(1)因果関係理解が, 言語的になんらかの形でなしうるのは, 4才程度であって, 5〜7才の間は, 感性的な理解が確立していく時期であり, 8〜9才にいたっては具体的理解へと転換されてゆく。(2)しかしながらこの段階はけっして固定的なある年令にのみ対応する態のものではなく, 前段階と載然と一線を画して現われるものでもない。説明の類型は質問の内容によっておおいに異なるものであって, 段階は結局比較的特徴が顕著に現われる年令層に附せられるものに過ぎない。しかし, 因果思考は決して単一の機能のモノトーニックな連続量としての変化として律してしまうことはできない。(3)児童の説明類型は, 質問の内容によって異なる。演示実験を伴なわぬ質問のばあいの方が, 非物質的な説明の出現が多くみられるが, しかし両質問系列を通じて児童の説明は自然的・物質的である。また, 演示実験を伴なう質問のばあいに, より論理的な説明が多くなされる。(四)一般に女児は男児に劣る。とくに実験演示を伴なう質問系列の場合にいちじるしく, また, 8〜9才にいたるとその差が顕著である。以上の4点に要約した事実が明らかになった。これらの事実は, 第1報に報告した事実とまったく矛盾なく一致するものである。

Purpose and Mcthods :This is the 2nd report of the study on the development of children's understanding of causal relations. We used for subjects 10 boys and 10 girls each from the ages of 5 to 9, and 6 boys and 5 girls of the age 4 in Kakogawa City. (total :111 children) We selected two series of questions related to natural phenomena. One series is of 6 questions with demonstrable experiments, and the other is of 5 questions without demonstrable experiments. To get exact answers, we interviewed the subjects individually and gave orally these question series. Results : 1) Children are more or less than 4 years old when they linguistically understand "causal relation" in a certain form. They establish their "sensory understanding" at the ages of 5 to 7, and it is developed into "concrete understanding" when they reach the ages of 8 or 9. 2) This stage, however, never responds to a certain definite age, nor is it distinctively different from the preceding stage. Types of explanations are greatly different according to the contents of the questions ; and the stages are divided merely by the periods of age in which certain characteristics are comparatively remarkable. Furthermore, causal thinking can never be decided as a monotonous, continuous value of a unique function. 3) Children's explanations are different according to the contents of the questions. When they are asked questions without demonstrable experiments, non-materialistic explanations seem to appear more frequently; although, their explanations are natural and materialistic through the two series of questions. When asked questions with demonstrable experiments, logical explanations seem to appear more. 4) Generally speaking, girls are inferior to boys. It is especially remerkable in the series of questions with demonstrable experiments, and is also notable when they reach the ages of 8 or 9.