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.
Action theory (sociology)
Parsons' action theory is characterized by a system-theoretical approach, which integrated a meta-structural analysis with a voluntary theory. Parsons' first major work, "The Structure of Social Action" (1937) discussed the methodological and meta-theoretical premises for the foundation of a theory of social action. It argued that an action theory must be based on a voluntaristic foundation—claiming neither a sheer positivistic-utilitarian approach nor a sheer "idealistic" approach would satisfy the necessary prerequisites, and proposing an alternative, systemic general theory.