Op art perhaps more closely derives from the constructivist practices of the Bauhaus. This German school, founded by Walter Gropius, stressed the relationship of form and function within a framework of analysis and rationality. Students learned to focus on the overall design or entire composition to present unified works. Op art also stems from "trompe-l'œil" and anamorphosis. Links with psychological research have also been made, particularly with Gestalt theory and psychophysiology. When the Bauhaus was forced to close in 1933, many of its instructors fled to the United States. There, the movement took root in Chicago and eventually at the Black Mountain College in Asheville, North Carolina, where Anni and Josef Albers eventually taught.