The present investigation aims at studying factors which may influence sucking behavior of school children in terms of their personality traits. Out of 1354 elementary school children, 34 Ss were selected as a sucking group and 29 Ss as nonsucking group. The teachers in charge of the children were requested to fill series of questionnaires on sucking behavior in the Oriod of infancy, and childhood, and on family environment and nursery history of children in the both groups. Results of this investigation revealed: 1) In addition to the sucking habit, most of the children of sucking group were found to possess in overlap some of its accompanied movements of biting and finger-touching habits. 2) Analyzing the situations where high frequencies of the habit responses were reported, the following conditions were found to be closely related to those responses. They are, in the order of importance, situations of weariness, thinking, frustration, loneliness, etc. for the period of infancy, and those of hunger, sleepiness, loneliness, frustration, etc. for the period of childhood. 3) Since these habits were equally observed in most of the children in the period of their infancy regardless of the group they belong to, the mere fact that a child once possessed the sucking habit in their infancy can not be considered a direct cause for child sucking in the period of childhood. 4) As to the personality rating scale with 68 items, group differences were found to be significant in twenty-seven items. Chidren of sucking group are characterized with such personality traits as lack of emotional stability, lack of frustration torelance, regression, unsociality and so forth, and children of non-sucking group, as emotional stability, high sociality and so on. 5) Among the ten items for the family environment questionnaire, the following four items were negatively related with the sucking habit: family atmosphere, economic status, parents' correct expectation on their children. 6) Analyzing responses to questionnaire on nursery history of children which included seventeen items such as for artificial feeding, early weaning, technique of weaning and so on (these items had been generally considered to be the main causes for infancy sucking), only one item for “infancy sucking in sleepy time” was positively related with sucking habit in the period of childhood.
1. In “An Analysis of Identical Twin's Intelligence (Part 1)” we reported that identical twins' correlation between 80 pairs showed 0.87. In this study, we have tested 103 pairs, consisting of 48 pairs of boys and 55 pairs of girls, each living together in the same family, who are 6-15 years of age, and found that identical twins' correlation shows 0.934 by WISC full I. Q. and 0.829 by Tanaka-B (Group Test). 2. There is a tendency that twin's performence on Comprehension, Picture Completion, Picture Arrangement, and Object Assembly of WISC are influenced by emotional frustrotion and that male pairs are more significantly ineflunced by their character and environment than female ones, especially on sub-tests of Comprehension, Object Assembly, Digit Symbol of WISC. 3. It has been found that identical twins make little difference in the Linguistic Factor, but that they make significant difference in the Spatial and Emotional Factors. 4. We shall hereafter make research on the studies of interaction between intelligence and char acter step by step.