McCollough Effect

Experiencing the Effect

One needs some patience to experience the ME. First one looks at a test figure, containing regions of black-and-white lines of opposite orientations, such as vertical and horizontal (see color insert, Figure 26a). All the regions should appear black-and-white.

Next, one views induction stimuli for about five minutes. One can do this by staring alternately for about 10 seconds each at black lines of one particular orientation on a background of one color (e.g., vertical black-and-red; color insert Figure 26b) and black lines of the opposite orientation on a background of a complementary color (i.e., horizontal black-and-green; color insert Figure 26c).

Finally, when one looks again at the test figure, one should now see that the vertical white parts look greenish and the horizontal white parts look reddish. Similar tints may also be visible in the dark parts. The test figure may now look like Figure 26(d) of the color insert.

History

The first CAE was reported by Ivo Köhler in 1951. After looking through prisms producing bluish and orange fringes on the left and right of vertical contours respectively, he observed illusory complementary colors contingent on whether a vertical edge was left or right facing. That is, left-facing edges appeared orange and right-facing edges appeared blue. Celeste McCollough realized that similar aftereffects could be made contingent on the orientation of contours; in 1965 she reported the effect that came to bear her name.

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