(A) Effects of repeated oral administration of 0.25, 0.5, or 1.25 μmol/kg of IMD or 0.56 and 1 μmol/kg of ALP alone, and a combination of ALP with IMD during repeated administration of 1.25 μmol/kg of IMD on percent errors in each component of the multiple schedule for three subjects. Points and vertical lines at V and ALP indicate the mean and range for at least 10 vehicle (⧫) and two ALP (□) sessions, respectively. The points in the time effect curves without vertical lines indicate single determinations of the effects of IMD alone (▴) or in combination (○, arrows) with a single dose of ALP. Monkeys A and G received 1 μmol/kg and Monkey F received 0.56 μmol/kg of ALP. All monkeys received repeated administration of increasing doses (0.25, 0.5, and 1.25 μmol/kg) of IMD for 4, 4, and 15 days, respectively. (B) Effects of repeated oral administration of 0.25, 0.5, and 1.25 μmol/kg of IMD and a single 0.56 or 1 μmol/kg of ALP alone, and a combination of ALP with IMD during repeated administration of IMD (1.25 μmol/kg) on response rates in each component of the multiple schedule for three subjects. All drug doses, symbols, keys, and schedule of treatments and subjects are the same as in A.