Orientation-contingent Color Aftereffect Research Articles

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

According to feature-integration theory (Treisman & Gelade, 1980), separable features such as color and shape exist in separate maps in preattentive vision and can be integrated only through the use of spatial attention. Many perceptual aftereffects, however, which are also assumed to reflect the features available in preattentive vision, are sensitive to conjunctions of features. One possible resolution of these views holds that adaptation to conjunctions depends on spatial attention. We tested this proposition by presenting observers with gratings varying in color and orientation. The resulting McCollough aftereffects were independent of whether the adaptation stimuli were presented inside or outside of the focus of spatial attention. Therefore, color and shape appear to be conjoined preattentively, when perceptual aftereffects are used as the measure. These same stimuli, however, appeared to be separable in two additional experiments that required observers to search for gratings of a specified color and orientation. These results show that different experimental procedures may be tapping into different stages of preattentive vision.

Overshadowing and blocking of the orientation-contingent color aftereffect: Evidence for a conditioning mechanism

Orientation-contingent color aftereffects have been interpreted by nonassociative mechanisms (adaptation of neural units that are both color and orientation specific) and by associative mechanisms (conditioning resulting from the pairing of pattern and hue). To evaluate associative accounts, contingent aftereffects were induced by exposing subjects to compound chromatic grid patterns consisting of two component gratings: one was horizontal or vertical, and the other a left- or right-learning diagonal. The ability of a component grating to elicit a color aftereffect depended on the relative salience and the aftereffect training history of the grating components. That is, orientation-contingent color aftereffects, like other conditional responses, display overshadowing and blocking. The results suggest that conditioning contributes to these aftereffects.

Contingent aftereffects in duration judgments.

It has been shown that judged duration of tones depends on pitch (the kappa effect), on order of presentation (the time-order error), and on repetition (a negative duration aftereffect). Recently, a duration aftereffect contingent on pitch and a duration aftereffect contingent on order of presentation have been described. Our results suggest that these contingent duration aftereffects differ from the McCollough effect, a color aftereffect contingent on orientation, in two ways. They have a relatively short life and they are not symmetrical, in that while a pitch-contingent duration aftereffect could be established, a duration-contingent pitch aftereffect could not. In contrast, the McCollough effect persists for days and both an orientation-contingent color aftereffect and a color-contingent orientation aftereffect have been reported. A decision theory account for contingent duration aftereffects is outlined.

Investigations of perception and imagery using CAEs: the role of experimental design and psychophysical method.

Orientation-contingent color aftereffects (CAEs) were measured using 174 observers ran-domly allocated to one of eight experimental conditions formed by the factorial combination of three two-level factors. These were experimental design (pretest and posttest measures taken vs. posttest measures taken alone), psychophysical method (forced-choice vs. magnitude estimation), and inspection procedure (inspection of real contours vs. inspection of imagined contours). In addition to color responses, written introspective reports of the strategies used in providing color responses were obtained. As a basis for the rejection of observers using inappropriate strategies, reported strategies were coded as appropriate or inappropriate. An analysis of the color reports of all observers was performed, as well as two analyses of the color reports of only those observers identified as using appropriate response strategies. In all cases, the results showed that CAEs were reported after inspection of real contours irrespective of the experimental design or psychophysical method used. There were no significant CAEs reported in any conditions that involved the imagination of contours. A separate analysis of the relationship between observers’ response strategies, the coding of these strategies, and observers’ actual color reports revealed some problems concerning the use of such introspective techniques. The implications of these findings are discussed in terms of theoretical assumptions about the nature of imagery and perception.

Orientation-contingent color aftereffects: Retinal specificity

Hayman and Allan (1980) concluded that the color aftereffects they obtained were orientation contingent rather than angle contingent, and they argued that these orientation-contingent color aftereffects were retinally specific. Additional data in support of the Hayman and Allan (1980) conclusion are reported. These data point to the important role of eye fixations and eye movements on contingent color aftereffects.

Interocular transfer of orientation-contingent color aftereffects with external and internal adaptation.

The issue of whether McCollough effects transfer interocularly was examined in two experiments. In Experiment 1, as in previous experiments, no interocular transfer of McCollough effects was obtained when subjects adapted monocularly to externally present patterns with their unused eyes fully occluded. However, when subjects adapted monocularly (with the unused eye fully occluded) to visual images of those patterns superimposed on physically present chromatic backgrounds, McCollough effects transferred interocularly. In Experiment 2, subjects adapted to either physically present patterns or to images of those patterns (as in Experiment 1), but the unused eye was exposed to unpatterned diffuse white light. In contrast to Experiment 1, the externally adapted subjects showed interocular transfer of McCollough effects. In Experiment 2, the magnitude of the interocular transfer effects produced by imagery was significantly larger than the magnitude of the effects produced by external adaptation, but the magnitude of the imagery-induced aftereffects did not differ from Experiment 1 to Experiment 2. These results extend earlier findings by Kunen and May (1980) and show that McCollough effects can be produced through adaptation to imagery, even though the direction of the imagery-induced aftereffects indicates adaptation to higher spatial frequencies whereas externally derived aftereffects indicate adaptation to lower spatial frequencies. It is concluded that failure of previous studies to obtain interocular transfer of McCollough effects may have resulted from complete occlusion of the contralateral eye. These data point up some interesting similarities and some important differences between imagery and actual vision. The implications for analogical models of visual imagery are discussed.

The influence of imagery ability on color aftereffects produced by physically present and imagined induction stimuli.

Two methods of induction were used to produce orientation-contingent color aftereffects for observers assigned to one of three groups (high, medium, and low) on the basis of self-rated imagery ability. In Experiment 1, observers were required to make magnitude estimates of color aftereffects following inspection of stimulus patterns normally used to produce McCollough effects (e.g., red vertical contours, green horizontal contours). Experiment 2 was a partial replication of Experiment 1, with additional induction conditions in which observers were required to imagine the presence of appropriately oriented contours when particular homogeneous color patches were presented. The results indicated that self-rated imagery ability was not a significant factor in differentiating between observers’ performance when orthodox induction procedures were used (Experiment 1). In addition, there were no reliable indications (Experiment 2) that imagined stimulus attributes can be effectively substituted for real stimulus attributes in order to produce orientation-contingent color aftereffects. The results are discussed in terms of their implications for the use of imagery-induced perceptual phenomena as a paradigm for investigating the possibility of common neural mechanisms in perception and imagination; in addition, the general implications of the results for understanding the functional significance of self-reported imagery ability are examined.

Contrast and frequency competition for orientation-contingent color aftereffects.

A “competition” paradigm was developed to examine separately the effects of pattern contrast and spatial frequency characteristics on the strength of orientation-contingent color aftereffects (McCollough effects). After adapting to alternately presented red/black and green/black square-wave gratings (one horizontal, one vertical), 11 subjects viewed seven different kinds of test patterns. Unlike Standard McCollough effect test stimuli, the present patterns had variable luminance profiles running both horizontally and vertically within each test pattern area. Forced choice responses were used to determine which aftereffect color (red or green) appeared, as characteristics of vertical and horizontal luminance profiles were varied separately among test stimulus types. We conclude that pattern contrast and human contrast sensitivity account for aftereffect colors in such stimuli. When contrast is taken into consideration, aftereffects are not predicted by similarity between adaptation and test pattern Fourier characteristics, nor are they predicted by the width, per se, of pattern elements.

Persistence of simple and contingent motion aftereffects

Jones and Holding (1975) showed that orientation-contingent color aftereffects can persist for at least 3 months, but are depleted by repeated testing. We applied the same paradigm to a simple motion aftereffect (MAE) and found that it can persist for up to 1week and is only slightly diminished by testing. It was further found that simple MAEs appear to persist longer than color-contingent MAEs, although when procedures for inducing and measuring both kinds of aftereffect are equalized, contingent MAEs last longer. Finally, no tendency was found for color-contingent MAEs to diminish with repeated testing. Although both simple and color-contingent MAEs can be relatively persistent, there are certain differences between them. Furthermore, contingent aftereffects should not be considered interchangeable, as there appear to be large differences in the persistence of orientation-contingent color aftereffect and color-contingent MAEs.

Color aftereffects contingent on perceptual organization

The present experiment demonstrated that (a) cognitive organizational factors influence an orientation-contingent color (McCollugh) aftereffect, and (b) adaptation to colored gratings affected the perceptual organization of a reversible figure. Following adaptation to colored gratings, color aftereffects were reported in only one of two organizations of a reversible figure, and the colors conformed to the subjective contours of the test pattern rather than exclusively to the regions defined by horizontal and vertical pattern elements. In addition, an organization of the reversible figure that segregated vertical and horizontal pattern elements was dominant subsequent to adaptation.

Summation of successively established orientation-contingent color aftereffects

Orientation-contingent color aftereffects (CAEs) were studied using a color-cancellation technique for measurement. Procedures involved more than one period of inspection, each of which established CAEs, carried out successively to produce a combined or net CAE (akin to “nullification” used in other studies). When opposite color-orientation pairings were used in successive inspections, the net CAE was predicted faithfully by summation of the constituent CAEs as measured from each period of inspection independently, and thus showed qualitative as well as quantitative changes in coloration over time. This implies that “nullification” does not truly eliminate CAEs as has previously been assumed, and suggests that the units of measure used here may be linearly representative of CAE strengths. When the successive inspections used identical color-orientation pairings, however, summation was poor. This can be explained if inspection alters the mechanisms underlying CAEs, rendering retention of a successively established CAE of the same kind less effective.

A neural network model of the McCollough effect.

A self-organizing, feature-extracting network (von der Malsburg, 1973) is extended to two feature dimensions to encompass line orientation and color. It is applied to McCollough effects, particularly longlasting, contingent-aftereffects. McCollough effects are thought to involve low-level associative memory in the form of synaptic modification. The McCollough-Malsburg Model (MMM) embodies positive synaptic modification with correlated firing of units in an input layer and an excitatory cortical layer. Computer simulation of MMM reproduces orientation-contingent color aftereffects. The model embodies many of the mechanisms thought to be operating in developmental plasticity, suggesting that equivalent mechanisms may be involved in adult long-term adaptation as well.

Orientation constancy of the McCollough effect

Two different techniques were used to determine the orientation constancy of orientation-contingent color aftereffects, McCollough effects. The results from both investigations agree and indicate That the aftereffect fails to exhibit orientation constancy other than that which can be explained by ocular countertorsion. Thus, the retinal rather than phenomenal orientation of the adaptation stimuli appears to be the determinant of aftereffect orientation. In fact, it is concluded that the aftereffect can be used to accurately monitor torsional eye position over long periods of time.

Luminance as a parameter in establishment and testing of the McCollough effect

McCollough effect strengths depend on the luminances of patterns used to establish or to test them. The strengths of these orientation-contingent color aftereffects were assessed by color cancellation; chromatic light was added to test gratings to attain psychophysical null matches. The purities of colors needed for cancellation of the colored aftereffects are greater: (1) following inspection at high luminances and (2) on test patterns of low luminances.

A texture-contingent visual motion aftereffect

The following procedure produces a new motion aftereffect. Two visually textured disks—one fine and the other coarse—rotate in opposite directions, and the O fixates the center of each disk alternately for 4 sec. After 4 min of viewing, the disks are stopped. Each stationary disk, when fixated, then appears to rotate in the opposite direction from its prior objective rotation. This phenomenon, a texture-contingent negative motion aftereffect, is analogous in some respects to the McCollough effect, an orientation-contingent color aftereffect.