Color Aftereffects Research Articles

Gaze direction modulates visual aftereffects in depth and color

Prior physiological studies indicate that gaze direction modulates the gain of neural responses to visual stimuli. Here, we test gaze modulation in the perceptual domain using color and depth aftereffects. After confirming retinotopy of the effects, we employed a balanced alternating adaptation paradigm (adaptation alternates between opponent stimuli) to demonstrate that opposite color and depth aftereffects can co-develop at the same retinal location for different gaze directions. The results provide strong evidence for (a) gaze modulation of aftereffects, (b) generality of gaze modulation across two visual attributes, and (c) perceptual correlates of the modulation of neural activity by gaze direction.

Interactions between pattern and color in the visual system: Temporal aspects of the McCollough Effect

The perception of the color of a surface can be influenced by many factors including its material properties and the composition of the illuminant. McCollough demonstrated that sensory conditioning could also influence the perception of surface color by inducing a long-lasting pattern specific color aftereffect. This effect has been extensively studied since its original report and a number of increasingly complex explanations have been proposed. In this article I examine the temporal properties of a simple learning model of the McCollough effect (ME). This model has previously been used to account for quantitative data sets obtained from a series of monocular and binocular variants of the ME. The model replicates the acquisition and decay of the ME, pre- and post-induction interference effects, and can also simulate the effects of various cholinergic and anticholinergic drugs that have been shown to influence ME induction and decay.

Adaptive modulation of color salience contingent upon global form coding and task relevance

Extensive research on local color aftereffects has revealed perceptual consequences of opponent color coding in the retina and the LGN, and of orientation-and/or spatial-frequency-contingent color coding in early cortical visual areas (e.g., V1 and V2). Here, we report a color aftereffect that depends crucially on global-form-contingent color processing. Brief viewing of colored items (passively viewed, ignored, or attended) reduced the salience of the previewed color in a subsequent task of color-based visual search. This color-salience aftereffect was relatively insensitive to variations (between color preview and search) in local image features, but was substantially affected by changes in global configuration (e.g. the presence or absence of perceptual unitization); the global-form dependence of the aftereffect was also modulated by task demands. The overall results suggest that (1) color salience is adaptively modulated (from fixation to fixation), drawing attention to a new color in visual-search contexts, and (2) these modulations seem to be mediated by global-form-and-color-selective neural processing in mid to late stages of the ventral visual pathway (e.g., V4 and IT), in combination with task-dependent feedback from higher cortical areas (e.g., prefrontal cortex).

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.

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.

Color—luminance relationships and the McCollough effect

The McCollough effect is an orientation-specific color aftereffect induced by adapting to colored gratings. We examined how the McCollough effect depends on the relationships between color and luminance within the inducing and test gratings and compared the aftereffects to the color changes predicted from selective adaptation to different color-luminance combinations. Our results suggest that the important contingency underlying the McCollough effect is between orientation and color-luminance direction and are consistent with sensitivity changes within mechanisms tuned to specific color-luminance directions. Aftereffects are similar in magnitude for adapting color pairs that differ only in S cone excitation or L and M cone excitation, and they have a similar dependence on spatial frequency. In particular, orientation-specific aftereffects are induced for S cone colors even when the grating frequencies are above the S cone resolution limit. Thus, the McCollough effect persists even when different cone classes encode the orientation and color of the gratings.

The unseen color aftereffect of an unseen stimulus: insight from blindsight into mechanisms of color afterimages.

We show here that, in the absence of a direct geniculostriate input in human subjects, causing loss of sight in the visual half-field contralateral to the damage, the pupil responds selectively to chromatic modulation toward the long-wavelength (red) region of the spectrum locus even when the stimulus is isoluminant for both rods and cones and entirely restricted to the subjects' "blind" hemifields. We also show that other colors are less or wholly ineffective. Nevertheless, red afterimages, generated by chromatic modulation toward the green region of the spectrum locus, also cause constrictions of the pupil even when green stimuli are themselves completely ineffective in the blind hemifield. Moreover, human subjects with damage to or loss of V1 are typically completely unaware of the stimulus that generates the aftereffect or of the aftereffect itself, both of which can be seen clearly in normal vision. The results show that pupillary responses can reveal the processing of color afterimages in the absence of primary visual cortex and in the absence of acknowledged awareness. This phenomenon is therefore a striking example of "blindsight" and makes possible the formulation of a model that predicts well the observed properties of color afterimages.

Perception of the Mccollough Effect Correlates with Activity in Extrastriate Cortex: A Functional Magnetic Resonance Imaging Study

The McCollough effect is a striking color aftereffect that is linked to the orientation of the patterns used to induce it. To produce the McCollough effect, two differently oriented grating patterns, such as a red-and-black vertical grating and a green-and-black horizontal grating, are viewed alternately for a few minutes. After such colored gratings are viewed, the white sections of a vertical black-and-white test grating appear to be tinged with green, and the white sections of a horizontal grating appear to be tinged with pink. We present evidence from a functional magnetic resonance imaging study that the perception of the McCollough effect correlates with increased activation in the lingual and fusiform gyri—extrastriate visual areas that have been implicated in color perception in humans.

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.

Learning and homeostasis: drug addiction and the McCollough effect.

The contribution of conditioned responses (CRs) to homeostasis may be seen by examining seemingly disparate phenomena of color vision (aftereffects and chromatic adaptation) and drug addiction (withdrawal symptoms and tolerance). Color aftereffects may be elicited by nonchromatic stimuli previously paired with color (the McCollough effect, [ME]). Similarly, pharmacological aftereffects may be elicited by nonpharmacological stimuli previously paired with a drug (withdrawal symptoms). The authors summarize evidence indicating that both the ME and withdrawal symptoms are CRs. The chromatic CR is expressed as chromatic adaptation in the presence of color, and the ME in the absence of color. The pharmacological CR is expressed as pharmacological adaptation (tolerance) in the presence of the drug, and withdrawal symptoms in the absence of the drug. Both drug withdrawal symptoms and the ME are manifestations of the contribution of conditioning to normal homeostatic regulation. The authors discuss the implications of this conclusion for understanding regulatory processes and the evolution of behavioral mechanisms.

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.

Visual Associative Memory Simulates the McCollough Effect

The McCollough effect (ME) refers to the phenomenon that, after a few minutes' exposure to gratings differing in both orientation and colour, subjects perceive similarly oriented achromatic gratings as if they were tinted with complementary hues. The traditional explanation of the ME as an adaptation of detectors selective for colour and orientation suffers from a number of inconsistencies: (i) the ME lasts much longer than ordinary adaptation, the decay of the effect being completely arrested during a night's sleep, or by occluding the eye for a long time; (ii) the strength of the ME is practically independent of the intensity of the adapting light; and (iii) a set of related pattern-contingent aftereffects discovered later would require, for explanation on similar lines, new detectors specific to other patterns. These properties can be explained, however, in the framework of associative memory and novelty filters. A computational model has been developed which consists of (i) an input layer of two (left and right eyes) square matrices with two analog receptors (red and green) in each pixel; (ii) an isomorphic associative neural layer, each neuron being synaptically connected with all receptors of both eyes; and (iii) an output layer (novelty filter). Modification of synaptic efficacies conforms to the Hebb learning rule. After a few presentations of coloured gratings the model displays the ME, which is slowly destroyed by subsequent presentations of random pictures. With a sufficiently large receptor matrix the effect lasts a thousand times longer than the period of learning. Continuous darkness does not change the strength of the effect. Like the real ME, the model does not display interocular transfer, but with other adapting patterns it shows the disparity-contingent colour aftereffect (thus confirming the connections with both eyes). The model can account for different pattern-contingent colour aftereffects without assuming any predetermined specific detectors. Such detectors are constructed in the course of adaptation to specific stimuli (gratings).

Assessing a new analysis of contingent color aftereffects

Assessing a new analysis of contingent color aftereffects

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.

The widespread influence of the Rescorla-Wagner model

The theory of Pavlovian conditioning presented by Robert Rescorla and Allan Wagner in 1972 (the Rescorla-Wagner model) has been enormously important in animal learning research. It also has been applied in a variety of areas other than animal learning. We summarize the contribution of the Rescorla-Wagner model to research in verbal learning, social psychology, human category learning, human judgments of correlational relationships, transitive inference, color aftereffects, and physiological regulation. We conclude that there have been few models in experimental psychology as influential as the Rescorla-Wagner model.

An associative interpretation of the indirect McCollough effect.

Following an induction procedure in which a coloured grid is alternated with a square of a complementary colour, subjects report colour after-effects on both the grid orientation present during induction and the orthogonal non-induced grid orientation. The after-effect reported on the induced grid orientation is called the McCollough effect (ME). The after-effect reported on the non-induced grid orientation is called the indirect ME. There is evidence that the ME represents an instance of Pavlovian conditioning. The present results support a conditioning interpretation of the indirect ME and are inconsistent with interpretations of the indirect ME that attribute the phenomenon to special orthogonal coding mechanisms within the visual system.

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.

Dichoptically viewed colour aftereffects produced by monocular adaptation.

Colour aftereffects were observed in dichoptically viewed achromatic striped patterns after a 25 s period of monocular adaptation to an homogeneous coloured field of red, green, or blue. Three test conditions of dichoptic viewing were used. In condition 1, black line patterns were viewed dichoptically on fused white backgrounds. Stimuli used in condition 2 were similar except that they were white line patterns on black backgrounds. Last, condition 3 was realised with the same stimulus patterns utilised in condition 1, except that the mode of dichoptic viewing produced a juxtaposition rather than a fusion of the two white backgrounds containing the line patterns. Some colour aftereffect was obtained for each colour-adaptation condition and in each test condition. It consisted in a negative colour aftereffect (NCA) in the adapted eye (the colour seen was roughly the complementary of the adaptation colour) and/or a positive colour aftereffect (PCA) in the unadapted eye (the colour seen tended rather to be similar in hue to the adaptation colour). In fact, the following four kinds of responses were obtained: (i) two colour aftereffects, one seen by each eye, ie a NCA involving the adapted eye and a PCA involving the unadapted eye; (ii) a NCA involving the adapted eye only; (iii) a PCA involving the unadapted eye only; (iv) no colour aftereffect at all. Results obtained in different test conditions permitted us to assert that both kinds of colour aftereffect could be produced with white patterns on dark backgrounds as well as with black patterns on white backgrounds and did not require binocular fusion of the white backgrounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Text-contingent color aftereffects: a reexamination.

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.

Colored aftereffects contingent upon global transformations?

Dodwell and Humphrey (Psychol. Rev. 97, 78-79, 1990) have argued that colored aftereffects (CAEs) are contingent on the global geometries of local orientation and edge components in induction patterns. The spatiotopic dimensions underlying these geometries are derived from previous applications of the mathematics of continuous transformations (Lie groups) to the stimulus dynamics of perceptual invariance. In these terms, complementary CAEs induced by inspecting alternating colored bullseyes and spokes are attributed to the adaptation of orthogonal spatiotopic channels; the former characterized by vectorfields dealing with object invariance under rotation, and the latter by vectorfields dealing with object invariance under dilation. Importantly, the pattern-contingent CAEs induced in this pair of pattern channels are independent of CAEs induced in channels characterized by vectorfields dealing with object invariance under vertical and horizontal translations (e.g. vertical and horizontal gratings). The present investigation examined whether CAEs contingent on the stimulus dynamics originally used to define these spatiotopic channels exhibit comparable properties. It is confirmed that pairs of complementary CAEs can be induced simultaneously with radially expanding and contracting bullseyes, and clockwise- and counter-clockwise-rotating spokes (Experiment 1); and it is shown that these CAEs combine linearly in generalizing to and from the radial and rotational components of spiral motion (Experiments 2 and 3 respectively). In direct contrast to findings for CAEs induced with stationary versions of these patterns, however, it is demonstrated that complementary pairs of CAEs induced by expanding and contracting bullseyes interact with CAEs induced by left- and right-moving vertical gratings, suggesting that the components of motion underlying these contingent effects are locally and not globally determined (Experiment 4).