A movement that emerged in the 1960s in [[Europe]] and the [[United States]], using geometric patterns and precise color relationships to create optical illusions of movement, vibration, and depth on flat surfaces. Key figures include [[Bridget Riley]]—whose [[Current - Bridget Riley (1964)|Current]] produces a powerful sense of visual movement from simple undulating lines—and [[Victor Vasarely]]. It grew out of [[Minimalism]]'s interest in pure visual perception and the color experiments of [[Neo-Impressionism]] and [[Bauhaus]] theory, prioritizing the viewer's perceptual experience above all else.