Simultaneity in Simultaneity, presented in Buenos Aires, Argentina, on 24 October, 1966, by Marta Minujin was probably the first performance piece in history to make use of several coordinated mass media. In part of the work, each “spectator” was alone in his own home: relatively few perceived every dimension of the performance, but aspects of it were available to anyone with a radio or television set.

The piece which eventually became Simultaneity in Simultaneity was originally conceived as part of an intercontinental presentation. At the same time that Minujin's work was being done in Argentina, Allan Kaprow in the United States and Wolf Vostell in Germany were to do performances. The three had talked of making use of the telstar communications satellite to transmit video material from one part of the performance to another, of flying performers from one country to another so that they could appear in person in more than one “section,” etc. This original plan was not carried through when both Kaprow and Vostell failed to realize their segments, but it determined some of Minujin's imagery, and, eventually, provoked an interesting juxtapositioning of “truth” and “falsity” in art.