SOME music has always been about the performance. Watching a rock band live, for example, is not just a matter of appreciating the quality of the sound. What the musicians get up to on stage is almost as important. But you might think that classical music would be immune from such distractions—doubly so when a performance is being judged as part of a competition. However, a study by Chia-Jung Tsay, a concert pianist who is also a researcher at University College, London, suggests that even judges awarding prizes can be swayed by what they see as well as what they hear.

Dr Tsay’s study, just published in the Proceedings of the National Academy of Sciences, employed over 1,000 volunteers (half novices and half experts) to evaluate the performances of candidates in ten prestigious music competitions, to see if they agreed with the judges’ decisions. Each volunteer assessed 30 performances—the top three from each competition. The catch was that only a third of volunteers were shown the performances accompanied by the soundtrack. The other two-thirds got either to see each performance or to hear it, but not both.

Novices who saw and heard the whole thing, or merely heard it, did little better than chance at working out who had won—guessing right slightly more than a third of the time. Those who only saw it, however, did much better. They agreed with the actual decision almost half the time. Even more intriguingly the experts, who one might think would be trained to screen out histrionic flummery on the part of performers and concentrate entirely on the sound of the music itself, did worse than the novices when they could hear the performance, whether or not they could see it as well: they guessed right slightly under a third of the time. When they could see but not hear it, they did precisely as well as the novices, agreeing with the judges just under half the time.

Still worse, for those who believe competitions truly pick the best musician, when both novice and expert participants watched silent videos that showed only the performers’ outlines (as illustrated at the top of the article), they still got it right just under half the time. What they seemed to be picking up on were gestures that they thought conveyed passion. It was these that gave a performer his or her edge.

One moral of this story, then, is that music competitions really are a bit of a lottery. If even experts cannot pick the winner from the top three when they can see and hear the performances, it suggests that real judges in such competitions might, once they have winnowed out the no-hopers, just as well toss a coin to decide who is actually top. The other lesson, given that this is never really going to happen, is that competitors should brush up on their stage skills as well as their musical ones.