The McCollough effect: Dissociating retinal from spatial coordinates

Abstract

Three experiments were conducted to dissociate the perceived orientation of a stimulus from its orientation on the retina while inducing the McCollough effect. In the first experiment, the typical contingency between color and retinal orientation was eliminated by having subjects tilt their head 90 0 for half of the induction trials while the stimuli remained the same. The only relation remaining was that between color and the perceived or spatial orientation, which led to only a small contingent aftereffect. In contrast, when the spatial contingency was eliminated in the second experiment, the aftereffect was as large as when both contingencies were present. Finally, a third experiment determined that part of the small spatial effect obtained in the first experiment could be traced to hidden higher order retinal contingencies. The study suggested that even under optimal conditions the McCollough effect is not concerned with real-world properties of objects or events. Implications for several classes of theories are discussed.

Probing Unconscious Visual Processing with the McCollough Effect

“…As first noted by McCollough (1965), the hallmark of the effect is its dependence on contour orientation; that is, the dependence of the perceived color on the orientations of the test patterns (and their relation to the orientations of the patterns used during the induction period). Further, this orientation contingency depends on orientation with respect to the retina; there is no ''correction'' for head tilt (e.g., Bedford & Reinke, 1993;Ellis, 1976). Because neurons in V1 of the visual cortex of cat and monkey are the first to show orientation selectivity, the effect likely involves cortical structures.…”

Mystery of the anti-McCollough effect

“…If so, does that then imply that color can be made contingent on the spatial or perceived orientation, rather than on the retinal orientation? The regular McCollough effect is contingent on retinal, not spatial, orientation (e.g., McCollough, 1965) and, moreover, cannot be made contingent on the spatial orientation (Bedford & Reinke, 1993). Spatial orientation likely reflects a "higher level," in the sense of a later step in visual processing, because it corresponds to what subjects perceive, in contrast to retinal orientation, which is processed earlier.…”

“…Outcome: minimal pink seen on the horizontal and minimal light green on the vertical. f Rescuing a color-orientation relation by viewing the second and fourth stimuli with head tilted 90° (Bedford & Reinke, 1993). (Creating the inverse-spatial without a retinal relationdoes not lead to an aftereffect.)…”

False categories in cognition: the Not-The-Liver fallacy

“…After a few minutes of induction, the white stripes of a vertical black and white test grating appear pink, but the white stripes of a horizontal grating appear green (see e.g. McCollough, 1965;Bedford and Reinke, 1993). Can the patient, who cannot see the difference between vertical and horizontal lines, see the illusory pink and green colors which depend on those very orientations?…”