In 1969 Nauman had devised a set of mental exercises in which a live performer was to concentrate on sinking into the floor or allowing the floor to rise up over him or her. This videotape was based on these exercises and were the first videotapes Nauman made in a professional studio. They also were the first to use performers other than himself and to utilize an optical effect. (His earlier videos all employ a fixed camera and a single long take.) "We used two cameras and changed locations from time to time," recalled Nauman in a 1979 interview. "What I was investigating at that time was how to examine a purely mental activity as opposed to a purely physical situation which might incur some mental activity." -- EAI