Punished behavior: increases in responding after d-amphetamine.

Responding maintained in squirrel monkeys under a 10-min fixed-interval schedule of food presentation was suppressed by presenting a shock after every 30th response (punishment). During alternate 10-min periods of the same experimental session, but in the presence of a different discriminative stimulus, responding either had no effect (extinction) or postponed delivery of an electric shock (avoidance). During sessions when the avoidance schedule was not in effect, d-amphetamine sulfate decreased punished responding. When the avoidance schedule was present during alternate 10-min periods, however, d-amphetamine (0.01 minus 0.56 mg/kg, i.m.) markedly increased responding during punishment components. Increases in responding during avoidance components were also evident. The effects of d-amphetamine on punished responding depend on the context in which that responding occurs.