closed-circuit work to interactive media-art installations to open processes–exist as parallel possibilities.

From the «open work» in happening and Fluxus (1960s) to the conditioned spectator (1970s)

The first steps towards active participation and interaction were taken by John Cage, Allan Kaprow, George Brecht and others connected with the Happening and Fluxus movements in the 1950s and 1960s. John Cage's famous compositions «4'33''» (1952) or «Imaginary Landscape No. 4» (1951) can be cited as exemplifying the «open work.» The piece «433» consists of four minutes and thirty-three seconds of silence, whose character is naturally dependent on the conditions of its public performance (noise made by the audience and performer, the surroundings, and so forth). In «Imaginary Landscape No. 4» twelve radios are employed as musical instruments, meaning that every performance is unrepeatable and unique due to

the fact that the choice of frequencies varies according to the time and place of execution.[9] With his minimal predefinitions, Cage intended to «initiate an individual and social creative process which successively detaches itself from the intentions of its author.»[10] While the silence in «4'33''» heightens the potential creativity of audience reception (but does not yet actively involve the listeners in the artistic process), «Imaginary Landscape No.4» emphasizes the non-defined role of the performers (who do, however, remain performers). From the late 1950s onward, the Happening[11] art form established by Allan Kaprow went one step further by making the spectators themselves participants, executors and performers of the artistic process (see «18 Happenings in 6 Parts,» 1959). In the 1960s, this interaction among audience, work and artist became the major element of an aesthetic situated outside established genres, categories and institutions, and is generally described by the term «intermedia.»