The data analysed in the present study were laboriously collected for ten years by Dr. Hiroshi Kano and other members of the Institute for Science of Labour, and the author is much obliged to Dr. Kano for making the data available for her analysis. The main purpose of the present study is to construct the absolute scale of intelligence developed by Thurstone, L. L., on the basis of raw scores of Suzuki-Binet Intelligence Test administered once a year to apprroximately four or five hundred children for nine successive years since they entered a elementary school in Tokyo in 1946 (first group) and in 1947 (second group) till they graduated from the adjacent junior high school. The original data were rescored for the sake of convenience according to new criteria, among which the following one is important: an item is regarded to be solved by an examinee if it has been solved by him at least once in the preceding testings no matter it is practised to him this time or not. In the absolute scale construction it is assumed that the variable x, representing the mental ability required in solving Suzuki-Binet items, is normally distributed for the examinees at each grade level i, on one dimension with Mi as the mean and σi as the standard deviation, and the critical value ls corresponding to each raw score s is also located on the same continuum, and that only those examinees who possess more or less higher values of x than ls get higher marks than s in testings. However, in the course of analysis it was discovered that the assumption of normality was needed to be slightly modified as it was the case in the author's previous study of absolute scale construction of the same Suzuki-Binet Test data collected by Dr. Jisaburo Suzuki. The two distributions were contrasted and the present one proved to be more leptokurtic (see Fig. 4). The scaled values for ls, Mi and σi were obtained by using the method of successive intervals and the graphical least squares solution developed by Diederich, G. W., and those values were converted to l′s, M′a and σ′a with newly defined origin and unit for being compared with the values ls, Ma and σa obtained from Dr. Suzuki's data (see Table 5, 6 and 7, and Fig. 5). The average growth curve of intelligence developed from the values of M′a and the standard deviation as a function of age were illustrated and compared with those obtained from Dr. Suzuki's data respectively (see Fig. 6 and 7). The two growth curves coincide with each other in spite of the fact that the two samples differ in various respects, in time and district and that the former consist for the most part of the same examinees throughout all the grade levels while the latter consist of different examinees at each age level. The standard deviation σ′a was found to be more invariant from age to age than in the case of σa obtained from Dr. Suzuki's data, and this fact seems to have some connection with the slightly different definitions of the raw scores in the two cases.
1) In order to examine the relationship between intelligence and conceptualization, the picture-card classification task was given to the high intelligent children (IQ>120) and the result was compared with theprevions experiment on the normal (90<IQ<110) and the feebleminded (80<IQ) chidren. 2) The procedure and the specification of the result was same as the previous report (Jap. J. Psychol., 1962, 33, 71-82). 3) The parallel relationship between the MA level and the development of conceptualization noted in the previous report (Jap. J. Psychol., 1962, 33, 71-82) was again confirmed in this case. 4) Meanwhile, the qualitative characteristics of the preconceptual responses of these high intelligent children are; i) The concentration of the respons es to the thematic grouping and the functional or structural grouping. ii) Much more thematic grouping compared to the normal and the rapid decrease of it in higher MA, showing clear contrast to the much slower decrease in the case of the feeble-minded. 5) The theoretical implication of the above-mentioned results was briefly discussed.
After years of study on the problem of hereditary and environmental factors in human behavior by the twin method, the writer has reached the conclusion that the psychological functions connected more with the activity of the cerebral cortex are rather influenced by the environmental conditions while those more dependent upon lower parts of the brain are predominantly determined by the hereditary factors. This indicates that the psychological and brain functions are characterized by the functionally corresponding structures of strata, and the writer should like to consider it further as an evidence for the strata theory of personality of K. Gottschaldt. The purpose of the present paper is to give another experimental evidence to the strata hypothesis in terms of the brain waves of twins. The brain waves in the twins of 26 MZ (or EZ in German) pairs and 19 DZ (or ZZ) pairs were investigated either in the state of rest or under stimulation (i, e., sound of a bell, instruction to open the eyes, light stimulus and mental arithmetic) by the 7 FG-040 EEG recorder and the EA-101 EEG analyzer of the San-ei Sokki Co. Ltd. in Japan. The hereditary and environmetal factors are quantitatively specified by the following three kinds of ratio: (1) the ratio of mean intra-pair differences; H:E=mDd:mDm (or E:U=mDz:mDe), where H is hereditary factor; E, envion-mental factor; mDd, mean of intra-pair differences for DZ and mDm, the same mean for MZ, (2) the ratio of mean square of intra-pair differeneces; (3) the ratio of intra-class correlation coefficients; H:E=(ir-fr):(1-ir), where ir is the intra-class correlation coefficient for MZ; fr, the same coefficient for DZ, the correlation coefficient being computed after R. A. Fischer, i.e., r=NΣi=1(xr-x)(x′-x)/Ns2. The definition of this ratio is after K. J. Holzinger and others who originally used it for inter-class correlation. The writer here applies it to intra-class correlation. The main results are as follows: (1) The hereditary factor in EEG in the state of rest differs in its strength from one frequency band to another. It is very strong in the α waves and weak in the β, δ and θ waves. (2) The three indices of the ratio of hereditary and environmental factors show a parallel relation, particularly in α, β1 and β2. Hence any of these indices may be used as a measure of hereditary factor, if the absolute values of the indices are not always equal. Actually, the ratio of intra-class correlation coefficients is the greatest and the ratio of mean intra-pair differences is the least. Gottschaldt's method, that is, the ratio of mean intra-pair differences, has often been criticized from the theoretical point of view. However, it is simple to compute and may be practically used for a general indication, though the three indices must be taken together into more careful consideration. (3) The hereditary factor is considerably suppressed under experimental stimulation as compared with that in the state of rest. The rate of suppression is more or less different according to the mode of stimulation and greatest under the instruction to open the eyes.