Learned variability

Abstract

Potential contributors to sustained levels of variability in the topography of the rat's barpress were investigated in two experiments. Behavior was classified into discretely defined components, and changes in components and their sequential organization were analyzed. Experiment 1 showed that topographic variability in the rat is modulated by shifts in reinforcement schedules. Variability decreased between either dipper training or extinction and continuous reinforcement (CRF), and increased between CRF and extinction. Once the press was acquired, variability did not change if the schedule (CRF) did not change. Experiment 2 showed that, regardless of subsequent changes in topographic requirements, rats initially shaped to press under more stringent criteria sustained higher levels of variability during CRF, but not during extinction, than rats shaped with less stringent criteria. The results suggest that subjects learn not only what to do during reinforcement but also how differently or variably to do it. © 1995 Psychonomic Society, Inc.