Figure 1. Experimental task and design.

(a) Learning task 2 × 2 factorial design with 4 different contexts: reward/partial, punishment/partial, reward/complete, and punishment/complete. P_Gain= probability of winning 0.5€; P_Loss= probability of losing 0.5€. Note that the coloured frames are introduced in the figure for illustrative purposes, but were not present in the original task. (b) Successive screens of typical trials in the reward partial (top) and complete (bottom) contexts. Durations are given in milliseconds. (c) Time course of the experiment. Note that the post-learning test was uniquely based on the eight options of the last learning session.