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PubMed1995

The perception of color from motion.

We introduce and explore a color phenomenon which requires the prior perception of motion to produce a spread of color over a region defined by motion. We call this motion-induced spread of color dynamic color spreading. The perception of dynamic color spreading is yoked to the perception of apparent motion: As the ratings of perceived motion increase, the ratings of color spreading increase. The effect is most pronounced if the region defined by motion is near 1 degree of visual angle. As the luminance contrast between the region defined by motion and the surround changes, perceived saturation of color spreading changes while perceived hue remains roughly constant. Dynamic color spreading is sometimes, but not always, bounded by a subjective contour. We discuss these findings in terms of interactions between color and motion pathways.

Color Perception↗
PubMed1980

Children's perception of Munsell colors.

This study examined perception of Munsell notation color by seven third-graders and three college adults (both with normal color vision) and three children (from the same family) who were red-green color blind. The stimuli varied in terms of Munsell Hue (red, green, and purple), Munsell Value (brightness), and Munsell Chroma (saturation). Each S judged the dissimilarity of 325 color pairs (from 26 stimuli). The data were analyzed via individual difference multidimensional scaling that defined a common perceptual space for the group. The results indicated that the third-graders' color perception was like that of the adults. The color circle was reproduced, as were dimensions based on Munsell Value and Chroma. The color deficient children's data did not fit into that common space. Their perception was guided primarily by the brightness of the stimulus. In sum, the data indicated that, for the domain of Munsell colors, results obtained from adults concerning the dimensionality of the color space could be applied to young children (as long as they have normal color vision).

Adolescent↗
PubMed2006

Color naming deficits and attention-deficit/hyperactivity disorder: a retinal dopaminergic hypothesis.

BACKGROUND: Individuals with Attention-Deficit/Hyperactive Disorder (ADHD) have unexplained difficulties on tasks requiring speeded processing of colored stimuli. Color vision mechanisms, particularly short-wavelength (blue-yellow) pathways, are highly sensitive to various diseases, toxins and drugs that alter dopaminergic neurotransmission. Thus, slow color processing might reflect subtle impairments in the perceptual encoding stage of stimulus color, which arise from hypodopaminergic functioning. PRESENTATION OF HYPOTHESES: 1) Color perception of blue-yellow (but not red-green) stimuli is impaired in ADHD as a result of deficient retinal dopamine; 2) Impairments in the blue-yellow color mechanism in ADHD contribute to poor performance on speeded color naming tasks that include a substantial proportion of blue-yellow stimuli; and 3) Methylphenidate increases central dopamine and is also believed to increase retinal dopamine, thereby normalizing blue-yellow color perception, which in turn improves performance on the speeded color naming tasks. TESTING THE HYPOTHESIS: Requires three approaches, including:1) direct assessment of color perception in individuals with ADHD to determine whether blue-yellow color perception is selectively impaired; 2) determination of relationship between performance on neuropsychological tasks requiring speeded color processing and color perception; and 3) randomized, controlled pharmacological intervention with stimulant medication to examine the effects of enhancing central dopamine on color perception and task performance IMPLICATIONS OF HYPOTHESIS: If substantiated, the findings of color perception problems would necessitate a re-consideration of current neuropsychological models of attention-deficit/hyperactivity disorder, guide psycho-education, academic instruction, and require consideration of stimulus color in many of the widely used neuropsychological tests.

Journal Article↗
PubMed2003

Is color "categorical perception" really perceptual?

Roberson and Davidoff (2000) found that color categorical perception (CP; better cross-category than within-category discrimination) was eliminated by verbal, but not by visual, interference presented during the interstimulus interval (ISI) of a discrimination task. On the basis of this finding, Roberson and Davidoff concluded that CP was mediated by verbal labels, and not by perceptual mechanisms, as is generally assumed. Experiment 1 replicated their results. However, it was found that if the interference type was uncertain on each trial (Experiment 2), CP then survived verbal interference. Moreover, it was found that the target color name could be retained across the ISI even with verbal interference (Experiment 3). We therefore conclude that color CP may indeed involve verbal labeling but that verbal interference does not necessarily prevent it.

Adolescent↗
PubMed2006

Evaluation of cerebral dyschromatopsia using color afterimage.

Cerebral dyschromatopsia is traditionally evaluated by color discrimination tests such as the Farnsworth-Maunsell 100 Hue Test. These tests are also used to evaluate color-perception deficits caused by eye disease, and they do not tell us whether color perception is impaired in the eye or in the brain. Here, we used color afterimage to isolate color-perception deficits in the brain from those in the eyes, in a patient with cerebral dyschromatopsia. The results showed that the patient perceived color afterimage of yellow and blue with abnormal duration and chromaticity. On the other hand, the patient performed normally on the Farnsworth-Maunsell 100 Hue Test. We conclude that the color afterimage test would be useful to evaluate color perception in the brain.

Color Perception↗
PubMed2002

Color contrast and contextual influences on color appearance.

We used a hue-scaling task to examine changes in color perception resulting from adaptation or induction to color contrast in spatially-varying backgrounds. Observers judged the perceived color of tests after or while viewing backgrounds composed of color differences along selected axes in color space. Both contrast adaptation and contrast induction produced large and selective shifts in perceived hue angle, and interacted in similar ways when combined, suggesting that they had functionally similar influences on perceived hue. Both also consistently biased perceived hue away from the color axis of the background, implying response changes within multiple channels tuned to different directions in color space. Selective hue changes were also observed when the gamut of colors forming the backgrounds were drawn from natural color distributions. This suggests that color perception in different environments may be systematically biased by adaptation to the distributions of colors in those environments. However, we did not find these biases when the same test stimuli were judged after adapting to actual natural scenes.

Adaptation, Ocular↗
PubMed2001

Richer color experience in observers with multiple photopigment opsin genes.

Traditional color vision theory posits that three types of retinal photopigments transduce light into a trivariate neural color code, thereby explaining color-matching behaviors. This principle of trichromacy is in need of reexamination in view of molecular genetics results suggesting that a substantial percentage of women possess more than three classes of retinal photopigments. At issue is the question of whether four-photopigment retinas necessarily yield trichromatic color perception. In the present paper, we review results and theory underlying the accepted photoreceptor-based model of trichromacy. A review of the psychological literature shows that gender-linked differences in color perception warrant further investigation of retinal photopigment classes and color perception relations. We use genetic analyses to examine an important position in the gene sequence, and we empirically assess and compare the color perception of individuals possessing more than three retinal photopigment genes with those possessing fewer retinal photopigment genes. Women with four-photopigment genotypes are found to perceive significantly more chromatic appearances in comparison with either male or female trichromat controls. We provide a rationale for this previously undetected finding and discuss implications for theories of color perception and gender differences in color behavior.

Adult↗
PubMed2000

Visual and audiovisual speech perception with color and gray-scale facial images.

Research has shown that auditory speech recognition is influenced by the appearance of a talker's face, but the actual nature of this visual information has yet to be established. Here, we report three experiments that investigated visual and audiovisual speech recognition using color, gray-scale, and point-light talking faces (which allowed comparison with the influence of isolated kinematic information). Auditory and visual forms of the syllables /ba/, /bi/, /ga/, /gi/, /va/, and /vi/ were used to produce auditory, visual, congruent, and incongruent audiovisual speech stimuli. Visual speech identification and visual influences on identifying the auditory components of congruent and incongruent audiovisual speech were identical for color and gray-scale faces and were much greater than for point-light faces. These results indicate that luminance, rather than color, underlies visual and audiovisual speech perception and that this information is more than the kinematic information provided by point-light faces. Implications for processing visual and audiovisual speech are discussed.

Adolescent↗
PubMed2003

Effects of illumination, viewing distance, and lighting color on perception time.

A laboratory study was carried out to investigate the effects of illumination, viewing distance, and lighting color on perception time with center high-mounted stop lamps comprised of light-emitting diodes. Analysis indicated that illumination, viewing distance, and lighting color are significant factors in perception time. Low illumination resulted in shorter perception time than high illumination. A viewing distance of 20 m resulted in shorter perception time than 40 m. The perception time was shorter for blue than for red or yellow light. The interaction of illumination and lighting color was significant. Mean difference in perception time among lighting colors was not significant under low illumination, but was significantly shorter for blue light under high illumination. Based on the results, blue light seemed to be the optimal lighting color for center high-mounted stop lamps comprised of light-emitting diodes.

Color Perception↗
PubMedDate not supplied

Effects of motion and configural complexity on color transparency perception.

We tested whether motion and configural complexity affect perceived transparency. A series of five coherent chromatic transformations in color space was applied across a figure: translation, convergence, shear, divergence and rotation. The stimuli consisted of a bipartite or a checkerboard configuration (10 x 10 degrees), with a central static or moving overlay (5 x 5 degrees). Three different luminance conditions (the plane of chromatic transformation oriented toward higher, lower, or equal luminances) were also tested for each of three modulation depths. For each stimulus, the observer judged whether the overlay appeared transparent or not. The main results indicated an interaction between the type of chromatic transformation and stimulus motion and complexity. For example, convergences are judged to appear transparent significantly more often when motion is added for bipartite configurations, or when they are generated in a checkerboard configuration. Surprisingly, shears that have been reported to appear opaque, are more frequently reported to appear transparent with short vector lengths and when combined with motion. Other transformations are also affected by motion, although the effectiveness of figural complexity on transparency seems to depend on both the type of color shifts and the presence of motion. The results indicate that adding motion and stimulus complexity are not necessarily neutral with respect to the chromatic shifts evoking transparency. Thus, studies that have used motion to enhance transparency may yield different results about the color shifts supporting transparency perception from those that did not. The same might be supposed for stimulus complexity under some conditions.

Color Perception↗
PubMed1997

Influence of boundary information on the perception of color.

The integration of color and form to produce a unified percept is a central problem in vision research. We know that the spatial arrangement of colored stimuli influences their detectability. In the gap effect, for example, a small gap between two colored fields enhances their discriminability [Opt. Acta 24, 159 (1977)]. Chromatic thresholds are also reduced when test fields are spatially demarcated. To explore the mechanisms underlying these types of effect, the influence of spatial structure on chromatic sensitivity for gratings was measured. For sine-wave and square-wave gratings modulated in different directions in color space, contrast sensitivity was measured by using a two-alternative forced-choice procedure with a QUEST staircase. Thin lines, of the same orientation as that of the grating, were superimposed on it at half-cycle intervals. The phase of the superimposed lines was varied. For S-cone modulated gratings, dark lines placed at the midpoints between peaks and troughs (90 degrees) increased sensitivity. As the phase of the lines moved toward the peaks (0 degree), their effect on sensitivity declined to zero. A similar but smaller effect was seen for isoluminant L- and M-cone modulated gratings. The superimposed lines always impaired contrast sensitivity for achromatic gratings, especially at a phase of 0 degree. Spatial structure superimposed on gratings can both facilitate and impair contrast sensitivity. In the presence of sharp boundaries, chromatic sensitivity is increased. This effect may depend more on the salience of boundaries, since isoluminant lines superimposed on S-cone modulated gratings and gray lines of similar cone contrast can facilitate detection if they are of sufficient contrast. Achromatic contrast sensitivity is reduced when the boundaries are present. The additional luminance information at the boundaries masks the grating. A simple model in which spatial integration is arrested at the positions of the superimposed lines fits only the isoluminant conditions. For both luminance and chromatic contrast the change in sensitivity depends on phase.

Color Perception↗
PubMed1985

A central spectrum model for the perception of coloration in filtered Gaussian noise.

In this paper we describe a monaural auditory signal-processing model for the perception of coloration. The model gives a central spectrum display of a stationary input signal. The central spectrum level for a nerve fiber tuned to a given frequency is computed as a combination of the average firing rate and the firing synchronized to the center frequency of the nerve. The model incorporates a critical-band filter bank, steady-state representations of the average and synchronized firing rates, and temporal integration. The central spectrum model, when used to process simulated data, accurately predicts the perception of coloration in filtered Gaussian noise.

Auditory Perception↗
PubMed2002

Color vision and occupational chemical exposures: I. An overview of tests and effects.

The paper presents a summary of the literature published until December 2000 on effects from some industrial chemical exposures on color perception, as well as short descriptions of the tests applied. Several different tests have been used to study acquired alterations of color vision. These changes are frequently found in the blue-yellow axis. Many of the tests were originally designed to detect congenital alterations in the red-green axis, and thus have relatively low sensitivity when studying chemically induced deficits in color perception. At present, the Lanthony D15-desaturated panel seems most suitable for application in industrial settings, since it is clearly the most sensitive and easily administered test. Color vision seems to be a physiological function very sensitive to several chemicals. The potency of industrial chemicals to induce color vision deficiencies has often been investigated during the last two decades. The chemicals most frequently studied are different solvents and mercury. Pronounced effects on color perception have been reported following chronic exposure to organic solvents such as styrene, carbon disulphide, perchloroethylene, n-hexane and solvent mixtures, and to organic as well as inorganic mercury. The effect of occupational toluene exposure seems not as well established, since only slight effects and several negative studies have been reported. For some of these compounds the effect on color vision has been further established through the finding of clear dose-effect relationships. In a few cases, even acute exposure situations, e.g. exposure to toluene for a few hours or acute alcohol intake, seem to affect color perception. Follow-up studies are needed to investigate the possible reversibility of effects in relation to discontinued or reduced exposures.

Color Perception Tests↗
PubMed1998

Reversible color vision loss in occupational exposure to metallic mercury.

Color vision was evaluated in twenty-one mercury exposed workers and referents matched for sex, age, tobacco smoking, and alcohol habits. The Lanthony 15 Hue desaturated panel (D-15 d) was applied. In the workers, mean urinary Hg (HgU) was 115+/-61.5 microg/g creatinine; in all but one the values exceeded the biological limit (BEI) proposed by the American Conference of Governmental Industrial Hygienists. A dose-related subclinical color vision impairment was observed in Hg-exposed workers compared to the referents. Just after the survey, working conditions were improved. Twelve months later the workers were reexamined. Mean HgU was 10.0 microg/g creatinine and in no subjects was the BEI exceeded. Color perception was significantly improved compared to the first examination and, furthermore, no differences were observed between exposed workers and referents. The results add evidence that the color vision loss observed during the first part of the study was related to Hg exposure and, moreover, show that this effect is reversible. These data indicate that metallic Hg can induce a reversible impairment in color perception. This suggests that color vision testing should be included in studies on the early effects of Hg. The possibility of applying the D-15 d as an early effect index in the biological monitoring of Hg exposed workers should also be entertained.

Adult↗