Belke, T.W., Pierce, W.D. & Duncan, I.D. (2006).
Reinforcement value and substitutability of sucrose and wheel running: implications for activity anorexia.
Journal of the Experimental Analysis of Behavior, 86, 131-158.
Choice between sucrose and wheel-running reinforcement was assessed in two experiments. In the first experiment,
ten male Wistar rats were exposed to concurrent VI 30 s VI 30 s schedules of wheel-running and sucrose
reinforcement. Sucrose concentration varied across concentrations of 2.5, 7.5, and 12.5%. As concentration
increased, more behavior was allocated to sucrose and more reinforcements were obtained from that alternative.
Allocation of behavior to wheel running decreased, but obtained wheel-running reinforcement did not change.
Overall, the results suggested that food-deprived rats were sensitive to qualitative changes in food supply
(sucrose concentration) while continuing to defend a level of physical activity (wheel running). In the second
study, 15 female Long Evans rats were exposed to concurrent variable ratio schedules of sucrose and wheel running,
wheel-running and wheel-running, and sucrose and sucrose reinforcement. For each pair of reinforcers,
substitutability was assessed by the effect of income-compensated price changes on consumption of the two
reinforcers. Results showed that, as expected, sucrose substituted for sucrose and wheel running substituted for
wheel running. Wheel running, however, did not substitute for sucrose; but sucrose partially substituted for
wheel running. We address the implications of the interrelationships of sucrose and wheel running for an
understanding of activity anorexia.
Key words: choice, reinforcement value, substitutability, activity anorexia, behavioral economics, sucrose, wheel running, lever press, rat