LEARNED VARIABILITY

Potential contributors to sustained levels of variability in the topog raphy of the rat's barpress were investigated in two experiments. Beha vior was classified into discretely defined components, and changes in components and their sequential organization were analyzed. Experimen t 1 showed that topographic variability in the rat is modulated by shi fts in reinforcement schedules. Variability decreased between either d ipper training or extinction and continuous reinforcement (CRF), and i ncreased between CRF and extinction. Once the press was acquired, vari ability did not change if the schedule (CRF) did not change. Experimen t 2 showed that, regardless of subsequent changes in topographic requi rements, rats initially shaped to press under more stringent criteria sustained higher levels of variability during CRF, but not during exti nction, than rats shaped with less stringent criteria The results sugg est that subjects learn not only what to do during reinforcement but a lso how differently or variably to do it.