Op art

Optical art is a method of painting concerning the interaction between illusion and picture plane, between understanding and seeing." Op art works are abstract, with many of the better known pieces made in only black and white. When the viewer looks at them, the impression is given of movement, hidden images, flashing and vibration, patterns, or alternatively, of swelling or warping.
The term first appeared in print in Time magazine in October 1964,though works which might now be described as "op art" had been produced for several years previously. For instance, Victor Vasarely's painting, Zebras (1938), is made up entirely of curvilinear black and white stripes that are not contained by contour lines.