ABSTRACT

In 1932, L. S. Vygotsky delivered a series of lectures in Leningrad and in 1934 his classic monograph Thinking and Speech was first published in Russian. In addition to differences in subject matter and style, these two works are separated by an important conceptual shift in Vygotsky's thinking which occurred in 1932 and 1933. During 1933 and 1934, Vygotsky attempted to explain psychological development in terms of the differentiation and development of social systems of interaction and action in which the individual participates. Vygotsky's explanation of the origin of the higher mental functions included two components. First, he argued that the higher mental functions rely on the mediation of behavior by signs and sign systems, the most important of which is speech. Second, to explain the historical and ontogenetic development of mediated or instrumental forms of behavior, Vygotsky turned to the primary function of speech as a means of social interaction and communication.