Benham's top

Benham's top, also called Benham's disk, is named after the English newspaper-man, amateur scientist, and toymaker Charles Benham, who in 1895 sold a top painted with the pattern shown. When the disk is spun, arcs of pale color, called Fechner colors or pattern-induced flicker colors (PIFCs), are visible at different places on the disk. Not everyone sees the same colors. Benham was inspired to propagate the Fechner color effect through his top after his correspondence with Gustav Theodor Fechner, who had observed and demonstrated the said effect. Benham's top made it possible for speakers of the English language to learn of the Fechner color effect, about which Fechner's original reports were written in German.

A sample of a Benham's disk

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