If you’re happy and you know it, clap your hands! Turns out, clapping is as infectious as a communicable disease, a social contagion that spreads through a crowd rather than the summation of individuals’ spontaneous responses to a moment of rapture.

Greta Bradman, Applause, Classical Music Greta Bradman

So, in live performance, is concert etiquette of “no-clapping-until-the-end” a handy workaround, a buffer against the effects of infectious clapping? I asked around, and to quote a surprisingly common remark from some eminent musicians and conductors: “people should clap wherever the eff they want to”. “Are they joking?” I wondered. No, they assured me, they weren’t. Though there’s more to it.

We’re intelligent, intuitive creatures; for applause to become contagious it takes several of us dotted through the concert hall to clap for broad applause to break out. Chances are, when mass applause breaks out, it’s the result of canny musical prompts embedded in the music by the composer. The “whenever the eff” remark reflects an understanding of the role of applause, its history, giving credit where credit’s due to composers and their capacity for mass manipulation through music, and a dollop of quasi-flippancy underscoring the...