Contrast Effect

The earliest scientific description of perceptual contrast comes from 11th-century physicist Ibn al-Haytham, who observed that paint patches appear darker on white backgrounds and lighter on black ones. The formal term "contrast" was introduced by Hermann von Helmholtz in his landmark 1866 work on physiological optics. Social psychologist Muzafer Sherif and Carl Hovland later extended the principle to attitude change in their 1961 book Social Judgment, establishing it as a foundational concept in psychology.