ネズミの自発的交替現象の研究 III

Abstract

In a previous paper (Fujita, 1955), the author found that the percentage of spontaneous alternation in a T-maze with the reward at both ends decreased as the period of food deprivation increased. From this result and other related facts, the author concluded that the reinforcement seemed to be the cause of this repetition tendency. However, there is another possibility that food deprivation itself might have decreased the percent alternation. Hence the same experiment under the non-rewared condition remained to be performed to check the effect of reinforcement on alternation.Moreover, the author's paper was followed by several experiments and theories on the relationship between alternation and reinforcement, among which two (Fowler, et al, 1959; Thompson, 1960) agreed with, and two (Iwahara, 1956; Walker, 1956) opposed to the author's result.From above reasons, the main porpose of the present experiment was to find the effect of food deprivation and reward on alternation behavior to add another datum on this problem. The effect of the intertrial interval was tested too.Seventy-two rats were subjected to the following feeding and experimental schedule of five weeks. The first week was the five days of the continuous satiated period and two days of the continuous deprivated period. The same feeding schedule was repeated in the second week, and then the rat were randomly divided into three equal groups (Gr. I, II and III).On the third week, while the feeding schedule was the same as before, the test of alternation began. The Gr. I was tested on the last day of the satiation period, i.e., 0 hour of food deprivation. For the Gr. II and Gr. III, the test were after the deprivation of 24hr and 48hr, respectively. Half the Ss of each of these groups were given the food reward in both goalboxes, and half were not given. Each S runs 11 successive free choice trials per test. This schedule continued for the 4th and 5th week. Three kinds of inter-trial intervals, i.e., 0, 60 and 300sec, were used for all rats in different orders on three weekly tests.It was found that a) under non-rewarded condition, there was a tendency to increase the percent alternation with an increment of the hours of food deprivation. This tendency, however, was not significant. b) Under rewarded condition, an increment of hours of deprivation significantly decreased the frequency of the spontaneous alternation as found in the previous experiment. c) Compared with the non-rewarded condition, reward significantly decreased the percent alternation in the group of 48hr food deprivation, d) The longer the inter-trial intervals, the lower was the percent alternation in all conditions. e) The running time was significantly decreased by the increment of the hours of food deprivation in both the rewarded and non-rewarded conditions.From above results, an increment of food deprivation itself did not seemed to be the cause of the decrement of the alternation, but the interaction with the presence of reward seemed to be more determinative factor on this phenomena.