When approached, this device will become active with a dance of its own composition, and will continue if a body remains in its range. There is a 'sweet spot' in that range within which subtle motion by a body will affect the variables of the dance. The dancer chooses the location of the sensitive area over a long period of time (sometimes a matter of days). If a body moves close to the surface of the dancer, it will always become strident and unresponsive.