LASTING EFFECTS OF A BEHAVIORAL HISTORY OF LOW-RATE RESPONDING IN RATS

This study examined the effects of a history of responding under a dif ferential-reinforcement-of-low-rate 60-s schedule on subsequent respon ding under a fixed-ratio 10 schedule in rats. Additionally, the effect s of a fixed-ratio 10 history on responding under a differential-reinf orcement-of-low-rate 60-s schedule were investigated. The most promine nt finding was that a differential-reinforcement-of-low-rate schedule history resulted in rats emitting significantly lower response rates a nd longer post-reinforcement pauses under the subsequent fixed-ratio s chedule. These effects lasted for at least 35 sessions. in contrast, a history of responding under the fixed-ratio IO schedule produced only a transient (15 sessions) elevation in the rate of responding when th e rats subsequently responded under the differential-reinforcement-of- low-rate 60-s schedule, relative to rats without a history of respondi ng under the fixed-ratio 10. These data demonstrate that responding ma intained under ratio contingencies is susceptible to long-lasting infl uence by historical factors. The magnitude and longevity of these effe cts are, in many cases, more potent than those previously obtained wit h fixed-interval schedules. This challenges the notion that ratio perf ormance is relatively less sensitive than interval performance to hist orical factors. (C) 1998 Academic Press.