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PubMed1992

Cortical area V4 and its role in the perception of color.

The color and lightness vision of three monkeys with bilateral removal of cortical area V4 and three unoperated controls were tested by measuring their ability to discriminate between two rows of colored or gray stimuli. In one row, the stimuli were ordered in terms of either chromaticity or luminance, whereas in the other row they were disordered. Their ability to select the odd-one-out in an array of colors or grays and to select the colored patch from an array of achromatic grays was also assessed. Unlike an achromatopsic patient tested previously in an identical fashion, monkeys with V4 lesions performed indistinguishably from controls in the oddity test. The animals lacking V4 were slightly impaired at discriminating between ordered and disordered arrays of colors or grays, but the color impairment was no more severe than the impairment with grays. These deficits were readily accounted for in terms of the conspicuous deficits in pattern discrimination apparent in a nine-choice pattern oddity task. The results do not support the view that cortical area V4 in the monkey is the homolog of the cortical "color center" in humans, located in the lingual and fusiform gyri and damage to which leads to the clinical syndrome of cerebral achromatopsia, unless it is the additional damage to underlying white matter that leads to the severe color disorder in patients.

Animals↗
PubMedDate not supplied

[Diagnosis and classification of variants of color vision in the light of new methodological approaches].

The authors suggest that the parameters of color force of the receptors and the possible abnormal disposition of their maximal sensitivity by the spectrum be taken into consideration in the diagnosis of color perception. Assessment of color force was acknowledged to be more significant than of color abnormalities, both from a viewpoint of occupational selection, and from a clinical viewpoint. This is reflected in the suggested classification of color vision and in recommendations for use in practical ophthalmology of new threshold tables created by Yustova-Alexeyeva et al. These tables are based on the results of colorimetric investigations, and the results of their trials are reliable.

Calorimetry↗
PubMed1990

Role of color in perception of attractiveness.

In this color study females reported a favorite color significantly more often than males. Males preferred bright colors significantly more than females, with a converse finding for preference for soft colors. The 276 subjects, when asked to evaluate the attractiveness of stimulus models in photographs, gave as the reason color significantly more often than style of clothing or facial expressions. Subjects significantly concurred with expert choices of recommended and nonrecommended colors in five of the six sets of photographs. This study lends credence that wearing recommended colors makes a difference in judgments of what looks best by subjects over the age of 12.

Adolescent↗
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↗
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↗
PubMed1984

The effect of glaucoma on central visual function.

Glaucoma has traditionally been thought to affect peripheral visual function in its early stages and to spare central visual function until late in the disease process. The basis for this assumption has been the reliance on Goldmann-type perimetry, a rather sensitive method for assessing the peripheral visual function, and on Snellen-type visual acuity measurements, a rather insensitive method of assessing central visual function. This belief has persisted despite frequent complaints from patients with glaucoma that their central vision is disturbed. Over the past two decades, several investigations of central visual functions and their anatomic substrate have challenged this assumption. Histologic studies of the nerve fiber layer in eyes with glaucoma suggest that the number of ganglion cells subserving macular function is decreased even in early stages of the disease. In addition, afferent pupillary defects (a gross measurement of macular nerve fiber function) may also be present in eyes with early glaucoma. Several studies have demonstrated that color perception (largely mediated by the fovea) is defective in glaucoma. Furthermore, defects in color perception may even precede the development of visual field abnormalities. Seventy-eight percent of patients with early glaucomatous visual field defects were found to have a defect in color perception when tested with a desaturated D-15 color panel that tests only the central 1.5 degrees. In addition, both chromatic and achromatic foveal perception channels are defective in eyes with glaucoma and even in some eyes of those with suspected glaucoma. Contrast sensitivity has become recognized as an important component of visual function. Partial loss of contrast sensitivity may cause a degradation in the quality of perception even though the Snellen visual acuity remains normal. Although contrast sensitivity is not entirely a macular function, it has been shown that as little as 3 degrees of disturbance of the macula (eg, with macular degeneration or with an artificial central scotoma) will reduce the contrast sensitivity, suggesting that this modality is indeed mediated to a significant extent by this portion of the retina. Spatial contrast sensitivity appears to be reduced in patients with glaucoma. However, because of overlap and lack of a sharp cutoff measurement, present testing procedures fail to allow a clear distinction between the glaucomatous and normal populations. Although reduced temporal contrast sensitivity has been demonstrated in glaucomatous eyes by others, I undertook a systematic investigation of this function in a large group of patients with glaucoma and with suspected glaucoma.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMedDate not supplied

A model of color vision based on cortical reentry.

It is known that the perceived color of an object depends on the context in which it is viewed, its reflectance properties and the spectral distribution of the illuminating light. What is not known, however, is how the visual system functions so that color percepts depend upon the integration of local and contextual cues. While phenomenological theories of color vision exist, robust neurally based theories consistent with psychophysical observations are sparse. In the present study we develop such a theory and establish its self-consistency by computer simulations of cerebral cortical areas involved in color perception. The simulations test the hypothesis that long-range reciprocal connections within and between cortical areas mediate a dynamic process of reentry that integrates contextual cues into the color percept. When stimuli similar to those used in psychophysical testing of contextual influence were used, firing patterns consistent with psychophysical data on color constancy and color induction in humans were observed. Selective disruption of reciprocal inter- or intra-areal connections reduced the correspondence between the model's responses and the psychophysical data. The findings are consistent with the proposal that reentrant interactions within and between cortical areas provide a major basis for the context-sensitive aspects of color vision.

Animals↗
PubMed1990

[The study of color vision in children].

The paper analyses results after investigation of color perception in 520 children (264 boys and 256 girls), aged 3-5 years, by means of two simple tests: a "Pflüger-Trident Test" (Velhagen) and a "Simplified Test of Color Vision" (Fletcher). It is proved that in children of under school age color perception is already developed enough and can be investigated for detecting disturbances in color vision.

Child, Preschool↗
PubMed1978

Dichromatic color language: "reds" and "greens" don't look alike but their colors do.

When protanopes or deuteranopes arrange the Farnsworth Dichotomous Test colors in order of similarity, they reveal their lack of red/green hue discriminations by alternating chips that the normal trichromat sees as reddish and greenish test colors. The dichromatic orderings follow a systematic variation in saturation of blue hues through neutral and into yellow hues as described by theory for each of the two types. Some dichromats who show the typical test behavior nevertheless use reddish and greenish hue terms appropriately when instructed to name the same test colors. Lightness cues are probably used by these dichromats in the naming task but ignored in the perceptual similarity task. Thus, unlike normal trichromats, who use similar names for perceptually similar colors, dichromats may use dissimilar names for perceptually similar colors. In this way they can achieve concordance with the normative language system despite its discordance with their impoverished color perceptions.

Color Perception↗
PubMedDate not supplied

[Color vision in diabetics].

Color perception is often already altered even if the ocular, anatomic and functional exams maintain their results within the normal limits. This fact is more important in diabetes, where chromatic abnormalities exist at half of the subjects, even if they do not reveal any signs of diabetic retinopathy. The authors present some of the methods in clinical exam of color perception, the characters of dyschromatopsia and glycemic self control using the method of coloured bandelets, types of dyschromatopsia which may appear during the evolution of the diabetes, and also the predictive effect of dyschromatopsia for the appearance of diabetic retinopathy.

Color Perception↗