Fig. 1.

Diagrammatic representation of the behavioral task. During the stimulus portion of the trial, the stimulus (Kanji character) was presented for 400 ms, followed immediately by the response mapping cue (blue and yellow fish) for 400 ms, followed by an intratrial jitter period. During the preparation period, subjects viewed 2 horizontal yellow dashes, which stayed on the screen for the entire time, including the intratrial jitter. At response, the yellow dashes were replaced by blue arrows (700 ms), indicating it was time to make the button press responses; this was followed by another intratrial jitter period. Finally, at feedback, subjects viewed 1 of 4 possible displays indicating whether the response was correct or incorrect and, if correct, what the reward received was, if any (incorrect, correct, correct + $0.10, or correct + $0.50). All intratrial jitter periods (indicated by black dashed arrows) extended for a variable amount of time ranging from 1,000 to 6,000 ms and featured a blank (black) screen, excepting the preparation jitter period as described above. Between trials there was a variable intertrial jitter period that extended for a variable amount of time ranging from 1,000 to 7,000 ms and during which subjects viewed a fixation cross. ITI, intertrial interval.