“Let’s hear a round of applause for . . . !” We’ve all heard and complied with this request, clapping as a singer, keynote speaker or graduating class walks on stage. This welcoming applause might sound much like any other—the applause that comes after an event, or sometimes during—but it carries a different message. 

Discourse analysts categorize applause as introductory, closing or rewarding. In most public events the first two of these are essentially obligatory: It would seem rude not to clap a symphony conductor onto the stage, or to sit silently as actors bow after the curtain call, even if we didn’t enjoy the performance. Spontaneous “rewarding applause,” in contrast, expresses the flow of the crowd’s reactions. Athletes win raucous acclaim with great feats o...