Abstract
Why don’t rats prefer a longer opportunity to run? The current study addressed this question by having rats respond on concurrent fixed ratio (FR) 1 fixed ratio 1 schedules that provided 30-s opportunities to run. Following the termination of one, but not the other wheel-running reinforcement interval, .1 ml of 15% sucrose solution was delivered. Wheel-running reinforcement intervals on both alternatives were systematically decreased across values of 10 s, 5 s, 2.5 s, 1 s, and 0.5 s. Results showed that rats remained indifferent until both alternatives decreased to 2.5 s. At 2.5 s and below a strong preference for the alternative followed by sucrose developed. The correspondence between these results and those for choice between different durations of wheel-running reinforcement implies that revolutions beyond a few seconds also do not affect operant responding. Further research, however, should investigate the effect of stimuli during wheel-running reinforcement intervals on choice between reinforcement of different durations.