Text-contingent color aftereffects: A reexamination

Abstract

Five experiments reexamined color aftereffects contingent on the semantic properties of text (Allan, Siegel, Collins, & MacQueen, 1989). The influence of different assessment techniques and the effect of eye movements and overlapping contour information on the induction of color aftereffects by word and nonword letter strings were determined. Experiment 1 showed that no aftereffect was found when a traditional method of assessing color aftereffects was used. Experiments 2 and 4 demonstrated color aftereffects for both words and nonwords, but only when subjects fixated the same locus during induction and testing and only when assessed with the technique described by Allan et al. (1989). If, however, eye movements were made during induction, no color aftereffect was obtained (Experiment 3). Induction to nontext patterns with properties similar to those of text but with fewer overlapping contours resulted in a strong color aftereffect (Experiment 5). These results suggest that the color aftereffect contingent on text is very weak and is not dependent on semantic factors, but that it is a product of induction to local color and orientation information. 405In 1965, McCollough reported negative color aftereffects contingent on the orientation ofinduction and test patterns. Now known as the McCollough effect (ME), this visual illusion has been the topic of considerable research, most of which supports McCollough's original contention that the effect occurs at an early stage in the visual system. However, in a recent study, Allan, Siegel, Collins, and MacQueen (1989) obtained results which suggest that higher level, semantic processes might be involved in the effect.Induction of the ME involves the alternate viewing of two grating patterns of roughly complementary colors. In McCollough's (1965) original experiments, a grating of orange-and-black vertical stripes alternated with a grating ofblue-and-black horizontal stripes. The gratings were viewed at 5-sec intervals with 1 sec of darkness in between for approximately 2--4 min. When black-andwhite horizontal and vertical gratings were viewed fol-

Probing Unconscious Visual Processing with the McCollough Effect

“…If the retinal location or spatial frequency is changed between induction and testing, the aftereffect is considerably weakened or absent, depending upon the magnitude of the change (e.g., Harris, 1980;Humphrey, Herbert, Symons, & Kara, 1994;Humphrey, Skowbo, Symons, Herbert, & Grant, 1994;Lovegrove & Over, 1972;Stromeyer, 1972a,b). In short, the McCollough effect does not show translational invariance or size constancy.…”

The indirect McCollough effect: An examination of an associative account

“…In another experiment, Stromeyer (1972) found that the ME weakened or disappeared when a test grating was moved to a different retinal area from the induced area. Results of other experiments also indicate that the ME is retinotopic (Broerse & Grimbeek, 1994;Broerse & O'Shea, 1995;Humphrey, Herbert, Symons, & Kara, 1994;Humphrey, Skowbo, Symons, Herbert, & Grant, 1994; for review, see Humphrey, 1998;, but and Siegel, Allan, & Eissenberg (1992 have presented results suggesting that the ME is spatiotopic. It appears that much of the evidence favors a retinotopic account of the ME, but there is certainly room for more research to decide this issue definitely.…”

Do McCollough effects provide evidence for global pattern processing?

“…Advocates of the conditioning explanation (Allan & Siegel, 1997b;Siegel, Allan, & Eissenberg, 1994) agree that induction with strict fixation will produce CAEs interpretable in terms oflocal (retinotopic) factors, but they contend that CAEs dependent on global (spatiotopic) factors can be obtained with nonfixating subjects. A similar controversy over CAEs contingent on text (Allan, Siegel, Collins, & MacQueen, 1989;Humphrey, Skowbo, Symons, Herbert, & Grant, 1994) also remains unresolved.…”