Op art, or optical art is based on the idea that an artist can influence the spectator by creating optical illusions that appear as visual illusions. The movement was started in the United States as a protest to action painting in about 1960. Op art was preceded by geometrical abstraction and its proponents asserted that op art was carrying geometrical abstraction one step further. Additionally, experiments that were conducted at the Bauhaus influenced the beginning of optical art. Josef Albers, who became an instructor at Yale after having taught at the Bauhaus, was a primary mover for the optical art movement. His book "Interaction of Color", that was published in 1963, greatly influenced many young painters.
Examples of work that is considered op art are the patterns that were designed by Vasarely and Riley that appear to move, even though they are, in fact, static. Clear and colored paper layers were arranged so artistically by Olsen and Sobrino that illusions of both depth and space are seen by the viewer. Painted nails by Uecker and string compositions by Sue Fuller are other examples of op art. Other artists who considered themselves to be part of the movement were Francis Hewitt, Edwin Mieczkowski, John Goodyear, Henry Pearson and Mon Levinson, to mention a few. Groups in other countries (such as the Group Zero in Dusseldorf) were started as a result of the op art that was designed in the United States.