WHEEL-RUNNING IN DISCRETE TRIAL AND OPERANT PARADIGMS UNDER VARIOUS EFFORT REQUIREMENTS

Two experiments were conducted in which the wheel-running behavior of rats under various effort requirements was investigated. The specific effort requirements were obtained by varying the tangential force requ ired to initiate wheel movement. In the first experiment, a discrete t rial preparation was used in which 4 groups of rats received training with high effort levels of 90, 110, 130, and 150 g. The results showed that increasing effort requirements slowed the rate of acquisition, l owered the asymptotic running speeds, and reduced resistance to extinc tion. In the second experiment, using an operant preparation, running speeds were examined for baseline (nonreinforced) and fixed-interval 1 min schedules of reinforcement at effort levels of 45, 90, and 180 g. The results clearly showed wheel-running to be schedule-induced. Howe ver, the effects of effort on Fl behavior were less clear due to incon sistencies between subjects. Results are discussed in terms of the pot ential benefits of bridging operant and discrete trial preparations an d methods for studying the effects of effort on animal behavior.