Qualitatively varied reinforcement does not increase rates of schedule-induced behaviour

Abstract

Qualitatively varied reinforcement (QVR) refers to the delivery of two or more consequences for the same operant response. It has been suggested that QVR ought to elicit higher response rates than a single reinforcer. Schedule-induced behaviours, like wheel running, have been compared to operant behaviours, thus they could be thought to be controlled by the same variables. The aim of this study was to compare the rates of lever pressing and wheel running during a component in which QVR was available to those in which a single reinforcer was available. Subjects were 8 experimentally naïve male Wistar rats deprived of food and water. Subjects were exposed to a multiple schedule with 3 components in which different consequences were available: food, water, or either food or water, according to a variable interval 120-s schedule for lever pressing. Each component lasted 30 minutes. During experimental sessions subjects also had access to a running wheel. Higher, albeit not significant, lever-pressing rates were recorded during the food component than during the water component or the qualitatively-varied one, and no systematic differences were found between components in wheel-running rates. A second experiment with a similar procedure but in which rats received double amount of reinforcer (food, water, and food and water) yielded similar results, but with slightly higher response rates during the qualitatively varied component than in Experiment 1. Results are consistent with the findings that schedule-induced behaviours are affected by the same variables than operant behaviours. There was no significant effect of QVR to produce higher response rates than single reinforcers.

Keywords

• qualitatively varied reinforcement
• variable interval food and/or water reinforcement
• lever pressing
• wheel running
• rats