Figure 2: Temporal discounting task design.

On each trial, patients were presented with two financial options, in sequence. Each option consisted of an amount of money and a delay. After both options had been presented (for 3 seconds each), subjects made their choice with a button key-pad, and moved on to the next trial after a short period. Patients knew that at the end of the task, their chosen option from one randomly-picked trial would be paid faithfully.