After eading a few posts by Bernhard I realized something.
Ok... so on one of the threads the topic of taking quick breaks during practicing a passage and playing it in your mind comes about. I had previously noticed this and done this to some extent, but I have been thinking about something else. If, lets say, we take a passage that gives us trouble and play it in our mind over and over paying close attention to our finger movments and positions and hearing the sound come from it (all in our head of course) and we slept on it, would this be the equivalent of actually playing it physically? I tried playing through about five or six pages of the Waldstien sonata in my head and found myself to be equally fatigued as if I was sitting at the piano. Can you get the same results like this? I'm going to experiment...
Yes, do that and you will hit the jack pot.

Here is an interesting story. A friend of mine was a taichi instructor. Unfortunately she had a very serious car accident, and as a result she was immobilised in bed for almost two years. After two months, she got really depressed about the very real possibility that she would never recover her full range of movement, or even practise taichi anymore. At that point she was visited in hospital by her instructor, who – being an instructor and all – instructed her to do the taichi form in her mind. But she was to do it in real time with as many details as possible. She had to “feel” the muscles moving through the form. If she chose (in her mind) to do it in a park, she should smell the grass and listen to the sounds of the children running about. You get the idea.
She did as she was instructed,religioulsy everyday, and in fact was usually physically tired from doing it in her mind. When she finally got out of bed, she surprised herself and the physiotherapists, by being in a much better form than what she (and they) expected. She was even more surprised that she could actually do the taichi form to a much higher standard than when she was at the peak of her form, before the accident.
As you go through any mental rehearsal of physical movements, even though you think you are not moving, the muscles are contracting minimally, so minimally in fact as to be undetectable, but make no mistake, they are getting a workout.
Have you ever heard of pendulum divination? You hold a string with a pendulum over a line, and decide which direction (parallel or perpendicular) to the line is yes, and which direction is no. Now ask a question and just hold the pendulum over the line without trying to influence it in any way. You will find to your great surprise that the pendulum
will move and give you an answer. This sort of thing has generated a huge market for “magical pendulums” made of crystal and with all sorts of “magical properties” depending in the material. This is of course rubbish. It has nothing to do with the pendulum. As you ask the question, your unconscious will answer it by these tiny imperceptible muscle movements. You will not feel it, and no one will be able to see them, but they will move the pendulum which makes the whole thing – albeit perfectly explainable – eerie nonetheless.
Scientifically minded people, once they hear the explanation tend to dismiss the pendulum as so much hocus pocus, but in my opinion they are throwing away the baby together with the bath water, since the pendulum although useless for divination purposes provides a unique chanel of communication with your own unconscious – and the unconscious knows a lot more than we fathom. So why not ask the unconscious some questions from time to time? Specially when we are stuck. But do not just give it a yes/no choice. Add to it “maybe”, “I don’t know”, “I know but it is not safe to tell you”. Draw lines on a piece of paper radiating from a centre and write down one answer for each line. Hold the pendulum right above the central point from which the lines irradiate, and ask your question. Your unconscious will move the pendulum over the appropriate line. Needless to say, you should not try to influence the pendulum movement in any way.
Here is something fun to try. Get a friend to ask a personal question for which you do not know the answer (like “do I have a car”, or “Is the colour of my underwear red?” – assuming you do not “consciously” know the answer). Then use the pendulum to find out if you know it unconsciously (you will have to phrase the question in a yes or no format). You may be quite surprised at how much you know unconsciously! By the way, Ouija boards (ever heard of them) work on the same principle. They are excellent ways to get unconscious information.
But I digress.
Unfortunately mental practice at the piano is easier said than done, so the usual way to get there is to break it down in manageable steps:
1. First you just hear the piece/passage (in real time – so use a metronome so that you do not speed up unconsciously, and watch like a hawk that you do not skip bits – so work with a score in front of you). [aural representation]
2. Then see yourself (your hands) pressing the appropriate keys. Because this is all in your mind, you can make it perfect! However again, this takes a lot of concentration (I believe that a lot of mistakes people make when playing is simply because they are unconsciously making such mistakes in their minds) [visual representation]
3. Then you must “feel” the physical sensations associated with pressing the keys, from correct fingering to body movement, etc. (when I say feel I am not referring to emotions) [kinaesthetic representation]
4. Then you must try to put together all the three above so that you have a complete (aural, visual and kynesthetical) mental representation of your playing. If you are detailed enough, you may end up “hallucinating” the playing to such an extent that it will be difficult to tell apart from reality (there is nothing extraordinary about this: we do it every night when we dream).
5. One important caveat: this is not for exploratory work, this is for pieces/passages you have already figured out the exact physical co-ordinates. Otherwise there is no guarantee that you will be mentally practising the correct thing.
Now go and watch the “Matrix”! (And watch out for Mr. Smith!)

Best wishes,
Bernhard.