Habit Reversal as a Function of Length of Partial Delay of Reinforcement

While the effects of delay of reinforcement on response acquisition are well known ( 6 ) , there is comparatively little information regarding its effects upon resistance to extinction. Recently, Fehrer ( 3 ) has demonstrated that a constant delay of reinforcement produces an instrumental response that is more resistant to extinction than when reward is immediately forthcoming. In the case of partially delayed reinforcement, in which delay of reward is imposed on a fraction of the training trials, there is considerable evidence (1, 8, 9, 10, 11) that delay of reinforcement enhances resistance to extinction. In addition Logan, et al. ( 7 ) have shown that that effect of partially delayed reinforcement is directly related to the length of delay. When the magnitude of partial delay was increased to 30 sec., the partially delayed Ss ran more rapidly during extinction than control Ss with either no delay or a partial delay of 9 sec. Since all these studies of partially delayed reinforcement have used runways, it appears desirable to investigate the generality of some of these findings in a more complex situation. In the present study a selective learning situation, a single unit T-maze, is employed, and the time required to achieve reversal in a position response constitutes the index of response strength. Some advantages of this criterion of response strength have been pointed out elsewhere ( 5 ). The purpose of the present investigation is then to determine whether or not the acquisition and reversal of a T-maze position response are affected by the length of partially delayed reinforcement.