“Tell Me More”: Vaccines and the Illusion of Knowledge

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Feb 12, 2021

The newly minted president has an ambitious goal: vaccinating 300 million Americans by the end of summer or the beginning of fall.1 One obstacle that stands between President Biden and his goal is vaccine hesitancy. As of December 2020, 27% of the public said that they probably or definitely would not get the vaccine, even if it were free and deemed safe by scientists.2

Public opinion on vaccines

Despite findings from large clinical trials demonstrating the safety and effectiveness of the vaccines, misinformation regarding the vaccines has spread like wildfire.3,4 This is problematic, as studies have shown that exposure to vaccine-skeptical websites and blogs significantly reduces intentions to get vaccinated.5,6 Judging from the number of people who are vaccine-hesitant, it seems like many people have fallen prey to the falsehoods shared by people on various social media platforms. 

According to Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, we need to vaccinate at least 75% of Americans in order to achieve herd immunity.7 If vaccination rates are significantly lower than that benchmark by the end of the summer, we may not be able to return to a life resembling pre-pandemic times this year.7 Needless to say, if we don’t reach herd immunity, the death toll will continue to rise. 

Can states require their residents to get vaccinated so that we reach herd immunity as soon as possible? The short answer is yes. The 1905 U.S. Supreme Court case Jacobson v. Massachusetts established a legal precedent giving states the authority to mandate vaccinations.8 However, Lawrence Gostin, a law professor at Georgetown University said, “I think it’s very unlikely that they [states] will exercise that power. They would be fearful of causing a backlash and politicizing the vaccine.”9 His concern is not unfounded: only 57% of workers say they would support a workplace vaccine mandate once the shot becomes available to the public.10

In cases like these, leveraging insights from behavioral science might be the answer. 

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Why don’t people listen to experts?

Among experts, support for existing COVID-19 vaccines is overwhelming—but clearly, this is not enough to convince many people. This is in line with previous research, which has found that people do not typically revise their beliefs to be more in line with expert opinion than lay opinion.11

What’s yours is mine: Knowledge and transactive memory

People tend to believe that they store all their knowledge within their own brains. But in actuality, people rely on the knowledge of others to obtain and maintain an accurate model of the world.12 People store their knowledge of the world in others through transactive memory, where instead of remembering the exact details about a subject, they remember the markers for the people who are likely to possess knowledge of it.13,14,15,16 

Sometimes, however, people might fail to distinguish other people’s knowledge from their own.17 Because of this, people often hold an “illusion of explanatory depth,” wherein they overestimate how much they know about inherently complex and ostensibly simple phenomena.18 In the case of COVID-19 vaccines, if people believe that they possess the knowledge of experts, then there is little reason for them to update their beliefs in response to expert opinion. 

Shattering the illusion of knowledge

But what if people were forced to confront their lack of knowledge about how COVID-19 vaccines work? This was the question posed by Ethan Meyers and colleagues in a recent article for the journal Judgment and Decision Making.12 The researchers suggest that by exposing the illusion of knowledge that people hold, people will become more receptive to the opinions of medical professionals than the falsehoods shared by laymen on the internet. 

The following diagram details the procedure of one study used by Meyers and colleagues to answer this question.

The researchers hypothesized that by asking participants to explain the mechanics of a process in detail, the illusion of knowledge would be exposed, and consequently, participants will rely more on expert opinion than lay opinion. In addition, the researchers wanted to examine whether exposing an illusion of knowledge would reduce position extremism on economic issues. 

Results showed that participants changed their agreement in response to receiving consensus information, regardless of the source. However, they changed their agreement significantly more when they received consensus information from professional economists than from the general public. However, the results also showed that when participants held more extreme views on the issue, exposing the illusion of knowledge did not cause them to change their minds. 

Implications for COVID-19 vaccines

These findings suggest that public figures and media outlets may be able to persuade some people to receive the COVID-19 vaccine by making them realize how little they know about how vaccinations actually work. For example, news programs can first quiz their audience on COVID-19 vaccines, then proceed to give them the correct answers and advice from medical professionals. 

This intervention achieves two objectives: First, it causes people to reflect on what they actually know and don’t know about COVID-19 vaccines; and second, once the illusion of knowledge is exposed, people may become more receptive to the advice of medical professionals. Although this strategy isn’t likely to work with hardline anti-vaxxers, it could prove very effective among people who are on the fence about vaccine safety.

This intervention is also useful when we want to convince our friends and family who are hesitant to get the shots. We can simply ask them, “Do you know how COVID-19 vaccines work?”

Of course, this intervention alone is not enough to increase vaccination rates to where it needs to be. Ending this pandemic requires a concerted effort by healthcare workers, policy-makers, government officials—and most of all, you. So if you’re given the opportunity, please consider making plans to get vaccinated as soon as possible. 


  1. Biden, J. R., Jr. (2021, January 26). Remarks by President Biden on the Fight to Contain the COVID-19 Pandemic. Retrieved January 31, 2021, from
  2. Hamel, L., Kirzinger, A., & Brodie, M. (2020, December 15). KFF COVID-19 Vaccine Monitor: December 2020. Retrieved January 23, 2021, from
  3. Ensuring the Safety of COVID-19 Vaccines in the United States. (2021, January 19). Retrieved January 23, 2021, from
  4. COVID-19 vaccine myths debunked. (2020, December 8). Retrieved January 23, 2021, from
  5. Betsch, C., Renkewitz, F., Betsch, T., & Ulshöfer, C. (2010). The influence of vaccine-critical websites on perceiving vaccination risks. Journal of health psychology15(3), 446-455.
  6. Nan, X., & Madden, K. (2012). HPV vaccine information in the blogosphere: how positive and negative blogs influence vaccine-related risk perceptions, attitudes, and behavioral intentions. Health communication27(8), 829-836.
  7. Powell, A. (2020, December 10). Fauci says herd immunity possible by fall, ‘normality’ by end of 2021. Retrieved January 11, 2021, from
  8. Rosen, J. (2020, November 17). Can COVID-19 Vaccines Be Mandatory in the U.S. and Who Decides? Retrieved January 08, 2021, from n-the-u-s-and-who-decides.html
  9. Hauck, G. (2020, December 07). Yes, some Americans may be required to get a COVID-19 vaccine but not by the federal government. Retrieved January 24, 2021, from
  10. Wronski, L., & Cohen, J. (2020, December 18). 57% of workers support a mandatory Covid-19 vaccine for return to office: CNBC Survey. Retrieved January 24, 2021, from
  11. Johnston, C. D., & Ballard, A. O. (2016). Economists and public opinion: Expert consensus and economic policy judgments. The Journal of Politics78(2), 443-456.
  12. Meyers, E. A., Turpin, M. H., Bialek, M., Fugelsang, J. A., & Koehler, D. J. (2020). Inducing feelings of ignorance makes people more receptive to expert (economist) opinion. ​Judgment and Decision Making,​ ​15​(6), 909-925. 
  13. Hardwig, J. (1985). Epistemic dependence. The Journal of philosophy82(7), 335-349.
  14. Wagenknecht, S. (2015). Facing the incompleteness of epistemic trust: Managing dependence in scientific practice. Social Epistemology29(2), 160-184.
  15. Wegner, D. M. (1987). Transactive memory: A contemporary analysis of the group mind. In Theories of group behavior (pp. 185-208). Springer, New York, NY.
  16. Wegner, D. M., Erber, R., & Raymond, P. (1991). Transactive memory in close relationships. Journal of personality and social psychology61(6), 923.
  17. Sloman, S. A., & Rabb, N. (2016). Your understanding is my understanding: Evidence for a community of knowledge. Psychological science27(11), 1451-1460.
  18. Rozenblit, L., & Keil, F. (2002). The misunderstood limits of folk science: An illusion of explanatory depth. ​Cognitive science​, ​26​(5), 521-562.

About the Author

Shi Shi Li

Shi Shi Li

Shi Shi is currently a graduate student studying behavioral and decision sciences at the University of Pennsylvania. She is interested in using insights from behavioral science to solve a wide range of problems facing our society today. When she is not reading the latest behavioral science papers, she enjoys painting and playing video games with her friends. She also holds bachelor’s degrees in economics and psychology from the University of Southern California.

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