William Greaves, a pioneering black film actor, went on to direct over 200 documentaries, host and executive produce NET’s Black Journal, and teach acting. For this eccentric 1968 experiment, he got two white actors to play a quarreling couple in Central Park and proceeded to film not only them (in both rehearsal and performance) but also himself and his camera crew and various other people, often juxtaposing separate angles in split screen in the final edit. The crew’s own doubts and speculations about the film being made were also included. The couple’s quarrel is singularly unpleasant, the acting variable, the collective insight into what Greaves is up to mainly uncertain. The title modifies a term referring to the interactions between people and their environment, and the notion of a shifting center is what gives this experiment much of its interest and also limits it from going very far in any single direction. 75 min.