Behavioral contrast in rats when qualitatively different reinforcers are used

Abstract

Behavioral contrast was studied during multiple schedules which provided qualitatively different reinforcers in the two components. Five rats responded on a baseline schedule in which both components delivered food reinforcers (food-food), and then on a contrast schedule in which one component delivered food and the other delivered water (food-water). Following this, baseline was recovered. Five other rats responded on a baseline schedule in which both components delivered water reinforcers (water-water), then on a food-water schedule, and then on the baseline, water- water, schedule. Contrast was not observed when relatively low rates of reinforcement were use but it was sometimes observed when high rates of reinforcement were used. The rate of responding for a constant water reinforcer decreased when food replaced water in the other component. The rate of responding for a constant food reinforcer did not change when a water reinforcer replaced food in the other component. These results are similar to those reported by Ettinger and McSweeney (1981) when pigeons served as subjects.