実験的消去とその回復に関する実験的研究

抄録

The nature of experimental extinction was studied by checking the effect of intertrial intervals in exp. 1, and the rate of reinforcement in exp. 2, upon the rate of spontaneous recovery.
In the first experiment, 18 rats were trained on an elevated straight alley, 20 trials per day for 5 days. Then extinction was performed for one group with intertrial interval of 7.5 minutes, and for the other with much shorter interval of a few seconds. The session of spontaneous recovery followed the extinction after 24 hours, in which the intertrial interval was 3.5 minutes for both groups the same as in the training session. The results are shown in Figs. 1 & 2 and Tables 1 & 2. The massed group reached the criterion earlier than the spaced group in extinction while in the session of spontaneous recovery the former showed a relatively high response tendency. These results support the assumption that the extinc-tion is a complex of the transitional inhibition which disappears with time and the permanent one, and the control of intertrial interval seems to regulate the proportion of the amount of those two kinds of inhibition during the session of extinction.
In the second experiment three groups, 7 rats for each, were trained on the same alley as the one in the first experiment, 15 trials per day until each individual reached a criterion. The experimental group 1 was reinforced one time and the experimental group 2 two times for every three trials while the control group was reinforced on every trial. Extinction session followed the training. Twenty four hours after the criterion of extinction was reached, the spontaneous recovery was investigate. This time, the intertrial interval was 20 seconds for all sessions. The results are shown in Figs. 3 & 4 and Table 3 & 4. The experimental groups showed greater resistance against extinction than the control groups while the former showed a more spontaneous recovery. This relationship between the rate of reinforcement, resistance to extinction and the spontaneous recovery seems to exist among the experimental groups. Considering the reinforcement as an agent of stimulus complex, the above experimental procedure and results resemble the traditional experiments of retroactive inhibition in memory, in that the rate of reinforcement forms a continuity of generalization between the sessions of training and extinction where the rate is zero. From the above experiments, it is also concluded that the experimental extinction not merely is an arithmetical subtraction of habit acquired in the training but possesses an interaction with the training procedure.