The cognitive probabilistic learning task involves a training phase in which participants learn to discriminate the feedback probabilities (positive feedback: green check mark; negative feedback: red cross) associated with different pairs of symbolic stimuli [18]. Participants learn from trial-and-error that symbol A was being rewarded with positive feedback in 80% of the trials, whereas symbol B was being rewarded in 20%. The distribution of positive-feedback probabilities for other pairs range from 70% versus 30% for Pair C–D, and 60% versus 40% for Pair E–F. Feedback is given for each trial. At the end of the training phase (128 trials), participants should learn that symbol A is the most favorable choice and the one most likely to get positive feedback, whereas symbol B is the least favorable one and should be avoided. During the testing phase, symbols A and B are paired with the other four symbols to create 8 new pairs for a total of 96 trials, and no feedback is given during the test. The results were tallied according to the proportions of trials in which symbol A was
