Figure 2.

Schematic of a single trial from a Monetary Incentive Delay (MID) task, with example time intervals. The subject is first presented with a cue, depicting the valence and magnitude of the potential outcome (see inset). Following a variable inter-stimulus interval (ISI; filled in this case by a black screen with a fixation star), a target stimulus (e.g., a white cross on a black background) appears, prompting the participant to respond within a target time window. Following another ISI, the actual outcome is displayed. If a participant responds within the acceptable response window on a gain trial, the total amount of money increments by the associated amount; if not, the total increments by a nominal (small) amount, or not at all. If a participant responds within the acceptable response window on a loss trial, the total amount of money decrements by a nominal (small) amount, or not at all; if the subject is too slow, the subject loses the full predicted amount. Because the interval between the cue and the outcome is variable and long, the cue and outcome regressors are not collinear, and, thus, brain responses to the cue (thought to be associated with outcome anticipation) and outcome receipt can be modeled separately in functional imaging experiments.