1. The EEG and heart rate responses were recorded simultaneously during the avoidance conditioning in the rats.
2. Habituation of the EEG and heart rate responses to the CS took about 15 trials and 100 trials, respectively.
3. In the initial stages of the avoidance conditioning there could be seen the marked increases in heart rate response and low voltage fast waves in the EEG response to the CS, both of which were discussed as the signs of high emotional state.
4. In the final stages, the increases in heart rate response were gradually disappearing. Low voltage fast waves of the EEG responses were also gradually disappearing as the avoidance response was becoming automatic.
5. In the early stages of the reality testing there could be seen again the marked increases in heart rate responses and low voltage fast waves of the EEG responses, both of which were discussed as a different emotional reaction from that simply elicited by the CS.

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Recently, D'AMATO et al. (2) found, opposed to their hypothesis, negative effect of extinction trials on discrimination reversal learning in the rat. Their hypothesis was that some degree of extinction of original discrimination will facilitate the subsequent reversal learning. It was deduced from the notion that for the reversal learning to take place, it is necessary, first, to extinguish the old response, and then to acquire a new one. According to D'AMATO et al. 's assumption, the retardation of reversal compared with original learning is at least in the rat, attributed to the so-called cue function of reward (3) which serves to maintain responding that is appropriate to the initial discrimination.
The purpose of the present experiment was to retest the same hypothesis that D'AMATO et al. presented. Twenty chicks received color discrimination trainings, with red positive and blue negative as stimuli, in a T-maze for 10 days (Fig. 1). The daily session consisted of 10 trials. This schedule was enough to enable all Ss to reach the learning criterion of successive two days of 90% correct responses (Fig. 2). Then they were divided into two groups of 10 each on the basis of the original scores : the one (Group I ; average number of days required to reach the criterion was 7. 7, SD= 1. 95) was given 4 day extinction followed by 6 day reversal learning, the other (Group II ; 7. 5, SD=1. 57) 10 day reversal learning only, with red negative and blue positive as stimuli. The extinction trials for Group I were performed, in order that Ss of this group could respond only to the previously positive stimulus, with correction procedure. It is different from D'AMATO et al. 's experiment in which the free response procedure was employed. The daily session now again consisted of 10 trials both in the extinction and reversal trainings.
The comparison of two groups in correct response for the reversal trainings reveals a marked tendency of the positive effect of extinction trials (Fig. 5). That is, the differences between the scores of Group I and Group II on the 5 th as well a 10 th day of reversal training (including extinction days) were statistically significant (U=85, p<. 01 : U=83. 5, p<. 01, respectively) in favor of the former. This means that the hypothesis was confirmed by the experiment. It should be added here that both the latency and running time of Group I were neither lengthened nor shortened during extinction (Fig. 6 and 7 ; solid lines lst-4 th day).
To conclude, these results appear to indicate that the critical factors which determine the direction of the effect of extinction trials on reversal learning are the procedure of extinction and also the number of extinction trials probably.

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This study is concerned with the relation between the change of intensity of illumination introduced after giving some amount of training and the influence of that change on the trained response.
The experiment was run in 2 × 2 designs of conditions. The change of illumination of which intensities were 180 Lux to one group of rats and 18 Lux to another was introduced into a simple runway after groups of rats had received 18, or 36 reinforced training trials, and the rewards were continued to be given during test trials as well as during training trials. It was assumed in this case that the response decrement induced by the change of illumination of strong intensity (i. e., 180 Lux) would be more significantly different from that induced by the change of illumination of weak intensity (i. e., 18 Lux) when the same amount of training was given to animals, because the strong curiosity drive should be evoked by the illumination of strong intensity, and moreover, the more the training given before introducing that change, the greater would be the relative response decrement brought about.
The results showed that no relative response decrement (i. e., the increasing of running time) was induced by any change of illumination introduced after giving 18 training trials, but that the response decrement was significantly induced only by the change of illumination of weak intensity introduced after giving 36 training trials. There were no significant results in relation to latency.
It was suggested that these results are compatible with BINDRA'S view at least concerning with the response decrement induced by the stimulus change as a function of amount of training. But so far as we were concerned with the illumination, these results require further discussions on the nature of exploratory response provided by it.

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The purpose of the study reported here was to investigate changes in revolving activity in the rat following transition from ad libitum feeding to a 23-hr. per day deprivation cycle.
The Ss were seven male albino rats, aged about 90 days at the beginning of the experiment. The apparatus consisted of four activity wheels equated for frictional torque by the method of O. L. LACEY. Each wheel with a small, stationary living cage, located in a soundproof box, was always illuminated by 2 cp. lamp throughout the experiment. The temperature record in the box throughout the experiment averaged 20°C with a range of 19° to 23 °C.
The experiment was conducted in two sessions (Sept. -Nov. '59 and Feb. -Apr. '60) with conditions duplicated as similarly as possible. Each of these equivalent sessions consisted of two successive phases : (a) the four rats were first given a 15-day ad libitum feeding phase in the activity wheels. Food and water were always available, replenished at 1 : 00 P. M. (b) There followed a 30-day food deprivation phase during which food was available from 1 : 00 P. M. through 2 : 00 P. M. each day. Water was continuously available. The number of revolutions for every two hours interval was read by each counter at 1 : 00 P. M., thus the total number of revolutions per an activity wheel was provided by 12 counters.
The ad libitum feeding phase and the food deprivation phase are both divided into 5-day periods. Table 1 presents the means of individual means of revolutions in each 2-hr.-interval for successive 5-day periods. The percentages of revolving activity performed in each 2-hr.-interval during three 5-day periods under the ad libitum feeding schedule are presented in Fig. 1. This form of curve clearly indicates the nocturnal cyclic activity which is relatively stable. But, as would be seen in Fig. 2 which indicates the percentages of revolution under the condition of 23-hr. food deprivation during the first three 5-day periods (1-15 days), the type of the nocturnal cyclic activity is gradually changed. The most clear-cut change is found in the activity during the 2-hr. (11 : 00 A. M. -1 : 00 P. M.) just preceding the daily feeding. This consistent change is clearly shown in Fig. 3 which presents the percentages of revolution in the succeeding three 5-day periods of 23-hr. food deprivation (16-30 days). The results shown in these Figures may suggest that the progressive increase in prefeeding activity is due primarily to the increase in habit strength of the running response.

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[in Japanese]

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[in Japanese]

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