Acquisition of the free-operant under delayed reinforcement conditions: A review

Abstract

Recent studies have shown that the acquisition of free operant responding may occur under conditions of delayed reinforcement and without explicit shaping. The purpose of the present review is to coherently present the studies generated on the subject. The studies conducted so far suggest the phenomenon is general across a number of different animal species and procedures. The studies also suggest the phenomenon is less apparent with delay durations in the vicinity of one minute and with combinations of contingent and non contingent reinforcers. Exteroceptive stimuli presented during the delay interval and non-contingent food delivered before the exposure to the schedule considerably enhance response acquisition. As a future research agenda, this review suggests different operational definitions of response acquisition be empirically tested; additionally procedural differences between the studies conducted so far should be systematically studied.