Unrewarded trials and resistance to extinction of a bar-pressing response

Abstract

Two experiments in a free-operant situation tested the generality of Lawrence & Festinger's (1962) hypothesis that the total number of nonreinforced trials, not percentage of reward, is the critical variable in determining resistance to extinction. This was supported by Experiment 1. However, when rate of responding was held constant in Experiment 2 the hypothesis was not supported. The results suggest that S's with faster rates of responding in acquisition make more responses in extinction indicating an energizing effect of nonreinforcement. Lawrence & Festinger (1962) have hypothesized that the partial reinforcement effect (PRE) may be understood in terms of a theory of cognitive dissonance. ACCOrding to the hypothesis, dissonance occurs on each unrewarded trial but S learns to reduce this dissonance by finding "extra attractions" in the situation and so continues to perform the response in the absence of the normal reward. A corollary of this hypothesis is that it is the total number of unrewarded trials that determines resistance to extinction, and not, as commonly assumed, percentage of reward. In support of this Lawrence and Festinger report an experiment in which three levels of unrewarded trials and three percentages of reward were combined in a 3 by 3 factorial design. The apparatus was an S-shaped rwlway conta,ining obstructions. Results showed that the only significant effect was number of unrewarded trials. Since recent theorizing on the PRE suggests that discrete trial and free responding situations may not yield comparable data (Amsel, Rashotte, & Mac-Kinnon, 1966), it would seem profitable to test the generality of Lawrence and Festinger's finding by attempting to replicate the results in a standard free operant situation. EXPERIMENT 1 Subjects Ss were 44 experimentally naive male albino rats of the Wi star strain with ages ranging from 155 to 175 days at the commencement of the experiment. Procedure Apparatus consisted of three Skinner boxes each equipped with a bar requiring a force of 15 g to depress. The reinforcing mechanism was a modified Deutsch Spaghetti Gun (Trotter, 1956) which dispensed pieces of commercial spaghetti with a mean weight of 20 mg. Three weeks before the beginning of the experiment Ss were deprived of food for 48 h and thereafter

Continuous trial between- and within-subject partial reinforcement effect.

“…In the continuous trial situation, resistance to extinction is a function of the absolute number of nonreinforced trials (Dutch and Quartermain, 1967). This suggests that "persistence," defined as a specific energy or work requirement, is necessary for PR to be effective in obtaining a PRE.…”

Partial reinforcement acquisition effects within subject

“…They suggest that in the free operant situation response chaining may occur and that this may result in a confounding of response patterns from the feedback stimulation from any trial or trials. Dutch & Quartermain (1967) in a between-S free operant experiment observed a faster response rate in acquisition and greater resistance to extinction for groups receiving hig~er numbers of nonreinforced trials. They suggested that nonremforcement increased the speed of responding in acquisition, and that the faster the rate in acquisition, the higher the extinction score.…”