Portland State University. Department of Psychology
Gerald M. Murch
Term of Graduation
Date of Publication
Master of Science (M.S.) in Psychology
Color vision, Visual perception, Conditioned response
1 online resource (iv, 40 pages)
A model based on the laws of classical conditioning is posed as an explanation for the McCollough Effect, an orientation-specific color aftereffect. This model stands as an alternative to the color-coded edge detector hypothesis. Background and relevant issues are presented. Two experiments were performed. The first demonstrated that an auditory stimulus causes the effect to appear stronger to some subjects, a disinhibiting effect. It was also shown that some subjects experience spontaneous recovery of the effect after it has been extinguished.
The second experiment demonstrated that the after-colors will generalize to lines of varying orientation, including 45°. Subjects adapted to both red-vertical and green-horizontal lines saw mostly pink on test lines more than 30° off horizontal. Subjects adapted to red only or green only saw the appropriate after-colors on patterns of all orientations between 0° and 90°. These results conflict with the color-coded, edge detector theory and an explanation in terms of classical conditioning is offered.
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Lord, Andreas D., "A Conditioning Model for the McCollough Effect" (1975). Dissertations and Theses. Paper 2419.