A large component of your initial memory will be hand memory, which comes from repeated practice. The hand just goes on playing without your really remembering each note. Although we will discuss all the known types of memory below, we will start with analyzing hand memory first because historically, it was frequently thought of as the only and best method of memory although, in reality, it is the least important. “Hand memory" has at least two components: a reflex hand motion that comes from touching the keys and a reflex in the brain from the sound of the piano. Both serve as cues for your hand to move in a pre-programmed way. For simplicity, we will lump them together and call them hand memory. Hand memory is useful because it helps you to memorize at the same time that you practice the piece. In fact, everybody must practice common constructs, such as scales, arpeggios, Alberti accompaniments, etc., from hand memory so that your hands can play them automatically, without having to think about every note. Therefore, when you start to memorize a new piece, there is no need to consciously avoid hand memory. Once acquired, you will never lose hand memory, and we show below how to use it to recover from blackouts.
The biological mechanism by which the hands acquire hand memory is not well understood but my hypothesis is that it involves nerve cells outside the conscious brain, such as the nerve cells in the spinal chord, in addition to the brain. The number of nerve cells outside the brain is probably comparable to the number in the brain. Although the piano playing commands must originate in the brain, it is quite probable that the rapid playing reflexes do not travel all the way up to the conscious brain. Thus hand memory must be a type of reflex that involves many types of nerve cells. In response to playing the first note, the reflex plays the second note, which stimulates the third note, etc. This explains why, when you get stuck, hand memory will not help you restart unless you go all the way back to the first note. In fact, restarting a piece at some arbitrary place is an excellent test of whether you are playing from hand memory or you have another backup memory method. Because it is just a conditioned response, hand memory is not true memory and has numerous serious disadvantages.
When we talk about hand memory, we usually mean HT memory. Because hand memory is acquired only after many repetitions, it is one of the most difficult memories to erase or change. This is one of the main reasons for HS practice -- to avoid acquiring incorrect HT habits that will be so difficult to change. HS memory is fundamentally different from HT memory. HS play is simpler and can be controlled directly from the brain. In HT memory, you need some kind of feedback in order to coordinate the hands (and probably the two halves of the brain) to the accuracy needed for music. Therefore, HS practice is the most effective method for avoiding the dependence on hand memory.
It is not possible to draw a clear distinction between technique and memory. A pianist with more technique can memorize faster. One reason you cannot separate memory from technique is that both are needed to play, and unless you can play, you can demonstrate neither technique nor memory. Therefore, there is a deeper biological basis (besides mere convenience of saving time, etc.) underlying the method of this book by which memory and technique are simultaneously acquired.