Many of Woody Vasulka's and Steina's early tapes such as 'Black Sunrise' (1971), and 'Soundprints' (1972) illustrate one type of signal determining the form of another. In 'Artifacts/Keysnow' by Woody Vasulka sound is modulated by the image. A camera organised texture is set to travel at various harmonic speeds of the line frequency of video. The work is an important example of early attempts to visualise the materiality of an electronic signal.