Action Lecture, first presented in 1968 in Cologne, consisted of various films, some of them showing the artist himself, that were projected both onto Peter Weibel and the screen behind him. Weibel was wearing a magnetophon on his body, which played one of his speeches while he himself gave the same speech live over a microphone. The central element of the action was a circuit mechanism that allowed the audience to influence the operation of the film projector, the Magnetophon and a cassette recorder. A lamp would begin to shine depending on how loud the audience was. That lamp was connected to a light-sensitive sensor wired to the audio and visual devices. Current flowed only if there was enough clamor. In other words, audio-visual information was produced only with audience participation; at the same time, the clamor meant that the tape recordings could not be understood at all. Every promise of communicative exchange was taken ad absurdum.