Effects of reinforcer magnitude on an animal model of impulsive behavior

The effects of altering sucrose solution concentration on discounting of delayed rewards in rats were examined. Five different delays were used (0, 1, 2, 4, and 8s) and three different sucrose solution concentrations (3, 10, and 30%). It was hypothesized that high value sucrose solution concentrations would be discounted less than low value sucrose solution concentrations. The results indicated that the rats discounted the 30% sucrose solution concentration at a higher rate than the 3 or 10% sucrose solution concentration, a finding that apparently contradicted the hypothesis that higher value sucrose solution concentrations would be discounted less than lower value sucrose solution concentrations. However, a follow up experiment indicated that the 3 and 10% sucrose solution concentrations were preferred over the 30% concentration. Thus the results of Experiment 1 can be interpreted as supporting the hypothesis that high valued sucrose solution concentrations are discounted less than lower valued sucrose solution concentrations.