The Psyche displays itself in the process of active interaction of the individual with the environment, and investigating this process of interaction is the right way to analyze and explore Psyche.

These Rubinstein positions laid the foundations for Russian psychology of the Soviet period. For the greater part of the XXth C, Activity Theory in Russia was the indisputable methodological basis of all psychological research, bearing the official label of the "right" Marxist psychology (and after the 1923 no psychology but Marxist was legitimate in Russia[16]). On this basis a number of brilliant theories emerged.

Internationally, Russian AT is mostly known by the few translated works of Alexei N. Leontiev, by his theoretical model of activity (Activity – acts – operations (Leontiev, 1976 Russian, 1978 English). Leontiev (1903–1979) developed his theoretical model as a rather late invention (in the 1970s) of his lifetime, and it should not be supposed to be Russian AT as a whole. The Ruian AT trend, though integrative, was never a monolithic one. It comprised a set of psychological theories, more or less divergent, developed by Sergey L. Rubinstein (1889–1960), Boris G. Ananiev (1907–1972) and others. In the Russian literature this trend is named the "Sub'ekt Approach".

Leontiev himself wrote, that activity in psychological science can be approached in two ways: a) as a research of psychological aspects of activity (and all psychological schools and even all sciences can be engaged in research of activity); b) considering activity as the generating source of psyche development (Leontiev, 1986). Leontiev acknowledges and stresses that AT is the "b)" approach. Still, in his works which were translated, the "a)" approach seems more articulated. But there are his other works and especially works by Rubinstein and Ananiev (the so called "Leningrad school"), where the generative function is well explained (Mironenko, 2009a). The "b)" approach is naturally focused on ontological problems.

Considering the place of Russian AT in the history of international psychological science, Rubinstein designated as the primary achievement and the basic sense of AT the overcoming of the separation of psyche from the physical world, the disruption of the so called psychophysical parallelism. AT opened the way to use the principle of determinism without simplification and reduction of psychic phenomena, considering psyche as an element of the real life in the real world, as an attribute of evolution (Rubinstein, 1945).

Russian AT is an essentially materialistic theoretical approach. Materialistic psychological perspectives, such as behaviorism and psychobiology are mostly based on a straight-forward interpretation of Darwin's theory, putting the sources and the causes of the development in the external world. It is the stimulus, the change of the environment, which is the cause of the change of the behavior and the structure of living beings for these theories. Dialectical materialism, realized in the Russian AT, on the contrary, accounts for both continuity and discontinuity, seeking internal origins and causes of development, which are viewed as a result of resolving internal conflicts. This entailed a primary focus on ruptures and discontinuities in evolution: on the principle differences between animate and inanimate matter and between human and animal. The former was implemented in wide-scale investigations of sensory processes, supposed to be adjacent to the border between physiological and psychological aspects of reality, and the latter accounts for enhanced development and specific character of Soviet comparative psychology (Mironenko, 2009b; 2010).

There is an important point of linguistic origin which has caused confusion in the notions "Sub'ekt Approach" and "Theory of Dejatelnost" in the international literature, which we have to consider. There are two key words in the context of the AT:

• Sub'ektnost (субъектность),

• Dejatelnost (деятельность).

The translation of both usually turns out to be the same: Activity. But in Russian these words differ in their meaning. And moreover – there is another Russian word – "activnost", which is precisely translated as "activity". So the English translation does not allow us to obtain the right understanding of the difference.

Let's consider the exact meanings of the concepts "Sub'ektnost" and "Dejatelnost".

The concept of Sub'ekt (and "Sub'ektnost" for a quality to be a Sub'ekt) refers to S. L. Rubinstein whose main idea was that Psyche is a procreation of active interaction of individual with the environment. Sub'ekt means somebody whose activity is generated by his own needs, who is choosing and pursuing his own aims, serving his own purposes: a self-determined and self-actualizing agent[17]. According to Rubinstein, Psyche has developed in the course of evolution as a means for a living being to promote its survival and to pursue its needs. Psychic structure is determined by the inner needs of the individual; so to reveal a psychic set up, the needs should be analyzed. It is the inner sources of activity which Rubinstein focused on.

Vygotsky accepted the idea of "Sub'ektnost" and relied on that in his Cultural-Historical theory. Vygotsky points out: An infant is a "sub'ekt" of development" (Vygotsky, 1982, V. 2, p. 281). He emphasized that culture is not just poured into the child: on the contrary, the child actively enters into culture, and commandeering culture elements which he needs, taking them from the outside and internalizing them.

"Dejatelnost" means a process of active and purposeful treatment of the environment, the outward activity. This was the main concept in Leontiev theory. He based on the Vygotsky's idea that human mental functions are structured in the process of social interaction, in the process of outward activity (Dejatelnost), and believed that analysis of Dejatelnost is the only way to understand Psyche.

Leontiev's Activity Theory

The theory of Leontiev was based on a combination of ideas of Rubinstein and Vygotsky. Vygotsky is mostly known outside Russia for his concept of the zone of proximal development. But his main contribution is a more general theory of internalization, known also as the socio-cultural historical theory. According to this theory the main part of human psychic set-up is formed in the course of socialization through interaction with other people and operating with tools. So