"...the theory of developmental instruction is a sensation in world psychological science..."
Professor Kunio Kumbayashi
Based on the results of many years of experimental and theoretical research, it is impossible not to conclude that the problems of developmental instruction and upbringing are among the most significant problems of contemporary psychology, especially in the fields of developmental and pedagogical psychology. The overall orientation of pedagogical thought and practice will in large part depend on their successful elaboration. The essence of these problems can be expressed concisely as follows: Do a personís instruction and upbringing determine the processes of his psychical development, and if they do determine them then is it possible to understand the nature of the link between psychical development and instruction and upbringing? In other words, can we assert that developmental instruction and upbringing exist, and, if they exist, then what laws do they obey? In everyday life, these problems sometimes take the form of the question: Can we, by means of instruction and upbringing, develop in a person certain psychical capacities or qualities that previously did not exist?
In the history of psychology, several theories have been created with respect to these problems, each of the theories being based on data from a given pedagogical practice, on materials derived from experience. These theories may provisionally be divided into two groups. The adherents of the first group of theories deny that instruction and upbringing can have any significant effect on a personís psychical development, i.e. they deny the very existence of developmental instruction and upbringing. Adherents of the second group of theories acknowledge the determining role of instruction and upbringing in a personís psychical development and try to study the laws of developmental instruction and upbringing. Each of these two basic groups of theories has many different variants. The authors notes that the accepted techniques of instruction and upbringing in different educational institutions are in some way connected with these theories. Therefore, the pedagogical practitioners who are guided by such techniques realize, consciously or unconsciously, fully or partially, the principles of one or the other of these groups of theories.