Abstract Expressionism, which lasted from the 1940s to the 1960s, was an American movement influenced by European modernism, Surrealism, and non-Western art traditions. Surrealist principles of psychic automatism were particularly influential, as was the influence of psychology and mythology. Abstract Expressionist paintings tend to be very large and intense, and feature dynamic, bold colors. For many abstract expressionist artists, the creative process itself was as important as the work. Abstraction expressionist paintings do not represent a specific visible subject, but they do communicate emotions and other less tangible subjects. Artists labeled as abstract expressionists were diverse in their approach and styles. The movement can be divided into multiple categories and sub-styles, the most prominent being action painting and color-field painting.