With the closure of the Bauhaus under Nazi pressure in 1933, Albers emigrated to the United States. In 1950 Albers was appointed head of the Department of Design at Yale University. In 1963 he published "Interaction of color" which presented his theory that colors were governed by an internal and deceptive logic. A key idea, which he proved by examples, was that our perception of color is not constant. It is influenced by the juxtaposition (placing together) of one color with another. This interested artists interested in optical illusions (Op art).