PAUSING UNDER VARIABLE-RATIO SCHEDULES - INTERACTION OF REINFORCER MAGNITUDE, VARIABLE-RATIO SIZE, AND LOWEST RATIO

Pigeons pecked a key under two‐component multiple variable‐ratio schedules that offered 8‐s or 2‐s access to grain. Postreinforcement pausing and the rates of responding following the pause (run rates) in each component were measured as a function of variable‐ratio size and the size of the lowest ratio in the configuration of ratios comprising each schedule. In one group of subjects, variable‐ratio size was varied while the size of the lowest ratio was held constant. In a second group, the size of the lowest ratio was varied while variable‐ratio size was held constant. For all subjects, the mean duration of postreinforcement pausing increased in the 2‐s component but not in the 8‐s component. Postreinforcement pauses increased with increases in variable‐ratio size (Group 1) and with increases in the lowest ratio (Group 2). In both groups, run rates were slightly higher in the 8‐s component than in the 2‐s component. Run rates decreased slightly as variable‐ratio size increased, but were unaffected by increases in the size of the lowest ratio. These results suggest that variable‐ratio size, the size of the lowest ratio, and reinforcer magnitude interact to determine the duration of postreinforcement pauses. 1990 Society for the Experimental Analysis of Behavior