1985'6, p.45
Smirnova E. O.
Conditions for the transition from external to internal operations in the preschoolers solving problems
(RESUME)

A hypothesis has been experimentally checked that verbal means of problem solving first develop on the social-type material and only then are transferred onto inanimate objects. It has been shown that the speech accompaning operations with social and quasi-social objects is much richer in its qualitative and quantitative aspects. The fact is explained by the impossibility of direct physical interaction with living objects and by the specificity of their nature.