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At least 343 records · Page 19Linked to original sources
PubMed1992

The Bezold-Brücke effect in the color vision system of the honeybee.

Evidence is presented that intensity dependent color shifts (Bezold-Brücke effect) occur in the color vision system of the honeybee. The evidence comes from a fit between the choices of monochromatic lights in training experiments (Menzel, R., 1981; Journal of Comparative Physiology A, 141, 389-393) and the choice percentages derived now from recently presented quantitative predictions from the color opponent coding (COC) model for the bee (Backhaus, W., 1991; Vision Research, 31, 1381-1397) for the Bezold-Brücke effect. The only open parameter in the simulations of the training experiments is an experiment type dependent factor describing the weighting of color differences (judgement values) in the choice behavior. The results show (1) that the Bezold-Brücke effect exists in the bee. The results (2) confirm the color opponent coding (COC) model which was developed to describe the physiological components of the color vision system in the bee, (3) the general psychophysical assumptions about the structure of the color space, (4) the color difference formula, and (5) the general psychophysical assumptions about the (triadic) structure of judgements as tested in color similarity experiments.

Animals↗
PubMed1997

Color vision discrimination in the capuchin monkey Cebus apella: evidence for trichromaticity.

Primates display significant differences in color vision. The purpose of this study was to assess the ability of capuchin monkeys in discriminating chromatic and achromatic Munsell color chips through behavioral tests. The subjects were trained in a simple and reverse discrimination learning procedure. All subjects were capable of discriminations along five color categories investigated. The results are discussed in terms of the hypothesis of male dichromatism in New World monkeys, the role of color vision in adaptation to feeding ecology, as well as to aspects regarding primate evolution.

Animals↗
PubMed1952

[Color vision].

Explore the source record for details and available documents.

Color Perception↗
PubMed1953

[Color vision].

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Color Perception↗
PubMed1996

[Color vision test for detection and evaluation of dyschromatopsia].

METHODS: The color vision test for diagnosis and evaluation of the dyschromatopsias consists of a set of 92 colored test charts of the pseudochromatic type, a lamp and a test report giving a graphic image of the sensitivity to color deficiency. RESULTS: The test makes it possible to identify each neutral zone of all types of dyschromatopsia, places the neutral zone within the color spectrum and establishes its extent according to 6 axes (Protan, Deutan, Tritan, Tetartan, Scotopic and Monochromatic) and 10 levels. The visual sensitivity to color is measured on a 10 point scale, just as visual acuity is. Between a normal sensitivity to color, which is marked 1, and an anopia (i.e complete lack of visual sensitivity to color along one axis), marked 0, there are 9 intermediary levels marked 0.9; 0.8: 0.7; 0.6: 0.5; 0.4; 0.3; 0.2 and 0.1. CONCLUSION: Testing is important for all kinds of eye diseases or common diseases which affect eyesight making possible not only early diagnosis of a disease but also treatment follow-up.

Color Perception Tests↗
PubMed1980

Filter-mediated color vision with one visual pigment.

The compound eye of the grasshopper Phlaeoba has alternating bands that appear clear or brown. Electroretinograms recorded from the individual bands have different action spectra: The spectrum of the clear band peaks at 525 nanometers and that of the brown band at 545 nanometers. Spectrally selective whole-eye adaptation with light of eight long of short wavelength yields identical action spectra. This evidence suggests that this eye has only one visual pigment, whose spectrum is altered in the brown bands by a screening pigment. In behavioral tests of spontaneous choices between stimuli that appear green to the normal human and those that appear red, the green stimuli are preferred even when the relative intensity is varied by 0.9 log units around the equal-brightness level (determined by the electroretinogram). When some red light is mixed with the green light, the preference for the mixture is less than for the green light alone, even though the mixture is more intense. True color vision therefore seems to exist. Painting the bands shows that behavioral color vision requires the presence of both types. These data suggest that Phlaeoba has true color vision mediated by one visual pigment and suitable optical filters.

Animals↗
PubMed1981

Color vision and other parameters of macular function after retinal reattachment.

Patients with a preoperatively detached macula and operated upon between October 1976 and July 1978 were analyzed for three parameters of macular function after surgical repair. Reattachment was achieved by cryopexy, an external sponge plombage and nondrainage. The observation period was a minimum of 1 year. Visual acuity increased in all patients with a maximum improvement in the first 3 months after macular reattachment. Color vision was postoperatively defective in every second patient. In the majority of cases it was a trito disturbance. The disturbance in color vision was most prominent in patients over 60 years old. During the period of 1 year, normalization of color vision occurred for the most part only in patients under 60 years of age. Metamorphopsia proved to be the most sensitive indicator of an episode of previous macular detachment. It occurred in every patient independently of age and was still present at the end of 1 year. It could be considered as a 'scar in the Amsler grid.' The occurrence of metamorphopsia was independent of whether subretinal fluid was drained or allowed to absorb spontaneously.

Adult↗
PubMed2003

The role of lenticular senescence in age-related color vision changes.

PURPOSE: It has been reported that greater age-related losses in sensitivity occur for short-wavelength visual stimuli than for medium- and long-wavelength visual stimuli. The purpose of the current experiment was to determine to what extent optical, receptoral, and postreceptoral factors contribute to these age-related changes in color vision. METHODS: One hundred two observers (ages 18-87) completed a minimum motion task to determine isoluminance between red and green and between red and blue. A motion-nulling task was also performed to assess the L-M postreceptoral chromatic mechanism. RESULTS: No significant age-related changes occurred in red-green isoluminance values. Red-blue isoluminance values showed a significant and systematic decrease with age in observers with phakic eyes. Pseudophakic eyes in older subjects performed this task as well as phakic eyes in young subjects. The motion-nulling results demonstrated small age-related losses in the postreceptoral color mechanisms. CONCLUSIONS: The findings of this experiment, particularly those of the red-blue isoluminance task, indicate that the optical factor of lenticular senescence is the main contributor to the age-related changes observed in color vision. A model based on age-related changes in lenticular absorbance shows good fit with the experimental data of observers with phakic eyes, suggesting that optical factors are the main cause of the age-related changes in these color vision tasks.

Adolescent↗
PubMed2003

Detecting color vision in a malingerer.

A patient describing himself as totally color blind was ordered by the judicial system to have his color vision investigated in order to establish his suitability for military service. Basic clinical (Farnsworth Panel D-15, Moreland and Rayleigh anomaloscope equations), electroretinographic (ERG) and psychophysical techniques (spectral sensitivities) were applied to determine the extent of his color discrimination performance and cone function. These standard procedures were complemented by a test for cone interaction (transient tritanopia) and by newly developed cone-isolating flicker large-field ERG recordings. The patient's data consistently indicate the function as well as the functional interaction of the middle-wavelength-sensitive (M-) and the short-wavelength-sensitive (S-) cones. But the function of the long-wavelength-sensitive (L-) cones was completely absent. Hence the patient was correctly demonstrated to be a protanope. This study establishes that standard classical procedures, in combination with newly developed and easy to apply psychophysical and ERG ones, which can be reliably used to assess true color discrimination performance, in difficult cases of malingering.

Adult↗
PubMed1999

[Representation of normal and pathologic macular color vision].

INTRODUCTION: The computerized chromatic test allows a graphic visualization of the colors perceived by normal and pathologic retina. MATERIAL AND METHOD: This test was returned by an album (six series of plates with ten levels of saturation), a lamp and a program for graphic representation. RESULTS: The graphic image was returned by the computer. For a normal eye, the aspect of the chart was a set of ten concentric saturation levels: the most saturated circle were located on the outside. For an acquired or congenital dyschromatopsia, the limits of the neutral zone are located in the center and are constituted by the most saturated level of blind charts of the album. DISCUSSION AND CONCLUSION: The informatized chromatic test is a very easy one to appreciate color vision defects.

Color Perception Tests↗