variably delayed reinforcement

A contingency specifies the conditions under which responses produce consequences and determines both the contiguities of events at particular moments and the correlations of events over time. When contingencies maintain behav-ior, the properties that are responsible for that maintenance can be studied with procedures that remove or relax the contingent relation between a response and a reinforcer and with procedures that alter the rate at which reinforcers are deliv-ered. The present research extended procedures involving pigeons ’ pecks on a single key (Catania & Keller, 1981) to those in which the changes in contingencies could also be accompanied by the concurrent reinforcement of pecks on a second key. Contingencies between a pigeon’s key pecks and food deliveries can be terminated in two ways: either pecks have no scheduled consequences and reinforcers are delivered noncontingently or reinforcer deliveries are terminated in extinction. In both cases the response-reinforcer contingency is discontinued, but only in the latter are reinforcer deliveries discontinued. Extinction has typically been the preferred method for discontinuing This paper is based upon a 1981 Master’s Thesis presented by the first author to the Department of Psychology at UMBC. We thank the staff and students who participated in the work of the laboratory during these experiments and we especially acknowledge the contributions of Wayne Murphy and Mark Reynolds. The sec