Both Dada and Surrealist writers and artists experimented with "automatic" creative production. Dadaists including Francis Picabia, Tristan Tzara, Hans Arp, and Kurt Schwitters wrote "automatic" poems from 1918, so called because they were transcribed without delay, serious consideration, or revision. Dada visual artists, including Arp, Sophie Tauber, and Marcel Duchamp also relinquished creative control of their works by employing chance. At the same time a group of writers in France around André Breton experimented with automatic writing as a new method of exploring the unconscious. In 1919 Breton and Philippe Soupault published Les Champs magnétiques, the result of their first experiments with automatic writing that tried to tap new poetic imagery through uncontrolled outbursts of imagination. In the period 1922–4 dream accounts were added to automatism. In the First Manifesto of Surrealism (1924) the movement is defined by Breton as "pure psychic automatism by which it is intended to express, either verbally or in writing, the true function of thought." Surrealist visual artists also explored automatism. Surrealist automatism was influential in the development of modernist visual art. Robert Matta’s (1911–2002) concerns with psychological states in the late 1930s set a precedent for American abstraction. CoBrA (1948–51), an avant-garde collective established in Europe, favored automatic techniques and influenced developments in European abstraction.