In connection with a study on fatigue and stress in Norway rats, the responses of four of ten subjects used on a treadmill, were described. These four subjects showed convulsive seizures similar in pattern to those previously described as audiogenic fits (1). With the exception of the running phase of the seizure, which did not appear, due in all probability to the architecture of the treadmill, the fits were in every way similar to those shown in some laboratory rats subjected to high frequency sound stimulation.
The behavior of one animal in particular was described as an illustration, apparently, that the convulsions may be conditioned.
Since precautions were taken to control sound, shock, and nutrition, as possible complicating factors in seizure etiology, and pending further detailed study, we have tentatively concluded that the epileptoid responses described were of emotional origin.

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Using the method of discrimination learning, the reported experiments investigated variations in the minimum discriminable time (M.D.T.) attended on the detention location in the maze. Detentions at the middle of path, near the start and near the goal were studied in relation to their effects on the M.D.T. It was found that the M.D.T. recorded when the detention-rooms were located near the startpoint or near the goal shifted progressively, as compared with the M.D.T. obtained when they were located at the mid-points. However, the difference between the M.D.T. near the startpoint and that near the goal was not always significant. When two detention-rooms were located in each pathway, near the startpoint and near the goal, and when the relation between the longer detention-period and the shorter was reversed in one of the paths, the animals did not show a greater preference for either. In this latter experiment, however, only three subjects were employed and it would desirable to initiate further study with an adequate number of subjects.
Special acknowledgement is due to Miss M. Taniguchi and Miss K. Kosaka for their persevering assistance in these experiments.

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A) When a rabbit is set free in a strange place, his behavior is not at random, but has a certain behavioral pattern in its place. The behavioral pattern in this case is as follows : 1) At first he settles his provisional shelter (the settlement of the dynamic center of his behavior). 2) He carefully makes radial movements with the provisional shelter as its center, and then he moves about it in a considerably unrestrained way. 3) He walks and runs around its region many times (the reinforcement of his cognition of his explored region). 4) He rests in the shelter for a while. 5) He leaves off his timid behavior which he has been taking up to that time and assumes a completely changed action to settle his true shelter (insight behavior).
B) The stranger set free in a strange place is aggressed by the former residents. The stranger is defeated at once and runs about trying to escape, but even then the behavioral pattern mentioned above is not changed by their violent aggressions. At first he explores his strange place in order to get his psychological stability. When he cannot finish his exploring behavior, it is usual that he, without psychological stability; is defeated by the aggressive former residents. But on the other hand, when a rabbit, even if it has been a strange place for him, invades it on his own initiative exploration, or when he is set free in the place he has already known, he fights against the former residents. It is observed that one of the factors deciding the dominance subordination relation depends upon whether a rabbit has already finished his exploring behavior and obtained his psychological stability in his life field or not.

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There was experimented on the conditioned response in groups of Carchesium polypinum EHRENBERG.
The vibration (unconditioned stimulus) and the light (conditioned stimulus) were given simultaneously to the animals in culture medium. They respond originally to the vibration by contracting their bodies, but not to the light.
In the present experiment an appropriate apparatus was devised. The animal behavior was projected on the screen set in it to make our observation easy.
Three kinds of control experiment were undertaken as follows : 1) the vibration only, 2) the light only and 3) none of stimuli was given.
After 50 times conditioning within about 30 minutes they were able to respond to the light stimulus with statistical significance.

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In 1949, G. R. GRICE performed an experiment to compare the processes of simultaneous and successive discrimination learning. He found that there were no differences between these two processes, and concluded that the two were essentially the same. These results were considered as supporting the stimulus-response theory of discrimination learning. But it is well known, in the “continuity-non-continuity controversy” in the discrimination learning, that variables such as type of apparatus, nature of the stimulus and general experimental procedures will have considerable influences upon the results. In the present experiment, the author intended to test whether or not the same results would be obtained under conditions which were different from the GRICE's experiment.
Seven female albino rats were trained in the jumping-stand apparatus. They were divided in two groups, four animals in one and three in the other. Two white circles which were 5.0cm.and 6.2cm. in diameter were used as stimuli. Half of each group was trained to the larger circle and the other half to the smaller. For group I (simultaneous discrimination), the percentage of correct responses was used as a measure of performance. In accordance with GRICE, the reaction latency was used with group II (successive discrimination) in order to determine the percentage of correct responses. Training, was continued until a criterion of 90% correct responses was reached. The learning situation was switched for the groups.
The results obtained were as follows ;
(1) Since the rats of group II were superior in both trials and errors to the rats of group I, so that their learning curves were not identical, the two learning processes could hardly be regarded as the same.
(2) In simultaneous discrimination learning, two types of solution were evidenced ; gradual and sudden.
(3) Since the difference between response latencies of the animals to the positive and negative stimulus was very small, GRICE's use of median latency as a method of measuring correct responses in successive discrimination problem is of doubtful value.
(4) Although there was incomplete transfer between simultaneous and successive discrimination when the learning situations were switched for the groups, relearning occured quite readily.
From the above results, it wa considered that although some common elements might be present in simultaneous and successive discrimination learning, they presented quite different situations for the subjects. Consequently, it seems premature for GRICE to regard these situations as identical and to cite them as evidence for support of a S-R theory of discrimination learning.

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In this study, it was intended to observe the individual, differences on the “insight” maze, and by the way, to examine the existence of the “insight” behavior of rats. Ten white and pigmented rats (female) which were about 89 months old were used. TOLMAN's “insight maze” and his technique were employed.
In general, “insight” behavior was not evidenced.
In order to observe the individual differences, analysis was made about the running time, the reaction latency and the emotional responses such as urination etc. as the indications of behavior. As the results, it was found that there existed some constant tendencies in each animals, and moreover, high correlations among these tendencies in each indication.
But there was not a clear-cut relationship between these tendencies and the success or the unsuccess of the “insight” behavior. Consequently, it might be inadequate to discuss the learning performance of rat only with the response time, because the confusion of the problem-solving-process with the emotionality of animals might be committed. This is te reason to support the O. H. MOWRER's theory of dual nature of learning.

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1. The author repeated the SHEFFIELD & TEMMER's escape-avoidance procedures (6) with one supplemental group (intermittent escape group). On the whole the same results were obtained (see Fig.2).
2. Intermittent escape group (group 3) received electric shock from the begining of land on at the trials in which the paired partner in the avoidance group failed to avoid shock, and were omitted shock entirely at the trials in which the partner succeeded to avoid. As shown in Table 2, group 3 showed faster locomotion than avoidance group at shock trials, and slower at no-shock trials. These differences are significant at 5%, 1% level, respectively (sign test). At shock trials, however, before the beginning of shock 1.5 sec. limited time has elapsed in avoidance procedure only. Values in brackets shows locomotion time from shock, not from land on. Then, locomotion speed becomes greater in avoidance group than group 3 (1% significance level). This implies that the limited time (no-shock) had some effects on locomotion response even at shock trials.

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The aim of this experiment was to criticize a controversy as to the, discrimination-learning process, so-called the continuity controversy, by means of cue-reversal technique.
The cue-reversal technique here employed was a procedure which was as follows. As to the experimental group, it was designed to observe the. negative transfer of the pre-training effect which was acquired during the. presolution period. Namely, each rat trained a pair of cues during, three.days, was trained to discriminate the reversed cues in the final learning situation. The control group which was not subjected to the procedure, trained to the same cues in the final learning situation as during the pre- solution period.
Seventeen naive albino rats divided into two groups, the experimental (N=8) and the control (N=9), were trained with the LASHLEY'S jumping stand ten trials per day.
The results obtained were as follows.
First, contrary to the continuity theorie's assumption, it could be observed neither the negative transfer in the experimental nor the positive in the control group's final learning scores. In other words, theoretically it accorded with the non-continuity theorie's assumption.
Second, in spite of the above results, it was demonstrated that there were some questions in the KRECHEVSKY's interpretation about the discrimination learning process, for the position habits which were characteristic behavior pattern during the pre-solution period, could not be assumed as the “attempted solution” or the “hypothesis” in rats. It was reasonable to interprete as a sort of abnormal fixation.
According to these considerations it was concluded that some different experimental design might be necessary to get the evidence about the nature of the discrimination learning process.

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The purpose of the present experiment was to investigate the effect of drive level upon digging behavior during acquisition and extinction.
METHOD. The apparatus was a modified Stone's sand-tube obstruction apparatus which is shown in Fig. 1 (see Text).
The subjects were 38 male albino rats, 90 to 120 days old at the beginning of preliminary observation.
On the first day each subject was placed in the observation box (C) with the tube full of sand for 10 min.under 12 hr. of food deprivation. On the second day subjects were observed under 24 hr. of deprivation.
Experiment 1. Thirty subjects were given 22 trials with empty tube and allowed to eat food for 2 min. in the food box (A). They were run 3 trials a day under a randomized schedule of three deprivation conditions (12, 24 and 36 hr.). After 8 days the mouth of tube was filled with sand. The subjects were divided into 4 groups and tested under 1, 12, 24 and 36 hr. of deprivation.
Experiment 2. Ten subjects used in the first experiment and 8 new subjects trained to remove sand were given 3 trials per day under 24 hr. of deprivation. After 7 days or 20 trials, they were divided into 4 groups and subjected, to experimental extinction under 1, 12, 24 and 36 hr. of deprivation. In extinction trial sand was poured into the tube endlessly until the subject became to show no response for 10 min.
Two subjects from each group were trained again for 7 days and then assigned to a 16 hr. group and a 20 hr. group. Two groups were subjected to experimental extinction as before.
Other 2 subjects from each group received successive experimental extinction for 10 days one trial per day.
RESULTS. Experiment 1. No difference among 4 groups was found in latency and running time during last 6 trials in the training session. Number of subjects who were able to remove the obstruction and to reach the food box within 15 min. was shown in Table 1. Null hypothesis of no difference among 3 groups (12, 24 and 36 hr.) was rejected (p. <.01). This finding would suggest that high drive at the time of testing might facilitate the formation of “insight reaction”. However, the effect of drive level upon either response latency or digging time was not found. (Table 2).
Experiment 2. Since variances of subjects in digging time and time. needed to reach food box were not homogeneous, the analysis of variance. was not made. However, the x² test applied to the variances in weight of sand removed by the subjects supported the homogeneity in variance. The analysis of variance for these data showed no difference among 4 groups. (Table 3)
In extinction experiment, digging time, time to extinction, and weight of sand removed by the, subjects were used as measures of response. Using any one of these measures, significant difference was found between the. groups of lower drive (1 and 12 hr. of deprivation) and that of higher drive. (24 and 36 hr. of deprivation). (Table 4, 5 and, 6. Fig. 2, 3 and 4)
During repeated extinction trials, groups of lower drive seemed to extinguish more rapidly. (Table 7 and 8)
These results support previous findings that response strength, which is measured as resistance to extinction, increases with increased deprivation time.

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[in Japanese]

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