Effect of sucrose reinforcement on operant wheel running on a fixed ratio schedule

Abstract

In the current study, I investigated the effect of sucrose reinforcement on operant wheel running on a fixed ratio (FR) schedule. Rats responded on a FR-40 schedule in which wheel-running produced the opportunity to consume sucrose solution. Sucrose reinforcement was removed after 25 sessions and rats were returned to baseline (water). Based on the traditional concept of reinforcement, wheel-running rates were expected to increase close in time before sucrose reinforcement was delivered. Alternatively, there could be a marked increase in running at the beginning due to a schedule-induced effect of sucrose presentation. Results were not consistent with either prediction. Sucrose reinforcement systematically increased running over the entire 40 revolutions. Possible explanations for this extended reinforcement effect are that wheel running, unlike other operant behaviors, such as lever pressing, generates its own automatic reinforcement effect and is a continuous, rather than a discrete, behavior. Further research is required to explore these aspects of wheel running.