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.
Leading activity
The notion of a leading activity is part of a broader theory of activity that attempts to integrate cognitive, motivational, and social aspects of development. Despite many detailed descriptive accounts of the developmental forms of memory, perception, and cognition in various phases of childhood (e.g. Piaget's work), often missing is an explanation for "how" or "why" the child develops these psychological processes (Karpov 2003: 138). The exploration of leading activities seeks to illuminate these questions. Rather than biological maturation or stimulus-response learning, specific types of social activity are seen as generating human development. Because of its attention to causal dynamics, the neo-Vygotskian theory has been called "the most comprehensive approach to the problem of determinants and mechanisms of child development (Karpov 2003: 138)."