Differential effects of amphetamine on succesive post-reinforcement periods in variable schedules.

Abstract

Four pigeons responded under a variable-interval schedule of food presentation. Lo­cal response rates were recorded in three successive post-reinforcement periods. The cf­fects of aniphetamine (0.5, 1.0, asid 2.0 mg/kg) on local responde rates were relatively greater on the 10-sec period followlng reinforcements than on later periods. A rate-dep­endent effect was observed, but iii the opposite direction of that predicted by dic rate­dependency hypothesis: Iowa local response rates were proportionately more depressed by the 2.0 mg/kg dose than higher local response rates.