Conditioned reinforcement strength as a function of the pattern of reward and nonreward

Abstract

Two groups of rats (N = 20) received 50% reinforcement for responding in the presence of a light stimulus. For one group, there were long runs of reinforced and nonreinforced stimulus presentations; for the other group, the runs were short. Response latencies indicated that the reinforcement pattern was not discriminated. A test for conditioned reinforcement strength revealed that the stimulus acquired more strength in the group which had experienced longer runs of reinforcement and nonreinforcement. The pattern of rewards and nonrewards in a partial-reinforcement schedule would seem to be a factor affecting resistance to extinction, especially under conditions of relatively short intertrial intervaI. Capaldi (1966, 1967) has suggested that the average length of runs of consecutive nonreinforced trials (N-length) is one of the crucial factors in determining resistance to extinction (RE). Since variables which have been found to influence the RE of a conditioned response have usually been found also to influence the RE of a conditioned reinforcer, McCausland (1969) investigated the effects of the pattern of stimulus-reinforcement pairings on conditioned reinforcement strength. Two grOUPS of rats were conditioned to leverpress in the presence of a light stimulus.