The McCollough effect tshirt

The McCollough effect is a phenomenon of human visual perception in which colourless gratings appear coloured contingent on the orientation of the gratings. It is an aftereffect requiring a period of induction to produce it. For example, if someone alternately looks at a red horizontal grating and a green vertical grating for a few minutes, a black-and-white horizontal grating will then look greenish and a black-and-white vertical grating will then look pinkish. The effect is remarkable for often lasting an hour or more, and in some cases after prolonged exposure to the grids, the effect can last up to three and a half months.