Figure 1.

Auditory discrimination paradigm. Each participant performed a reward and a punishment session on two occasions. Each trial started with a frequency modulated tone and participants had to judge whether the tone was longer or shorter than 600 ms. Depending on the session participants received either (A) a reward of 10 or 50 Euro cent for correct answers and no money (indicated by a 0) for incorrect answers or (B) no money (indicated by a 0) for correct answers and a subtraction of either 10 or 50 Euro cent from a starting value of 25 Euros for incorrect answers. The value of the reinforcement depended in both cases on the direction of the frequency modulated tone which was unknown to the participant and randomized across subjects.