Two experiments were conducted to determine which of two hypotheses, the original Thorndikian spread hypothesis or the serial response (guessing-sequence) hypothesis, is more adequate in explaining the “spread of effect” phenomenon. In Experiment I, inter-response intervals were varied (2.5sec. and 5sec.) in an orthodox “spread of effect” experiment. When the interval was longer (5sec.), S-R connections would be more strongly reinforced than when it was shorter (2.5sec.) and thus a spread phenomenon should show up more clearly under the former conditions if the Thorndikian view is correct. The reverse would be predicted from the hypothesis of serial response habits because the habits would be more disturbed when S-R connections were stronger, i.e., when responses were more distributed. The results confirmed the serial response hypothesis rather than the spread hypothesis (Table 1). This was especially true when the rewarded responses were repeated (Table 2, Fig. 1), and the findings were in accordance with our previous study in which one group of S's was required to give a number (1 to 10) at a rate of 3sec. and another group at a rate of 6sec. in a non-learning situation. Analysis of intra-trial serial response repetitions was also made. The average percentage of such repetitions was 8 or 9 per cent (Table 4). This was contrary to Smith's probability bias hypothesis according to which the serial repetition was assumed 0. Besides, two interesting facts were observed: responses immediately preceding reward were mostly frequently repeated and rewarded responses were least frequently repeated on the following positions (Table 4). In place of inter-response intervals, inter-trial time intervals were changed (20sec. 3min., and 10min). in Experiment II which was otherwise similar to Experiment I. As the responses were massed (2.5sec.) within trials, the differences in inter-trial intervals would not significantly affect S's learnig massed “wrong” responses but isolated “right” responses would be better recalled with longer inter-trial intervals. The Thorndikian hypothesis would predect steeper spread gradients around reward with longer inter-trial intervals but the response-oriented hypothesis expects insignificant differenses among the three conditions. Again the latter hypothesis was supported in place of the former (Table 6 and Fig. 2). Marx and Goldbeck conducting a similar experiment to ours reported strong after-gradients for those who failed to repeat the rewarded response. Analysis of the present data also shows after-gradients following the nonrepeated rewarded response in both of the two experiments (Table 3) but the gradients were always lower compared with those following the repeated rewarded response and these findings were in agreement with our previous results under a non-learning situation. The two findings concerning intra-trial serial response repetitions in Experiment I were also observed in Expeiment II but they were less clear. Tentative explanations were given but further research is necessary.
This report contains three experimental studies. The first experimental study was planned and undertaken as the continuation of the previous report. Now we changed the length of stimulus series, and the subjects on the experiment of tachistoscopic identification were university students, while the subjects on the experiment of memory were middle school students. As a result of this study, previous conclusions were verified in spite of the change of the length of stimulus series. In the second study, pseudo-English was used to clarify the nature of recognition of verbal materials. The subjects were the Japanese students studying English as a foreign language. The findings obtained were as follows: (1) The recognition of pseudo-English, though the language was graded according to the order of approximation to English, gave no differences corresponding to such grades when compared with the subjects who use Englih as their mother language. (2) With the same Japanese students, the length of the period they had learned English had an influence on the recognition of the pseudo-English. (3) Japanese students, even if they had difficulty in a foreign language, could recognize their mother language according to the order of approximation to Japanese. Therefore, the important factor in recognition according to the order of approximation to language was whether they had learned and become familiar with it or not. In the third study, it was clarified that the errors which were made in the recognition of English, approximated the familiar pattern of the language. (1) Error responses had a positive correlation with the relative frequencies of letters which are used in English. (2) Whether the responses were more English-like or not was judged by women college students. The most frequent case was that the responses were judged more English-like than the original stimuli. Then it may be said that the recognition of letter sequences had a tendency to elicit responses approximating the familiar pattern of a language.
The present study was designed to measure quantitatively the change of size of colored after-image with the passing of time and also, to confirm the relationship between the change of size and the positive-negative phase alternation of after-image. The results obtained were as follows: 1) When, in a dark room a red rectangle patch placed vertically (A-form patch) was thrown on a dark screen for thirty seconds and then it was removed, the same color after-image-positive after-image- of enlarged size appeared in about two seconds, and afterwards it got by degrees smaller to agree strictly with the stimulus size in about six seconds. The shrinking of the after-image continued to reach a maximum point in about thirteen seconds, then after returning to neutral state- the same size as the stimulus-, the after-image shifted to expansion (enlargement) phase. Afterwards it kept on enlarging for a while, until the image disappeared. Thus the oscillation of waxing and waning in size of after-image was quantitatively confirmed. (Exp. 1). 2) In the inspection of red B-form patches (two rectangles fixated vertically) under the same condition as in Exp. 1 the result showed a similar one as in Exp. 1, with the exception that the amount of shrinking was less. (Exp. 2). 3) The effect of the distance between the two stimulus-rectangles. When red B-form stimuli with the distance between the two rectangles of 1, 3, 6, 9, and 12mm were Presenteb darkroom, it was found that the curves of oscillation for each distance displayed a similar feature. In regard to the effect of the distance between the two rectangles, the following was confirmed: the larger the distance was, the larger were the amplitude and the period of oscillation in the curve of after-image (Exp. 3). 4) The effect of the stimulus color. When the stimulus-colors of four kinds, red, yellow, green, and blue, were used, almost the same results were obtained excepting that the period of first appearance of after-images for the green and the red stimuli were a little earlier than the rest, and at that time the amount of expansion of after-image for the green and the yellow stimuli was slightly greater than the others. (Exp. 4). 5) Concerning the relationship between the size oscillation of after-image and its positive-negative alternation, it was indicated that the positive phase of each after-image corresponds to the period of the enlargement and the negative phase to the shrinking one. This leads us to conclude the existence of close relationship between the size dimension of after-image and its sensory property. (Exp. 4). 6) The adequate theory of the optical illusion as well as the figural after-effect requires that the above mentioned facts are explained together with them.