mccollough effect

   The eponym McCollough effect refers to the American scientist Celeste McCollough Howard, who described the concomitant phenomenon in 1965. The McCollough effect is classified as a " contingent aftereffect. It can be induced by the alternate viewing of two gratings of different orientations (i.e. vertical and horizontal) and different colours (in the original paper by McCollough a vertical grating of blue and black stripes, and a horizontal grating of orange and black stripes). After alternately viewing these gratings for various minutes, the test subject is confronted with another pattern of vertical and horizontal gratings, but this time in black and white. The McCollough aftereffect consists of the black and white gratings being seen in colours complementary to the coloured ones priorly perceived (i.e. the vertical stripes in yellowish and the horizontal ones in purplish). The McCollough effect is distinguished from the " afterimage by the fact that the colours are contingent on the orientation ofthe gratings and by their tendency to last extremely long (i.e. up to 24 hours after an induction period of 10 min). The physiological correlates of the McCollough effect are still subject to debate. Hypotheses range from the involvement of the lateral geniculate nucleus to the involvement of cells within the visual cortex that are responsive to both colour and orientation, to the involvement of so-called higher centres of the CNS.

   References

   Jones, P.D., Holding, D.H. (1975). Extremely long-term persistence of the McCollough effect. Journal of Experimental Psychology: Human Perception & Performance, 1, 323-327.

   McCollough, C. (1965). Conditioning of color perception. American Journal of Psychology, 78, 362-378.