The basis of this pedagogical school of thought is quite logical: any motor movements begin in the central nervous system. The muscles do not move without the guidance of the brain. So, even though repetitive, mechanical-type practice may seem to be effective in some cases, it is the brain which is making new connections. It is not merely a matter of muscles getting stronger. In other words, it is important to realize that what many people call "muscle memory" is something of a misnomer. It is the brain which (either consciously or unconsciously) is making new connections to improve the efficiency of the motor movements.
Perhaps this is obvious to most people, but since it can be easy to fall into the imperfect routine of exercising the fingers in a purely mechanical manner, it is important to remind ourselves: "The roots of talent are in the gray substance of the brain, not in the hands" (Kochevitsky).
The following are some words which support the view of the psycho-technical school:
Dr. Friedrich Steinhausen: "A quantitatively small alteration in the brain has much greater importance than the most significant muscle enlargement."While training the finger muscles is an important component of piano-playing, we must remind ourselves that this training happens in our nervous system, and the learning is not contained in the fingers themselves. We must train our brains to understand music theoretically, to hear music aurally, to create a clear artistic vision, and to connect these ideas with the muscles involved so that the music may be executed correctly and clearly.
Otto Ortmann: The acquisition of pianistic movements is primarily a psychological process."
Michelangelo: "la mano che obbedisce all' intelletto" (the hand which obeys the intellect)
Franz Liszt: "Aus dem Geiste schaffe dir Technik, nicht aus der Mechanik" (Create your technique from your own inspiration, not from mechanics)