Normal, chiasm-sectioned, split-brain monkeys (M. mulatta) were binocularly trained to press a lever after onset of a visual warning signal and to release it after various forperiods terminated by a second visual signal. The use of hand was restricted to one side. After training, they were monocularly tested in each of the eye-hand combinations. When ipsilateral eye-hand combination was used, significantly prolonged reaction times (RTs) were found in two of three chiasmsectioned and three of four split-brain monkeys, but in different hands. The distribution of RTs in these conditions was characterized by a group of extremly long RTs. Data were represented in the cumulative probability distributions, which were used to estimate the means and σ of the response criterion by an application of variable criterion model. Mean criterions of the split-brain monkeys were significantly higher than those of the chiasm-sectioned monkeys, which were not different from that of the normal monkey. Finally, an exponential growth function of sensory recruitment to these different criterions was demonstrated on a common units across the eight subjects. The results of these analysis imply that two components were involved in the delayed RTs appearing in these split-brain monkeys. One is related to the process of signal detection and the other to the process of response evocation.

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Eight Japanese monkeys were split into two groups. One experimental, the other control. Both experimental and control S_S first received discrimination training with Orange cylinder (+) and Green cylinder (-) using a modified WGTA.
S_S in experimental group received so called direct placement i. e., S_S themselves could not directly manipulate both stimulus objects, but the experimenter himself opened the positive stimulus object (Orange cylinder) and pulled it toward the experimenter 15 trials and immediately after the operation, ordinal experimental extinction were given. Whereas S_S in control group received ordinal extinction.
In the ordinal extinction session, seven colors were employed and the preference of colors were measured in experimental group, but in control group only five colors were employed.
Japanese monkeys might have some preferred colors, but unfortunately they were not well known, and first session all S_S had experienced discrimination training, so that it might be necessary to check the innately preferred colors. 50 days after finishing the all experiment, 7 colors were presented on the tray in a raw and the preference of the colors were measured. If the 7 colors equally preferred the probability of choice would resulted in 1/7=14.3 percent respectively.
Main results were as follows :
1) Fig. 2 clearly shown that the previously positive object (Orange colored cylinder) reduced the incentive function by just looking at the empty food well.
2) Previously negative object (Green colored cylinder) reversely increased the percentage of preference.
3) S_S in control-2 group have preferred rather equally the 7 colors, and X²-test to the data obtained revealed no significant differences.
Apart from ordinal r_g hypothesis a plausible assumption to explain the results was postulated in discussion phase.

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The subject, a young female chimpanzee, was reared in a room where the room light was controlled by an automatic timer, turning on at 6 a. m. and off at 6 p. m. for a few years. During experimental sessions, switching of the light was left to the care of the subject through a manual switch in the room.
The time pattern of illumination of each day, generated by the subject, showed a continuous 12-hr rest period while the subject kept the light off and stayed in the nest and a 12-hr active period while the subject turned the light on and off repeatedly. Further, the starting time of the active period became earlier and earlier with daily sessions until the phase shift reached a 3-hour difference from the original state. The termination of the shift was probably caused by a fixed feeding-time occurring around 11 : 45 a. m. on each day.
According to ASCHOFF'S rule, it can be concluded that periodicity of light switching generated by the subject is analogous to continuous illumination with respect to circadian rhythm. Based upon this observation and analysis of effects of light upon operant behavior, it is proposed that the light-effect as a “Zeitgeber” may be weak at least in higher primates.

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MOTOYOSHI and MITANI (3) have reported that exploratory experience on the transparent glass floor above the enclosed-maze was effective on the solution of the maze problem. In their experiment, rats were given successively 12 maze problems (the modified HEBB-WILLIAMS Intelligence Test) on the glass floor for 6 successive days, looking down into the each maze for 4 minutes per day, and 9 days after, rats were tested within each maze. The purpose of the present study was to examine the result of their experiment under slightly different conditions.
RABINOVITCH-ROSVOLD Intelligence Test for Rats (6) was used as the apparatus throughout the present experiments. All the barriers (blocks), including the tops of them, were painted black to contrast with the painted white floor and the white fixed walls surrounding the field. Two sheets of transparent glass were used, the one covering the maze and the other the second floor above the maze (Fig. 1). Eighteen albino rats, aged 10 weeks at the beginning of handling, were used as S_S. After adaptation to the enclosed-field without barriers and RABINOVITCH-ROSVOLD'S Practice Problems A, B, and C (Fig. 2), S_S were divided into two groups. E-Group (Experimental) : The barriers were introduced into the enclosedfield. S_S were landed on the glass floor above the maze (No. 4 Test Problem as shown in Fig. 2), and permitted free exploration for 10 minutes per day for 5 consecutive days. C-Group (Control) : Free exploration trials were procedually identical to E-Group except that all the barriers were removed from the enclosedfield. On the next day, testing was conducted. All S_S were given 5 trials in the maze (No. 4 Test Problem), and the number of errors committed was recorded. The results are shown in Fig. 3 and Table 1. There is no significant difference between two groups. It seems to be concluded that the visual latent learning was not demonstrated in this experiment. In MOTOYOSHI and MITANI' s study, however, a kind of cumulative effect by giving 12 problems successively may result in statistically significant difference between two groups. To see whether there is the cumulative effect or not, 5 problems (No. 5, 9, 2, 10, and 4 Test Problems) were used in this experiment. Ten rats were used for E-Group, .and 8rats for C-Group. After giving exploratory experience on the glass floor above the enclosed-field (barriers constracted for E-Group and no barriers for C-Group) for 10 minutes twice, S was run in the maze for testing. Three days after, this procedure was replicated using the next problem, and so on. From the results shown in Fig. 4, 5, Table 2, and 3, it is unreasonable to assume that there are any cumulative effects in maze performance. Next experiment III was designed to ascertain whether the effect of exploratory experience on maze performance is increased by giving attention to the maze. To turn the rat's attention to the maze pattern, two naive rats were put into the maze when S was permitted free exploration on the glass floor. For C-Group there were no barriers in the enclosedfield, but for E-Group barriers were introduced, i. e., No. 3 and No. 6 Problems (Fig. 2). Testings were conducted on each problem. The results are presented in Fig. 4, 5, Table 4 and 5. With a single exception (the first trial on No. 6 Problem), there are no significant difference between two groups.
To sum up, neither “visual latent learning” nor “cumulative effect” was demonstrated in the present study. But that the variances of the error scores of E-Group are quite smaller than C-Groups' (Table 2-5) might suggest the possibility that E-Group rats had learned something about the maze.

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There are reported on the social facilitation of the feeding behavior in the Himedaka, Oryzias latipes. Before the experiment, each reacting fish was isolated in an aquarium without food, and then, transferred to an experimental basket, in which they were kept in quiet condition at least in an hour. Experimental apparatus was used the 2-cells basket (UEMATSU, 5). The stimulators (0, 1 and 3individuals) in one cell of the basket were shown for the reacting fish in opposite cell. At the beginning of experiment, 50 individuals of Daphnia pulex per a fish were given for the reacting fish. The feeding amount of fish was calculated at each observation time (10, 20, 40, 80 and 120 minutes).
The results obtained are as follows :
1) The feeding amount of the Himedaka showed a rapid rate of increase during 10 minutes from the beginning of experiment. During other later period the value increased with almost constant speed, though the speed was low.
2) The social facilitation in the feeding amount was clearly observed at each observation time.
3) Female ate more heavily than male in almost all cases.
4) The social facilitation rate (FR) increased with time, although the value was small during the later period (40-120 min.).
5) The social facilitation rate of female was higher than that of male.

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[in Japanese]

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