Home > Cognitive Bias > The Optimism Bias: (Don’t) Stop Kidding Yourself

The Optimism Bias: (Don’t) Stop Kidding Yourself

Imagine you’ve just finished a long, tiring week of classes. It’s a Saturday afternoon and you’ve decided to reward yourself with a lazy day. You make some popcorn, grab your laptop and pull up Netflix. You’re watching Grey’s Anatomy, and you’re in the middle of season 5. You are shocked to find out that Izzie, a young doctor on the show, has been diagnosed with a brain tumor. You watch episode after episode until you reach the heart wrenching season finale when a different favorite character dies in a tragic accident. As you exhaust your box of tissues, you wonder how producer Shonda Rhimes concocts these episodes. You think about your own life and conclude that, at the end of the day, none of the tragedies in this medical soap opera could ever happen to you. You’ll never get sick like the fictitious characters of whom you’ve grown fond. You’ll never get in that car accident and wind up as a trauma patient. Bad things will not happen to you. If you’ve ever had a conversation like this with yourself- one in which you underestimate the likelihood that negative events will impact your life – you have demonstrated the optimism bias.

…or will it? (Taken from behappy.me)

The optimism bias is the cognitive bias that leads us to overestimate the likelihood that a positive event will happen in our lives and underestimate the likelihood that a negative event will occur in our futures (Sharot, 2011). Optimism, by definition, is the expectation that good things will happen. Pessimism refers to the expectation that bad things will happen.

One of the first studies to experimentally explore the optimism bias took place at Rutgers University in 1980. In this study, 200 college undergraduate students were given a list of 42 events to read and imagine. Some of the events were positive, including items like living past 80, graduating in the top third of the class, and not getting sick all winter. Other events were negative, such as dropping out of college, developing cancer, and being injured in a car accident. The participants were then asked to rate how likely they were to experience each one of the events compared to how likely their classmates were to experience the events. Students rated that their chances of experiencing positive events were significantly above average, while they predicted that their chances of experiencing a negative event was significantly below average (Weinstein, 1980). People tend to underestimate the likelihood of future negative events occurring. College students are not the only people to show the optimism bias; is seen across people of all races, age groups, and genders (Sharot, 2011).

We live in a world where we have access to all sorts of information at the tips of our fingers. We should be very aware that certain negative events are likely to occur.  We know from reading the news and keeping up to date on social media that horrible, tragic things happen each and every day. However, we are somehow able to maintain positive predictions about the future. Why does the optimism bias happen? Why are we kidding ourselves with these optimistic thoughts? The optimism bias is maintained because people selectively update their beliefs about their futures in response to positive information. Sharot and colleagues (2011) conducted a study in which they asked participants to estimate how likely they were to experience negative events in their lives. They then presented participants with the average frequency that each event would occur. For example, participants were asked to estimate their chances of developing Alzheimer’s disease. After making their estimate, they were then told that about 20% of people actually develop Alzheimer’s. After reading the actual statistics, people were asked to go back and re-estimate their chances of developing Alzheimer’s. People who said that their chances of developing the disease were below 20% (a more optimistic estimate compared to the reported average) did not change their estimates and maintained their optimistic beliefs. However, people who said their chances were 40% (a more pessimistic estimate than the average) significantly changed their answers to match the average of 20%, updating their beliefs in a more optimistic direction (Sharot et al., 2011). The optimism bias arises when people hear positive information and they selectively update their beliefs of their futures to match the positive news.

This pattern of selective updating happens all the time in our daily lives. Let’s say you and your friend are taking organic chemistry together and you just took a really difficult final. You’re feeling terrible about the exam and you predict that you probably got a 65%. Your friend thinks she crushed the exam, and predicts she got a 95%. Later in the week, you check online and learn that the average of the exam was an 82%. You say to yourself “Huh, maybe I didn’t do that poorly after all! I bet I was average, and a B- isn’t even that bad.” Your friend looks at the average and says, “Cool, I was above average!” The optimism bias is more than just expecting that you got a 100% on the exam and refusing to acknowledge that you might have failed. This bias has to do with how we update our beliefs when we are exposed to positive information. If you think you failed an exam but you learn the average is a B-, this behavior of updating your beliefs and telling yourself you are closer to the average is a demonstration of the optimism bias.

Why do we selectively update our beliefs about the future based on positive information? The answer lies within the frontal lobe. The frontal lobe is the region of your brain that manages your problem solving, social interactions, reasoning, and planning for the future. When we are presented with information that is worse than what we expected (like that our chances of getting a divorce are 50%, not 10%), the frontal lobe does not want to hear it. Our brain does not efficiently code or process information that would require us to negatively update our beliefs about the future. On the other hand, when we hear information that is better than what we originally expected, our brain eats it up. Our brains are very good at processing positive information, which leads us to update our beliefs to match the positive information (Sharot et al., 2011). This is why you updated your belief about your organic chemistry exam score but your friend did not; your brain efficiently processed the information about the average score because it was better than what you expected, but your friend did not process that information because it would require her to negatively update her beliefs about her exam grade. At the end of the day, we display the optimism bias because our brains do not fully process negative information about the future (Sharot et al., 2011).

taken from quickmemes.com

Now I know what you might be thinking. Why doesn’t my brain efficiently code negative information? Is there something wrong with me? As it turns out, optimism is good for us! Being a ‘glass half-full’ person is linked to several positive life outcomes. When we think positively about the future and underestimate how susceptible we are to experiencing negative events, we are actually reducing stress and anxiety associated with negative expectations and boosting our immune systems (Sharot et al., 2011). As we learn from the negativity bias, things of a negative nature impact our psychological wellbeing more than things of a positive nature, so focusing on the positives and not dwelling on the negatives is better for our overall health. Optimistic patients are more likely to exercise, eat healthy, and behave in certain ways that aid recovery from illness because believing that recovery will happen promotes health behaviors (Conversano, Rotondo, Lensi, Della Vista, Arpone, & Reda, 2010). Optimism helps people cope with many mental and physical health problems, as well as with problems that occur in everyday life like at work or in school. Interestingly, compared to people with no mental health disorders, people with major depressive disorder do not demonstrate the optimism bias (Korn, Sharot, Walter, Heekeren, & Dolan, 2014). People who display severe depressive symptoms are more likely to overestimate the likelihood that bad things will happen to them and underestimate the potential of good things happening.

Unrealistic optimism can be harmful in some situations. Sometimes, underestimating the possibility of negative events happening may lead us to act in ways that make us susceptible to experiencing the onset of these events. If individuals believe they are healthy, invincible, and will never have to experience an adverse health event, they may choose to drink excessively, smoke, or engage in other unhealthy behaviors. It is times like these when extreme optimism may lead us to take more risks, resulting in the occurrence of certain negative events (Conversano et al., 2010).  

taken from pinterest.com

When all the risks and benefits from the current research are weighed, it seems that optimism does more good than bad for our mental and physical wellbeing. Our capacity to anticipate future events is an extremely important part of our cognition. Our ability to make predictions about what will occur in the future helps us make decisions, and these decisions lead us to behave in certain ways that can help us avoid harm (Sharot, 2011). Though we as humans are less than perfect at accurately predicting the likelihood of positive and negative events happening in our lives, the optimism bias may lead us to behave in adaptive ways that put us in a position to lead happier, healthier lives.





Conversano, C., Rotondo, A., Lensi, E., Della Vista, O., Arpone, F., & Reda, M. A. (2010). Optimism and its impact on mental and physical well-being. Clinical Practice and Epidemiology in Mental Health: CP & EMH, 6(10). doi.org/10.2174/1745017901006010025

Korn, C. W., Sharot, T., Walter, H., Heekeren, H. R., & Dolan, R. J. (2014). Depression is related to an absence of optimistically biased belief updating about future life events. Psychological Medicine, 44(3). doi:10.1017/S0033291713001074

Sharot, T. (2011). The optimism bias. Current Biology, 21(23). doi.org/10.1016/j.cub.2011.10.030

Sharot, T., Korn, C. W., & Dolan, R. J. (2011). How unrealistic optimism is maintained in the face of reality. Nature Neuroscience, 14(11). doi:10.1038/nn.2949

Weinstein, N. D. (1980). Unrealistic optimism about future life events. Journal of Personality and Social Psychology, 39(5). DOI:10.1037//0022-3514.39.5.806


  1. May 16th, 2018 at 14:38 | #1

    Hey Sammy! I found this post really interesting to read, especially considering that I wrote on the opposite topic of the negativity bias. It is kind of crazy that our biases contradict each other, in a way, and I find myself wondering what factors lead to an individual experiencing more of one over the other. In my case, I found specifically that individuals with depression were more prone to the negativity bias. You talk about a study done by Sharot et al. in which participants show evidence of the optimism bias. I wonder if they were to do a similar study with a control group and a group of individuals with clinical depression if they would find different results? That is, do you think that the control group would show evidence for the optimism bias and the depressed individuals would show the negativity bias? Great work on your post, it was cool to compare to mine and really made me think 🙂

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