Scanning and form-contingent color aftereffects.

Abstract

G. K. Humphrey, A. M. Herbert, L. A. Symons, and S. Kara (1994) and J. Broerse and P. Grimbeek (1994) suggested that the form-contingent color aftereffect reported by S. Siegel, L. G. Allan, and T. Eissenberg (1992) would not be obtained if Ss were instructed to scan the induction and assessment forms. The authors present data from Ss who were instructed to scan the forms. These scanning Ss displayed aftereffects that were no different from those described earlier by Siegel et al. Scanning Ss do display spatiotopic contingent color aftereffects.

Contingent color aftereffects: Reassessing old conclusions

“…The results reported by Siegel et al (1994) do not support the hypothesis advanced by and by Broerse and Grimbeek (1994) that instructions to scan would eliminate (or at least attenuate) the color aftereffect. Rather, Siegel et al's results suggest that scanning subjects do display form CCAEs.…”

“…They then inferred that would not have obtained form CCAEs if their subjects had been instructed to scan the forms. Siegel et al (1994) assessed this inference. They compared subjects who were given no explicit scanning instructions (like those in the Siegel et aI., 1992, study) with subjects who were given explicit instructions to scan the forms.…”

“…The induction and assessment stimuli were outline geometric forms, a square and a "tic-tao-toe" cross, used by Siegel et al ( , 1994 and and similar to the forms used by Foreit and Ambler (1978) and Broerse and Grimbeek (1994). were two induction groups (n = 10 subjects per group).…”

“…They reported that CCAEs were not observed after induction with these geometric forms, and concluded that "line configurations or forms per se are difficult to link with color to produce McCollough effects [CCAEs]" (p. 302). More recently, a number of investigators have reported that CCAEs are observed after induction with simple geometric forms similar to those used by Foreit and Ambler (e.g., Broerse & Grimbeek, 1994;Siegel et al, , 1994. There is disagreement, however, among these investigators regarding the nature of these aftereffects.…”

“…There is disagreement, however, among these investigators regarding the nature of these aftereffects. Siegel et al ( , 1994 suggested that the induced aftereffects are spatiotopic; that is, that the aftereffects are contingent on form, and forms (like other patterns) can serve as CSs eliciting chromatic CRs that are CCAEs. Broerse and Grimbeek (1994) and , in contrast, suggested that the induced aftereffects are retinotopic, and that forms constructed of the same orientation components do not elicit spatiotopic CCAEs.…”