Figure 1.

Course of the experimental paradigm. A, Reward at stake is presented (e.g., 50 Swiss centimes). B, Subject chooses color via button press. C, The inner rectangle starts alternating and stops after 3500–3800 ms. D, If the chosen color (outer rectangle) and the inner rectangle match, the subject wins. If the two rectangles are of different color, the potential reward is omitted. E, After the presentation of a blank screen for 1 s, the next trial starts with a different reward value at stake. iti, Intertrial interval.