Figure 1.

Modified Monetary Incentive Delay task participants have to respond as quickly as possible with left or right index finger to hit a target (white square) that appears for a short time on the left or right side of the screen. When subjects hit the target in time on the appropriate side, they score points. A preceding clue provides information on the points to be won. A triangle indicates no points, a circle with one line, two points, and a circle with three lines, ten points. For each condition (no win, small win, and big win), 22 trials were presented in equal proportion for each target side. A short training period outside the scanner was carried out to ensure a full understanding of the task.