Performers practise extensively for their concerts, yet they aim for a fresh and spontaneous performance each time. How can a thoroughly practised performance remain spontaneous? This was the question asked by CPS Research Fellow Tania Lisboa and her collaborators Alexander Demos (University of Illinois at Chicago) and Roger Chaffin (University of Connecticut).

They tested the hypothesis that performers achieve spontaneity by varying the musical gestures that express their interpretation of a piece. They studied 12 performances of J. S. Bach’s Cello Suite No. 6 (Prelude) for solo cello and 8 performances of the Italian Concerto (Presto) for solo piano.

The researchers examined how tempo changed across the course of each phrase, measuring the tempo of each bar. They also measured tempo stability across performances. Both related systematically to the musical structure: slower, less stable tempi occurred at the beginnings and ends of phrases while faster, more stable tempi were maintained mid-phrase. The consistent decrease of stability at phrase boundaries suggests a systemic method to introduce spontaneity into their performances. The researchers proposed that slower tempi at phrase boundaries may provide the opportunity for slower, conscious thought processes to moderate the fast, automatic motor sequences of the highly practised performance.

The effects of practice were complex and the findings begin to explain how musicians achieve spontaneity in highly practised performances. They provide empirical support for the description of the Russian pianist Emil Gilels’ description of his own playing: “When I am in top form… the ideas are always different… it is different each time I play, and it is a process which… includes mastery of the work, knowing the details, being comfortable with it, and then adding the fantasy.“

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