Cunningham had been intrigued by the fact that the dictionary definition of “polarity” refers not only to the separation of two poles but also to their attraction. “Polarity,” a work for seven dancers, was in part a response to this. The dance had two distinct types of movement: one done in place involving isolated articulation of different body parts, the other more active and traveling through the space. David Tudor’s music, “Virtual Focus,” depended on the interaction among strips of metallic material on the dancers’ costumes, metal screens behind the backdrop, and radar and ultrasonic frequencies controlled by the composer. The backdrop, designed by William Anastasi, consisted of two enlarged drawings by Cunningham.