Occasional reinforced trials during extinction can slow the rate of rapid reacquisition

Two appetitive conditioning experiments with rats examined reacquisition after conditioned responding was eliminated by either extinction or by a partial reinforcement procedure in which reinforced trials were occasionally presented among many nonreinforced trials. In Experiment 1, reacquisition to a conditional stimulus (CS) that had been conditioned and extinguished was more rapid than acquisition in a group that had received no prior conditioning. However, the addition of occasional reinforced trials to extinction slowed this rapid reacquisition effect. Experiment 2 replicated the result and showed that a procedure in which the CS and the unconditional stimulus (US) were unpaired in extinction interfered even further with reacquisition. The results suggest that rapid reacquisition is ordinarily produced when reinforced trials provide a contextual cue that can renew responding by signaling other acquisition trials (Ricker & Bouton, 1996). The effects of partial reinforcement in extinction are surprising from several theoretical perspectives and have useful clinical implications.     

Occasional reinforced responses during extinction can slow the rate of reacquisition of an operant response

Three experiments with rats examined reacquisition of an operant response after either extinction or a response-elimination procedure that included occasional reinforced responses during extinction. In each experiment, reacquisition was slower when response elimination had included occasional reinforced responses, although the effect was especially evident when responding was examined immediately following each response-reinforcer pairing during reacquisition (Experiments 2 and 3). An extinction procedure with added noncontingent reinforcers also slowed reacquisition (Experiment 3). The results are consistent with research in classical conditioning (Bouton, M. E., Woods, A. M., & Pineño, O. (2004). Occasional reinforced trials during extinction can slow the rate of rapid reacquisition. Learning & Motivation, 35, 371-390) and suggest that rapid reacquisition after extinction is analogous to a renewal effect that occurs when reinforced responses signal a return to the conditioning context. Clinical implications are also discussed.     

Effect of interpolated extinction after partial delay of reward training on subsequent reacquisition and extinction

Four groups of albino rats were run four trials a day in a straight runway for 44 days. On the first 15 days, two groups were given continuous immediate reward (IR) and two groups a 50 per cent, schedule of 30-sec. partial delay of reward (PDR). On the next 15 days, one IR group and one PDR group were extinguished, while the other IR and PDR groups remained on their original schedules. In the third phase, all groups received 8 days of training on IR. Finally, all groups were given 6 days of extinction training. In the first extinction, PDR produced greater resistance to extinction than IR. In the second extinction period, the PDR group which had previously been given extinction and the two IR groups extinguished relatively rapidly and at approximately the same rates, while the PDR group which had not been extinguished was significantly more resistant to extinction than the other three groups.     

Acquisition, extinction and reacquisition of a conditioned response in the cockroach: The effects of orotic acid

Cockroaches can be trained to keep their metathoracic leg out of a saline solution. Isolated metathoracic ganglia learnt faster than headless animals, which in turn learnt faster than intact animals. Extinction took longer in the isolated ganglion than in the other two preparations. Extinction times increased with increasing dose of orotic acid, a precursor of RNA. Orotic acid did not systematically affect the times for acquisition and reacquisition of the learnt response.