Figure 3.

Mean proportion of responses made to stimulus “A” versus stimulus “B” on each of the 3 test days (±SEM) for (a) control (n = 4), (b) DA-depleted (n = 4), and (c) 5-HT-depleted (n = 4) groups. Mean distribution of responses to stimulus “A” (black portion) and stimulus “B” (white portion) on the final test day is shown in (d). 5-HT depleted monkeys responded more to stimulus “A” than stimulus “B,” DA-depleted and control groups did not. *5-HT depleted monkeys responded more to stimulus “A” on days 2 and 3 than day 1, P = 0.01.