FIG. 1.

Behavioral task and cue-outcome contingencies. A: sequence of events in the visually triggered bar-release task with incentive cue. The monkey initiates each trial by touching a lever. The monkey is required to respond by releasing the lever when the color of a visual target changed from red to green. A trial is scored as correct if the monkey releases the lever 200-1,000 ms after the target changes to green (Go). If the trial is correctly performed, a blue spot replaces the green target. Water reward is delivered after a delay period. A visual cue presented at the beginning of the trial indicates the duration of the delay or the reward size. B–E: relationship between cue and outcome (size and timing of the reward). B: the 4 cues used in the reward-size task. C: the 3 cues used in the reward-delay task. D: the 3 cues used in the next-trial-delay task. E: the 8 cues used in the reward-size-and-delay task.