Document Type



Four experimentally naive White Carneau pigeons acquired a key-peck response without specific response shaping or other training when such responding was reinforced according to a tandem variable-interval t-s differential-reinforcement-of-other-behavior 30-s schedule. This schedule defined an unsignaled, resetting delay-of-reinforcement procedure. When subsequently exposed to a variable-interval schedule of immediate reinforcement, response rates increased rapidly, usually within a single 9O-min session. The response rates of the pigeons under this latter condition were comparable to those of other pigeons with a history of responding only on variable-interval schedules of reinforcement, with reinforcement rates and distributions yoked to the delay of reinforcement condition. Two other pigeons exposed to a schedule of response-independent food delivery, yoked in terms of food delivery rate to the tandem schedule, did not peck consistently and eventually stopped responding. The results suggest that the persistence of low-rate responding often reported in studies of behavioral history effects is not universal. Rather, it is a product of both experimenter-arranged and naturally occurring specific past and current contingencies.