Op art, short for optical art with the echo of "Pop Art" included, is a term the media invented in 1964 for works that feature retinal or optical phenomena to confound the normal processes of perception. Op art creates illusions of movement, afterimages, or moiré effects, and requires viewer's participation to complete the phenomenon. With origins in trompe l'oeil (deceives the eye), Op art is also related to Fluxus and to gestalte psychology (the whole perceived as greater than sum of parts). The idea spread quickly in the '60s to fashion, graphics, etc., and because such rapid popularity is usually viewed with suspicion, Op art was often dubbed a gimmick (like all that Magic Eye junk a few years ago).
Bridget Riley (1931- ) started out with black-and-white works in the early '60s which the fashion industry made chic, somewhat to her dismay. These and her later more colorful works (from 1965 onwards) are not comforting. They are disturbing through their subversive effects of disorientation and dislocation. In the dazzlingly intense Cataract 3 (1967), red, turquoise, and grey curves undulate in uniform, shimmering, vibrating waves.
Victor Vasarely (1908-1997), born in Hungary and raised in France, participated in a 1965 show when the art world looking for a Pop Art successor. The physical effect of the work was more important to him than any intellectual appreciation on the part of the viewer. He tended to juxtapose violently dissimilar colors that then creates an effect that appears to distort the canvas. Vasarely coined the term "Cinetic Art" to express the virtual rather than actual movement of the works. He also hoped for "the new city," which would be geometrical, sunny, and full of colors.
Patrick Hughes (1939- ), a British artist, has been creating 3D works since 1964. An '80s revival of interest in Op Art led to some appreciation of his work.
Dempsey, Amy. Art in the Modern Era: A Guide to Styles, Schools & Movements. NY: Harry N. Abrams Inc., Pub., 2002.