[Experimental studies on chromatic perception; light and color in the phenomena of simultaneous contrast; constancy and of equalization].
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Color↗
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The categorical perception of colors and facial expressions: the effect of verbal interference.
A series of five experiments examined the categorical perception previously found for color and facial expressions. Using a two-alternative forced-choice recognition memory paradigm, it was found that verbal interference selectively removed the defining feature of categorical perception. Under verbal interference, there was no longer the greater accuracy normally observed for cross-category judgments relative to within-category judgments. The advantage for cross-category comparisons in memory appeared to derive from verbal coding both at encoding and at storage. It thus appears that while both visual and verbal codes may be employed in the recognition memory for colors and facial expressions, subjects only made use of verbal coding when demonstrating categorical perception.
Adolescent↗
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↗
[The development of the skin-optical perception of color and images in blind schoolchildren on an "internal visual screen"].
In profound impairement of vision the function of colour and seen objects perception is absent, with the person being unable to orient himself in space. The uncovered sensory sensations of colour allowed their use in training the blind in recognizing the colour of paper, fabric, etc. Further study in those having become blind will, we believe, help in finding eligible people and relevant approaches toward educating the blind, which will make for development of the trainee's ability to recognize images on the "inner visual screen".
Blindness↗
[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↗
[Comparative study of the impact of diet versus pravastatin on color vision in Brodman area 19 detected by computerized chromatic analysis (CARDIOCOLOUR Study)].
INTRODUCTION AND OBJECTIVES: Hypercholesterolemia causes important neurodegenerative changes in the cerebral cortex, which are manifested by defects in the color perception by the neurons of Brodman area 19. Extensive interventional epidemiological data from both primary and secondary-prevention clinical trials indicate that cardiac ischemic events decrease when total cholesterol or LDL-C is reduced. Our goal was to elucidate the effects of diet compared with a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor (pravastatin) on color perception using computerized chromatic analysis (CCA) and plasma cholesterol levels. PATIENTS AND METHODS: We studied 191 normotensive patients (133 men and 58 women) with pre-study plasma cholesterol levels in excess of 200 mg/dl. Seventy of these patients were treated with the American Heart Association Step II diet for six months. The remaining 121 were treated with pravastatin, 61 patients with 10 mg and 60 patients with 40 mg. They were examined by CCA after excluding any general or ophthalmological pathology. RESULTS: Chromatic vision recovered by 23% with diet, 38% with pravastatin 10 mg and 92% with pravastatin 40 mg. CONCLUSIONS: This study confirmed a strong association between therapeutic intervention with either diet or pravastatin and improved color vision.
Adult↗
Color stability of compomer after immersion in various media.
PURPOSE: The purpose of this study was to evaluate the effect of various media on the color stability of compomer and to compare these results to those of other materials that could be used in similar clinical circumstances. MATERIALS AND METHODS: In this test, six materials (shade A2) were used: four compomers (Dyract, Compoglass F, Xeno, F2000), one composite resin (Clearfil AP-X), and one resin-modified glass ionomer cement (Fuji II LC). There were four test solutions: one alcoholic (whiskey), two low pH soft drinks (Coca Cola, orange juice), and deionized water as a control. A plastic ring mold (9-mm diameter x 1-mm height) was used to prepare 120 disk specimens. For 60 days, the test specimens were immersed in the various media daily for 3 hours then transferred to the deionized water. Color was measured by CIE L* a* b* relative to CIE source against a white background, using a colorimeter. Color change (delta E*) was calculated as delta E* = [(delta L*)2 + (delta a*)2 + (delta b*)2]1/2. Color changes (delta E*) were recorded after 1, 7, 30, and 60 days. RESULTS: The results indicated that compomer and resin-modified glass ionomer were susceptible to discoloration in various solutions over an extended period of time. Composite resin showed minimal perceptible color change. Specimens immersed in whiskey showed a significantly high perceptible color change (p < .0001). Water caused no perceptible color changes.
Analysis of Variance↗
Discoloration of a compomer by stains.
This study evaluated the color stability of a polyacid-modified composite (compomer) upon exposure to stains. Five disks were prepared for immersion in each of five stains: coffee, chlorhexidine, cola, red wine, and water as a control. Color measurements were made on a reflection spectrophotometer at baseline, after 24-hour incubation, and after 24, 48, and 72 hour immersion in each stain. At 24 hours, perceptible color changes occurred for specimens in red wine and coffee. After 48 hours, perceptible color changes occurred for specimens in cola. Chlorhexidine and water caused no perceptible color changes. A compomer is susceptible to staining by coffee, red wine, and cola.
Analysis of Variance↗
Absence of smooth motion perception in color vision.
We have tested the behavioral evidence for a separation of the processing of color contrast from motion in the human visual system. Two different aspects of motion perception are examined; the identification of the direction of movement of a chromatic grating and the perception of smooth motion. The results show that color vision is at no great disadvantage in the identification of direction of movement, since this can be done at color contrasts quite close to detection threshold over a wide range of spatial and temporal frequencies. However, we find that subjects can identify direction without having the genuine perception of smooth motion. Smooth motion perception is revealed to be highly impaired since it is detected only at very high color contrasts and over a narrow range of spatial temporal conditions.
Color Perception↗
Color stability of provisional restorative materials after accelerated aging.
PURPOSE: Color of 11 provisional restorative materials (4 acrylic resins and 7 resin composites) was evaluated by reflection spectrophotometry immediately after fabrication, after aging for 15 kJ/m(2), and after aging for 60 kJ/m(2) to determine relative color stability under experimental aging conditions. MATERIALS AND METHODS: Specimens of provisional restorative materials were polymerized according to manufacturers' instructions and aged in an artificial aging chamber with exposure to a total ultraviolet irradiation of 60 kJ/m(2) in increments of 15 kJ/m(2). Color was measured by CIE L*a*b* on a reflection spectrophotometer before and after aging. Color change (Delta E*) was calculated and analyzed statistically by analysis of variance with repeated measures after 15 and 60 kJ/m(2) intervals of aging. RESULTS: Statistically significant changes in color were observed after accelerated aging at both the initial and final aging intervals. Five of the 11 provisional materials tested showed perceptible color change (Delta E* from 3.6 to 9.3) after accelerated aging of 15 kJ/m(2). Seven of the 11 provisional materials tested showed perceptible color change (Delta E* from 3.4 to 9.4) after accelerated aging of 60 kJ/m(2). CONCLUSIONS: Clinically perceptible color changes (Delta E* Delta 3.3) can be expected in some acrylic resin and composite resin provisional materials after accelerated aging.
Acrylic Resins↗
Color vision in epilepsy patients treated with vigabatrin or carbamazepine monotherapy.
PURPOSE: To investigate color vision in epilepsy patients treated with vigabatrin or carbamazepine monotherapy and to evaluate the association between vigabatrin-induced visual field defects and dyschromatopsia. DESIGN: Nonrandomized comparative trial. PARTICIPANTS: Thirty-two epilepsy patients treated with vigabatrin monotherapy, 18 patients treated with carbamazepine monotherapy, and 47 age-matched healthy controls were examined. MAIN OUTCOME MEASURES: Color vision was examined with Standard Pseudoisochromatic Plates 2 (SPP2) screening test, Farnsworth-Munsell 100 (FM 100) hue test, and Color Vision Meter 712 anomaloscope. RESULTS: Abnormal color perception was found in 32% of the epilepsy patients treated with vigabatrin monotherapy and 28% of the epilepsy patients treated with carbamazepine monotherapy. The total error score in the Farnsworth-Munsell 100 hue test was abnormally high in the vigabatrin monotherapy patients who had concentrically constricted visual fields and a statistically significant correlation was found between the temporal visual field extents and the age-adjusted Farnsworth-Munsell 100 total error score in vigabatrin monotherapy patients (R = .533, P = 0.003 in the right eye, R = .563, P = 0.001 in the left eye). Four of 31 (12%) vigabatrin monotherapy patients, and 1 of 18 (6%) carbamazepine monotherapy patients had a blue axis in Farnsworth-Munsell 100 hue test. In the anomaloscope, there were a few pathologic findings in both groups. In the SPP2 screening test, a few plates were not seen in both groups. CONCLUSIONS: Both examined antiepileptic drugs, vigabatrin and carbamazepine, cause acquired color vision defects. The abnormal color perception seems to be associated with constricted visual fields in the vigabatrin monotherapy patients. The duration of carbamazepine therapy correlates with high FM100 total error score. The best method for detecting dyschromatopsia in patients treated with vigabatrin or carbamazepine was the Farnsworth-Munsell 100 hue test. The SPP2 screening test does not seem to be useful in clinical practice.
Adult↗
Learning space perception with colors.
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Child↗
Preserved color imagery in an achromatopsic.
The loss of color vision secondary to central nervous system disease (achromatopsia) is thought to preclude visual imagery of colors. We report a patient with achromatopsia, secondary to bilateral temporo-occipital infarcts inclusive of the lingual and fusiform gyri, with preserved color imagery. Our findings, in conjunction with previous cases in the literature, are consistent with a single neural network for color processing in which a disconnection of internal activation from stored color representations produces impaired color imagery with preserved color perception, whereas a disconnection of visual input to these representations produces achromatopsia with preserved color imagery.
Cerebral Infarction↗
[Standardized evaluation of red, green and blue perception. Comparison between color arrangement and computer-assisted test procedures].
BACKGROUND: Computerized colortests offer the possibility of determining quantitative color contrast thresholds under standardized conditions. Arrangement tests allow semi-quantitative evaluation of the red, green and blue color sense. To validate the results of a new computerized test, its results are compared to those of arrangement tests. PATIENTS AND METHODS: Thirty-five patients with retinitis pigmentosa (RP, mean age 38.51, +/- 15.14) as well as 30 normal observers (mean age 36.52, +/- 14.33) were evaluated. The computerized color test COLDEF was used, which is a calibrated screen that presents color optotypes on a colored background. All colors are chosen from three-color confusion axes of the CIE-Lu'v' color chart (protan, deutan and tritan axis). By a staircase procedure, the colors of the optotype and background were varied until the observers minimal color contrast threshold is detected. To compare the results of COLDEF with a routine diagnostic tool, the Farnsworth panel D-15 and Lanthony désaturé test were chosen. The results of the arrangement tests were scored by a categorization scheme. RESULTS: Normal observers showed no elevated thresholds either in COLDEF nor in the panel tests. In the RP group increased thresholds along the blue confusion axis could be detected in most cases. Furthermore, COLDEF showed increased thresholds along the red and green axes in some patients. With the computerized test it is always possible to identify the color axis concerned. The new test allows a fast and quantitative assessment of acquired color vision deficiencies.
Adult↗
Molecular patterns of X chromosome-linked color vision genes among 134 men of European ancestry.
We used Southern blot hybridization to study X chromosome-linked color vision genes encoding the apoproteins of red and green visual pigments in 134 unselected Caucasian men. One hundred and thirteen individuals (84.3%) had a normal arrangement of their color vision pigment genes. All had one red pigment gene; the number of green pigment genes ranged from one to five with a mode of two. The frequency of molecular genotypes indicative of normal color vision (84.3%) was significantly lower than had been observed in previous studies of color vision phenotypes. Color vision defects can be due to deletions of red or green pigment genes or due to formation of hybrid genes comprising portions of both red and green pigment genes [Nathans, J., Piantanida, T.P., Eddy, R.L., Shows, T.B., Jr., & Hogness, D.S. (1986) Science 232, 203-210]. Characteristic anomalous patterns were seen in 15 (11.2%) individuals: 7 (5.2%) had patterns characteristic of deuteranomaly (mild defect in green color perception), 2 (1.5%) had patterns characteristic of deuteranopia (severe defect in green color perception), and 6 (4.5%) had protan patterns (the red perception defects protanomaly and protanopia cannot be differentiated by current molecular methods). Previously undescribed hybrid gene patterns consisting of both green and red pigment gene fragments in addition to normal red and green genes were observed in another 6 individuals (4.5%). Only 2 of these patterns were considered as deuteranomalous. Thus, DNA testing detected anomalous color vision pigment genes at a higher frequency than expected from phenotypic color vision tests. Some color vision gene arrays associated with hybrid genes are likely to mediate normal color vision.
Color Perception↗
Accelerated aging affects color stability of provisional restorative materials.
PURPOSE: The color stability of two shades each of five acrylic resin and seven resin composite provisional restorative materials was evaluated by reflection spectrophotometry following in vitro accelerated aging. MATERIALS AND METHODS: Specimens of provisional restorative materials were polymerized according to manufacturers' instructions and aged in an artificial aging chamber with exposure to a total ultraviolet irradiation of 60 kJ/m2. Color was measured by CIE L*a*b* on a reflection spectrophotometer before and after aging. Color change (delta E*) was calculated and analyzed statistically. RESULTS: Statistically significant changes in color were observed after accelerated aging. Nine of the 12 provisional materials tested showed perceptible color change of at least one of the shades tested. The most color-stable materials were the acrylic, Alike, and the resin composites, Luxatemp and Protemp Garant, which had no perceptible color changes under these conditions. CONCLUSIONS: Some acrylic resin and composite provisional materials change color significantly and perceptibly when exposed to in vitro accelerated aging conditions.
Acrylic Resins↗
Testing color discrimination without the use of special stimuli or technical equipment.
Recently a number of self-report inventories have been developed to provide quick, valid, and reliable measures of sensory function without the use of technical equipment. One such measure, the 10-item Color Screening Inventory, was developed to detect individuals with deficient color perception. In the present study we used a sample of 268 subjects who were tested on both the Farnsworth-Munsell 100-hue test and the Color Screening Inventory. Analysis showed that inventory scores also predict continuous variations in and individuals' ability to discriminate colors, with an eta of .69, which explains 48% of the predictive variance. It was possible to describe the data using a quadratic regression equation which has a corrected correlation of .52. Using this, a conversion table was generated to allow rapid estimation of 100-hue test scores from the inventory. On the basis of the results, the Color Screening Inventory appears to be a quick and effective means of testing color discrimination without requiring special stimuli, technical equipment, or controlled testing environments.
Adult↗
A functional MRI case study of acquired cerebral dyschromatopsia.
Evidence from imaging studies suggests that primary visual cortex and multiple areas in ventral occipitotemporal cortex subserve color perception in humans. To learn more about the organization of these areas, we used structural and functional MRI (fMRI) to examine a patient with damage to ventral cortex. An art professor, KG, suffered a cerebrovascular accident during heart surgery that impaired his ability to perceive color. The Farnsworth-Munsell 100-Hue test was used to assess the extent of his deficit. When tested 12 months after the lesion, KG performed worse than 95% of age-matched normals on the 100-Hue test, but well above chance. Structural and functional MRI studies were conducted 3 years after the lesion to investigate the neuroanatomical correlates of KG'ss remaining color ability. Structural MRI revealed bilateral damage to ventral occipitotemporal cortex. In young and age-matched normal controls, an fMRI version of the 100-Hue reliably activated bilateral, color-selective regions in primary visual cortex and anterior and posterior ventral cortex. In subject KG, color-selective cortex was found in bilateral primary visual cortex. In ventral cortex, no color-selective activity was observed in right ventral cortex, and only a small area of activity was observed in left anterior ventral cortex. However, significant color-selective activity was observed in posterior left ventral cortex spared by the lesion. This posterior left ventral activation was similar in extent, position, and degree of color-selectivity to the posterior left posterior activation observed in normal controls, suggesting that this focus may be the cortical substrate underlying KG's remaining color perception.
Adult↗