Orientation-contingent Color Aftereffect Research Articles

The Mechanisms of the Visual System Behind Visual Illusions: From Eye to Brain

Visual illusion is a psychological phenomenon characterized by perception that appears to differ from physical reality. Illusory perception persists even though the sufferers are aware of the physical properties of what they are observing. Thus, studying visual illusions has led to an improved understanding of the neural mechanism underlying visual information processing. Visual illusions are important tools in neuroscience. Some brightness illusions, such as the Hermann grid illusion or Chevreul illusion, can be explained by the function of the center-surround antagonistic receptive field of retinal ganglion cells. Additionally, color aftereffects were found to be produced in the retina. In addition, neurons in the primary visual cortex are responsible for the orientation-contingent color aftereffect, known as the McCollough effect. ISI reversal, a visual motion illusion, is known to be caused by a biphasic temporal mechanism located in the retinal or lower visual areas. Higher visual areas are responsible for the production of visual illusions such as the Ponzo illusion, size constancy illusion, or tabletop illusion. These illusions are perceived through the process of achieving size constancy from a two-dimensional retinal image. Thus, both low-level and high-level vision are involved in the perception of visual illusions.

McCollough world: A novel induction method for orientation-contingent color aftereffects

McCollough world: A novel induction method for orientation-contingent color aftereffects

Mystery of the anti-McCollough effect

The McCollough Effect (ME) is a complex perceptual aftereffect that remains of interest half a century after its discovery. It is argued that a recently reported variant, dubbed the anti-McCollough effect, is not the reverse of the ME, with aftereffect colors in the same direction as the inducing stimuli. A red-horizontal stimulus leads to a reddish aftereffect not because of red-horizontal parings, but despite them. The anti-ME is a weak standard-direction ME produced by complementary afterimage colors (afterimage green with horizontal), rather than by environmental colors, first shown decades ago. It is not a new type of contingent aftereffect. The red-horizontal pair does not interfere with the afterimage green-horizontal pair it produces because a single color-orientation pairing provides more ambiguous input than does the standard two orientation-color pairings (red-horizontal, green-vertical) of the ME. It is also argued that not even one orientation-contingent color aftereffect is convincingly shown in the "anti"-ME, let alone, as has previously been suggested, two simultaneous orientation-contingent color aftereffects in opposite directions at different levels of the visual system, in which the higher-level effect suppresses the downstream effect from reaching consciousness. The "anti"-ME can be explained by existing theories of contingent aftereffects, including perceptual-learning theory.

Using Structural Equation Modeling to Examine McCollough Effects (Orientation-Contingent Color Aftereffects): Influence of Dissociative Experiences and Age on Illusory Aftereffects

Conventional accounts of the McCollough Effect (ME) have focused on strictly bottom-up processing accounts of the phenomenon, most commonly involving the fatiguing of orientation-selective neurons; although association-learning mechanisms have also gained acceptance. These lower order accounts do not take into account higher order variables related to key personality traits and/or associated cognitive control processes. This article reports the use of confirmatory factor analysis and follow-up structural equation style regressions that model MEs and also the part played by the personality trait of dissociation. After considering the relative impact of age and dissociative processes, the article concludes that trait dissociation is positively associated with reports of MEs.

Face-contingent motion aftereffect

The demonstration of many types of contingent visual aftereffects suggests the existence of interactions between the two contingent properties somewhere in the visual processing stream. For example, the McCollough effect, or the orientation-contingent color aftereffect, implies that interaction between color and orientation. One view holds that contingent aftereffects are due to adaptation of neurons that are sensitive to the particular combination of the two visual features; another view maintains that contingent aftereffects are the result of associative learning. Although the exact neural mechanism of contingent visual aftereffects remains elusive, it is nevertheless informative to know what pairs of visual properties can induce contingent aftereffects. Here we examined whether motion aftereffect can be made contingent on human faces. Subjects (the two authors and two naïve observers) viewed alternating expanding faces and contracting scrambled faces for 5 minutes. After various amount of delay, static test images were presented to the observers. A weak, but reliable, face-contingent motion aftereffect was reported by both the authors as well as the two naïve observers. An static face was seen briefly moving in the opposite direction to the adapting face motion, whereas a static scrambled face was seen briefly moving in the opposite direction to the adapting scrambled face. Similar face-contingent motion aftereffect was seen with rotating motion. These contingent aftereffects were very weak immediately after the adaptation, but gained strength after minutes of delay, a signature of contingent visual aftereffects. This result suggests that, somehow and somewhere in the brain, motion of faces is represented differently than motion of non-faces.

Adapting to an aftereffect

We report a new type of orientation-contingent color aftereffect in which the color aftereffect is opposite to the classical McCollough effect, i.e., the perceived color of the aftereffect is the same as the inducer's color. Interleaved exposure to red, horizontal and achromatic (gray), horizontal gratings led to a long-lasting aftereffect in which achromatic horizontal gratings appeared reddish. The effect, termed the anti-McCollough effect, although weaker than the classical aftereffect, remained stable for a moderate duration of time (24 hours). Unlike the classical aftereffect, which is known to not transfer interocularly, the new after-aftereffect transferred 100%, suggesting that its locus in the brain was downstream of the classical effect. It is likely that neurons in a higher-order area adapted to the classical color aftereffect that was represented in a lower-order area, thus forming an aftereffect of an aftereffect, i.e., an after-aftereffect. Our finding has implications as to how neural activity in lower- and higher-level areas in the brain interacts to yield conscious visual experience.

Illusory colors promote interocular grouping during binocular rivalry

When dissimilar monocular images are presented separately to each of a person's eyes, these images compete for visual dominance, with dominance of one image or the other alternating over time. While this phenomenon, called binocular rivalry, transpires, local image features distributed over space and between the eyes can become visually dominant at the same time; the resulting global figure implicates interocular grouping. Previous studies have suggested that color tends to influence the incidence of global dominance; in this study, we assess whether illusory color can also influence interocular grouping. To test this, we exploited the McCollough effect, an orientation-contingent color aftereffect induced by prolonged adaptation to different colors paired with different orientations. Results show that during binocular rivalry, illusory colors induced by the McCollough adaptation enhance strong interocular grouping relative to preadaptation testing, to an extent comparable in strength with the enhancement induced by real colors. Thus, illusory colors that are present only in an observer's mind are sufficiently potent to influence low-level visual processes such as binocular rivalry.

Color promotes interocular grouping during binocular rivalry

During binocular rivalry local image features distributed over space and between the eyes achieve simultaneous dominance at times; the resulting global figure implicates interocular grouping. Anecdotal evidence suggests that color tends to influence the incidence of global dominance, and in this study we have assessed the strength of this influence on interocular grouping. Experiment 1: We used rival targets like those created by Diaz-Caneja (1928): concentric semi-circles and parallel horizontal lines distributed between the eyes. Using both achromatic and colored versions of these targets, we measured the percentage of time a single coherent figure (e.g., a complete bullseye) was perceived (implicating interocular grouping). Color congruence significantly increased the incidence of interocular global dominance. Experiment 2: Knowing that different parts of an occluded object tend to be perceptually grouped, we manipulated both the color and the shape of partially occluded objects that comprised rival targets. Relative to results with achromatic figures, uniform color paired with shape coherence enhanced interocular grouping, while conflict between color and shape coherence reduced interocular grouping. Experiment 3: Prolonged adaptation to different colors paired with different orientations induces an orientation-contingent color aftereffect (the McCollough effect). Observers first alternately adapted to a red diagonal grating tilted clockwise and to a green diagonal grating tilted counterclockwise. Immediately after prolonged adaptation, observers tracked rivalry between rival figures consisting of achromatic diagonal lines that appeared colored owing to the McCollough effect. Illusory color promoted strong interocular grouping relative to preadaptation testing. Conclusion: Both real and illusory colors are potent contributors to interocular grouping during binocular rivalry.

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.

Isoluminance and contingent color aftereffects.

In the typical induction of the orientation-contingent color aftereffect (CCAE), the stimuli are composed of elements that differ in both color and luminance. Three experiments are reported that show that chromatic contrast between stimulus elements is insufficient for the induction of the orientation-CCAE and that luminance contrast is necessary. These experiments expand on previous research concerned with the role of luminance contrast in the induction of orientation-CCAEs by eliminating alternative explanations.

Orientation and color processing for partially occluded objects

The McCollough orientation-contingent color aftereffect could be equally well elicited by either a full test pattern of black and white stripes or a similar test pattern that was largely occluded by white surfaces, provided the latter stripes were made to appear as through continuing under the white surfaces-by means of stereo depth cues. The color aftereffect appeared concentrated around the edges of the stripes that protruded out from under the white surfaces; surfaces that themselves continued to appear a uniform white as shown by color matches. These results suggest that occluded, perceptually-continued edges can elicit the McCollough effect, which is generally thought to occur quite early in the visual pathway.

Orientation-contingent color aftereffects mediated by subjective transparent structures.

We examined whether the orientation-contingent color aftereffect (the McCollough effect) could be mediated by subjective horizontal and vertical structure induced by the perception of transparency. In our experiments, red vertical bars and green horizontal bars were alternated as an adapting stimulus. After adaptation, subjects (n = 6) were asked to adjust the green and red saturation of a test pattern until they obtained a neutral gray. Horizontal and vertical stripes were combined in the test pattern in three different ways: (1) overlapping with a luminance combination that gave rise to a perception of transparent overlays of horizontal and vertical stripes (valid transparency condition), (2) overlapping with luminance combinations that did not induce a perception of transparency (invalid transparency condition) and that appeared more as a patchwork of checks, and (3) presented in adjacent, nonoverlapping areas. Our results showed that the McCollough effect was significantly greater in the valid transparency condition than in the invalid transparency conditions. The effect in the valid transparency condition was nevertheless less strong than was the effect seen with the standard test stimulus made up of nonoverlapping vertical and horizontal stripes. Our results suggest that the McCollough effect can be mediated by the subjective spatial organization (inner representation of vertical and horizontal stripes) that accompanies the perception of transparency in our stimulus.

The associative basis of contingent color aftereffects.

According to a conditioning analysis of the orientation-contingent color aftereffect (McCollough effect, ME), orientation stimulus (grids) become associated with color. Contrary to this interpretation are reports that simple forms cannot be used to elicit illusory color and that the ME is not degraded by decreasing the grid-color correlation. The present results indicate: (a) Form stimuli can contingently elicit color aftereffects; (b) even a non-patterned stimulus--the lightness of a frame surrounding a colored area--can contingently elicit color aftereffects; (c) this frame lightness-contingent aftereffect, like the ME, persists for at least 24 hr; and (d) the frame lightness-contingent aftereffect can be used to demonstrate that correlational manipulations affect the ME, as they affect other types of conditional responses.

Assessment of the McCollough effect by a shift in psychometric function

Following adaptation to chromatic grids, we assessed the orientation-contingent color aftereffect with a new procedure—a shift in the psychometric function from the preadaptation level. With this procedure, the conditions that did and did not induce the aftereffect were the same as those previously reported with other measurement procedures. The psychometric function shift provides a new, simple, and objective technique for evaluation of illusory color.

Spatial contingency and the McCollough effect

On the basis of a conditioning analysis of the orientation-contingent color aftereffect (McCollough effect, ME), orientation stimuli become associated with simultaneously presented chromatic stimuli. This account suggests that decreasing the contingency between the grid orientation and color should decrease the strength of the aftereffect. Results of previous research indicate that decreasing the temporal contingency (by presenting homogeneous chromatic stimuli between presentations of chromatic grids) does not decrease the ME. However, it has been suggested that the appropriate contingency-degradation procedure would involve decreasing spatial (rather than temporal) contingency. That is, the illusion should be attenuated by extending the color beyond the confines of the grid. Contrary to this hypothesis, the results of the present experiments provide no evidence that decreasing the spatial contingency between grid and color decreases the ME; rather, the aftereffect is increased by such a manipulation.

Overprediction and blocking in the McCollough aftereffect.

The Rescorla-Wagner theory (Rescorla & Wagner, 1972) of associative learning offers specific predictions about the associative strength of CS-US pairs when two or more CSs are conditioned to the same US separately and subsequently paired in a compound with the same US. The magnitude of orientation-contingent color aftereffects (AEs) was used as an index of associative strength in this study. The results of experiments using an "overprediction" (Rescorla, 1970) and a "blocking" (Kamin, 1969) paradigm conformed to the predictions of the Rescorla-Wagner theory. In Experiment 1, AEs were established simultaneously for horizontal-vertical and diagonal patterns. When observers subsequently viewed compound induction patterns, AE magnitude was found to be significantly decreased, relative to a condition in which observers did not view such an induction pattern. In Experiment 2, AE magnitude for a given test pattern following inspection of compound induction stimuli was significantly reduced by inspection of the other component prior to viewing the compound induction stimuli. The applicability of associative learning and feature-adaptation models of the McCollough effect is discussed.

Orientation-contingent color aftereffects are determined by real color, not induced color.

Three experiments were concerned with whether orientation-contingent color aftereffects (McCollough effects) occur when the perceived colors of differently oriented gratings derive from colored shadows, a compelling instance of simultaneous color contrast. Whereas strong orientation-contingent aftereffects occurred with pink light reflected from vertical gratings viewed in alternation with green light reflected from horizontal gratings, none occurred when pink and green colored shadows were presented with the same physically achromatic gratings (Experiment 1). No aftereffects were evident even after an extended (15-min) period of alternating presentation (Experiment 2). In Experiment 3, colored bars matched in chromaticity to the colored shadows produced strong aftereffects. These outcomes agree with those of Thompson and Latchford (1986), who showed that the McCollough effect is a function of the real color of reflected light, rather than of the apparently constant color of gratings in different illuminants. The implications of the present findings for the neural basis of simultaneous color contrast and the McCollough effect, and for Thompson and Latchford’s explanation of the latter, are considered.

Simultaneous color contrast from McCollough effects is spatially contingent.

In two experiments, orientation-contingent color aftereffects (CAEs) were induced by presenting in alternation red/black vertical and green/black horizontal gratings. The CAEs induced second-order simultaneous color contrast in a 45° patterned test field but not in a patternless field. These CAE-induced second-order color effects were measured using both color cancellation (Experiment 1) and color matching (Experiment 2) techniques. The spatial selectivity of the second-order effects and their manifestation outside the orientation range typically used in studies of orientation-contingent color effects are discussed in terms of neural explanations of color misperceptions.

Contingency and the McCollough effect.

According to a Pavlovian conditioning analysis of the orientation-contingent color aftereffect (the McCollough effect), orientation stimuli become associated with simultaneously presented chromatic stimuli. This account suggests that decreasing the contingency between the putative conditional stimulus (grid orientation) and the unconditional stimulus (color) should decrease the strength of the aftereffect. In the present experiment, the effect of presentations of achromatic grids and/or homogeneous chromatic stimuli between presentations of chromatic grids was evaluated. Although interpolated achromatic grid presentations did decrease the magnitude of the McCollough effect, interpolated chromatic stimuli had no effect on the magnitude of the phenomenon. The results are discussed in terms of current research concerning the selective associability of certain categories of conditional and unconditional stimuli, and differences in the development of associations between simultaneously (compared with successively) presented conditional and unconditional stimuli.

Conjunction of color and form without attention: Evidence from an orientation-contingent color aftereffect.

Conjunction of color and form without attention: Evidence from an orientation-contingent color aftereffect.