McCollough afterimages were produced by 20 presentations of a vertically lined pattern on a red ground alternated with a horizontally lined pattern on a green background. 16 undergraduates viewing a test pattern of black horizontal and vertical lines on a white background reported differing chromatic aftersensations for both lined areas. Judgments of the size of the afterimages were obtained at 3 distances (2, 4, and 8 ft.) in Exp. I and for 3 test pattern sizes (3, 6, and 12 in.) in Exp. II. Size judgments were also obtained after the presentation of a single color. The size of the complementary afterimages corresponded to Emmert's law, whereas the size of the McCollough afterimages did not. Rather, the size of these afterimages was dictated solely by the size of the test pattern. (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.
