Abstract: It is an experimental study along the line of Piaget and A. A. Verger. The results confirmed Verger's hypothesis, and moreover showed that: 1) Pre-school children are able to realize the causality in simple physical phenomena; 2) The process of the development of causality thinking is the process from the external practical action of reflecting the causal relations between objects to the formation of image of causality, and finally, to an internal causality thinking; 3) The catisality thinking of pre-school children does not grow spontaneously but develops gradually under the social and educational influences.

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