DISCRIMINATION OF A RESPONSE‐INDEPENDENT COMPONENT IN A MULTIPLE SCHEDULE1

Pigeons were trained to respond in non‐differential reinforcement pre‐discrimination training, with a multiple variable‐interval 1‐min variable‐interval 1‐min schedule. Each bird then received discrimination training with a multiple variable‐interval 1‐min variable‐time 1‐min schedule. Thus, discrimination training was between response‐dependent (variable‐interval) and response‐independent (variable‐time) schedules with the rate of reinforcement equated. In Experiment I, only three sessions of non‐differential reinforcement preceded discrimination training and for half the birds, a 0° line was correlated with the response‐dependent schedule; for the remaining birds the 0° line was correlated with the response‐independent schedule. Post‐discrimination gradients of excitatory stimulus control were obtained from the former group, while the latter group showed little evidence of post‐discrimination stimulus control by the 0° line. Differential responding to the variable‐time schedule was not accompanied by behavioral contrast to the variable‐interval schedule. In Experiment II, 20 sessions of non‐differential reinforcement preceded discrimination training and the 0° line was correlated with variable‐time reinforcement for each bird. Differential responding to the 0° line was accompanied by negative induction to the variable‐interval schedule and by inhibitory stimulus control about the 0° line during a post‐discrimination generalization test.