A Multiple Schedule of Conditioned Reinforcement with Chimpanzees

Abstract

The purpose of the present experiment was to study the sustaining of lever-pressing over lengthy experimental sessions by means of conditioned reinforcers (poker chips) which could be exchanged for food at the end of a session. A previous article ( 5 ) presented data which showed that under a 5-min. fixed-interval schedule of conditioned reinforcement, lever-pressing could be sustained when the animals were required to earn groups of poker chips (ranging from 1 to 6 ) before exchange for food was possible. Extinction occurred when poker chips could only be exchanged hourly or when 8 poker chips were required before exchange. On the other hand, an earlier study by Cowles (1 ) indicated that behavior could be sustained under continuous conditioned reinforcement at exchange delays up to 60 min. A comparison of the results suggested that other schedules of conditioned reinforcement should be investigated. This experiment is concerned with a multiple schedule of conditioned reinforcement which is comprised of randomly programmed sequences of 5-min. fixed-intervals and 20-response fixed-ratios ( 3 ) .