A. Grant Young

ECS effects: The PRE

Sixty-four naive male albino rats were trained to leverpress for sucrose using a discrete trial procedure. Half of the Ss were trained on a continuous reinforcement schedule (CRF), and the other half were trained on a fixed-ratio schedule (FR). Following acquisition, on treatment day, a leverpress produced footshock followed by ECS (SECS), footshock only (SO), ECS only (ECSO), or no treatment (OO). Results of an extinction test 24 h after treatment showed that: (1)ECS produced apparent amnesia for footshock; (2) ECS eliminated the partial reinforcement effect (PRE); (3) footshock appeared to be a more effective suppressor in FR- than in CRF-trained Ss; (4) ECS alone produced a significantly increased rate of responding for CRF-trained Ss and a nonsignificant increased rate of responding for FR-trained Ss.

The effects of electroconvulsive shock on extinction

Seventy-two naive male albino rats were trained to leverpress for sucrose using a discrete trial procedure. The Ss were trained on a continuous reinforcement schedule, a fixed-, or a variable-ratio schedule. Following acquisition, for one-third of the Ss in each group, a leverpress produced an ECS; for the other two groups, which served as controls, no treatment was given. All groups were extinguished 24 h later. Immediately following this extinction session, one control group experienced ECS, and 24 h later all Ss were subjected to a second extinction session. Results showed that ECS maintained responding and prolonged extinction. Results further showed no loss of the partial reinforcement effect.

Resistance to extinction as a function of partial reinforcement and external stimuli: A within- S design

Ninety-six male albino rats were conditioned to leverpress for sucrose. The basic design of within-S groups was a 2 by 2 by 2 factorial, incorporating light-ON or light-OFF extinction conditions; CRF(ON)-PR(OFF) or PR(ON)-CRF(OFF) training schedules; and 1,600 or 3,200 total training trials. In addition, there was a 100% reinforcement condition constituting a 2 by 2 factorial of between-S groups incorporating light ON or light OFF, and 1,600 or 3,200 total training trials. Results showed that for within-S groups there were no differences in resistance to extinction and that for between-S groups there were no differences in resistance to extinction; however, all Ss which experienced PR training were significantly more resistant to extinction than Ss which experienced CRF training only. Results were discussed in terms of the response specificity of the PRE.

ECS effects on the extinction of a running response following CRF or VR training

Thirty-two male albino rats were trained to run a straight runway on either a continuous reinforcement schedule (CRF) or a variable ratio (VR) schedule of reinforcement. Following 100 acquisition trials, half of the subjects in each reinforcement group received a single electroconvulsive shock (ECS) while the other half received no treatment. Results of 30 extinction trials showed that, overall, VR-trained subjects ran faster than did CRF-trained subjects; however, those CRF-trained subjects which experienced ECS were not significantly different from VR-trained subjects. The ECS treatment thus eliminated the usual partial reinforcement effect. Results were interpreted in terms of an increased drive or hyperactivity produced by the ECS.

Resistance to extinction as a function of reinforcement schedule: A within-subject design

Sixty-four male albino rats were trained to run a straight runway. Half of the subjects were trained on a continuous reinforcement schedule (CRF) and half on a partial reinforcement schedule (PR). On reinforced trials, a lever was introduced into the goalbox and the subject was allowed to make 10 discrete trial leverpresses for sucrose. The lever was not introduced into the goalbox on nonreinforced trials. The subjects were trained under either a CRF or PR leverpress schedule. Upon completion of acquisition half of the subjects in each subgroup were extinguished in the runway and the other half were extinguished in the goalbox on the lever. Results showed that for subjects extinguished on the lever the partial reinforcement effect (PRE) was a function only of the lever reinforcement schedule and was independent of the runway reinforcement schedule. However for subjects extinguished in the runway, PR runway-trained subjects receiving CRF leverpress training were more resistant to extinction than were PR runway-trained subjects receiving PR leverpress training.

A within-S test of the response specificity of the PRE

Sixty-four male albino rats were trained to leverpress in an operant chamber and to run a straight runway. Half of Ss were trained on a continuous reinforcement schedule (CRF), and the other half on a partial reinforcement schedule (PR). Upon completion of acquisition, the groups were subdivided and given acquisition training in the other apparatus, half under conditions of CRF and the other half under conditions of PR. Upon completion of acquisition on both pieces of apparatus, half of Ss in each subgroup were extinguished in the runway, and the other half were extinguished in the operant chamber. Results showed that resistance to extinction of either response was a function only of the training reinforcement for that response, and was independent of the schedule of reinforcement received in training of the other response. Results were discussed in terms of the response specificity of the partial reinforcement effect (PRE).

The effect of ECS on extinction

Sixty naive male albino rats were trained to leverpress for sucrose on either a continuous reinforcement schedule (CRF), fixed ratio (FR), or variable ratio (VR). Following acquisition, half of Ss in each group experienced ECS, while the other half experienced no ECS. Results of an extinction test 24 h after treatment showed that ECS produced a significantly increased rate of responding for CRF-trained Ss, and a nonsignificant increased rate of responding for Ss trained on ratio schedules.

ECS effects: An attempt to stimulate recovery of the PRE

Eighty naive male albino rats were trained to leverpress for sucrose on either continuous reinforcement (CRF) or partial reinforcement (PR). Following training, S experienced treatment consisting of either footshock plus ECS or footshock only. Four hours after original treatment, half of the Ss in each group received a “reminder” shock. Results of an extinction test 24 h after original treatment showed that: (1) ECS produced apparent amnesia for footshock, (2) ECS eliminated the partial reinforcement effect (PRE), (3) “reminder” shock produced at least partial recovery from ECS-induced amnesia, and (4) “reminder” shock did not reinstate the PRE. Results were interpreted as not supportive of a memory consolidation hypothesis.

Punishment and resistance to extinction

Forty-eight naive male albino rats were trained to leverpress for sucrose on a continuous reinforcement schedule. Experimental groups received different intensities of footshock on a VR-2 schedule during acquisition. Extinction results suggested that the function relating intermittent punishment during acquisition to resistance to extinction may be quadratic.

Compound conditioning: Component strength in a compound CS as a function of test trial ratio

An active avoidance conditioning paradigm was used in training 48 male albino rats to a compound CS, light and tone. Four groups of subjects, each divided into three subgroups, were overtrained to the compound with intervening test trials to the compound, tone, or light according to the ratios 1/60, 1/30, 1/10, 1/5. The same CS was given on all test trials. After overtraining, each subject received an extinction session to all stimuli. The results showed the component response strengths increased during overtraining. On the first test trial, the response strength to the compound was greatest, whereas on the last test trial, the response strengths to the compound, light, and tone were similar. The effects of test trial ratios were minimal.