Effects of experiencing the COVID-19 pandemic on optimistically biased belief updating.

Optimistically biased belief updating is essential for mental health and resilience inadversity. Here, we asked how experiencing the COVID-19 pandemic affected optimismbiases in updating beliefs about the future. One hundred and twenty-three participantsestimated the risks of experiencing adverse future life events in the face of beliefdisconfirmingevidence either outside the pandemic (n=58) or during the pandemic (n=65).While belief updating was optimistically biased and Reinforcement-learning-like outsidethe pandemic, the bias faded, and belief updating became more rational Bayesian-likeduring the pandemic. This malleability of anticipating the future during the COVID-19pandemic was further underpinned by a lower integration of positive belief-disconfirminginformation, fewer but stronger negative estimations, and more confidence in base rates.The findings offer a window into the putative cognitive mechanisms of belief updatingduring the COVID-19 pandemic, driven more by quantifying the uncertainty of the futurethan by the motivational salience of optimistic outlooks.