In this study the results of the comparative investigation of publications of two main psychological schools in Russia (Moscow and St. Petersburg ones) since 1949 to 2019 are described. Use of so called natural-scientific domain was compared. Five indexes were analysed: quantity of editions and articles that used studied approach, biological, physical and mathematical terms frequency. The study has showed that the representatives of the St. Petersburg psychological school tend to use the natural-scientific domain, but the representatives of the Moscow psychological school tend to use the philosophical one. The majority of Moscow psychological school authors (S.L. Rubinstein, A.N. Leontyev, L.S. Vygotsky) paid less attention on the biological aspect of human mind. But at the same time L.S. Vygotsky and D.B. Elkonin created the mental development theory based on natural development and ageing of human organism; also there is the theory of mind evolution created by A.N. Leontyev and K.E. Fabry and based of biological evolution theory. A.R. Luria studied brain functional asymmetry, the concept of system localisation of higher mental functions was the result of this study. B.M. Teplov, V.D. Nebylitsyn and V.M. Rusalov investigated nervous system features and temperament - the biological basics of personality. On the opposite, the authors of St. Petersburg psychological school used widely principles and methods of such sciences as biology, physics and mathematics. For example, V. Bekhterev’s reflexology really was a part of physiology of higher nervous activity studied by the Pavlovian Physiological School. B. Ananyev and B. Lomov, used sciences (including such integrative sciences as synergetics and cybernetics) in proving of human phenomenon integrity. L. Vekker used the invariance principle that exists in physics, for his own theory of stages of perceptive image formation. V. Ganzen and G. Sukhodolsky created a new discipline called mathematical psychology. The method of semantic analysis of publications in the Moscow State University Bulletin since 1977 to 2019 was used to investigate the development of the natural-scientific domain in the Moscow Psychological School. The hypothesis of the research was that during its evolution the St. Petersburg (Leningrad) psychological school is more orientated to the natural-scientific domain than the Moscow psychological school; the leading aspects of the Moscow school are the biological and the philosophical ones, and the leading aspects of the St. Petersburg school is the physical one. The method used in this study is the author’s “inciampata” model that consists in classification of scientific terms found in the articles in three groups according to three aspects of studied domain: biological, physical and mathematical ones; Pearson's correlation coefficient, P. Terentyev’s method and L.Vykhandu’s method were used for statistical data processing. The results of the study show that the authors of the Moscow Psychological School used the elements of sciences in particular studies, and the main aspect of natural-scientific domain is the physical one, not biological one; the authors of the St. Petersburg (Leningrad) Psychological School used natural science in the whole, not the elements of particular disciplines, because they were focused on the integration of sciences. These schools are mostly independent from each other in their studies, but psychologists from Moscow are mostly orientated to innovations, and ones from St. Petersburg are orientated to stability.