awareness of one’s own knowledge. A recent study found that one third of people in their sample thought they knew more about the causes of autism than doctors and scientists (Motta, Callaghan, & Sylvester, 2018). They also found out that these people also had low levels of accurate autism knowledge to begin with. People who are misinformed and who overestimate their own knowledge because tend to do so because they believe that experts’ knowledge is inaccurate in some way. This is presumably because it is at odds with the misinformation they have come to believe as truth. This also has to do with the fact that along with the inability to gauge your own skill level, the Dunning-Kruger effect also leads to the inability to accurately judge the skills of others. One complaint some anti-vaxxers have is that it is hard to find studies that support the idea that vaccines are harmful. If these individuals had more metacognitive awareness, they would be able to step back and look at the big picture: if you can’t find any valid clinical research to back up your argument, especially when your argument has been repeatedly invalidated by the research you’re fighting against, there’s a pretty good chance that your argument is wrong. But, they are so set in their belief that they are right, they would rather jump onto anti-vaccine conspiracy theories than admit that they were misinformed.

A lack of metacognition can leave people with the inability to judge their own knowledge level.

For the past few years the spread of misinformation online, and even in mainstream news, has become an important conversation. Particularly, much of what we have heard about online misinformation has been the 2020 presidential election as well as misinformation regarding the Covid-19 pandemic. Although the internet is a place containing a wealth of facts and research, it has also acted like a petri dish for the cultivation and spread of misinformation about vaccines. Memory is a reconstructive process, meaning that when you retrieve a memory you are pulling together pieces of a previous memory rather than the memory as a whole. Each time you recall a memory new bits of information are unconsciously incorporated into it, and this can lead to incorrect details getting woven into the facts. Going back to our seasonal flu shot example, say you walked out that day with a Snorlax band-aid. But one day when your mother is reminiscing on that story with you, she tells you that you got a Pikachu band-aid after your shot. Since nothing about the story seems blatantly wrong, you incorporate the Pikachu band-aid into your memory of that day. Now when you recall it in the future you reconstruct the memory with a Pikachu band-aid without realizing that the original reconstruction of the memory had a Snorlax band-aid.

The same thing can happen when people are looking around online for information on vaccines. People use the internet to look for free medical information all the time, and although there is plenty of clinical evidence supporting the effectiveness and safety of vaccines in scientific journals, the internet at large can contain information about anything written by anyone, regardless of accuracy. Since Websites like personal blogs, Facebook, Instagram, Twitter, and YouTube videos are much more accessible than scientific journals, these are places where vaccine misinformation can spread like wildfire. Say a new parent turns to the internet for information about vaccinating their young child because they want to expand upon the information they got from the pediatrician. If they wind up diving down the rabbit hole of anti-vaxxer rhetoric, what they find will end up consolidated into their memory. This means that even well educated people can consume and buy into misinformation. Even celebrities such as Jenny McCarthy and Robert DeNiro have made public statements promoting the discredited idea that vaccines cause autism.

Speaking of celebrities, former reality TV star and current US President Donald Trump has demonstrated negative attitudes towards vaccines a multitude of times. Specifically, between the years 2012 and 2014 he made several tweets linking the MMR vaccine to autism diagnoses. This makes him the first US president in modern history to express anti-vax beliefs.

Although these alarming tweets were published well before his eventual presidential campaign and term as president, politicians’ views often reflect and shape the views of their supporters. A very recent study by Hornsey et al. (2020) found that among those surveyed, Trump voters expressed more concern about the safety concerns of vaccines, including the MMR vaccine, than those who did not vote for Trump. Now, what might this suggest about partisanship, anti-vaxxers, and the Dunning-Kruger effect? Well, one study discussed by Motta et al. (2018) found that those who have a more negative attitude towards vaccine experts tended to be less willing to trust scientific consensus when science and politics were intertwined. They also discussed how this anti-science sentiment has become increasingly common with the ideological right. However, the Dunning-Kruger effect does not follow partisan boundaries and anti-vaxxers can be of any political affiliation.

As we near the conclusion of this rollercoaster of a year known as 2020, there has never been a more important time to listen to doctors and scientists, fact check what you see on the internet, and to practice being self-aware. Now that we’ve investigated how being overconfident in your own knowledge can lead you into the misinformed echo chamber that is the anti-vaxxer community, remember to always stay aware of your own knowledge. And when you see your Aunt Karen sharing anti-vax memes on Facebook again, just remember that her memes simply can’t compete with science.


Hornsey, M. J., Finlayson, M., Chatwood, G., & Begeny, C. T. (2020). Donald Trump and vaccination: The effect of political identity, conspiracist ideation and presidential tweets on vaccine hesitancy. Journal of Experimental Social Psychology, 88. https://doi.org/10.1016/j.jesp.2019.103947

Kata, A. (2010). A postmodern Pandora’s box: Anti-vaccination misinformation on the Internet. Vaccine, 28, 1709-1716. https://doi.org/10.1016/j.vaccine.2009.12.022

Kata, A. (2012). Anti-vaccine activists, Web 2.0, and the postmodern paradigm – An overview of tactics and tropes used online by the anti-vaccination movement. Vaccine, 30, 3778-3789. https://doi.org/10.1016/j.vaccine.2011.11.112

Motta, M., Callaghan, T., & Sylvester, S. (2018). Knowing less but presuming more: Dunning-Kruger effects and the endorsement of anti-vaccine policy attitudes. Social Science & Medicine, 211, 274-281. https://doi.org/10.1016/j.socscimed.2018.06.032

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