We can’t build strength, flexibility or position sense in our bodies just by imagining, but, practising a piece in our head – imagining every fingering and bowing, either from memory or while reading the written music – can be a very useful practice method. Psychologists say that imagining something is often almost (or equally) as powerful as actually doing it.
This technique is especially appropriate when we are tired from playing too much. We can give our body – and our emotions – a break and just lie down and do our (mental) practice in bed or on the sofa !! It’s also a very good way to reinforce relaxation (especially the bed part). Without the physical tensions of actually playing, we can “practice” the piece in a state of total relaxation, which is very helpful when the time comes to pick up the instrument.
With mental practise, we can reinforce both our memory and our technical mastery of a piece of music anywhere and at any time, making use of idle moments in a bus, train, queue etc where we otherwise might just be getting bored or impatient. I do not recommend doing it while driving, however: if a difficult (musical) moment coincides with a difficult automotive moment, we may find ourselves going under a truck, which will not help our performance at all!
It is astonishing how, even without the instrument, a difficult passage will also be difficult to imagine clearly and fluently in our mind. And how “cleaning it up” in our mind will make it easier to play when we do actually pick up the instrument. Another type of mental practice is to simply listen to a recording of a piece while simultaneously “playing along” in our imagination, with or without the music in front of us. This is another sure way to reveal those insecure moments that need more reinforcing.
A well known English cellist used to have a fingerboard in her car. While stuck in traffic jams or at red lights she would “practice” the music she had to play that evening in a sort of mix of mental and physical practice. This is only for VERY busy people – otherwise it would be a sure sign of a compulsive-obsessive practice disorder !!