The mood set by music can change the way people operate. In a scientific study, when subjects were asked to solve math equations, they could solve fewer equations when slow, calming music was playing in the background than when there was no music. When rock ‘n’ roll was played, they solved more equations than when in silence.

A retailer made long playlists containing a variety of music arranged so that a fast, upbeat piece played approximately every 15 minutes. During these songs, more customers approached the sales counters.