Punishment avoidance experiment.

<p><b>a</b>) Cartoon of the task. The CS can either lead to a punishment (indicated by a sad face) or nothing. <b>b</b>) Performance of the subjects (percentage of trials in which they chose the fractal stimulus) as a function of the difference between the observed reward rate of the fractal being considered and the reward probability of the square. Pessimistic (red, LOT-R≤mean LOT-R) and optimistic people (blue, LOT-R>mean LOT-R) behave similarly. <b>c</b>) Correlation between subjects' LOT-R scores and the mean of their prior distribution p(c) that the fractal stimulus will lead to a reward (r = −0.049; p = 0.74).