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Optimism bias

"It won't happen to me; it only happens to others."


We have all taken risks without considering ourselves to be in danger, whether it was by riding a bike without a helmet or going over the speed limit in our car. Although these situations can represent a risk, it is common to underestimate the risk when we are personally involved. This phenomenon, which is called optimism bias or comparative optimism, causes people to have the mistaken belief that they are personally less at risk than others [1]. We can speak of an incongruity between the assessment of our risk and that of others. The bias varies with emotional proximity, so we tend to judge the risk to others as higher when we have less emotional proximity to them [2].


In 2020, as the global COVID-19 virus pandemic was raging, several thousand people gathered on beaches and in bistros, and even organized large parties while ignoring health risks. It is likely that the optimism bias played a role in these behaviours, as many people seemed to assume that the risks did not concern them, even as the media was reporting many cases of people who were dying from COVID-19.


Several explanations are used to account for the optimism bias in the literature. The bias may arise because people are motivated to believe that they are not at risk. Indeed, optimistic predictions about the future can be rewarding, in addition to reducing anxiety about negative events that might arise [2].

Another cause of the optimism bias relates to the way we absorb and retain information. We tend to pay more attention to what concerns us. Since we know ourselves, we will judge our risks differently from those of others [2]. For example, a person who smokes may say they are at lower risk for health complications from smoking than average because they believe they eat healthier foods and are more active than other smokers. This person, however, does not have information about the lifestyles of most smokers, and therefore is unable to make an accurate comparison. This lack of information leads to an imbalance in the judgment of risks between themselves and others.


Underestimating the risks we may run in the future can have several positive effects, for example, by increasing feelings of control and reducing anxiety [3]. This bias can also lead to better self-esteem as well as a general sense of well-being [2]. It should also be noted that this phenomenon is part of healthy human functioning, as the optimism bias is not present in people with depression [3].

However, the optimism bias can also lead to some negative consequences. Denying or underestimating the risks of a future action can lead to greater risk-taking [2]. Likewise, people exhibiting this bias may ignore information that aims to warn them about risks in order to maintain their misperception of future risks. It is therefore obvious that this bias is considered in the field of public health with regard to prevention campaigns [3].

Thoughts on how to act in light of this bias

  • Become aware of one’s tendency to minimize risks to oneself.

  • Imagine how we would advise others on risks in order to circumvent our tendency to underestimate our degree of risk.

  • Keep in mind that this bias has positive consequences that contribute to good mental health. Thus, efforts should not be made to eliminate it completely.

How is this bias measured?

Generally, optimism bias is measured by comparing a person's assessment of their own risk with that of the risk of a person of the same age and gender in the same situation. When the person considers themselves less at risk than others, there is an optimism bias. In addition, the measurement of optimism bias can be done directly or indirectly, depending on the research. For the direct method, participants are asked to compare themselves to a third party. In the indirect method, however, the research team asks the person to judge their own risk and to judge that of another person in the same situation. Thus, the person is not asked to compare themselves with others, rather the research team will compare the answers [4].

This bias is discussed in the scientific literature:


This bias has social or individual repercussions:


This bias is empirically demonstrated:



[1] Klein, Cynthia T.F. & Marie Helweg-Larsen (2002). Perceived control and the optimistic bias: A meta-analytic Review. Psychology and Health, 17(4), 437-446. (meta-analysis) 

[2] Shepperd, James A., Patrick Carroll, Jodi Grace & Meredith Terry (2002). Exploring the causes of comparative optimism. Psychologica Belgica, 42, 65-98. 

[3] Hichang, Cho, Lee Jae-Shin & Lee Seungjo (2013). Optimistic bias about H1N1 flu: testing the links between risk communication, optimistic bias, and self-protection behavior. Health Communication, 28(2), 146-158. 

[4] Helweg-Larsen, Marie & James A. Shepperd (2001). Do moderators of the optimistic bias affect personal or target risk estimates? A review of the literature. Personality and Social Psychology Review, 5(1), 74-95. See also Sharot, Tali (2017). The optimism bias. Current biology, 21(23), 941-945.


Individual level, Emotional heuristic, Availability heuristic, Need for security

Related biases


Gabriel Piuze-Bourgeois; Bachelor in psychology from the Université de Sherbrooke and undergraduate student in sexology at the Université du Québec à Montréal. 

Translated from French to English by Susan D. Renaud.

How to cite this entry

Piuze-Bourgeois, G. (2020). Optimism bias, trans. S. D. Renaud. In C. Gratton, E. Gagnon-St-Pierre, & E. Muszynski (Eds). Shortcuts: A handy guide to cognitive biases Vol. 1. Online:

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