PARTIAL-REINFORCEMENT IN APPETITIVE PAVLOVIAN CONDITIONING WITH RATS

Four experiments examined the effects of a partial reinforcement sched ule on extinction using appetitive Pavlovian conditioning. Extinction was slower after partial than after continuous reinforcement when the schedules were administered to different groups (Experiment 1). The op posite result was found in Experiments 2 and 3 when both schedules wer e presented to the same group in the same context. When the schedules were presented to the. same group in different contexts, then extincti on was again slower after partial reinforcement (Experiment 3). Experi ment 4 demonstrated that a change of context facilitates extinction to a greater extent after conditioning with a partial reinforcement sche dule than with a continuous one. The results are explained by assuming that the nonreinforced trials of a partial reinforcement schedule cre ate an internal state that serves as a contextual cue.