Text-contingent color aftereffects: a reexamination

Stimulus selectivity of figural aftereffects for faces

Viewing a distorted face induces large aftereffects in the appearance of an undistorted face. The authors examined the processes underlying this adaptation by comparing how selective the aftereffects are for different dimensions of the images including size, spatial frequency content, contrast, and color. Face aftereffects had weaker selectivity for changes in the size, contrast, or color of the images and stronger selectivity for changes in contrast polarity or spatial frequency. This pattern could arise if the adaptation is contingent on the perceived similarity of the stimuli as faces. Consistent with this, changing contrast polarity or spatial frequency had larger effects on the perceived identity of a face, and aftereffects were also selective for different individual faces. These results suggest that part of the sensitivity changes underlying the adaptation may arise at visual levels closely associated with the representation of faces.

Do McCollough effects provide evidence for global pattern processing?

Contingent color aftereffects (CAEs, or McCollough effects) were induced using two pairs of orthogonally related patterns (horizontal/vertical and concentric/radial) to determine whether the CAEs of the four patterns are independent. Tests using composite test patterns (like those employed by Emerson, Humphrey, & Dodwell, 1985) suggested independent aftereffects. However, tests using unitary patterns indicated additive or competing effects of the four patterns in regions where line orientations were similar, and tests isolating such regions showed clear interactions between the pattern aftereffects. The results fail to support the claim that global (rather than local) features of the patterns control these CAEs.

Motion after-effects and word contingency

Stimulus-selectivity in phenomena such as the McCollough effect and other contingent after effects are controversial. Word specific McCollough effects have been reported (Allan et al., Percept Psychophys 1989;45:104-113) that suggest an associative model rather then a neural one. However, failures to replicate make this finding controversial (Humphrey et al., J Exp Psychol: Gen 123:86-90). We applied the same contingency to the motion after-effect. Moving words, words paired with sine wave gratings and words composed of sine wave gratings failed to generate text contingent after-effects in stimulus situations that normally evoke motion after-effects. Thus, there was little evidence that motion adaptation can be made textually contingent.

The indirect McCollough effect: an examination of an associative account

It has been found that viewing, for example, a red-and-black vertical grating alternating with a green homogeneous field produces a color aftereffect--a McCollough effect--on a black-and-white vertical grating (i.e., green). Viewing such colored patterns also produces an aftereffect on a noninduced horizontal grating (i.e., pink)--the indirect McCollough effect. Humphrey, Dodwell, and Emerson (1989) argued that the indirect McCollough effect is caused by opponent properties of the visual system that organize the processing of contour and color along contrasting, probably orthogonal, dimensions. Recently, however, their interpretation of the indirect McCollough effect has been challenged by some findings of Eissenberg, Allan, Siegel, and Petrov (1995). These researchers have proposed that the indirect McCollough effect, like the McCollough effect, can be explained by associative principles. The results reported here question crucial aspects of the hypothesis of Eissenberg et al.

Probing unconscious visual processing with the McCollough effect

The McCollough effect, an orientation-contingent color aftereffect, has been known for over 30 years and, like other aftereffects, has been taken as a means of probing the brain's operations psychophysically. In this paper, we review psychophysical, neuropsychological, and neuroimaging studies of the McCollough effect. Much of the evidence suggests that the McCollough effect depends on neural mechanisms that are located early in the cortical visual pathways, probably in V1. We also review evidence showing that the aftereffect can be induced without conscious perception of the induction patterns. Based on these two lines of evidence, it is argued that our conscious visual experience of the world arises in the cortical visual system beyond V1.

Contingent color aftereffects: reassessing old conclusions

Although there is considerable evidence supporting an associative interpretation of contingent color aftereffects, there are data that appear inconsistent with this interpretation. New findings from seven experiments are presented indicating that, contrary to earlier claims, contingent color aftereffects are observed after induction with (1) single orthogonal black bars on colored backgrounds, (2) geometric forms, and (3) two orthogonal grids of the same color. The results of these experiments are relevant to an associative interpretation of contingent color aftereffects, as well as to assessing alternative interpretations of the phenomenon.

Visual aftereffect of texture density contigent on color of frame

An aftereffect of perceived texture density contingent on the color of a surrounding region is reported. In a series of experiments, participants were adapted, with fixation, to stimuli in which the relative density of two achromatic texture regions was perfectly correlated with the color presented in a surrounding region. Following adaptation, the perceived relative density of the two regions was contingent on the color of the surrounding region or of the texture elements themselves. For example, if high density on the left was correlated with a blue surround during adaptation (and high density on the right with a yellow surround), then in order for the left and right textures to appear equal in the assessment phase, denser texture was required on the left in the presence of a blue surround (and denser texture on the right in the context of a yellow surround). Contingent aftereffects were found (1) with black-and-white scatter-dot textures, (2) with luminance-balanced textures, and (3) when the texture elements, rather than the surrounds, were colored during assessment. Effect size was decreased when the elements themselves were colored, but also when spatial subportions of the surround were used for the presentation of color. The effect may be mediated by retinal color spreading (Pöppel, 1986) and appears consistent with a local associative account of contingent aftereffects, such as Barlow's (1990) model of modifiable inhibition.