Simultaneous color contrast from McCollough effects is spatially contingent

In two experiments, orientation-contingent color aftereffects (CAEs) were induced by presenting in alternation red/black vertical and green/black horizontal gratings. The CAEs induced second-order simultaneous color contrast in a 45° patterned test field but not in a patternless field. These CAE-induced second-order color effects were measured using both color cancellation (Experiment 1) and color matching (Experiment 2) techniques. The spatial selectivity of the second-order effects and their manifestation outside the orientation range typically used in studies of orientation-contingent color effects are discussed in terms of neural explanations of color misperceptions. © 1987 Psychonomic Society, Inc.