Most theories of the McCollough effect (McCollough, 1965; Stromeyer, 1969; Murch and Hirsch, 1972) attribute the 'greenish' color of white verticals and the 'reddish' color of white horizontals on a test pattern after prolonged alternate viewing of a red vertical and a green horizontal inspection pattern to an adaptation for color beyond the level of the retinal color receptors. In fact, Murch (1969) demonstrated that if the size of the test pattern eliciting the effect was twice as large as the inspection patterns, the colored area of the aftereffect still extended all over that test pattern. That is, the aftereffect failed to conform to Emmert's law failed to be confined to the specific area of the retina originally adapted. Also, Harris and Gibson (1968) demonstrated that the McCollough effect could be created by randomly presenting the inspection pattern to different parts of the retina. Both of these studies would indicate a lack of retinal area specificity for the McCollough effect. On the other hand, Harris (1969) found that opposing McCollough effects could be developed in adjacent retinal areas. He adapted his observers to an inspection pattern divided into several quadrants and found a red aftereffect on the verticals of the test pattern in one quadrant and a green aftereffect on the verticals in an adjacent quadrant. More recently, Stromeyer (1972) adapted three observers to a green vertical inspection pattern alternating with a red horizontal one while they fixated a point to the left of the patterns. After adaptation, colorless vertical and horizontal test patterns were interchanged every .5 sec while the fixation point was moved horizontally either to the left (i.e., away from the test pattern) or to the right (i.e., over the test pattern) and the observers were asked to indicate the positions of the fixation point producing the strongest