Two Hands Clapping

By David Bjerklie

The conductor's baton comes to a dramatic halt. The orchestra's final note rings in the air. There is a split second of awed silence, then thunderous applause as the audience expresses its appreciation.

To a mathematician's ears, there is something else going on. Typically, after a few seconds of chaotic clapping, an audience will slip into synchronized applause, like two people adjusting their strides until they walk in step. But just as walkers will reassert their natural gait, a clap-happy audience will fall in and out of synch repeatedly. According to a study of ovations in Romania and Hungary, this back-and-forthing is due to conflicting needs: the wish to make the most possible noise (random clapping) vs. the urge to clap in unison. People switch from one to the other by consciously adjusting the speed of their applause. Why do some folks seem to play this game with such gusto? According to the study, published last week in Nature, it may be a function of how closely knit the audience is. Maybe the crowd that feels like one claps like one.

--By David Bjerklie