Surrealist automatism is a method of art-making in which the artist suppresses conscious control over the making process, allowing the unconscious mind to have great sway. This drawing technique was popularized in the early 1920s, by Andre Masson and Hans Arp.
Origins

Automatism has taken on many forms: the automatic writing and drawing initially (and still to this day) explored by the surrealists can be compared to similar or parallel phenomena, such as the non-idiomatic improvisation. "Psychic automatism in its pure state" was how André Breton defined Surrealism, and while the definition has proved capable of expansion, automatism remains of prime importance in the movement.

Early 20th-century Dadaists, such as Hans Arp, made some use of this method through chance operations. Surrealist artists, most notably André Masson, adapted to art the automatic writing method of André Breton and Philippe Soupault who composed with it Les Champs Magnétiques (The Magnetic Fields) in 1919. The Automatic Message (1933) was one of Breton's significant theoretical works about automatism.