All of us stick to beliefs in the face of contradictory evidence. All of us have beliefs that do not match reality. It is unavoidable. But it’s possible that some people are better or worse than others at keeping an open mind.

Our previous research suggests that uncertainty makes people more willing to change their mind. The downside of that is that constant uncertainty can make us less willing to make decisions and act, which would make it hard to navigate life.

What we do know from work in our lab is that how certain you feel is not a good indicator of how certain you should feel based on the strength of the evidence. Research led by Louis Martí in our lab measured people’s confidence and accuracy as they were in the process of learning a new concept.

What we found was that people’s certainty was not predicted by the strength of the evidence. Instead, it was predicted by feedback. If people guessed the answer to a question and got it right by some fluke, their confidence remained high even when they got subsequent answers wrong. That early positive feedback created high certainty that couldn’t be shaken.

Let’s say you hear that sunlight heals sick people, and so you spend some time outside next time you get a cold, or open the bedroom blinds, and you do seem to heal quicker. You tell your friend, he tries it, he says he got better quicker too. Now you feel certain that sunlight cures sickness. But maybe sunlight made you less attentive to your symptoms, or maybe you had a minor cold that ran its course.

But because you are certain about the healing powers of sunlight, you aren’t open to subsequent data. So, if someone suggests that maybe sunlight does not cure illness, you are not really interested. Why should you be? You figured it out.