Tali Sharot: The optimism bias


Tali Sharot is an associate professor of cognitive neuroscience in the department of Experimental Psychology at University College London.


Optimism bias is a tendency to overestimate the likelihood of good things happening to you, and underestimating bad things. For example 40% of people divorce, but people marrying assume the probability for them is zero. Even people marrying for a second time don’t see it: “Remarrying is the triumph of hope over experience”. People tend to be optimistic about themselves and their family, while at the same time predicting a bad future for the world in general.

Optimism about your own traits gives you a confidence and sets you up for success. But are low expectations the secret to happiness? This will mean you will be happy with success in love and career, but are not disappointed if it doesn’t happen. Tali argues the opposite, that optimistic people are happier because:

  • optimists interpret things differently. Whether they win or lose, they interpret successes as due to their own traits and failures as poor luck or biases.
  • anticipation makes people happy – something pleasant (a kiss from a celebrity) immediately isn’t as enjoyable as one in 3 days time – which lets you look forward to it
  • optimism acts as a self-fulfilling prophecy – it makes you try harder to achieve your goals. Optimism leads to success.

So how do we maintain optimism in the face of reality? That is: stay optimistic despite evidence to the contrary. Tali did a study – asking people to estimate their cancer risk (for example), then giving the population rate (30%) and asking them again their likelihood. People did change their estimate, but they changed it a lot more if their first estimate was high (ie changing their estimate from 50% to 35%) rather than when it was low (going from 10% to 11%). Tali found that there were 2 regions of the brain: one responsible for receiving good news and one that processes bad news. The ‘bad news region’ did not trigger in optimistic people: they kept the rose tinted spectacles on.

She went a step further – passing a magnetic pulse through these regions of the brain to temporarily disable them, and found that she could switch off or increase the optimism bias. This led to the question: Given the benefits would you switch off the optimism bias if you could? Optimism can lead to risky decisions: for example firefighters being surprised by the movement of a fire despite the hints being obvious, or underestimating the cost to implement a city project.

Tali thinks we can gain the benefits of optimism while staying realistic about risk, just by better understanding the bias. Knowing about the bias doesn’t prevent optimism in general life, but it does make people aware when making risky decisions. You need to be able to imagine a better world before you can make it happen.

My Thoughts

The biggest surprise for me from this talk is that you can switch off parts of the brain. Whoa!

Aside from that it is important to acknowledge the points that optimism bias can be beneficial, despite being called a bias. People often oppose anything labelled a bias or fallacy, and while that is fair in pure economics or logic, it might not apply in general life.