McCollough Effect Research Articles

Orientation-specific luminance aftereffects

Prolonged viewing of bright vertical (horizontal) gratings alternating with dim horizontal (vertical) gratings generates negative brightness aftereffects that are contingent on the orientation of orthogonal test gratings. The effect is measured by a brightness cancellation technique, similar to the color cancellation technique used in measuring McCollough effects. Like the latter, brightness aftereffects appear to persist for long periods. The magnitude of these aftereffects is a positive monotonic function of the luminance difference between the inducing gratings, and it depends on the conditions of induction; monocular induction generates larger aftereffects than binocular induction does. The aftereffect transfers interocularly, although its magnitude in the contralateral eye is substantially attenuated; binocular measurement, following monocular induction, results in even smaller aftereffects. An attempt to understand these findings within the computational model of brightness perception developed by Grossberg and Mingolla (1985a, 1985b) is presented.

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.

A functional theory of the McCollough effect.

Pattern-contingent color aftereffects, or McCollough effects (MEs), are used to probe the visual brain's operations psychophysically. Their neural substrate is unknown, however, and theories about them are weak. Our theory proposes a strong functional role for MEs and a neuropsychological basis that accounts for "top-down" (global) constraints ignored by other theories. The functional aspect of the theory is based on the concept of contingent adaptation level, following Helson (1964), and on the "error-correcting device" of Andrews (1964), which tracks and adjusts internal representation to external-world contingencies. The neuropsychological part of the theory postulates that global properties are the result of MEs being generated not at the individual detector level but in vectorfields of which the detectors are elements. It is an implementation of Lie transformation group theory (Hoffman, 1966). Evidence for this model is assessed.

A functional theory of the McCollough effect.

A functional theory of the McCollough effect.

Negative afterimages and the McCollough effect.

Four experiments were conducted to test earlier claims about the relationship between the negative afterimage and the McCollough effect. The first claim (Hansel & Mahmud, 1978) is that long-lasting afterimages occur when induced by the same alternating-stimulus procedure as that used to induce the McCollough effect. The second claim (Murch & Hirsch, 1972) is that afterimages can themselves induce McCollough effects if they are induced and paired sequentially with grating patterns. In testing these claims, a reliable computer-controlled color-cancellation technique developed earlier was used to measure the apparent color of both afterimages and McCollough effects objectively. No support was found for the first claim following alternative presentation of two homogeneously colored regions for total periods of 5 min (Experiment 1) and 20 min (Experiment 2). The second claim was fully supported: After an induction period of 7.3 min, a McCollough effect occurred for a red-vertical pairing but not for a green-horizontal pairing (Experiment 3); but after an induction period of 20 min, McCollough effects occurred strongly for both pairings (Experiment 4). The theoretical implications of these outcomes are considered in the context of recent theories of color and pattern processing in the visual system.

Color aftereffect contingent on text.

During adaptation, two different letter strings (each five or six letters) were presented to subjects alternately, one in green and the other in magenta. The extent to which these letter strings subsequently elicited a color aftereffect was assessed. In different experiments, the chromatic letter strings consisted of words and nonwords. The results indicated that letter strings that form English words can contingently elicit a color aftereffect. This was the case even when the words were anagrams. There was no evidence that nonword letter strings could contingently elicit such an aftereffect, even when the nonwords conformed to English orthography. The results are relevant to understanding other contingent color aftereffects (McCollough effects), illusory color noted by computer operators who work at monochrome (green or amber) displays, and the processing of text.

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.

McCollough aftereffects in strabismus and amblyopia

In strabismic people, the functioning of the deviating eye is impaired. This impairment is binocular in origin since it depends on stimulation of the straight eye; sensitivity and acuity of the deviating eye are usually better when the straight eye is patched than when both eyes are viewing. We investigated interactions between the eyes in strabismic people by using the McCollough color aftereffect as an exploratory procedure. Both normal and strabismic people adapted to black and colored bars and then examined black and white test bars. They reported colors in the achromatic test bars that were complementary to the adapting colors; this is the McCollough aftereffect. Both a monocular McCollough effect and a binocular McCollough effect were induced in people having normal vision. Strabismic people did not show a binocular McCollough effect. Aftereffect strengths were the same in each eye of normal people but were stronger in the impaired eye of strabismic people. A speculation is offered as to why the “non-seeing” eye of strabismic people “sees” the aftereffect better.

Visual after-effects associated with the use of high-resolution visual display units.

A long-lasting visual after-effect associated with the use of a high-resolution green visual display unit (VDU) is described in eight normal volunteers. Its duration to a standard VDU exposure is measured. It is related to the McCollough effect and is thought to be either a fatiguing of green colour-coded edge-detectors or an associative phenomenon. A reduction or loss of the usual foveal peak of the critical flicker frequency (CFF) to red is also described.

Amnesia for the mccollough effect following unilateral electroconvulsive therapy: implications for laterality

The hemispheric lateralization of retrograde amnesia following unilateral electroconvulsive therapy (ECT) was measured by a novel nonverbal probe, the McCollough effect, which allowed equal and exclusive access to each hemisphere. Alternating exposure to perpendicular gratings of complementary colors (e.g., red vertical stripes alternated with green horizontal stripes) will cause subsequently presented black and white gratings to appear colored hours or even days later (the McCollough effect). Three of the patients examined (3 of 10) lost the effect in just the half visual field contralateral to the treatment side when unilateral nondominant ECT was interposed between the induction of the effect and the its test. Six patients lost the effect bilaterally following unilateral ECT. One patient retained a bilateral aftereffect. This patient had by far the shortest seizure (18 sec). Nine of 10 comparison patients, also suffering from major depression but without ECT intervening between induction and test, showed good bilateral retention of the McCollough effect. The remaining comparison patient showed no retention. These results imply that despite bilateral cortical spread of seizure activity, unilateral nondominant ECT has effects that are most pronounced over the stimulated hemisphere.

Interference with McCollough effects via pre- and postinduction exposure to achromatic gratings: time course and magnitude of aftereffect decrement.

The strength of McCollough effects (MEs) may be reduced by having subjects view achromatic gratings either before or after ME induction. Both types of interference effects were investigated in a series of experiments designed to describe and compare their properties. Among the results were the following major findings: (1) Recovery of ME strength following postinduction interference manifests itself as a convergence of the interference decay curve and a control curve; it occurs within 30–60 min, and may or may not involve an increase in ME strength in the interference curve. (2) Preinduction interference does not occur if more than a few minutes separate the achromatic and chromatic inspections; interference effects that occur when the interinspection interval is zero are evident throughout the decay of the subsequent ME. These results are discussed in terms of several explanations of interference effects.

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.

Erratum to: Individual differences in McCollough effects: A study of twins

Erratum to: Individual differences in McCollough effects: A study of twins

Conditioning and blocking of the McCollough effect.

The classical conditioning explanation of the McCollough effect was extended by investigating blocking and allied phenomena predicted by the Rescorla-Wagner (1972) equations. The subjects were first exposed to colored gratings or moving spirals and then were tested after induction with a compound of both types of stimuli. The effects appeared to be additive, and the stronger stimuli overshadowed the weaker stimuli during compound training. Blocking of the McCollough effect, or of the spiral, was observed after prior training on the other stimulus. A supplementary procedure suggested that it was possible to unblock either effect by increasing color saturation and contrast. The results show close agreement with the predictions of conditioning theory.

Erratum to: Further evidence against the classical conditioning model of McCollough effects

Erratum to: Further evidence against the classical conditioning model of McCollough effects

Erratum to: Does testing initiate decay of McCollough effects?

Erratum to: Does testing initiate decay of McCollough effects?

Similar-orientation McCollough effect and the classical negative afterimage in a common adaptation process

The McCollough effect was obtained using red and green gratings of similar orientation and spatial frequency with the subjects fixating during adaptation and test. The McCollough effect was again produced, along with the classical negative afterimage, in a single-adaptation sequence. The results show that the two aftereffects stem from different mechanisms in the visual system and that a common retinal area can be involved in both types of effect.

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.

Cortical dynamics of three-dimensional form, color, and brightness perception: II. Binocular theory.

A real-time visual processing theory is developed to explain how three-dimensional form, color, and brightness percepts are coherently synthesized. The theory describes how several fundamental uncertainty principles which limit the computation of visual information at individual processing stages are resolved through parallel and hierarchical interactions among several processing stages. The theory hereby provides a unified analysis and many predictions of data about stereopsis, binocular rivalry, hyperacuity, McCollough effect, textural grouping, border distinctness, surface perception, monocular and binocular brightness percepts, filling-in, metacontrast, transparency, figural aftereffects, lateral inhibition within spatial frequency channels, proximity-luminance covariance, tissue contrast, motion segmentation, and illusory figures, as well as about reciprocal interactions among the hypercolumns, blobs, and stripes of cortical areas VI, V2, and V4. Monocular and binocular interactions between a Boundary Contour (BC) System and a Feature Contour (FC) System are developed. The BC System, defined by a hierarchy of oriented interactions, synthesizes an emergent and coherent binocular boundary segmentation from combinations of unoriented and oriented scenic elements. These BC System interactions instantiate a new theory of stereopsis and of how mechanisms of stereopsis are related to mechanisms of boundary segmentation. Interactions between the BC System and the FC System explain why boundary completion and segmentation processes become binocular at an earlier processing stage than do color and brightness perception processes. The new stereopsis theory includes a new model of how chromatically broadband cortical complex cells can be adaptively tuned to multiplex information about position, orientation, spatial frequency, positional disparity, and orientational disparity. These binocular cells input to spatially short-range competitive interactions (within orientations and between positions, followed by between orientations and within positions) that initiate suppression of binocular double images as they complete boundaries at scenic line ends and corners. The competitive interactions interact via both feedforward and feedback pathways with spatially long-range-oriented cooperative gating interactions that generate a coherent, multiple-scale, three-dimensional boundary segmentation as they complete the suppression of double-image boundaries. The completed BC System boundary segmentation generates output signals, called filling-in generators (FIGs) and filling-in barriers (FIBs), along parallel pathways to two successive FC System stages: the monocular syncytium and the binocular syncytium. FIB signals at the monocular syncytium suppress monocular color and brightness signals that are binocularly inconsistent and select binocularly consistent, monocular FC signals as outputs to the binocular syncytium. Binocular matching of these FC signals further suppresses binocularly inconsistent color and brightness signals. Binocular FC contour signals that survive these multiple suppressive events interact with FEB signals at the binocular syncytium to fill-in a multiplescale representation of form-and-color-in-depth. To achieve these properties, distinct syncytia correspond to each spatial scale of the BC System. Each syncytium is composed of opponent subsyncytia that generate output signals through a network of double-opponent cells. Although composed of unoriented wavelength-sensitive cells, double-opponent networks detect oriented properties of form when they interact with FIG signals, yet also generate nonselective properties of binocular rivalry. Electrotonic and chemical transmitter interactions within the syncytia are formally akin to interactions in HI horizontal cells of turtle retina. The cortical syncytia are hypothesized to be encephalizations of ancestral retinal syncytia. In addition to double-opponent-cell networks, electrotonic syncytial interactions, and resistive gating signals due to BC System outputs, the FC System processes also include habituative transmitters and non-Hebbian adaptive filters that maintain the positional and chromatic selectivity of FC interactions. Alternative perceptual theories are evaluated in light of these results. The theoretical circuits provide qualitatively new design principles and architectures for computer vision applications.