Figure 1.

Experimental task. (a) There were two types of learning contexts in the present study. In the factual learning context, the subjects were shown only the outcome of the chosen option. In the counterfactual learning context, the subjects were shown the outcomes of both the chosen and unchosen options. (b) Task conditions Under the same condition, the option pair had an identical reward contingency. Under the different condition, one option had a higher reward probability than the other option. Under the reversal condition, the reward probability was reversed between the options after the first 12 trials were completed.