The Nervous System is the name given by Jacobs to the live projection setup that he developed and used for performances from 1975 to 2000. It consists of two identical motion-picture film prints on two 16mm analytic or 35mm filmstrip projectors capable of advancing one frame at a time and freezing single images on screen. An exterior shutter, in the form of a spinning propeller positioned between the two projectors, is used to rapidly alternate between, and blend together, the two frames by interrupting the projections with imageless intervals. The exterior shutter technique was discovered and first used with slide projectors by the artist Alfons Schilling, who invited Jacobs to apply the technique to film in 1980. It became an integral component to the Nervous System and was used in every work from THE IMPOSSIBLE: Chapter Four “Schilling” onwards. Using short film sequences projected as a series of stills, The Nervous System operates on the temporal and spatial differences between two near-identical film-frames that are often only one frame apart from one another in filmic sequence.