In my experience as a piano teacher, I have often noticed how pupils can radically and instantaneously improve, even to a surprising extent, simply thanks to what they are thinking of while they play. Nothing magical, of course; it's just one of those many instances of how our mind can inhibit or release our talent.
Very often, it's enough to ask a student who is playing in an inhibited, or in any case a rather scholastic fashion, to imagine being a great pianist: for example, to play the same piece trying to impersonate Vladimir Horowitz. At times, for the more resistant ones, it is more effective to ask them to produce a caricature of Horowitz. Well, this nearly always results in a performance that is not only more imaginative and free, but also more intense and coherent, compared to their previous effort. And to tell the truth, there are hardly ever any similarities to Horowitz (an artist particularly difficult not only to equal, but also to imitate).
What I have learnt from these experiences (which I sometimes apply to myself as well) is that our artistic and creative potential very often remains hidden, due to inhibitory mechanisms that lead us to express just a minimum part of our intentions and intuitions. Why does this happen? Maybe because we tend to concentrate more on controlling our defects (and in so doing emphasize them!) rather than on the music itself. And if our aim is “not to make mistakes” or “not to produce an ugly sound” or “not to overuse the pedal”, perhaps we will obtain the result that we set ourselves, but not one that at all matches our real, global expressive intention. So it may be enough to “distract” our mind from these inhibitory control mechanisms, for instance by forcing it to concentrate on imitating another pianist, to allow our true artistic individuality to emerge more naturally, and finally without obstacles.
Often during my master classes the students don't realize that their “imitation” of a great pianist gives rise to a better performance, and they continue to believe, instead, that it is an exaggerated or fabricated performance. But all you have to do is to record it, and let them hear and compare the two versions to make them understand the real situation.
Of course, I'm not saying that in order to play better you always have to think you are someone else. But this experiment can work like a path-opener: it's a way to discover new artistic potentials that are perhaps still dormant. After all, this is what master classes are for: to help each student to find, by comparing with the outside, the great artist that is inside him.