Figure 1.

Behavioral paradigm and performance. (A) Monetary incentive delay task: a reward cue (a dollar, a cent, or no money) appeared at the beginning of each trial. After a randomized interval between 1 and 5 seconds, a target box appeared on the screen and disappeared after a short period (response window). Participants were told to press the button as quickly as possible to collect the money in the target box (win) before it disappeared. Otherwise, participants would lose the reward, with the amount deducted from the total win. A premature button-press prior to the appearance of the target box terminated the trial and similarly resulted in loss. A feedback window was shown on the screen after each trial to indicate the amount of money won or lost. (B) Accuracy rate and (C) Reaction time (RT) of dollar, cent and no money (nil) trials (mean ± SE). *P < .05.