This book presents the study of psychological conditions of personality formation in professional activity (scientific research) and is considered not only in the context of general laws of functioning and stages of the creative act, but psychological determinants of the productivity of research activity. The undoubted merit of the results presented is the holistic consideration and resolution of diverse issues: the relationship between psychological mechanisms within scientific creative activity and the nature of self-determination of the formation of the subject of scientific research activity in highlighting the stages of this formation (optation, adaptation, internality, mastery).