The introduction of video in the 1960s radically altered the progress of art. The most important aspect of video was that it was cheap and easy to make, enabling artists to record and document their performances easily. This put less pressure on where their art was situated giving them freedom outside the gallery. One of the early pioneers of video art was Bruce Nauman who used video to reveal the hidden creative processes of the artist by filming himself in his studio. As video technology became more sophisticated, the art evolved from real-time, grainy, black and white recordings to the present day emphasis on large-scale installations in colour. Bill Viola's multi-screened works are theatrical and often have a narrative; and Gillian Wearing uses a documentary style to make art about the hidden aspects of society.