Effect of reward magnitude on choice behavior. Reducing the size of the delayed reward from 5 to 3 pellets increased the rate at which rats changed their preference from the large, delayed reward to the small, immediate one. A group of rats (N=16) were tested with 3 pellets as the delayed reinforcer and compared to the rats used in Figure 1, which had received 5 pellets as the delayed reinforcer (effect of reward magnitude × delay length, p=0.0301; asterisks indicate significant difference between 3 and 5-pellet groups, p<0.05, Bonferroni-corrected ANOVA post-hoc test.)