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.
Social exchange theory
During the beginning of this theory, The most comprehensive social exchange theories are those of the American social psychologists John W. Thibaut (1917-1986) and Harold H. Kelley (1921-2003), the American sociologists George C. Homans (1910-1989), Peter M. Blau (1918-2002), Richard Marc Emerson (? - 1982), and Claude Lévi-Strauss (1908-2009) . He defined social exchange as the exchange of activity, tangible or intangible, and more or less rewarding or costing between at least two persons. After Homans founded the theory, other theorists continued to write about it, particularly Peter M. Blau and Richard M. Emerson, who in addition to Homans are generally thought of as the major developers of the exchange perspective within sociology. Homans' work emphasized the individual behavior of actors in interaction with one another. Although there are various modes of exchange, Homans centered his studies on dyadic exchange. John Thibaut and Harold Kelley are recognized for focusing their studies within the theory on the psychological concepts, the dyad and small group. Lévi-Strauss is recognized for contributing to the emergence of this theoretical perspective from his work on anthropology focused on systems of generalized exchange, such as kinship systems and gift exchange.