The purpose of the experiment reported by Vygotsky in his book “Thought and Speech” was to discover the role that a word plays and the character of its functional use in the process of concept development. He emphasized the importance of words for the development of a child’s thought processes and his concept development.

A concept is impossible without words, thinking in concepts is impossible outside speech thinking. The most significant and central moment of the whole process is the specific use of words, the functional use of a sign as a means of concept formation.

Therefore, Vygotsky saw great value in words. He considered a word to be “a tool for developing concepts”. He insisted that, “the development of concepts and the development of word meanings are but two forms of one and the same process” (Vygotsky, 1986, p. 160).