Fig 1. Experimental task.

(A) Depiction of trial timeline and stimulus features. Participants performed miniblocks of 15 trials in which they collected points to reach either one or two goals, rewarding them with additional 5 or 10 Cents. Each trial started with a decision phase (maximum 3s) in which participants had to accept or reject a presented offer. Depending on the offer, accepting increased or decreased A- and B-points. The current amount of points was displayed by two grey bars flanking the stimulus screen. In the feedback phase (1.5s), gained points were displayed as a green area and lost points as a red area on the bar. The horizontal lines crossing the bars indicated the threshold for reaching goal A and goal B. After 15 trials, feedback for the miniblock was displayed (4s) informing the participant about the reward gained. (B) Summary of offer types and their effect on point count. Offers occurred with equal probability in each trial of the miniblock. Basic offers (A and B) increased either A or B points. Mixed offers (Ab and aB) added one point on one side but subtracted one point on the other side. Only accepting an offer had an effect on points. (C) Three different conditions modulated the difficulty to reach both thresholds by varying the number of initial points. Using an optimal agent, we chose the number of initial points, such that the agent’s probability of reaching both thresholds (G2-success) was 75% in easy, 35% in medium and 7% in hard.