Activity theory was developed in the Soviet Union. The philosophical underpinnings of this theory include the ideas of Hegel and Kant, as well as the theory of dialectical materialism developed by Marx and Engels. The theory evolved from the work of Vygotsky as he formulated a new method of studying thought and consciousness. Vygotsky was working on this theory at a time when the prevalent dominant psychological theories were based on reflexology (stimulus-response - which was later developed into behaviorism) and psychoanalysis. Reflexology attempted to ban consciousness by reducing all psychological phenomena to a series of stimulus-response chains.