SEARCH · PubMed Health

Results for “Color”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources

PubMed1992

The dermo-optical perception of color as an information source for blind travelers.

Dermo-optical color perception refers to a person's ability to distinguish color surfaces through "skin perception" without the use of sight. The aims of this study were (1) to assess prior research findings which apparently demonstrated the existence of dermo-optical color perception and (2) to explore the possibilities of using color to indicate reference points for blind travellers. Three experiments were conducted with 20 congenitally blind subjects and a sighted blindfolded control group matched on age, sex, and education. In Exp. 1 on a discrimination task subjects were asked if two boards were of the same color and on a pairing task were asked to match a colored board with one among a set of three boards having the same color. In Exp. 2 the discrimination task was identical to that in Exp. 1, but instead of using boards perceived through haptic exploration, we used colored cubicles in which the whole body would be exposed to the color. In Exp. 3 subjects were asked to walk along the corridor of a labyrinthine set-up and to identify any changes of color they could perceive. The experiments were designed to provide measures of reliability of subjects' responses. Analysis showed little or no support for the ability to perceive color by dermo-optical means. The comparisons of the blind and the sighted control groups were nonsignificant. On the basis of our findings, the use of color to help blind travellers has to be rejected. The paper concludes with a discussion suggesting reasons for the contradictory results emerging from studies on dermo-optical color perception.

Adolescent↗

PubMed2005

The visual-auditory color-word stroop asymmetry and its time course.

Four experiments examined crossmodal versions of the Stroop task in order (1) to look for Stroop asymmetries in color naming, spoken-word naming, and written-word naming and to evaluate the time course of these asymmetries, and (2) to compare these findings to current models of the Stroop effect. Participants named color patches while ignoring spoken color words presented with an onset varying from 300 msec before to 300 msec after the onset of the color (Experiment 1), or they named the spoken words and ignored the colors (Experiment 2). A secondary visual detection task assured that the participants looked at the colors in both tasks. Spoken color words yielded Stroop effects in color naming, but colors did not yield an effect in spoken-word naming at any stimulus onset asynchrony. This asymmetry in effects was obtained with equivalent color- and spoken-word-naming latencies. Written color words yielded a Stroop effect in naming spoken words (Experiment 3), and spoken color words yielded an effect in naming written words (Experiment 4). These results were interpreted as most consistent with an architectural account of the color-word Stroop asymmetry, in contrast with discriminability and pathway strength accounts.

Adult↗

PubMed2001

Understanding priming of color-singleton search: roles of attention at encoding and "retrieval".

We investigated how the performance of a color-singleton search (the search for a single odd-colored item among homogeneously colored distractors) left a persistent memory trace (lasting up to six intervening trials or approximately 17 sec) that facilitated a subsequent color-singleton search (when the same target-distractor color combination was repeated). Specifically, we investigated the roles of attention in the encoding and "retrieval" stages of this priming effect by intermixing trials in which the target location was precued by an onset cue. We found that the encoding of both target and distractor colors was automatic in that whether or not observers had to use color in locating the target in the preceding trial did not substantially affect priming. However, priming required that the color-singleton item be attended in the preceding trial. Once a color singleton display was encoded, our results indicated that priming facilitated the direction of attention to the color-singleton target on a subsequent trial. In short, when a color-singleton item happened to be a critical item to be attended in one situation, another color-singleton item defined by the same color combination tended to attract attention in subsequent encounters.

Adult↗

PubMed2004

[Effects of thickness and opaque resin on the color of Artglass].

PURPOSE: The purpose of this study was to measure the normal color value and the infinite optical thickness value of Artglass DA3,and evaluate the effect of different thickness and the use of opaque resin on the color values of Artglass. METHODS: A Minolta CS-321 portable colorimeter was used for color value measurement. The CIE L*a*b* color system was used to describe the color of specimens. Color difference,quantitated in deltaE units, were determined according to the following formula: DeltaE=[(DeltaL)(2)+(Deltaa)(2)+(Deltab)(2)](1/2). DeltaE values below 1.5 was used as being identical for human eyes. Artglass disks with a thickness of 4.0 mm were fabricated and the normal color value were obtained by two specimens pile up. Fifteen groups of specimens of 0.5 to 4.0 mm were made and the color of them were measured on the white and metal background color. The specimens used opaque resin with the thickness of 1.5 to 3.5 mm were determined by colorimeter. RESULTS: The normal color values of Artglass DA3 were L* 61.23,a* -1.18,b* 11.29. The infinite optical thickness value of Artglass DA3 was 2.75 mm. The opaque resin can increase the values of L*a*b* of Artglass. The effect will disappear until the thickness reaches 2.50 mm. CONCLUSIONS: From this study, we conclude that the color values of Artglass have a negative correlation between thickness when the background color is white. Thickness and opaque resin have significant effect on the color values of Artglass.

Color↗

PubMed1991

Influence of color on odor identification and liking ratings.

The effects of color on odor identification were tested under color appropriate, inappropriate, and blindfolded conditions. Subjects made fewer errors in identifying solutions that were colored appropriately (e.g., red-cherry) than in either the blindfolded condition, where there were no color cues, or the inappropriate color condition (e.g., red-lemon). Identification accuracy was greatest for typical odor-color combinations (e.g., red-cherry) compared with appropriate but nontypical odor-color combinations (e.g., red-watermelon). Response latencies were fastest for odors in the appropriately colored solutions. Subjects also rated appropriate color-odor combinations as most pleasant. However, this effect is probably due to the increase in identification accuracy of the appropriately colored solutions. In all three conditions, correctly identified odors were liked more than odors that were not correctly identified. Thus, color is an important perceptual variable in odor identification because it biases subjects toward a color category that facilitates identification if the color is "correct". This ability to identify an odor in turn influences the affective response to the odor.

Adult↗

PubMed1990

[Color differences between light-cured composite resin made shade guides and manufactured shade guides].

The purpose of this study was to investigate color differences between shade guides and light-cured composite resins. Resin specimens were made with resins and opaque resins of Silux Plus and Silux (3 M Co.) in a shade-guide metal mold. The resin specimens and the shade guides therefore were identical in shape and size. The sample resin specimens were compared with the shade guides provided with Silux Plus and Silux light-cured composite resins. Color measuring was performed with the Murakami Color Research Laboratory Fast Spectrophotometer C M S -500 and the Flexible Sensor F S -1. Specimens were placed on a plastic disc fixed to the top of the flexible sensor, and identical areas of their incisal, central, and cervical parts were measured. Conclusions. 1) The delta E*ab values between all shade guides and resin specimens showed color differences detectable to the naked eye. 2) Color differences between shade guides and resin specimens were great for the incisal colors (I, X L) and the deep and dark colors (D G, D Y, Y B, D G O, D Y O, Y B O, D D Y O). Color differences were relatively small, however, for the general colors (U, Y, G, U O, Y O, G O). 3) The L* values of shade guides ranged more widely than those of resin specimens. For many colors, L* values of the shade guides were lower than those of the resin specimens. 4) The a* values of shade guides and resin specimens were much more limited. The a* values of all colors showed minus values. The magnitude of a* values of shade guides were lower than those of resin specimens. 5) The b* values of shade guides were higher for some colors and lower for some colors than those of resin specimens.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1995

[Initial experiences with a new color technique: ultrasound angiography].

The sonographic diagnosis can be expanded by Color Doppler. Nevertheless something is missing, especially concerning the demonstration of the very slow velocities as it can be found in neovascularized malignant tumors. A recently developed new color technique--the Angio-Color of the Diasonics Corporation, Sonotron (other companies have prototypes of this color)--promises to improve the detection of very low flow velocities. Due to a method very different to the conventional Doppler technique the registered signal is coded in the color image of the blood flow: that means that the amplitude and not the frequency shift is coded in color. Therefore there is less noise in the color mode with the possibility of showing the lower flow in comparison to the conventional Doppler. In Gynaecology and Obstetrics the advantages in the demonstration of the placental blood flow were obvious. In eutrophic fetuses the blood flow could be registered over the whole breadth of placenta, while in dystrophic fetuses this was possible only at the margin of the placenta with some color pixels in the middle of the organ. The conventional Color Doppler was not able to show the flow in the placenta even in eutrophic fetuses. Also the flow in fetal organs produced different results using both methods. So the angio-technique showed more color pixels in the periphery. In 8 malignant breast tumors both methods were able to show blood flow, but the Angio-Color showed more color pixels as the conventional color did.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗

PubMed2002

Effect of opacifiers on color stability of pigmented maxillofacial silicone A-2186 subjected to artificial aging.

PURPOSE: This study was designed to determine the effect of opacifiers used at different ratios on the color stability of pigmented A-2186 silicone maxillofacial elastomers and to evaluate the color spectrophotometrically before and after artificial aging. MATERIALS AND METHODS: Sixty experimental groups of elastomers were made using various concentrations (5%, 10%, and 15%) of 4 opacifiers (Georgia kaolin powder neutral, kaolin powder calcined, Artskin white, and dry pigment titanium white) with 1 of 5 dry earth cosmetic pigment groups (no pigment [control], red, yellow ochre, burnt sienna, and a mixture of all pigments). Five specimens of each elastomer were tested, for a total of 300 specimens. All specimens were placed in an aging chamber and artificially aged by exposure to light, water spray, fluctuating temperatures, and humidity. CIE L*a*b* values were measured by spectrophotometer. The color differences (Delta E*) at various exposure energies (150, 300, and 450 kJ/m(2)) were subjected to 4-way analysis of variance with repeated measures (super ANOVA). Mean values were compared with Tukey-Kramer intervals calculated at the 0.05 significance level. RESULTS: The trained human eye can detect color changes (Delta E*) greater than 1.0. Adding all pigments to any of the kaolin groups did not protect silicone A-2186 from color degradation over time. Mixing red pigment in all groups at all times drastically increased DeltaE* values ranging from 0.1 to 1.3 up to 16.6 to 49.6. Yellow ochre had an effect only with 10% and 15% concentrations of kaolin powder calcined, increasing the value of Delta E* to greater than 1.0. Burnt sienna had an effect only with a 15% concentration of kaolin powder calcined, increasing the value of Delta E* at 300 and 450 kJ/m(2) to greater than 11.0. At the 5% concentration, kaolin powder calcined had the smallest color changes, followed by, in order, dry pigment titanium white, Artskin white, and Georgia kaolin. At the 10% concentration, Artskin white had the smallest color changes, followed by, in order, dry pigment titanium white, kaolin powder calcined, and Georgia kaolin. At the 15% concentration, Artskin white again had the smallest color changes, followed by, in order, dry pigment titanium white, Georgia kaolin, and the kaolin powder calcined. The smallest color changes in each kaolin group were at the 10% concentration for Artskin white, dry pigment titanium white, and kaolin powder calcined and at the 5% concentration for Georgia kaolin. CONCLUSIONS: Mixing dry earth cosmetic pigments with opacifiers did not protect silicone A-2186 from color degradation over time, especially in the case of red pigment. The group in which pigments were mixed with 10% Artskin white had the smallest color changes over time, followed by, in order, the groups in which pigments were mixed with 10% dry pigment titanium white, 10% kaolin powder calcined, and 5% Georgia kaolin. Red pigment had a significant effect on all opacifiers, especially Georgia kaolin and kaolin powder calcined. Yellow ochre and burnt sienna had an effect only on 15% kaolin powder calcined. Among all the pigment groups tested, yellow ochre remained the most color stable over time.

Analysis of Variance↗

PubMed2000

Color-to-figure matching in Alzheimer's disease.

Thirty-three patients with probable Alzheimer's disease were examined on a standardized Color-to-Figure Matching Test (CFMT) for which patients select appropriate colors from a set of colored pencils to match outline pictures of common objects. Seven patients performing below the CFMT cut-off score were further assessed using other tests investigating the naming of these outline pictures of common objects as well as the naming and sorting of colors: One patient performed badly in all tests; three other patients could not be considered true cases of poor object-color retrieval because of their inability to name the objects; and in the remaining three patients with unimpaired object naming (although two of them had word-finding difficulties), their impaired object-color retrieval was found to dissociate from both color sorting and color naming. These findings support the notion of a separation of pure color processing from object-color knowledge. Thus for patients with Alzheimer's disease, there is evidence in a few instances for a dissociation between object-color retrieval and both color sorting and color naming.

Journal Article↗

PubMed2003

Computer-synthesis of an interference color chart of human tear lipid layer, by a colorimetric approach.

PURPOSE: To synthesize an interference color chart for the specific tear lipid layer interference camera, DR-1, for the conversion of the tear film lipid layer thickness into color graphic information--that is, for the quantification of the tear interference image--by a colorimetric approach. METHODS: Because the color of the tear lipid layer interference image is visualized by a white light source interference phenomena, to produce gamma-corrected red, green, and blue (RGB) values of a specific interference color at a certain tear lipid film thickness, XYZ tristimulus values of the Commission Internationale de l'Eclairage (CIE) were obtained. XYZ tristimulus values were calculated from the light source spectrum of the DR-1 camera, the color-matching function of CIE, and the reflectance of the tear interference image in wavelengths ranging from 380 to 780 nm. These calculated interference colors were synthesized ranging from 0 nm to 1000 nm of lipid film thickness to produce a color chart. The applicability of the new color chart in the analysis of the lipid layer thickness was tested on a healthy control subject with normal tear function and a patient with dry eye who had aqueous tear deficiency and meibomian gland obstruction. RESULTS: The specific tear interference color chart for the DR-1 camera was obtained with RGB and XYZ tristimulus values. The interference chart ranged from 0 to approximately the 5th interference order. The interference colors from clinical DR-1 images could be converted to lipid thickness data by using the color chart system. CONCLUSIONS: A new tear interference color chart was developed in this study, which may be of benefit in converting tear interference color information to data describing the thickness of the tear film lipid layer.

Adult↗

PubMed2000

Upper-limit luminance for the surface-color mode appearance.

A series of experiments were carried out to reveal determinants for the mode of color appearance by measuring the upper-limit luminance of a color chip for the surface-color mode. We used a CRT color monitor to present test and surround stimuli in the surface-color mode. The stimuli were composed of a three-by-three array of color chips on a gray background with a white frame. The observer increased the luminance of a center test color until it just ceased to appear in the surface-color mode. Our results show that this upper-limit luminance was different among test colors, but their brightnesses, calculated from the luminance and brightness/ luminance values, were almost the same and were slightly below the brightness of the white frame. The existence of the surrounding color chips affected the results, but their sizes and spatial arrangements did not. When all of the luminances of the surrounds changed equally, the upper-limit luminances of the test colors for the surface-color mode appearance changed by the same ratio. This result indicates that the brightness of a target was a determinant for selecting the mode of color appearance and that the brightest surround stimulus acted as a cue for determining the judgment.

Journal Article↗

PubMed1998

[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↗

PubMed2000

Color stability of new-generation indirect resins for prosthodontic application.

STATEMENT OF PROBLEM: Several new-generation indirect resins are being advocated for full contour restoration of teeth. Previous indirect resin systems have failed in this application, due in part to color instability. PURPOSE: This study evaluated and characterized the color stability of various new-generation indirect resins (ceramic-polymers) when subjected to accelerated aging. MATERIAL AND METHODS: Four new-generation indirect resin systems, 1 direct resin system, and 1 dental porcelain control were subjected to accelerated aging for a period of 300 hours. Initial specimen color parameters were determined in the Commission International de l'Eclairage Lab (CIELAB) color order system with a colorimeter. Color changes (DeltaE) were calculated between baseline color measurements and measurements made after 150 and 300 hours of accelerated aging. Color difference data were subjected to a 1-way analysis of variance to examine the interaction between material and time interval of aging. Where significant interactions occurred, a least-squared means test was performed to identify differences in the color stability between the materials (P </=.05). RESULTS: After 300 hours of accelerated aging, color changes of the indirect resins ranged between 0.62 and 3.40 DeltaE units. Two of the products tested demonstrated color stability that was not significantly different from the porcelain control. CONCLUSION: All the indirect resins tested demonstrated color stability at or below a quantitative level that would be considered clinically acceptable. Color changes of ceramic-polymers occurred because of changes in chroma, rather than alterations in lightness.

Analysis of Variance↗

PubMed1996

Color stability: denture base resins processed with the microwave method.

Several quick heat-cured denture base resin systems and microwave processing resins have been introduced to provide easier and faster processing. The microwave processing method is the fastest of the heat-cured processing methods. Conventional acrylic resins processed with the microwave method seem to possess adequate physical properties, and one study indicated that a microwave acrylic resin was reasonably color stable under conditions of accelerated aging, although manufacturers do not recommend using them for microwave processing. The purpose of this study was to evaluate the color stability of seven conventional and one microwave heat-cured denture base materials processed with the microwave method. The samples were subjected to conditions of accelerated aging to test for color stability. The color stability was quantitatively measured and color measurements were made before weathering and at 300, 600, and 900 hours. The mean color change for each sample group was statistically analyzed with polynomial regression to determine the pattern of color change over time. The differences in color change for the acrylic resins were significant for all materials, but the color change for Lucitone Hy-pro was not noticeable on visual examination. The results of this study revealed that color changes occurred after accelerated aging in heat-cured denture base resins and Acron GC microwave acrylic resins processed with the microwave method. Hy-pro and TruTone materials exhibited the least color change; Hy-pro material was the most color stable material.

Acrylic Resins↗

PubMed2001

Ultrasound estimate of amniotic fluid volume: color Doppler overdiagnosis of oligohydramnios.

OBJECTIVE: To determine if concurrent use of color Doppler affects ultrasound estimates of amniotic fluid (AF) volume. METHODS: Study gravidas underwent ultrasound estimations of AF volume subjectively (visualization without measurements) and objectively (using amniotic fluid index [AFI]) and single-deepest pocket techniques, without and with concurrent color Doppler. Amniocentesis with the dye-dilution technique to measure actual AF volume was utilized for comparison. RESULTS: Sixty-seven women at a mean gestational age of 37.1 +/- 2.5 weeks were entered into this investigation between June 1999 and March 2000. Dye-determined AF volume was classified as low in 18 patients and as high in seven, with the remaining 42 within normal range. Using either ultrasound technique with color Doppler produced significantly lower estimates of AF volume (9.3 +/- 4.9) compared to those without color ([11.6 +/- 5], P <.001) for the AFI and (3.7 +/- 1.5) with color compared to those without color ([4.5 +/- 1.5], P <.003) for the single-deepest pocket. Using AFI without color identified two of 67 (3%) of the pregnancies as having low fluid compared to 14 of 67 ([21%] P =.002) using color. The increased classification of oligohydramnios with color did not accurately identify a greater number of dye-determined low volumes; instead, the AFI with color mislabeled nine pregnancies with normal fluid as low. The diagnosis of dye-determined low and high fluid volumes was not significantly different with or without color. CONCLUSION: Concurrent use of color Doppler with AFI measurements leads to the overdiagnosis of oligohydramnios.

Adolescent↗

PubMedDate not supplied

The dilemma of color deficiency and art.

No "major" painter is known to be color deficient. Are there truly no color deficient artists, or have they not been recognized? The historical literature cites criteria for recognizing color deficiency in artists, but they are hard to apply without knowing the intentions of an artist. The work and commentary of a color-deficient artist who works currently in Paris are presented as an example. He uses a limited palette of colors, based on advice from colleagues as much as his own perceptions, and he uses colors in ways that do not always fit with expectations for color deficiency. Biographies of earlier painters suggest that there were a few whose color sense was poor, but these painters used assistants to help. The color sense of others, such as the English landscape painter John Constable (1776-1837), has been questioned because of a preponderance of suspicious color, such as murky green. However, there are good reasons to doubt that Constable was color deficient. It is instructive to know how proven color deficiency has influenced an artist's style. When medical information is unavailable, the best advice for the diagnostically-inclined observer is just to enjoy the art.

Color Perception↗

PubMed2003

Color and motion: which is the tortoise and which is the hare?

Recent psychophysical studies have been interpreted to indicate that the perception of motion temporally either lags or is synchronous with the perception of color. These results appear to be at odds with neurophysiological data, which show that the average response-onset latency is shorter in the cortical areas responsible for motion (e.g., MT and MST) than for color processing (e.g., V4). The purpose of this study was to compare the perceptual asynchrony between motion and color on two psychophysical tasks. In the color correspondence task, observers indicated the predominant color of an 18 degrees x 18 degrees field of colored dots when they moved in a specific direction. On each trial, the dots periodically changed color from red to green and moved cyclically at 15, 30 or 60 deg/s in two directions separated by 180 degrees, 135 degrees, 90 degrees or 45 degrees. In the temporal order judgment task, observers indicated whether a change in color occurred before or after a change in motion, within a single cycle of the moving-dot stimulus. In the color correspondence task, we found that the perceptual asynchrony between color and motion depends on the difference in directions within the motion cycle, but does not depend on the dot velocity. In the temporal order judgment task, the perceptual asynchrony is substantially shorter than for the color correspondence task, and does not depend on the change in motion direction or the dot velocity. These findings suggest that it is inappropriate to interpret previous psychophysical results as evidence that motion perception generally lags color perception. We discuss our data in the context of a "two-stage sustained-transient" functional model for the processing of various perceptual attributes.

Analysis of Variance↗

PubMed2003

Achromatopsia, color vision, and cortex.

Brain damage can entirely abolish color vision in cases of complete achromatopsia. Other processes that depend on wavelength differences, however, can be retained. Form and motion defined by pure color differences can be perceived readily even when the colors themselves cannot be told apart. The loss of color vision in cerebral achromatopsia has been equated with the loss of a "color center" presumed indispensable for the phenomenal experience of hue. The "color center" has been assigned a role in the cortical construction of color, specifically in implementing the computations that underlie color constancy. Many features of the condition are consistent with this account. Other neurologic patients, however, retain conscious experience of hue, yet fail to disentangle the illuminant and the reflectance properties of surfaces. For them, color experience is determined by the wavelength composition of light reflected from a surface. If their wavelength-dependent vision is mediated by activity in early visual areas, then it is difficult to understand why these areas are unable to perform a similar role when they remain intact in achromatopsic observers. The prevalence of cells in the ventral visual areas of the monkey brain that code color and the further fractionation of color-related areas in human observers revealed by functional imaging suggest multiple color areas. Their different contributions are only just beginning to become apparent.

Brain Diseases↗