Activity theory
Activity theory (AT; ) is an umbrella term for a line of eclectic social sciences theories and research with its roots in the Soviet psychological activity theory pioneered by Lev Vygotsky , Alexei Leont'ev and Sergei Rubinstein. These scholars sought to understand human activities as systemic and socially situated phenomena and to go beyond paradigms of reflexology (the teaching of Vladimir Bekhterev and his followers) and classical conditioning (the teaching of Ivan Pavlov and his school), psychoanalysis and behaviorism. It became one of the major psychological approaches in the former USSR, being widely used in both theoretical and applied psychology, and in education, professional training, ergonomics, social psychology and work psychology.
Lev Vygotsky
In North America, Vygotsky's work was known from the end of the 1920s through a series of publications in English, but it did not have a major impact on research in general. In 1962 a translation of his posthumous 1934 book, "Thinking and Speech", published with the title,"Thought and Language", did not seem to change the situation considerably. It was only after an eclectic compilation of partly rephrased and partly translated works of Vygotsky and his collaborators, published in 1978 under Vygotsky's name as "Mind in Society", that the Vygotsky boom started in the West: originally, in North America, and later, following the North American example, spread to other regions of the world. This version of Vygotskian science is typically associated with the names of its chief proponents Michael Cole, James Wertsch, their associates and followers, and is relatively well known under the names of "cultural-historical activity theory" (aka CHAT) or—yet more distant from Vygotsky's legacy--"activity theory". Scaffolding, a concept introduced by Wood, Bruner, and Ross in 1976, is somewhat related to the idea of ZPD, although Vygotsky never used the term.