Problem : In the figure represented in Fig. 3 (Jap. Test p.88), the oblique line does not appear to meet the lower end of the vertical line, although it would meet objectively. The figure is a basic case of the directional illusion. The Poggendorff illusion, the Zöllner illusion and the Hering illusion are each nothing more than a combination of the figures like this.
At Obonai's hand these illusions have received an explanation in purely retinal terms, depending on the curvature of the retina. He has reminded us that the directions of lines which compose an angle on a flat surface cannot correspond with the directions on the curved retina. The directions of lines in the periphery are displaced towards the vertical as well as the horizontal axes, viz., directions of lines in the periphery shrink along their radial dimensions. The directional or angular illusion is thus attributed to the summation or combination of displacements of these line-directions. In the present study the authors offer another experimental finding to verify the validity of the above mentioned hypothesis.
Method and Results : A linear figure represented in Fig. 3 was employed. Observations were made under various conditions as to the fixation pointi The amount of illusion was measured by the method of adjustment.
Experimental results were as follows : The amount of displacement of the line-the so-called directional illusion-at each of the various directions of the oblique line composing the angles of 15°, 30°, 45° and 60° respectively with the vertical line was measured. When the fixation point was placed outside of the oblique line, the displacement of the line was greatest at 15°and it decreased with the increase in the size of angle (positive displacement). However, when the fixation point was changed to the inside of the oblique line, the reversal, of displacement occurred (negative displacement). The amount of this negative displacemenl was small at first, increased with the increase in the size of angle, reaching the maximum at 30°, then decreased gradually as the angle increased, and at 60°, it was changed into the opposite displacement (positive displacement).
When the fixation point was altered from place to place along inside or outside the oblique line at different distances from the lower end of the vertical line (Fig. 5), a conspicuous feature of displacement was observed. When the fixation point was placed outside the oblique line and near the vertical line, the results were similar to those mentioned above, while in the case of fixation at the distant part from the vertical line, the negative displacement was observed. The transition from positive to negative displacement is gradual and continuous. The reversed feature was observed when the fixation point was placed at the other side of the oblique line.
When the diagram was inclined at various degrees on the frontal-parallel plane, a periodical change of the amount of displacement was observed, which agreed precisely with Obonai's early findings.
Considering the anatomical and physiological properties of the eye, the authors conclude that retinal curvature is involved in the above mentioned illusion.

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The present investigation was designed to test the existence of a conditioned inhibition, sIr, which has been postulated by Hull, Kimble and others, on the basis of a critique already reported by the writer.
The significant difference between pre-rest massed- and spaced practice groups in initial post-rest performance has been considered as the index of sIr by Hull and other, but this phenomenon may rather be interpreted by the difference in the level of skill acquired during pre-rest practice. Then, in accordance with this critique, I propose that, after the same number of trials in pre-rest practice on a poor-skilled task, the level of skill for the massed group would differ from that for the spaced group. Consequently, the difference in performalce between the two groups may be seen after an interpolated rest. But I propose that for a well-skilled. task, the difference in performance between-the, two groups seen in the pre-rest practice would not be observed in the post-rest performance, as the level of skill has already reached the asymptote. But if the difference is observed in the post-rest. performance in the latter task, it may be a prominent evidence for sIr.
The present investigation consists of three experiments, each containing two tasks, a poor-skilled, task (correct-copying inverted Japanese Hirakana letters in each compartment provided, e. g., _??_) and a well-skilled task (_??_-check or ⊕ task-writing the circles and cross or × in it).
In the procedure of Exp. 1., all Ss received 20-30 sec. trials which massed group of 40 Ss received without rest, and which spaced group of 40 Ss received with 30 sec. intertrial rest. Following 10 min. rest interpolated between pre- and post-rest practices, all Ss received 15 trials without rest.
In Exp. 2., based on the reflexion that appreciable sIr may not develop at a short practice, and to supplement for such possibility, all Ss received 80 30-sec. trials which 20 Ss received without rest, and which other 20 Ss received with intertrial 30 sec. rest. Following 10 min. rest, all Ss receieved 10 massed trials.
In Exp. 3., in order to eliminate the influence of fatigue, all Ss practiced 4 sessions separated by rest for 24 hrs., each session being constituted of 20 trials, with massed or spaced conditions (50 Ss in massed group, 45 Ss in spaced group on Hirakana correct-copy task, and 40 Ss in each group of ⊕ task). After 10 min. rest interpolated following the fourth session, all Ss received 1O massed-trials.
The obtained results in Exp. 1. and 2. showed that spaced group was significantly superior to massed group during pre-rest practice in both tasks, but as regards post-resti performance, the significant difference between the two groups obtained on Hirakana correct-copy task was not obtained on ⊕ task.
The result in Exp. 3. showed that the difference between the two groups obtained at the first trial in each practice-session on Hirakana correct-copy task increased in a straight slope, but the significant difference between the two groups was not observed on ⊕ task. In addition, the significant difference between the two groups obtained in test performance on Hirakana correct-copy task was not observed on ⊕ task.
From the above-mentioned experimental results, the difference between massed- and spaced groups obtained on Hirakana correct-copy task over all experiments may be interpreted with different levels of skill acquired by each group during pre-rest practice, rather than as evidence for the existence of sIr. This proposition may be confirmed by comparison with ⊕ task and from the results of other investigators. Thus, we may conclude with Underwood, Ammons and others that sIr is probably an unnecessary construct.

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Purpose : The aim of this study was to determine the effects of group norm upon the change of opinions in the group, namely to investigate the attitude of conformity to group norm of the members of the group.
Subjects : 12 experimental groups and 2 control groups were established. The experimental groups were divided into groups composed of five or ten or thirty members and they were, at the same time, vote groups or discussion groups, and intimate groups or unknown groups. The situation of each group was shown in Table I. (See the text)
Procedure : 1) Before the decision of group norm was established, all the subjects in each group were asked to fill the questionnaire made up of ten questions (opinions). This was to measure how the subjects evaluated “Group Activities in Students”.
2) In the discussion groups, each of them was asked to discuss and evaluate opinions in the above-mentioned questionnaire and to make final group decision in regard to the desirable opinion for each item about the group activities. And, after that, each member was asked to fill the same questionnaire again.
3) In the vote groups, the results of questionnaire were reported to each group and then the members were asked to fill the questionnaire again.
4) In the control groups the members were asked to fill the questionnaire again on the following day.
5) By this procedure, the writer examined the opinion change in each group which was to be found between the two questionnaires of the same type.
Results : 1) There were significant differences in the opinion change between control group and experimental group, namely the members of experimental groups changed their opinions more conformably to the group norm than those of the control groups.
2) The amount of conformity to the group norm varied with the following factors :
Group size : 10 members group>30 members group>5 members group
Group cohesiveness : Intimate group>Unknown group
Norm decision : Discussion group>Vote group.

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Part 1. The aim of the first experiment was to examine whether extinction may be viewed as due to the changed direction of a psychological resultant force f* _{A, G} by providing a situation where two paths W _{A, E, G} and W _{A, F, G} in jumping apparatus lead to the same psychological goal (food reward) from the same jumping stand (See Fig.1).
Thirty-four male and female albino rats were given preliminary trials along each path. After these trials, they were divided into three groups, and were trained to jump along the path W _{A, E, G} with continuous (RR) and partial (RU and UR) reinforcement (food reward as indicated by R in Table 1) in the acquisition period of 31 trials. In the period of extinction procedure (U₁, U₂, .......... U_n, in Table 1), the resistance to extinction was measured by the number of trials along the path W _{A, E, G} before the subject substituted W _{A, F, G} for W _{A, E, G} in order to reach food.
Group RR showed much less resistance to extinction than the other groups. Between Groups RU and UR statistically significant difference was found (See Table 3). These results indicate that after continuous reinforcement the psiychological force f _{A, G} is much more changeable in direction than after partial reinforcement, and these facts mean that extinction can be viewed as due to the changed direction of a psychological resultant force f* _{A, G.}
Part II. The aim of the second experiment was to examine the effects of “relative” effortfulness (rk) of the conditioned, (continuously reinforced) response to that of the alternative response upon extinction and spontaneous recovery, by providing a situation where two paths, i. e., W _{A, E, G} and W _{A, F, G} lead to the same goal from the same starting-point : a runway maze with an electric grid at the first step of alley in the path W _{A, F, G} (5 Volts for Group I and 20 Volts, for Group II) (See Fig. 3). Hodologically, in this situation, the occurrence of the alternative response, i. e., locomotion along the path W _{A, F, G} would mean that the psychological force has changed its direction from d_{A, E, G} to d_{A, F, G}.
Twenty-two male and female albino and pigment rats were given at first running training in the straight runway. After the training, they were divided into two groups (Group I and Group II), and were given preliminary trials along each, path. They were, then, reinforced for running along the path W _{A, E, Q} in the acquisition period of 16 trials. In the period of extinction procedure, the resistance to extinction was measured by the number of trials along the path W _{A, E, G} before the subject substituted W _{A, E, G} for W _{A, F, G} in, order to reach food.
Group I showed much less resistance to extinction than Group II (See Table 4) : the greater the “relative” effortfulness of a response, the smaller the resistance to extinction. There could also be found a statistically significant difference in the tendency to spontaneous recovery between the two groups : the greater the “relative” effortfulness of a response, the weaker the tendency to spontaneous recovery.

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