Effects of Reward Magnitude on Key Pecking and Eating by Pigeons in a Closed Economy

Abstract

Three experiments examined the effects of reward magnitude on key pecking and eating by pigeons in a closed economy. In Experiment 1, one deprived pigeon and two nondeprived pigeons key pecked on increasingly higher fixed ratios to earn access to food for the remainder of the session. In Experiments 2 and 3, deprived pigeons working in a closed economy key pecked on either six fixed-ratio or two variable-interval schedules to earn access to one of three short durations of feeding. All pigeons initially key pecked more frequently as the ratio (or interval) size increased or reward magnitude decreased. In Experiments 1 and 2, the point of maximum key pecking varied directly with magnitude of reward and occurred at similar prices (number of key pecks per gram of food eaten). Key pecking on interval schedules also varied inversely with reward magnitude; however, maximum key pecking was sustained over a wider range of prices. The implications of these results for economic models and regulatory models of learned performance and the concept of ratio strain in a closed economy are briefly discussed.