VARIABLE-INTERVAL SCHEDULE CONTROL FOLLOWING RESPONSE ACQUISITION WITH DELAYED REINFORCEMENT

Four experimentally naive White Carneau pigeons acquired a key-peck re sponse without specific response shaping or other training when such r esponding was reinforced according to a tandem variable-interval t-s d ifferential-reinforcement-of-other-behavior 30-s schedule. This schedu le 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 sin gle 90-min session. The response rates of the pigeons under this latte r condition were comparable to those of other pigeons with a history o f responding only on variable-interval schedules of reinforcement, wit h reinforcement rates and distributions yoked to the delay of reinforc ement condition. Two other pigeons exposed to a schedule of response-i ndependent food delivery, yoked in terms of food delivery rate to the tandem schedule, did not peck consistently and eventually stopped resp onding. The results suggest that the persistence of low-rate respondin g often reported in studies of behavioral history effects is not unive rsal. Rather, it is a product of both experimenter-arranged and natura lly occurring specific past and current contingencies.