RUNNING AND RESPONDING REINFORCED BY THE OPPORTUNITY TO RUN - EFFECT OF REINFORCER DURATION

The present study investigated the effect of reinforcer duration on ru nning and on responding reinforced by the opportunity to run. Eleven m ale Wistar rats responded on levers for the opportunity to run in a ru nning wheel. Opportunities to run were programmed to occur on a tandem fixed-ratio I variable-interval 30-s reinforcement schedule. Reinforc er duration varied across conditions from 30 to 120 s. As reinforcer d uration increased, the rates of running and lever pressing declined, a nd latency to lever press increased. The increase in latency to respon d was consistent with findings that unconditioned inhibitory aftereffe cts of reinforcement increase with reinforcer magnitude. The decrease in local lever-pressing rates, however, was inconsistent with the view that response strength increases with the duration of the reinforcer. Response rate varied inversely, not directly with reinforcer duration . Furthermore, within-session data challenge satiation, fatigue, and r esponse deprivation as determinants of the observed changes in running and responding. In sum, the results point to the need for further res earch with nonappetitive forms of reinforcement.