n. a half-black, half-white disk with black concentric stripes on the white portion. When spun, the top produces pattern-induced flicker colors (PIFCs or Fechner colors) which vary depending on the person perceiving and the speed at which it is spinning. First conceptualized by British scientist Charles Benham (1860-1929).
BENHAM’S TOP: “Benham’s top illustrates perfectly how the human eye can perceive color differently from person to person.”