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Sample records for colour vision impairment

  1. Colour Vision Impairment in Young Alcohol Consumers.

    PubMed

    Brasil, Alódia; Castro, Antônio José O; Martins, Isabelle Christine V S; Lacerda, Eliza Maria C B; Souza, Givago S; Herculano, Anderson Manoel; Rosa, Alexandre Antônio M; Rodrigues, Anderson R; Silveira, Luiz Carlos L

    2015-01-01

    Alcohol consumption among young adults is widely accepted in modern society and may be the starting point for abusive use of alcohol at later stages of life. Chronic alcohol exposure can lead to visual function impairment. In the present study, we investigated the spatial luminance contrast sensitivity, colour arrangement ability, and colour discrimination thresholds on young adults that weekly consume alcoholic beverages without clinical concerns. Twenty-four young adults were evaluated by an ophthalmologist and performed three psychophysical tests to evaluate their vision functions. We estimated the spatial luminance contrast sensitivity function at 11 spatial frequencies ranging from 0.1 to 30 cycles/degree. No difference in contrast sensitivity was observed comparing alcohol consumers and control subjects. For the evaluation of colour vision, we used the Farnsworth-Munsell 100 hue test (FM 100 test) to test subject's ability to perform a colour arrangement task and the Mollon-Reffin test (MR test) to measure subject's colour discrimination thresholds. Alcohol consumers made more mistakes than controls in the FM100 test, and their mistakes were diffusely distributed in the FM colour space without any colour axis preference. Alcohol consumers also performed worse than controls in the MR test and had higher colour discrimination thresholds compared to controls around three different reference points of a perceptually homogeneous colour space, the CIE 1976 chromaticity diagram. There was no colour axis preference in the threshold elevation observed among alcoholic subjects. Young adult weekly alcohol consumers showed subclinical colour vision losses with preservation of spatial luminance contrast sensitivity. Adolescence and young adult age are periods of important neurological development and alcohol exposure during this period of life might be responsible for deficits in visual functions, especially colour vision that is very sensitive to neurotoxicants.

  2. Colour Vision Impairment in Young Alcohol Consumers

    PubMed Central

    Brasil, Alódia; Castro, Antônio José O.; Martins, Isabelle Christine V. S.; Lacerda, Eliza Maria C. B.; Souza, Givago S.; Herculano, Anderson Manoel; Rosa, Alexandre Antônio M.; Rodrigues, Anderson R.; Silveira, Luiz Carlos L.

    2015-01-01

    Alcohol consumption among young adults is widely accepted in modern society and may be the starting point for abusive use of alcohol at later stages of life. Chronic alcohol exposure can lead to visual function impairment. In the present study, we investigated the spatial luminance contrast sensitivity, colour arrangement ability, and colour discrimination thresholds on young adults that weekly consume alcoholic beverages without clinical concerns. Twenty-four young adults were evaluated by an ophthalmologist and performed three psychophysical tests to evaluate their vision functions. We estimated the spatial luminance contrast sensitivity function at 11 spatial frequencies ranging from 0.1 to 30 cycles/degree. No difference in contrast sensitivity was observed comparing alcohol consumers and control subjects. For the evaluation of colour vision, we used the Farnsworth-Munsell 100 hue test (FM 100 test) to test subject’s ability to perform a colour arrangement task and the Mollon-Reffin test (MR test) to measure subject’s colour discrimination thresholds. Alcohol consumers made more mistakes than controls in the FM100 test, and their mistakes were diffusely distributed in the FM colour space without any colour axis preference. Alcohol consumers also performed worse than controls in the MR test and had higher colour discrimination thresholds compared to controls around three different reference points of a perceptually homogeneous colour space, the CIE 1976 chromaticity diagram. There was no colour axis preference in the threshold elevation observed among alcoholic subjects. Young adult weekly alcohol consumers showed subclinical colour vision losses with preservation of spatial luminance contrast sensitivity. Adolescence and young adult age are periods of important neurological development and alcohol exposure during this period of life might be responsible for deficits in visual functions, especially colour vision that is very sensitive to neurotoxicants. PMID

  3. Colour vision impairment and alcohol consumption.

    PubMed

    Mergler, D; Blain, L; Lemaire, J; Lalande, F

    1988-01-01

    The relationship between alcohol intake and colour discrimination capacity was examined among 136 persons of whom 16 were undergoing treatment in a detoxification centre. Current weekly alcohol consumption (or prior to treatment for those in the centre) was obtained with a detailed questionnaire, which divided week and weekend drinking into types of alcohol (beer, wine, spirits). Alcohol consumption varied from 0-5824 g/week; median: 266 g/week. Qualitative and quantitative assessment of acquired dyschromatopsia was obtained with a colour arrangement test, the Lanthony D-15 desaturated panel. In all age categories, the prevalence of dyschromatopsia increased with alcohol intake. Moreover, all the heavy drinkers (greater than 751 g/week) presented a certain degree of dyschromatopsia, whether or not they were undergoing treatment for alcoholism in a detoxification centre. Colour loss was primarily in the blue-yellow range; however, 4 of the 16 persons from the detoxification centre presented complex dyschromatopsia patterns including red-green loss. This raises the question of possible progressive deterioration. Multiple regression analysis showed that colour vision loss was significantly related to both age (p less than 0.001) and alcohol intake (p less than 0.01). These results underline the importance of taking into account the contribution of alcohol consumption in studies on acquired dyschromatopsia.

  4. Blue-yellow colour vision impairment and cognitive deficits in occasional and dependent stimulant users.

    PubMed

    Hulka, Lea M; Wagner, Michael; Preller, Katrin H; Jenni, Daniela; Quednow, Boris B

    2013-04-01

    Specific blue-yellow colour vision impairment has been reported in dependent cocaine users and it was postulated that drug-induced changes in retinal dopamine neurotransmission are responsible. However, it is unclear whether these changes are confined to chronic cocaine users, whether they are specific for dopaminergic stimulants such as cocaine and amphetamine and whether they are related to cognitive functions such as working memory, encoding and consolidation. In 47 occasional and 29 dependent cocaine users, 23 MDMA (commonly known as 'ecstasy') users and 47 stimulant-naive controls, colour vision discrimination was measured with the Lanthony Desaturated Panel D-15 Test and memory performance with the Auditory Verbal Learning Test. Both occasional and dependent cocaine users showed higher colour confusion indices than controls. Users of the serotonergic stimulant MDMA (26%), occasional (30%) and dependent cocaine users (34%) exhibited more frequent blue-yellow colour vision disorders compared to controls (9%). Inferior performance of MDMA users was caused by a subgroup with high amphetamine co-use (55%), while MDMA use alone was not associated with decreased blue-yellow discrimination (0%). Cognitive performance was worse in cocaine users with colour vision disorder compared to users and controls with intact colour vision and both colour vision impairment and cognitive deficits were related to cocaine use. Occasional cocaine and amphetamine use might induce blue-yellow colour vision impairment, whereas the serotonergic stimulant MDMA does not impair colour vision. The association between colour vision impairment and cognitive deficits in cocaine users may reflect that retinal and cerebral dopamine alterations are linked to a certain degree.

  5. Colour, vision and ergonomics.

    PubMed

    Pinheiro, Cristina; da Silva, Fernando Moreira

    2012-01-01

    This paper is based on a research project - Visual Communication and Inclusive Design-Colour, Legibility and Aged Vision, developed at the Faculty of Architecture of Lisbon. The research has the aim of determining specific design principles to be applied to visual communication design (printed) objects, in order to be easily read and perceived by all. This study target group was composed by a selection of socially active individuals, between 55 and 80 years, and we used cultural events posters as objects of study and observation. The main objective is to overlap the study of areas such as colour, vision, older people's colour vision, ergonomics, chromatic contrasts, typography and legibility. In the end we will produce a manual with guidelines and information to apply scientific knowledge into the communication design projectual practice. Within the normal aging process, visual functions gradually decline; the quality of vision worsens, colour vision and contrast sensitivity are also affected. As people's needs change along with age, design should help people and communities, and improve life quality in the present. Applying principles of visually accessible design and ergonomics, the printed design objects, (or interior spaces, urban environments, products, signage and all kinds of visually information) will be effective, easier on everyone's eyes not only for visually impaired people but also for all of us as we age.

  6. Colour vision deficiency.

    PubMed

    Simunovic, M P

    2010-05-01

    Colour vision deficiency is one of the commonest disorders of vision and can be divided into congenital and acquired forms. Congenital colour vision deficiency affects as many as 8% of males and 0.5% of females--the difference in prevalence reflects the fact that the commonest forms of congenital colour vision deficiency are inherited in an X-linked recessive manner. Until relatively recently, our understanding of the pathophysiological basis of colour vision deficiency largely rested on behavioural data; however, modern molecular genetic techniques have helped to elucidate its mechanisms. The current management of congenital colour vision deficiency lies chiefly in appropriate counselling (including career counselling). Although visual aids may be of benefit to those with colour vision deficiency when performing certain tasks, the evidence suggests that they do not enable wearers to obtain normal colour discrimination. In the future, gene therapy remains a possibility, with animal models demonstrating amelioration following treatment.

  7. All Vision Impairment

    MedlinePlus

    ... Home > Statistics and Data > All Vision Impairment All Vision Impairment Vision Impairment Defined Vision impairment is defined as the ... Ethnicity 2010 U.S. Age-Specific Prevalence Rates for Vision Impairment by Age and Race/Ethnicity Table for ...

  8. Color vision impairment in type 2 diabetes assessed by the D-15d test and the Cambridge Colour Test.

    PubMed

    Feitosa-Santana, Claudia; Paramei, Galina V; Nishi, Mauro; Gualtieri, Mirella; Costa, Marcelo F; Ventura, Dora F

    2010-09-01

    Color vision impairment emerges at early stages of diabetes mellitus type 2 (DM2) and may precede diabetic retinopathy or the appearance of vascular alterations in the retina. The aim of the present study was to compare the evaluation of the color vision with two different tests - the Lanthony desaturated D-15d test (a traditional color arrangement test), and the Cambridge Colour Test (CCT) (a computerized color discrimination test) - in patients diagnosed with DM2 without clinical signs of diabetic retinopathy (DR), and in sex- and age-matched control groups. Both color tests revealed statistically significant differences between the controls and the worst eyes of the DM2 patients. In addition, the degree of color vision impairment diagnosed by both tests correlated with the disease duration. The D-15d outcomes indicated solely tritan losses. In comparison, CCT outcomes revealed diffuse losses in color discrimination: 13.3% for best eyes and 29% for worst eyes. In addition, elevation of tritan thresholds in the DM2 patients, as detected by the Trivector subtest of the CCT, was found to correlate with the level of glycated hemoglobin. Outcomes of both tests confirm that subclinical losses of color vision are present in DM2 patients at an early stage of the disease, prior to signs of retinopathy. Considering the advantages of the CCT test compared to the D-15d test, further studies should attempt to verify and/or improve the efficiency of the CCT test.

  9. Colour vision requirements of firefighters.

    PubMed

    Margrain, T H; Birch, J; Owen, C G

    1996-04-01

    To perform their job safely firefighters must be able to identify colours on industrial gas cylinders, portable fire extinguishers, road traffic signals and several pieces of firefighting equipment. Although good colour vision is necessary we believe that the existing colour vision standard, which bars entry to the fire service to applicants who fail more than two plates of the Ishihara test, is unnecessarily stringent. We have identified and quantified the colour coded information encountered by firefighters. Colours were plotted on the CIE chromaticity diagram (1931) and isochromatic zones, which document the colour confusions of colour deficient observers, superimposed. This novel technique established possible colour confusions in different types of colour deficiency. Analysis of the results showed that red/green dichromats (protanopes and deuteranopes), severe deuteranomalous trichromats who fail the Farnsworth D15 test, and protanomalous trichromats are unsuitable for firefighting work. However, people with slight deuteranomalous trichromatism who pass the D15 test, are not disadvantaged and can be employed safely as firefighters. A new colour vision standard and a new testing procedure is recommended.

  10. Evolution of colour vision in mammals.

    PubMed

    Jacobs, Gerald H

    2009-10-12

    Colour vision allows animals to reliably distinguish differences in the distributions of spectral energies reaching the eye. Although not universal, a capacity for colour vision is sufficiently widespread across the animal kingdom to provide prima facie evidence of its importance as a tool for analysing and interpreting the visual environment. The basic biological mechanisms on which vertebrate colour vision ultimately rests, the cone opsin genes and the photopigments they specify, are highly conserved. Within that constraint, however, the utilization of these basic elements varies in striking ways in that they appear, disappear and emerge in altered form during the course of evolution. These changes, along with other alterations in the visual system, have led to profound variations in the nature and salience of colour vision among the vertebrates. This article concerns the evolution of colour vision among the mammals, viewing that process in the context of relevant biological mechanisms, of variations in mammalian colour vision, and of the utility of colour vision.

  11. Thresholds and noise limitations of colour vision in dim light.

    PubMed

    Kelber, Almut; Yovanovich, Carola; Olsson, Peter

    2017-04-05

    Colour discrimination is based on opponent photoreceptor interactions, and limited by receptor noise. In dim light, photon shot noise impairs colour vision, and in vertebrates, the absolute threshold of colour vision is set by dark noise in cones. Nocturnal insects (e.g. moths and nocturnal bees) and vertebrates lacking rods (geckos) have adaptations to reduce receptor noise and use chromatic vision even in very dim light. In contrast, vertebrates with duplex retinae use colour-blind rod vision when noisy cone signals become unreliable, and their transition from cone- to rod-based vision is marked by the Purkinje shift. Rod-cone interactions have not been shown to improve colour vision in dim light, but may contribute to colour vision in mesopic light intensities. Frogs and toads that have two types of rods use opponent signals from these rods to control phototaxis even at their visual threshold. However, for tasks such as prey or mate choice, their colour discrimination abilities fail at brighter light intensities, similar to other vertebrates, probably limited by the dark noise in cones.This article is part of the themed issue 'Vision in dim light'.

  12. Colour Vision Deficiency and Physics Teaching

    ERIC Educational Resources Information Center

    Maule, Louise; Featonby, David

    2016-01-01

    1 in 12 males suffer from some form of colour vision deficiency (CVD) which in the present colour dominated world of education presentation can be a severe disadvantage. Although aware of "colourblindness" most teachers make little or no adjustment for these pupils for whom tasks may be more difficult. This article examines colour vision…

  13. Colour vision deficiency and physics teaching

    NASA Astrophysics Data System (ADS)

    Maule, Louise; Featonby, David

    2016-05-01

    1 in 12 males suffer from some form of colour vision deficiency (CVD) which in the present colour dominated world of education presentation can be a severe disadvantage. Although aware of ‘colourblindness’ most teachers make little or no adjustment for these pupils for whom tasks may be more difficult. This article examines colour vision deficiency and looks at ways in which we can help the many students who have this problem.

  14. Impairment of Colour Vision in Diabetes with No Retinopathy: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SNDREAMS- II, Report 3)

    PubMed Central

    Gella, Laxmi; Raman, Rajiv; Kulothungan, Vaitheeswaran; Pal, Swakshyar Saumya; Ganesan, Suganeswari; Sharma, Tarun

    2015-01-01

    Purpose To assess impairment of colour vision in type 2 diabetics with no diabetic retinopathy and elucidate associated risk factors in a population-based cross-sectional study. Methods This is part of Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular-genetics Study (SN-DREAMS II) which was conducted between 2007–2010. FM 100 hue-test was performed in 253 subjects with no clinical evidence of diabetic retinopathy. All subjects underwent detailed ophthalmic evaluation including cataract grading using LOCS III and 45° 4-field stereoscopic fundus photography. Various ocular and systemic risk factors for impairment of colour vision (ICV) were assessed in subjects with diabetes but no retinopathy. P value of < 0.05 was considered statistically significant. Results The mean age of the study sample was 57.08 ± 9.21 (range: 44–86 years). Gender adjusted prevalence of ICV among subjects with diabetes with no retinopathy was 39.5% (CI: 33.5–45.5). The mean total error score in the study sample was 197.77 ± 100 (range: 19–583). The risk factors for ICV in the study were women OR: 1.79 (1.00–3.18), increased resting heart rate OR: 1.04 (1.01–1.07) and increased intraocular pressure OR: 1.12 (1.00–1.24). Significant protective factor was serum high-density lipoprotein OR: 0.96 (0.93–0.99). Conclusions Acquired ICV is an early indicator of neurodegenerative changes in the retina. ICV found in diabetic subjects without retinopathy may be of non-vascular etiology. PMID:26053017

  15. Evolution of colour vision in mammals

    PubMed Central

    Jacobs, Gerald H.

    2009-01-01

    Colour vision allows animals to reliably distinguish differences in the distributions of spectral energies reaching the eye. Although not universal, a capacity for colour vision is sufficiently widespread across the animal kingdom to provide prima facie evidence of its importance as a tool for analysing and interpreting the visual environment. The basic biological mechanisms on which vertebrate colour vision ultimately rests, the cone opsin genes and the photopigments they specify, are highly conserved. Within that constraint, however, the utilization of these basic elements varies in striking ways in that they appear, disappear and emerge in altered form during the course of evolution. These changes, along with other alterations in the visual system, have led to profound variations in the nature and salience of colour vision among the vertebrates. This article concerns the evolution of colour vision among the mammals, viewing that process in the context of relevant biological mechanisms, of variations in mammalian colour vision, and of the utility of colour vision. PMID:19720656

  16. Molecular genetics of colour vision deficiencies.

    PubMed

    Deeb, Samir S

    2004-07-01

    Common variation in colour vision exists among both colour normal and colour deficient subjects. Differences at a few amino acid positions that influence the spectra of the L and M cone pigments account for most of this variation. The genes encoding the L and M photopigments are arranged in head-to-tail arrays on the X-chromosome, beginning with the L and followed by one or more M pigment genes. The L and M pigment genes are highly homologous, which predisposed them to unequal crossing over (recombination) resulting in gene deletions and in formation of L/M hybrid genes that encode a variety of pigments with either L-like or M-like spectra that account for the majority of colour vision defects. Only the first two pigment genes of the L/M array are expressed in the retina and, therefore, need to be considered in predicting colour vision. A common single amino acid polymorphism (serine or alanine) at position 180 of the L-pigment plays an important role both in variation in normal colour vision and in the severity of colour vision defects. Blue cone monochromacy is a rare form of colour vision deficiency that results from mutations that abolish function of both the L and M pigment genes. All the above defects are inherited as X-linked recessive traits. Tritanopia is also a rare autosomal dominant colour vision defect caused by mutations in the S pigment gene located on chromosome 7. Total colour blindness (achromatopsia or rod monochromacy) is a rare autosomal recessive trait caused by mutations in genes encoding the proteins of the photoreceptor cation channel or cone transducin that are essential for function of all classes of cone.

  17. Colour vision through intraocular lens.

    PubMed

    Mäntyjärvi, M; Syrjäkoski, J; Tuppurainen, K; Honkonen, V

    1997-04-01

    Fifty patients aged from 30 to 69 years (mean 54.7 +/- 11.3 years, SD) with a UV-protected monofocal polymethylmethacrylate intraocular lens (IOL) were examined with the Farnsworth-Munsell 100 hue (FM 100) test and the Color Vision Meter 712 anomaloscope. The spectral transmission of the same kind of IOLs as was used surgically was measured with Lambda 2 UV/VIS Spectrometer. In the FM 100 test, there was no significant difference between the results of the IOL eyes and normal eyes. However, the IOL eyes showed better error scores than the normal eyes in the blue-purple box IV in the FM 100 test. In the anomaloscope testing, the Rayleigh (red-green) equation showed no differences between the IOL patients and controls. In the Moreland (blue) equation, however, the mid matching point was significantly shifted towards more green (meaning better blue colour sensitivity) in the IOL eyes than in the control eyes. This is due to the spectral transmission of the IOLs which showed 80-90% transmission already starting at the wavelength of about 420 nm. In comparison, the transmission of the normal human lens reaches those percentages near 500 nm or even further at advanced age.

  18. Kids' Quest: Vision Impairment

    MedlinePlus

    ... most important job. Return to Steps World-Wide Web Search Kids Health: What is Vision Impairment What ... for the Blind (AFB) created the Braille Bug web site to teach sighted children about braille, and ...

  19. Colour vision and computer-generated images

    NASA Astrophysics Data System (ADS)

    Ramek, Michael

    2010-06-01

    Colour vision deficiencies affect approximately 8% of the male and approximately 0.4% of the female population. In this work, it is demonstrated that computer generated images oftentimes pose unnecessary problems for colour deficient viewers. Three examples, the visualization of molecular structures, graphs of mathematical functions, and colour coded images from numerical data are used to identify problematic colour combinations: red/black, green/black, red/yellow, yellow/white, fuchsia/white, and aqua/white. Alternatives for these combinations are discussed.

  20. Colour-grapheme synesthesia affects binocular vision.

    PubMed

    Paffen, Chris L E; van der Smagt, Maarten J; Nijboer, Tanja C W

    2011-01-01

    In colour-grapheme synesthesia, non-coloured graphemes are perceived as being inherently coloured. In recent years, it is debated whether visual processing of synesthesia-inducing achromatic graphemes is similar to that of chromatic graphemes. Here, we exploit the phenomenon of binocular rivalry in which incompatible images presented dichoptically compete for conscious expression. Importantly, the competition only arises if the two images are sufficiently different; if the difference between the images is small, the images will fuse into a single mixed percept. We show that achromatic digits that induce synesthetic colour percepts increase the incidence of binocular rivalry compared to achromatic non-digits that do not evoke such percepts. That is, compared to achromatically perceived non-digits, synesthesia-inducing digits increase the predominance of binocular rivalry over binocular fusion. This finding shows that the synesthetic colour experience can provide the conditions for promoting binocular rivalry, much like stimulus features that induce rivalry in normal vision.

  1. The Physics of Colour Vision.

    ERIC Educational Resources Information Center

    Goldman, Martin

    1985-01-01

    An elementary physical model of cone receptor cells is explained and applied to complexities of human color vision. One-, two-, and three-receptor systems are considered, with the later shown to be the best model for the human eye. Color blindness is also discussed. (DH)

  2. Colour vision requirements in visually demanding occupations.

    PubMed

    Barbur, J L; Rodriguez-Carmona, M

    2017-03-18

    Normal trichromatic colour vision (CV) is often required as a condition for employment in visually demanding occupations. If this requirement could be enforced using current, colour assessment tests, a significant percentage of subjects with anomalous, congenital trichromacy who can perform the suprathreshold, colour-related tasks encountered in many occupations with the same accuracy as normal trichromats would fail. These applicants would therefore be discriminated against unfairly. One solution to this problem is to produce minimum, justifiable CV requirements that are specific to each occupation. This has been done successfully for commercial aviation (i.e. the flight crew) and for Transport for London train drivers. An alternative approach is to make use of new findings and the statistical outcomes of past practices to produce graded, justifiable CV categories that can be enforced. To achieve this aim, we analysed colour assessment outcomes and quantified severity of CV loss in 1363 subjects. The severity of CV loss was measured in each subject and statistical, pass/fail outcomes established for each of the most commonly used, conventional colour assessment tests and protocols. This evidence and new findings that relate severity of loss to the effective use of colour signals in a number of tasks provide the basis for a new colour grading system based on six categories. A single colour assessment test is needed to establish the applicant's CV category which can range from 'supernormal', for the most stringent, colour-demanding tasks, to 'severe colour deficiency', when red/green CV is either absent or extremely weak.

  3. Mechanisms, functions and ecology of colour vision in the honeybee.

    PubMed

    Hempel de Ibarra, N; Vorobyev, M; Menzel, R

    2014-06-01

    Research in the honeybee has laid the foundations for our understanding of insect colour vision. The trichromatic colour vision of honeybees shares fundamental properties with primate and human colour perception, such as colour constancy, colour opponency, segregation of colour and brightness coding. Laborious efforts to reconstruct the colour vision pathway in the honeybee have provided detailed descriptions of neural connectivity and the properties of photoreceptors and interneurons in the optic lobes of the bee brain. The modelling of colour perception advanced with the establishment of colour discrimination models that were based on experimental data, the Colour-Opponent Coding and Receptor Noise-Limited models, which are important tools for the quantitative assessment of bee colour vision and colour-guided behaviours. Major insights into the visual ecology of bees have been gained combining behavioural experiments and quantitative modelling, and asking how bee vision has influenced the evolution of flower colours and patterns. Recently research has focussed on the discrimination and categorisation of coloured patterns, colourful scenes and various other groupings of coloured stimuli, highlighting the bees' behavioural flexibility. The identification of perceptual mechanisms remains of fundamental importance for the interpretation of their learning strategies and performance in diverse experimental tasks.

  4. Chromatic VEP in children with congenital colour vision deficiency.

    PubMed

    Tekavčič Pompe, Manca; Stirn Kranjc, Branka; Brecelj, Jelka

    2010-09-01

    Visual evoked potentials to chromatic stimulus (cVEP) are believed to selectively test the parvocellular visual pathway which is responsible for processing information about colour. The aim was to evaluate cVEP in children with red-green congenital colour vision deficiency. VEP responses of 15 colour deficient children were compared to 31 children with normal colour vision. An isoluminant red-green stimulus composed of horizontal gratings was presented in an onset-offset manner. The shape of the waveform was studied, as well as the latency and amplitude of positive (P) and negative (N) waves. cVEP response did not change much with increased age in colour deficient children, whereas normative data showed changes from a predominantly positive to a negative response with increased age. A P wave was present in 87% of colour deficient children (and in 100% of children with normal colour vision), whereas the N wave was absent in a great majority of colour deficient children and was present in 80% of children with normal colour vision. Therefore, the amplitude of the whole response (N-P) decreased linearly with age in colour deficient children, whereas in children with normal colour vision it increased linearly. P wave latency shortened with increased age in both groups. cVEP responses differ in children with congenital colour vision deficiency compared to children with normal colour vision.

  5. Colour vision experimental studies in teaching of optometry

    NASA Astrophysics Data System (ADS)

    Ozolinsh, Maris; Ikaunieks, Gatis; Fomins, Sergejs

    2005-10-01

    Following aspects related to human colour vision are included in experimental lessons for optometry students of University of Latvia. Characteristics of coloured stimuli (emitting and reflective), determination their coordinates in different colour spaces. Objective characteristics of transmitting of colour stimuli through the optical system of eye together with various types of appliances (lenses, prisms, Fresnel prisms). Psychophysical determination of mono- and polychromatic stimuli perception taking into account physiology of eye, retinal colour photoreceptor topography and spectral sensitivity, spatial and temporal characteristics of retinal receptive fields. Ergonomics of visual perception, influence of illumination and glare effects, testing of colour vision deficiencies.

  6. Hue-specific colour memory impairment in an individual with intact colour perception and colour naming.

    PubMed

    Jakobson, L S; Pearson, P M; Robertson, B

    2008-01-15

    Cases of hue-selective dyschomatopsias, together with the results of recent optical imaging studies [Xiao, Y., Casti, A. R. R., Xiao, J., & Kaplan, E. (2006). A spatially organized representation of colour in macaque primary visual cortex. Perception, 35, ECVP Abstract Supplement; Xiao, Y., Wang, Y., & Felleman, D. J. (2003). A spatially organized representation of colour in macaque cortical area V2. Nature, 421, 535-539], have provided support for the idea that different colours are processed in spatially distinct regions of extrastriate cortex. In the present report, we provide evidence suggesting that a similar, but distinct, map may exist for representations of colour in memory. This evidence comes from observations of a young woman (QP) who demonstrates an isolated deficit in colour memory secondary to a concussive episode. Despite having normal colour perception and colour naming skills, and above-average memory skills in other domains, QP's ability to recall visually encoded colour information over short retention intervals is dramatically impaired. Her long-term memory for colour and her colour imagery skills are also abnormal. Surprisingly, however, these impairments are not seen with all hues; specifically, her ability to remember or imagine blue shades is spared. This interesting case contributes to the literature suggesting that colour perception, naming, and memory can be clinically dissociated, and provides insights into the organization of colour information in memory.

  7. From spectral information to animal colour vision: experiments and concepts

    PubMed Central

    Kelber, Almut; Osorio, Daniel

    2010-01-01

    Many animals use the spectral distribution of light to guide behaviour, but whether they have colour vision has been debated for over a century. Our strong subjective experience of colour and the fact that human vision is the paradigm for colour science inevitably raises the question of how we compare with other species. This article outlines four grades of ‘colour vision’ that can be related to the behavioural uses of spectral information, and perhaps to the underlying mechanisms. In the first, even without an (image-forming) eye, simple organisms can compare photoreceptor signals to locate a desired light environment. At the next grade, chromatic mechanisms along with spatial vision guide innate preferences for objects such as food or mates; this is sometimes described as wavelength-specific behaviour. Here, we compare the capabilities of di- and trichromatic vision, and ask why some animals have more than three spectral types of receptors. Behaviours guided by innate preferences are then distinguished from a grade that allows learning, in part because the ability to learn an arbitrary colour is evidence for a neural representation of colour. The fourth grade concerns colour appearance rather than colour difference: for instance, the distinction between hue and saturation, and colour categorization. These higher-level phenomena are essential to human colour perception but poorly known in animals, and we suggest how they can be studied. Finally, we observe that awareness of colour and colour qualia cannot be easily tested in animals. PMID:20164101

  8. Assessment of colour vision in epileptic patients exposed to single-drug therapy.

    PubMed

    López, L; Thomson, A; Rabinowicz, A L

    1999-01-01

    Diplopia, blurred vision and colour disturbances are well-known side effects associated with anti-epileptic drugs (AEDs). Farnsworth-Munsell 100-hue colour test (F-100) is an accepted and sensitive tool to detect changes in colour perception. To determine the impact of AEDs upon colour vision, we evaluated 37 consecutive patients with complex partial seizures exposed to monotherapy with phenytoin (PHT, carbamazepine (CBZ) or valproic acid (VPA). All had normal IQ and no congenital disturbances in colour vision or ocular diseases. Twenty normal controls were used for statistical analysis. Thirteen patients were exposed to PHT, 12 to CBZ and 12 to VPA. Visual colour perception was impaired in 30/37 (82%) of the study group. The most significant abnormality was detected in the blue-yellow axis in 10/13 patients exposed to PHT (p < 0.02) and in 8/12 treated with CBZ (p < 0.009). In 8/12 patients taking VPA, no significant abnormality was observed (p < 0.06). None of the studied patients complained of colour vision disturbances. Our findings strongly support the negative effect of AEDs upon colour vision discrimination, most likely due to changes at the retinal processing level. F-100 proved to be very useful to assess early toxicity due to AEDs.

  9. Colour preferences and colour vision in poultry chicks.

    PubMed

    Ham, A D; Osorio, D

    2007-08-22

    The dramatic colours of biological communication signals raise questions about how animals perceive suprathreshold colour differences, and there are long-standing questions about colour preferences and colour categorization by non-human species. This study investigates preferences of foraging poultry chicks (Gallus gallus) as they peck at coloured objects. Work on colour recognition often deals with responses to monochromatic lights and how animals divide the spectrum. We used complementary colours, where the intermediate is grey, and related the chicks' choices to three models of the factors that may affect the attractiveness. Two models assume that attractiveness is determined by a metric based on the colour discrimination threshold either (i) by chromatic contrast against the background or (ii) relative to an internal standard. An alternative third model is that categorization is important. We tested newly hatched and 9-day-old chicks with four pairs of (avian) complementary colours, which were orange, blue, red and green for humans. Chromatic contrast was more relevant to newly hatched chicks than to 9-day-old birds, but in neither case could contrast alone account for preferences; especially for orange over blue. For older chicks, there is evidence for categorization of complementary colours, with a boundary at grey.

  10. Simulating Colour Vision Deficiency from a Spectral Image.

    PubMed

    Shrestha, Raju

    2016-01-01

    People with colour vision deficiency (CVD) have difficulty seeing full colour contrast and can miss some of the features in a scene. As a part of universal design, researcher have been working on how to modify and enhance the colour of images in order to make them see the scene with good contrast. For this, it is important to know how the original colour image is seen by different individuals with CVD. This paper proposes a methodology to simulate accurate colour deficient images from a spectral image using cone sensitivity of different cases of deficiency. As the method enables generation of accurate colour deficient image, the methodology is believed to help better understand the limitations of colour vision deficiency and that in turn leads to the design and development of more effective imaging technologies for better and wider accessibility in the context of universal design.

  11. Impairments to Vision

    MedlinePlus

    ... scotoma" right where you're looking. Glaucoma and Retinitis Pigmentosa Ring or Donut Scotoma Left Field Homonymous Hemianopia Although very different diseases, both glaucoma and retinitis pigmentosa (RP) cause a loss of side vision, leading ...

  12. [Quality demands on the assessment of colour vision].

    PubMed

    Krastel, H; Kolling, G; Schiefer, U; Bach, M

    2009-12-01

    Assessing colour vision comprises a wide spectrum of methods, many of which are practical and highly informative. Given this methodological variety this review aims to help select the most appropriate test and how to correctly execute it, thus achieving the highest quality.Some aspects of the physiology of colour vision are covered as far as is necessary for a basic understanding of colour testing methodology and possible pitfalls. For congenital colour anomalies most pertinent are questions of occupational aptitude. For acquired colour deficiencies assessing colour vision supplements diagnostics of the retina and the visual pathway, allowing both early diagnosis and/or monitoring. For both these fields colour tests provide different kinds of evidence and need to be adequately selected. Methodical artefacts due to both equipment design properties and testing procedures are highlighted so they can be avoided. A form is presented for recording colour examination results commensurate with quality objectives. Finally, a tabular overview of 19 common colour vision tests is provided.

  13. Colour Vision: Understanding #TheDress.

    PubMed

    Brainard, David H; Hurlbert, Anya C

    2015-06-29

    A widely-viewed image of a dress elicits striking individual variation in colour perception. Experiments with multiple variants of the image suggest that the individual differences may arise through the action of visual mechanisms that normally stabilise object colour.

  14. Parallel inputs to memory in bee colour vision.

    PubMed

    Horridge, Adrian

    2016-03-01

    In the 19(th) century, it was found that attraction of bees to light was controlled by light intensity irrespective of colour, and a few critical entomologists inferred that vision of bees foraging on flowers was unlike human colour vision. Therefore, quite justly, Professor Carl von Hess concluded in his book on the Comparative Physiology of Vision (1912) that bees do not distinguish colours in the way that humans enjoy. Immediately, Karl von Frisch, an assistant in the Zoology Department of the same University of Münich, set to work to show that indeed bees have colour vision like humans, thereby initiating a new research tradition, and setting off a decade of controversy that ended only at the death of Hess in 1923. Until 1939, several researchers continued the tradition of trying to untangle the mechanism of bee vision by repeatedly testing trained bees, but made little progress, partly because von Frisch and his legacy dominated the scene. The theory of trichromatic colour vision further developed after three types of receptors sensitive to green, blue, and ultraviolet (UV), were demonstrated in 1964 in the bee. Then, until the end of the century, all data was interpreted in terms of trichromatic colour space. Anomalies were nothing new, but eventually after 1996 they led to the discovery that bees have a previously unknown type of colour vision based on a monochromatic measure and distribution of blue and measures of modulation in green and blue receptor pathways. Meanwhile, in the 20(th) century, search for a suitable rationalization, and explorations of sterile culs-de-sac had filled the literature of bee colour vision, but were based on the wrong theory.

  15. Behavioural evidence of colour vision in free flying stingless bees.

    PubMed

    Spaethe, J; Streinzer, M; Eckert, J; May, S; Dyer, A G

    2014-06-01

    Colour vision was first demonstrated with behavioural experiments in honeybees 100 years ago. Since that time a wealth of quality physiological data has shown a highly conserved set of trichromatic colour receptors in most bee species. Despite the subsequent wealth of behavioural research on honeybees and bumblebees, there currently is a relative dearth of data on stingless bees, which are the largest tribe of the eusocial bees comprising of more than 600 species. In our first experiment we tested Trigona cf. fuscipennis, a stingless bee species from Costa Rica in a field setting using the von Frisch method and show functional colour vision. In a second experiment with these bees, we use a simultaneous colour discrimination test designed for honeybees to enable a comparative analysis of relative colour discrimination. In a third experiment, we test in laboratory conditions Tetragonula carbonaria, an Australian stingless bee species using a similar simultaneous colour discrimination test. Both stingless bee species show relatively poorer colour discrimination compared to honeybees and bumblebees; and we discuss the value of being able to use these behavioural methods to efficiently extend our current knowledge of colour vision and discrimination in different bee species.

  16. [Inherited colour vision deficiencies--from Dalton to molecular genetics].

    PubMed

    Cvetković, Dragana; Cvetković, Dobrosav

    2005-01-01

    In recent years, great advances have been made in our understanding of the molecular basis of colour vision defects, as well as of the patterns of genetic variation in individuals with normal colour vision. Molecular genetic analyses have explained the diversity of types and degrees of severity in colour vision anomalies, their frequencies, pronounced individual variations in test results, etc. New techniques have even enabled the determination of John Dalton's real colour vision defect, 150 years after his death. Inherited colour vision deficiencies most often result from the mutations of genes that encode cone opsins. Cone opsin genes are linked to chromosomes 7 (the S or "blue" gene) and X (the L or "red" gene and the M or "green" gene). The L and M genes are located on the q arm of the X chromosome in a head-to-tail array, composed of 2 to 6 (typically 3) genes--a single L is followed by one or more M genes. Only the first two genes of the array are expressed and contribute to the colour vision phenotype. The high degree of homology (96%) between the L and M genes predisposes them to unequal recombination, leading to gene deletion or the formation of hybrid genes (comprising portions of both the L and M genes), explaining the majority of the common red-green colour vision deficiencies. The severity of any deficiency is influenced by the difference in spectral sensitivity between the opsins encoded by the first two genes of the array. A rare defect, S monochromacy, is caused either by the deletion of the regulatory region of the array or by mutations that inactivate the L and M genes. Most recent research concerns the molecular basis of complete achromatopsia, a rare disorder that involves the complete loss of all cone function. This is not caused by mutations in opsin genes, but in other genes that encode cone-specific proteins, e.g. channel proteins and transducin.

  17. Bird colour vision: behavioural thresholds reveal receptor noise.

    PubMed

    Olsson, Peter; Lind, Olle; Kelber, Almut

    2015-01-15

    Birds have impressive physiological adaptations for colour vision, including tetrachromacy and coloured oil droplets, yet it is not clear exactly how well birds can discriminate the reflecting object colours that they encounter in nature. With behavioural experiments, we determined colour discrimination thresholds of chickens in bright and dim light. We performed the experiments with two colour series, orange and green, covering two parts of chicken colour space. These experiments allowed us to compare behavioural results with model expectations and determine how different noise types limit colour discrimination. At intensities ranging from bright light to those corresponding to early dusk (250-10 cd m(-2)), we describe thresholds accurately by assuming a constant signal-to-noise ratio, in agreement with an invariant Weber fraction of Weber's law. Below this intensity, signal-to-noise ratio decreases and Weber's law is violated because photon-shot noise limits colour discrimination. In very dim light (below 0.05 cd m(-2) for the orange series or 0.2 cd m(-2) for the green series) colour discrimination is possibly constrained by dark noise, and the lowest intensity at which chickens can discriminate colours is 0.025 and 0.08 cd m(-2) for the orange and green series, respectively. Our results suggest that chickens use spatial pooling of cone outputs to mitigate photon-shot noise. Surprisingly, we found no difference between colour discrimination of chickens and humans tested with the same test in bright light.

  18. Visual ecology of flies with particular reference to colour vision and colour preferences.

    PubMed

    Lunau, Klaus

    2014-06-01

    The visual ecology of flies is outstanding among insects due to a combination of specific attributes. Flies' compound eyes possess an open rhabdom and thus separate rhabdomeres in each ommatidium assigned to two visual pathways. The highly sensitive, monovariant neural superposition system is based on the excitation of the peripheral rhabdomeres of the retinula cells R1-6 and controls optomotor reactions. The two forms of central rhabdomeres of R7/8 retinula cells in each ommatidium build up a system with four photoreceptors sensitive in different wavelength ranges and thought to account for colour vision. Evidence from wavelength discrimination tests suggests that all colour stimuli are assigned to one of just four colour categories, but cooperation of the two pathways is also evident. Flies use colour cues for various behavioural reactions such as flower visitation, proboscis extension, host finding, and egg deposition. Direct evidence for colour vision, the ability to discriminate colours according to spectral shape but independent of intensity, has been demonstrated for few fly species only. Indirect evidence for colour vision provided from electrophysiological recordings of the spectral sensitivity of photoreceptors and opsin genes indicates similar requisites in various flies; the flies' responses to coloured targets, however, are much more diverse.

  19. Dark Adaptation of Colour Vision in Diabetic Subjects

    NASA Astrophysics Data System (ADS)

    Márquez-Gamiño, S.; Cortés-Peñaloza, J. L.; Pérez-Hernández, J. U.; Cruz-Rodríguez, E.; Caudillo, C.

    2004-09-01

    Eye disease, a late complication of diabetes mellitus (DM) occurs even under a careful glicemic control. It includes optic nerve, retina, vitreous humor, crystalline lens and pupillary affection. The physiopathological process could be independent of blood glucose levels or start at initial stages of the disease. Photoreceptors have specific physiological functions. The functional substrate of day light or colour vision in superior primates, the cones have different spectral sensitivity, 455, 530 and 560 nm. The rods, maximal sensitivity at 505 nm, are much more sensitive to light than are cones. Dark adaptation was tested to evaluate functional impairment differences in photoreceptors of diabetic subjects. 14 DM2 (type 2 DM), and 5 DM1 (type 1 DM) patients, as well as 9 healthy subjects were studied. Retinal affected individuals, were excluded. Dark adaptation curves seemed to be different between DM, and healthy subjects. Cones, specially those sensitive to 560 nm type, seems to be more labile to DM, as demonstrated by the lack of sensitivity to low, and medium intensity stimuli. Medical Physics and elementary Biomedical Engineering exhibited to be useful to discern malfunction between different types of photorreceptors. The inexpensive method used could be applied for early color vision alteration detection.

  20. Correlation between dichromatic colour vision and jumping performance in horses.

    PubMed

    Spaas, Julie; Helsen, Werner F; Adriaenssens, Maurits; Broeckx, Sarah; Duchateau, Luc; Spaas, Jan H

    2014-10-01

    There is general agreement that horses have dichromatic colour vision with similar capabilities to human beings with red-green colour deficiencies. However, whether colour perception has an impact on equine jumping performance and how pronounced the colour stimulus might be for a horse is unknown. The present study investigated the relationship between the colour of the fences (blue or green) and the show jumping performance of 20 horses ridden by two riders using an indoor and outdoor set of green and blue fences. In the indoor arena, significantly more touches and faults were made on blue fences in comparison to green fences (median difference of 2.5 bars). When only touched bars were included, a significant median difference of one bar was found. Mares (n = 4) demonstrated more faults and had a significantly greater difference in touches and faults between the two colours than male horses (n = 16). Repeating the same experiment with eight horses in an outdoor grass arena revealed no significant differences between the two colours. In order to draw any definite conclusions, more research concerning the colour perception, influence of contrast with the arena surface and sex of horse is required.

  1. Ultraviolet sensitivity and colour vision in raptor foraging.

    PubMed

    Lind, Olle; Mitkus, Mindaugas; Olsson, Peter; Kelber, Almut

    2013-05-15

    Raptors have excellent vision, yet it is unclear how they use colour information. It has been suggested that raptors use ultraviolet (UV) reflections from vole urine to find good hunting grounds. In contrast, UV plumage colours in songbirds such as blue tits are assumed to be 'hidden' communication signals, inconspicuous to raptors. This ambiguity results from a lack of knowledge about raptor ocular media transmittance, which sets the limit for UV sensitivity. We measured ocular media transmittance in common buzzards (Buteo buteo), sparrowhawks (Accipiter nisus), red kites (Milvus milvus) and kestrels (Falco tinnunculus) so that, for the first time, raptor UV sensitivity can be fully described. With this information, and new measurements of vole urine reflectance, we show that (i) vole urine is unlikely to provide a reliable visual signal to hunting raptors and (ii) blue tit plumage colours are more contrasting to blue tits than to sparrowhawks because of UV reflectance. However, as the difference between blue tit and sparrowhawk vision is subtle, we suggest that behavioural data are needed to fully resolve this issue. UV cues are of little or no importance to raptors in both vole and songbird interactions and the role of colour vision in raptor foraging remains unclear.

  2. Avian retinal oil droplets: dietary manipulation of colour vision?

    PubMed Central

    Knott, Ben; Berg, Mathew L.; Morgan, Eric R.; Buchanan, Katherine L.; Bowmaker, James K.; Bennett, Andrew T. D.

    2010-01-01

    Avian vision is highly developed, with bird retinas containing rod and double-cone photoreceptors, plus four classes of single cones subserving tetrachromatic colour vision. Cones contain an oil droplet, rich in carotenoid pigments (except VS/ultraviolet-sensitive cones), that acts as a filter, substantially modifying light detected by the photoreceptor. Using dietary manipulations, we tested the effects of carotenoid availability on oil droplet absorbance properties in two species: Platycercus elegans and Taeniopygia guttata. Using microspectrophotometry, we determined whether manipulations affected oil droplet carotenoid concentration and whether changes would alter colour discrimination ability. In both species, increases in carotenoid concentration were found in carotenoid-supplemented birds, but only in the double cones. Magnitudes of effects of manipulations were often dependent on retinal location. The study provides, to our knowledge, the first experimental evidence of dietary intake over a short time period affecting carotenoid concentration of retinal oil droplets. Moreover, the allocation of carotenoids to the retina by both species is such that the change potentially preserves the spectral tuning of colour vision. Our study generates new insights into retinal regulation of carotenoid concentration of oil droplets, an area about which very little is known, with implications for our understanding of trade-offs in carotenoid allocation in birds. PMID:19939843

  3. Origins of colour vision standards within the transport industry.

    PubMed

    Vingrys, A J; Cole, B L

    1986-01-01

    Colour vision standards should reflect changes in our understanding of the nature of these defects as well as technological advances that place less importance upon the visual senses of the human operator. Therefore it is suggested that visual standards be subject to routine reviews in order to assess their suitability for modern work environments. This paper gives a chronological account of the introduction of colour vision standards by several national transport authorities and identifies historical reasons that led to their implementation. It is concluded that the same factors that gave rise to the adoption of early colour vision standards are still relevant for modern transport systems. However the recent deployment of automatic or semi-automatic control or navigational systems has substantially altered man's role from being the primary source of information input to one of a monitoring process. This has generated a good deal of debate and uncertainty regarding the level of responsibility that a human operator has for the control of modern transport vehicles. Nevertheless, it is argued that in the absence of complete automation some type of visual standard is needed whenever visual judgements must be made by human observers.

  4. Colour change in cyanosis and the confusions of congenital colour vision deficient observers.

    PubMed

    McNamara, Renae; Taylor, Clair M; McKenzie, David K; Coroneo, Minas T; Dain, Stephen J

    2010-09-01

    Visual recognition of cyanosis is an important clinical activity. While pulse oximetry is almost universal in the hospital environment, there are circumstances where it is not available or may be unreliable. Cyanosis recognition is affected by lighting colour. In addition, there is, mainly anecdotal, evidence that people with greater colour vision deficiencies (CVDs) have particular difficulty and there is no effective lighting strategy to assist in the observation. The change of blood colour with oxygenation has been shown to lie close to the direction of colour confusions made by congenital red-green dichromats. The important sites of observation are lips, nail beds and palm creases. 10 subjects who were known to be chronically hypoxaemic were recruited from the chronic respiratory program. Their blood oxygen saturation (SpO(2)) varied from 84% to 96% pre-exercise, and 61-84% post-exercise. Ten normal subjects were recruited whose SpO(2) was 99% or 100%. The spectral radiances of lips, nail beds and palm creases were measured using a telespectroradiometer and compared with the spectral radiances of a white tile of known spectral reflectances measured in the same location. This is a non-contact method of measurement, avoiding the blanching caused by pressure of contact methods. The spectral reflectances were calculated, and the chromaticities calculated for a Planckian radiator T = 4000K. Measurements on lips yielded the most consistent results. The colour changes pre- and post-exercise and compared with normal colour lie generally along a deutan confusion line. These results show the direction of the colour change and confirm the, previously anecdotal, difficulties in detecting cyanosis by observers with CVDs.

  5. Prevalence of Colour Vision Anomalies Amongst Dental Professionals and its Effect on Shade Matching of Teeth

    PubMed Central

    Maini, Anuj Paul; Wangoo, Anuj; Singh, Sukhman; Mehar, Damanpreet Kaur

    2017-01-01

    Abstract Introduction The success of a restoration is dependent on accurate shade matching of teeth leading to studies evaluating the factors affecting the perception of shades. Colour vision anomalies including colour blindness have been found to exist in the population and it has been thought to be a potential factor affecting the colour perception ability. Aim The present study was done to evaluate the prevalence of colour vision anomalies and its effect on matching of shades of teeth. Materials and Methods A total of 147 dental professionals were randomly selected for the study and were first tested for visual acuity using the Snellen’s Eye Chart so as to carry on the study with only those operators who had a vision of 6/6. Then, the Ishihara’s colour charts were used to test the operators for colour vision handicap. In the last stage of the study, test for accuracy of shade selection was done using the Vitapan Classical shade guide. The shade guide tabs were covered to avoid bias. Percentage was used to calculate the prevalence of colour vision handicap and its effect on matching of shades of teeth as compared to normal vision, which was evaluated using Chi square test. Results Nineteen operators had colour vision anomalies out of hundred operators and only two operators presented with colour blindness. Colour vision anomaly was more prevalent than colour blindness and it was also found that it was more prevalent in males than females. The difference between the accuracy of shade matching between the operators with normal vision and colour vision defect and operators with normal vision and colour blindness was statistically not significant. Conclusion Colour blindness and colour vision handicap are rare conditions, with the latter being more common in the population. According to our study, it was concluded that no statistically significant difference existed amongst the operators with normal vision and colour vision anomaly or operators with normal vision

  6. A Standalone Vision Impairments Simulator for Java Swing Applications

    NASA Astrophysics Data System (ADS)

    Oikonomou, Theofanis; Votis, Konstantinos; Korn, Peter; Tzovaras, Dimitrios; Likothanasis, Spriridon

    A lot of work has been done lately in an attempt to assess accessibility. For the case of web rich-client applications several tools exist that simulate how a vision impaired or colour-blind person would perceive this content. In this work we propose a simulation tool for non-web JavaTM Swing applications. Developers and designers face a real challenge when creating software that has to cope with a lot of interaction situations, as well as specific directives for ensuring an accessible interaction. The proposed standalone tool will assist them to explore user-centered design and important accessibility issues for their JavaTM Swing implementations.

  7. iPad colour vision apps for dyschromatopsia screening.

    PubMed

    Campbell, Thomas Gordon; Lehn, Alexander; Blum, Stefan; Airey, Caroline; Brown, Helen

    2016-07-01

    Optic neuritis (ON) is a common and important cause of vision loss or vision disturbances in the community, particularly amongst the young, and it is often associated with a persistent dyschromatopsia. Traditionally screening for dyschromatopsia has been carried out using pseudo-isochromatic Ishihara plates. These colour plates were originally developed for testing of colour blindness, and indeed have only more recently been applied to ON. As the Ishihara plate books used for testing are expensive, unwieldy, and are not commonly available in many clinics or wards, many neurologists and ophthalmologists have taken to using untested and unstudied downloadable software packages on portable electronic devices for testing. This study compared the efficacy of printed and iPad (Apple, Cupertino, CA, USA) versions of the Ishihara plates in screening for dyschromatopsia in patients who were suspected of having ON. The main finding was that dyschromatopsia testing using a commercially available application on an iPad was comparable to using the current pragmatic clinical benchmark, the pseudo-isochromatic plates of Ishihara. These findings provide support for the increasingly common practice of screening for dyschromatopsia using the iPad.

  8. Is screening for congenital colour vision deficiency in school students worthwhile? A review.

    PubMed

    Ramachandran, Nishanthan; Wilson, Graham A; Wilson, Nick

    2014-11-01

    This review analyses the literature on screening for congenital colour vision deficiency in school students, which predominantly uses the Ishihara test. The review was framed with respect to the established Wilson and Jungner criteria for screening programs. These criteria relate to the characteristics of the condition concerned, the performance of the screening test, the existence of treatment options and the performance of screening programs. The literature reviewed suggests that congenital colour vision deficiency has not been shown to increase risk of road traffic crashes and is not a preclusion to driver licensing in most developed countries. The occurrence of congenital colour vision deficiency has been used to limit entry into certain occupations; however, the value of screening school students with regard to occupational preclusion is questionable. Stronger evidence exists indicating no association between congenital colour vision deficiency and level of educational achievement. Studies showing any association between congenital colour vision deficiency and other health and lifestyle impacts were rare. The most commonly used screening test (using Ishihara pseudoisochromatic plates) performs well with respect to detecting red-green colour vision deficiencies. Finally, the only interventions we identified for congenital colour vision deficiency were management ones around the availability of specific tinted lenses and computer programs to aid colour perception in certain tasks. Given this picture, the weight of evidence appears to be in favour of not adopting (or discontinuing) routine colour vision screening programs for school students; however, it may be worthwhile for a career advisor to refer school students to an optometrist or ophthalmologist for colour vision screening, upon expression of interest in an occupation where normal colour vision is either particularly desirable or is a regulatory requirement.

  9. Colour vision in normal subjects tested by the colour arrangement test 'Roth 28-hue desaturated'.

    PubMed

    Erb, C; Adler, M; Stübiger, N; Wohlrab, M; Zrenner, E; Thiel, H J

    1998-11-01

    The aim of the study was to obtain normal values for the colour-arrangement test, Roth 28-hue desaturated. In 146 healthy non-smokers colour vision was tested monocularly. The subjects were divided into four age groups: 0-19, 20-39, 40-59, and 60-79 years. The overall error score for all groups was 54 +/- 24 (median +/- mean absolute deviation). The values for the 20-39 year group were significantly lower than those for the other groups (Kruskal-Wallis: P < 0.0001 with subsequent multiple Mann-Whitney test). An increasing predominance of errors along the blue-yellow-axis was observed with increasing age. The error scores of normal subjects tested by the Roth 28-hue desaturated were comparable with those on the well-known Farnsworth-Munsell 100-hue (FM-100). Because the Roth 28-hue desaturated is shorter and simpler to administer, it is an alternative to the FM-100 in situations that need to assess colour discrimination and error axis quantitatively and quickly.

  10. Suitability of School Textbooks for 5 to 7 Year Old Children with Colour Vision Deficiencies

    ERIC Educational Resources Information Center

    Torrents, Aurora; Bofill, Francesc; Cardona, Genis

    2011-01-01

    Purpose: The aim of the present study was to determine, through colorimetric analysis, whether school textbooks for children aged 5 to 7 years contained tasks requiring normal colour vision discrimination for their resolution. In addition, the performance of a group of observers with diverse colour vision deficiencies was evaluated while…

  11. The fiddler crab Uca mjoebergi uses colour vision in mate choice.

    PubMed

    Detto, Tanya

    2007-11-22

    Although the role of colour in mate choice is well known, few tests of colour vision have been based on mating behaviour. Females of the fiddler crab Uca mjoebergi have recently been shown to use claw coloration to recognize conspecific males. In this study I demonstrate that the females use colour vision for this task; preferentially approaching yellow claws over grey claws regardless of their intensity while failing to discriminate between yellow claws differing in intensity. This is one of only a handful of studies confirming the involvement of colour vision in mate choice and the first conclusive evidence in fiddler crabs.

  12. Environmental factors which may have led to the appearance of colour vision.

    PubMed

    Maximov, V V

    2000-09-29

    It is hypothesized that colour vision and opponent processing of colour signals in the visual system evolved as a means of overcoming the extremely unfavourable lighting conditions in the natural environment of early vertebrates. The significant flicker of illumination inherent in the shallow-water environment complicated the visual process in the achromatic case, in particular preventing early detection of enemies. The presence of two spectral classes of photoreceptors and opponent interaction of their signals at a subsequent retinal level allowed elimination of the flicker from the retinal image. This new visual function provided certain advantages concerning reaction times and favoured survival. This assumption explains why the building blocks for colour vision arose so early, i.e. just after the active predatory lifestyle was mastered. The principal functions of colour vision inherent in extant animals required a more complex neural machinery for colour processing and evolved later as the result of a change in visual function favouring colour vision.

  13. Low Vision Aids for Visually Impaired Children

    ERIC Educational Resources Information Center

    Schurink, J.; Cox, R. F. A.; Cillessen, A. H. N.; van Rens, G. H. M. B.; Boonstra, F. N.

    2011-01-01

    It is a widely accepted belief in clinical practice that children with a visual impairment can profit from the use of a low vision aid (LVA). However, we found a considerable gap in our scientific understanding of LVA use, particularly in young children. This is the reason for the analysis presented in this paper. A selected overview of LVA use in…

  14. Psychological Adjustment in Adolescents with Vision Impairment

    ERIC Educational Resources Information Center

    Pinquart, Martin; Pfeiffer, Jens P.

    2012-01-01

    The present study compared psychological adjustment of 158 adolescents with vision impairment and 158 sighted adolescents with a matched-pair design using the Strengths and Difficulties Questionnaire. Adolescent self-reports and teacher reports on emotional problems, peer problems, and total difficulties showed higher scores in students with…

  15. Indoor Spatial Updating With Impaired Vision

    PubMed Central

    Legge, Gordon E.; Granquist, Christina; Baek, Yihwa; Gage, Rachel

    2016-01-01

    Purpose Spatial updating is the ability to keep track of position and orientation while moving through an environment. We asked how normally sighted and visually impaired subjects compare in spatial updating and in estimating room dimensions. Methods Groups of 32 normally sighted, 16 low-vision, and 16 blind subjects estimated the dimensions of six rectangular rooms. Updating was assessed by guiding the subjects along three-segment paths in the rooms. At the end of each path, they estimated the distance and direction to the starting location, and to a designated target. Spatial updating was tested in five conditions ranging from free viewing to full auditory and visual deprivation. Results The normally sighted and low-vision groups did not differ in their accuracy for judging room dimensions. Correlations between estimated size and physical size were high. Accuracy of low-vision performance was not correlated with acuity, contrast sensitivity, or field status. Accuracy was lower for the blind subjects. The three groups were very similar in spatial-updating performance, and exhibited only weak dependence on the nature of the viewing conditions. Conclusions People with a wide range of low-vision conditions are able to judge room dimensions as accurately as people with normal vision. Blind subjects have difficulty in judging the dimensions of quiet rooms, but some information is available from echolocation. Vision status has little impact on performance in simple spatial updating; proprioceptive and vestibular cues are sufficient. PMID:27978556

  16. Semantic impairment disrupts perception, memory, and naming of secondary but not primary colours.

    PubMed Central

    Rogers, Timothy T.; Graham, Kim S.; Patterson, Karalyn

    2015-01-01

    To investigate how basic aspects of perception are shaped by acquired knowledge about the world, we assessed colour perception and cognition in patients with semantic dementia (SD), a disorder that progressively erodes conceptual knowledge. We observed a previously undocumented pattern of impairment to colour perception and cognition characterized by: (i) a normal ability to discriminate between only subtly different colours but an impaired ability to group different colours into categories, (ii) normal perception and memory for the colours red, green, and blue but impaired perception and memory for colours lying between these regions of a fully-saturated and luminant spectrum, and (iii) normal naming of polar colours in the opponent-process colour system (red, green, blue, yellow, white, and black) but impaired naming of other basic colours (brown, gray, pink, and orange). The results suggest that fundamental aspects of perception can be shaped by acquired knowledge about the world, but only within limits. PMID:25637227

  17. Description and measurement of handicap caused by vision impairment.

    PubMed

    Keeffe, J E; McCarty, C A; Hassell, J B; Gilbert, A G

    1999-01-01

    To develop an instrument to describe and quantify handicap caused by vision impairment an item pool was derived from focus groups and from a review of vision-related quality-of-life questionnaires. Only items related to handicap were included and grouped into five subscales. The 76-item 'Impact of Vision Impairment' was administered to 95 people who were vision impaired. Content validity was established by consultation with professionals and with people with impaired vision. Forty-six items remained after the elimination of those found to be irrelevant and others with inter-item correlation coefficients of > or = 0.7. Univariate and multivariate analyses revealed an association between visual acuity and type and degree of handicap on subscales, except emotional reaction to vision loss, which is related to cause of vision impairment. The instrument is responsive to the level of vision loss and discriminates the different performances of people with different causes of vision loss.

  18. Colour vision and background adaptation in a passerine bird, the zebra finch (Taeniopygia guttata)

    PubMed Central

    2016-01-01

    Today, there is good knowledge of the physiological basis of bird colour vision and how mathematical models can be used to predict visual thresholds. However, we still know only little about how colour vision changes between different viewing conditions. This limits the understanding of how colour signalling is configured in habitats where the light of the illumination and the background may shift dramatically. I examined how colour discrimination in zebra finch (Taeniopygia guttata) is affected by adaptation to different backgrounds. I trained finches in a two-alternative choice task, to choose between red discs displayed on backgrounds with different colours. I found that discrimination thresholds correlate with stimulus contrast to the background. Thresholds are low, and in agreement with model predictions, for a background with a red colour similar to the discs. For the most contrasting green background, thresholds are about five times higher than this. Subsequently, I trained the finches for the detection of single discs on a grey background. Detection thresholds are about 2.5 to 3 times higher than discrimination thresholds. This study demonstrates close similarities in human and bird colour vision, and the quantitative data offer a new possibility to account for shifting viewing conditions in colour vision models. PMID:27703702

  19. Colour, face, and visuospatial imagery abilities in low-vision individuals with visual field deficits.

    PubMed

    Dulin, David; Cavezian, Céline; Serrière, Coline; Bachoud-Levi, Anne-Catherine; Bartolomeo, Paolo; Chokron, Sylvie

    2011-10-01

    This study investigates to what extent visual perception integrity is necessary for visual mental imagery. Sixteen low-vision participants with severe peripheral visual field loss, 16 with severe central field loss, 6 left brain-damaged patients with right homonymous hemianopia, 6 right brain-damaged patients with left homonymous hemianopia, and 16 normally sighted controls performed perceptual and imagery tasks using colours, faces, and spatial relationships. Results showed that (a) the perceptual and mental image>ry disorders vary according to the type of visual field loss, (b) hemianopics had no more difficulties imagining spatial stimuli in their contralesional hemispace than in their ipsilesional one, and (c) the only hemianopic participant to have perceptual and mental imagery impairments suffered from attentional deficits. Results suggest that (a) visual memory is not definitively established, but rather needs perceptual practice to be maintained, and (b) that visual mental imagery may involve some of the attentional-exploratory mechanisms that are employed in visual behaviour.

  20. A neuronal circuit for colour vision based on rod-cone opponency.

    PubMed

    Joesch, Maximilian; Meister, Markus

    2016-04-14

    In bright light, cone-photoreceptors are active and colour vision derives from a comparison of signals in cones with different visual pigments. This comparison begins in the retina, where certain retinal ganglion cells have 'colour-opponent' visual responses-excited by light of one colour and suppressed by another colour. In dim light, rod-photoreceptors are active, but colour vision is impossible because they all use the same visual pigment. Instead, the rod signals are thought to splice into retinal circuits at various points, in synergy with the cone signals. Here we report a new circuit for colour vision that challenges these expectations. A genetically identified type of mouse retinal ganglion cell called JAMB (J-RGC), was found to have colour-opponent responses, OFF to ultraviolet (UV) light and ON to green light. Although the mouse retina contains a green-sensitive cone, the ON response instead originates in rods. Rods and cones both contribute to the response over several decades of light intensity. Remarkably, the rod signal in this circuit is antagonistic to that from cones. For rodents, this UV-green channel may play a role in social communication, as suggested by spectral measurements from the environment. In the human retina, all of the components for this circuit exist as well, and its function can explain certain experiences of colour in dim lights, such as a 'blue shift' in twilight. The discovery of this genetically defined pathway will enable new targeted studies of colour processing in the brain.

  1. The uses of colour vision: behavioural and physiological distinctiveness of colour stimuli.

    PubMed

    Derrington, Andrew M; Parker, Amanda; Barraclough, Nick E; Easton, Alexander; Goodson, G R; Parker, Kris S; Tinsley, Chris J; Webb, Ben S

    2002-08-29

    Colour and greyscale (black and white) pictures look different to us, but it is not clear whether the difference in appearance is a consequence of the way our visual system uses colour signals or a by-product of our experience. In principle, colour images are qualitatively different from greyscale images because they make it possible to use different processing strategies. Colour signals provide important cues for segmenting the image into areas that represent different objects and for linking together areas that represent the same object. If this property of colour signals is exploited in visual processing we would expect colour stimuli to look different, as a class, from greyscale stimuli. We would also expect that adding colour signals to greyscale signals should change the way that those signals are processed. We have investigated these questions in behavioural and in physiological experiments. We find that male marmosets (all of which are dichromats) rapidly learn to distinguish between colour and greyscale copies of the same images. The discrimination transfers to new image pairs, to new colours and to image pairs in which the colour and greyscale images are spatially different. We find that, in a proportion of neurons recorded in the marmoset visual cortex, colour-shifts in opposite directions produce similar enhancements of the response to a luminance stimulus. We conclude that colour is, both behaviourally and physiologically, a distinctive property of images.

  2. Colorimetric evaluation of iPhone apps for colour vision tests based on the Ishihara test.

    PubMed

    Dain, Stephen J; AlMerdef, Ali

    2016-05-01

    Given the versatility of smart phone displays, it was inevitable that applications (apps) providing colour vision testing would appear as an option. In this study, the colorimetric characteristics of five available iPhone apps for colour vision testing are assessed as a prequel to possible clinical evaluation. The colours of the displays produced by the apps are assessed with reference to the colours of a printed Ishihara test. The visual task is assessed on the basis of the colour differences and the alignment to the dichromatic confusion lines. The apps vary in quality and while some are colorimetrically acceptable, there are also some problems with their construction in making them a clinically useful app rather than curiosity driven self-testing. There is no reason why, in principle, a suitable test cannot be designed for smart phones.

  3. A modified pseudoisochromatic ishihara colour vision test based on eastern arabic numerals.

    PubMed

    Heidary, Fatemeh; Gharebaghi, Reza

    2013-01-01

    Congenital colour vision defects affect about 8% and 0.5% of the male and female population, respectively. Pseudoisochromatic Ishihara plates have shown to be successful in an early diagnosis of colour vision defects. This commonly used colour vision test was initially intended to identify those who suffered from red-green aspect of congenital colour blindness; however, it may be of use to reveal acquired colour vision defects as well. Despite the Ishihara plates' value, there are a number of shortcomings in their current layout. We proposing a new colour plate modified from original Ishihara test. To best assist illiterates who are not able to read English, standard Ishihara plates have been translated to Eastern Arabic numerals, which are used in most parts of the Middle East, Central Asia and Africa populations. The purpose of the present modification was to present the new plates to these regions, but more research and study is required to work on the validity, reliability, and repeatability of these new plates.

  4. Polymorphism of the long-wavelength cone in normal human colour vision

    NASA Astrophysics Data System (ADS)

    Neitz, Jay; Jacobs, Gerald H.

    1986-10-01

    Colour vision is based on the presence of multiple classes of cone each of which contains a different type of photopigment1. Colour matching tests have long revealed that the normal human has three cone types. Results from these tests have also been used to provide estimates of cone spectral sensitivities2. There are significant variations in colour matches made by individuals whose colour vision is classified as normal3-6. Some of this is due to individual differences in preretinal absorption and photopigment density, but some is also believed to arise because there is variation in the spectral positioning of the cone pigments among those who have normal colour vision. We have used a sensitive colour matching test to examine the magnitude and nature of this individual variation and here report evidence for the existence of two different long-wavelength cone mechanisms in normal humans. The different patterns of colour matches made by male and female subjects indicate these two mechanisms are inherited as an X-chromosome linked trait.

  5. Technical note: the effect of refractive blur on colour vision evaluated using the Cambridge Colour Test, the Ishihara Pseudoisochromatic Plates and the Farnsworth Munsell 100 Hue Test.

    PubMed

    Thyagarajan, Sri; Moradi, Philip; Membrey, Luke; Alistair, D; Laidlaw, H

    2007-05-01

    The results of a prospective study examining the effect of refractive blur on colour vision performance in normal subjects measured with three different colour vision tests are reported. The Farnsworth Munsell 100 Hue (FM100) and Cambridge Colour Test (CCT) results were significantly affected at +6 D of spherical refractive blur, whereas those from the Ishihara Pseudoisochromatic Plate (IPP) test were not. In a clinical setting, correction of refractive error up to 3 D for colour vision testing with these tests may not be required. Poor colour vision should not be attributed solely to refractive causes of poor visual acuity (Snellen equivalent: >6/36). Fastest test times were achieved using IPP, followed by CCT.

  6. The intensity threshold of colour vision in a passerine bird, the blue tit (Cyanistes caeruleus).

    PubMed

    Gomez, Doris; Grégoire, Arnaud; Del Rey Granado, Maria; Bassoul, Marine; Degueldre, David; Perret, Philippe; Doutrelant, Claire

    2014-11-01

    Many vertebrates use colour vision for vital behaviour but their visual performance in dim light is largely unknown. The light intensity threshold of colour vision is known only for humans, horses and two parrot species. Here, we first explore this threshold in a passerine bird, the blue tit (Cyanistes caeruleus). Using classic conditioning of colour cues to food rewards in three individuals, we find a threshold ranging from 0.05 to 0.2 cd m(-2). Results are comparable to the two previously tested bird species. For tits, nest light conditions probably exceed that threshold, at least after sunrise. These results shed new light on the lively debate questioning the visual performance of cavity nesters and the evolutionary significance of egg and chick coloration. Although this needs further investigation, it is possible that blue tits exploit both colour and brightness cues when viewing their eggs, chicks or conspecifics in their nests.

  7. REVIEW ARTICLE: Optical and developmental constraints on colour vision with lens eyes

    NASA Astrophysics Data System (ADS)

    Kröger, Ronald H. H.

    2000-11-01

    Longitudinal chromatic aberration (LCA) is present in all animal lens eyes and is a limiting factor for colour vision. It is discussed how natural evolution has dealt with the problem of chromatic defocus in ways entirely different from technical solutions. Adaptations to LCA are present in the spectral sensitivities of photoreceptors, the architecture of the retina, the lens and the shape of the pupil. These adaptations raise interesting questions in developmental and cell biology, as well as regarding the evolution of lens eyes and colour vision. It is suggested that LCA has been a limiting factor in the evolution of the human visual system.

  8. Red-Green Color Vision Impairment in Duchenne Muscular Dystrophy

    PubMed Central

    Costa, Marcelo Fernandes ; Oliveira, Andre Gustavo Fernandes ; Feitosa-Santana, Claudia ; Zatz, Mayana ; Ventura, Dora Fix 

    2007-01-01

    The present study evaluated the color vision of 44 patients with Duchenne muscular dystrophy (DMD) (mean age 14.8 years; SD 4.9) who were submitted to a battery of four different color tests: Cambridge Colour Test (CCT), Neitz Anomaloscope, Ishihara, and American Optical Hardy-Rand-Rittler (AO H-R-R). Patients were divided into two groups according to the region of deletion in the dystrophin gene: upstream of exon 30 (n=12) and downstream of exon 30 (n=32). The control group was composed of 70 age-matched healthy male subjects with no ophthalmological complaints. Of the patients with DMD, 47% (21/44) had a red-green color vision defect in the CCT, confirmed by the Neitz Anomaloscope with statistical agreement (P<.001). The Ishihara and the AO H-R-R had a lower capacity to detect color defects—5% and 7%, respectively, with no statistical similarity between the results of these two tests nor between CCT and Anomaloscope results (P>.05). Of the patients with deletion downstream of exon 30, 66% had a red-green color defect. No color defect was found in the patients with deletion upstream of exon 30. A negative correlation between the color thresholds and age was found for the controls and patients with DMD, suggesting a nonprogressive color defect. The percentage (66%) of patients with a red-green defect was significantly higher than the expected <10% for the normal male population (P<.001). In contrast, patients with DMD with deletion upstream of exon 30 had normal color vision. This color defect might be partially explained by a retina impairment related to dystrophin isoform Dp260. PMID:17503325

  9. Red-green color vision impairment in Duchenne muscular dystrophy.

    PubMed

    Costa, Marcelo Fernandes; Oliveira, Andre Gustavo Fernandes; Feitosa-Santana, Claudia; Zatz, Mayana; Ventura, Dora Fix

    2007-06-01

    The present study evaluated the color vision of 44 patients with Duchenne muscular dystrophy (DMD) (mean age 14.8 years; SD 4.9) who were submitted to a battery of four different color tests: Cambridge Colour Test (CCT), Neitz Anomaloscope, Ishihara, and American Optical Hardy-Rand-Rittler (AO H-R-R). Patients were divided into two groups according to the region of deletion in the dystrophin gene: upstream of exon 30 (n=12) and downstream of exon 30 (n=32). The control group was composed of 70 age-matched healthy male subjects with no ophthalmological complaints. Of the patients with DMD, 47% (21/44) had a red-green color vision defect in the CCT, confirmed by the Neitz Anomaloscope with statistical agreement (P<.001). The Ishihara and the AO H-R-R had a lower capacity to detect color defects--5% and 7%, respectively, with no statistical similarity between the results of these two tests nor between CCT and Anomaloscope results (P>.05). Of the patients with deletion downstream of exon 30, 66% had a red-green color defect. No color defect was found in the patients with deletion upstream of exon 30. A negative correlation between the color thresholds and age was found for the controls and patients with DMD, suggesting a nonprogressive color defect. The percentage (66%) of patients with a red-green defect was significantly higher than the expected <10% for the normal male population (P<.001). In contrast, patients with DMD with deletion upstream of exon 30 had normal color vision. This color defect might be partially explained by a retina impairment related to dystrophin isoform Dp260.

  10. Research the mobile phone operation interfaces for vision-impairment.

    PubMed

    Yao, Yen-Ting; Leung, Cherng-Yee

    2012-01-01

    Due to the vision-impaired users commonly having difficulty with mobile-phone function operations and adaption any manufacturer's user interface design, the goals for this research are established for evaluating how to improve for them the function operation convenience and user interfaces of either mobile phones or electronic appliances in the market currently. After applying collecting back 30 effective questionnaires from 30 vision-impairment, the comments have been concluded from this research include: (1) All mobile phone manufactures commonly ignorant of the vision-impairment difficulty with operating mobile phone user interfaces; (2) The vision-impairment preferential with audio alert signals; (3) The vision-impairment incapable of mobile-phone procurement independently unless with assistance from others; (4) Preferential with adding touch-usage interface design by the vision-impairment; in contrast with the least requirement for such functions as braille, enlarging keystroke size and diversifying-function control panel. With exploring the vision-impairment's necessary improvements and obstacles for mobile phone interface operation, this research is established with goals for offering reference possibly applied in electronic appliance design and . Hopefully, the analysis results of this research could be used as data references for designing electronic and high-tech products and promoting more usage convenience for those vision-impaired.

  11. Screening for Vision Problems in Children with Hearing Impairments.

    ERIC Educational Resources Information Center

    Demchak, MaryAnn; Elquist, Marty

    Vision problems occur at higher rates in the deaf and hearing impaired population than in the general population. When an individual has a hearing impairment, vision becomes more significant in the instructional and learning process, as well as in social and communicative exchanges. Regular comprehensive visual screening of hearing impaired…

  12. Characterisation of flotation froth colour and structure by machine vision

    NASA Astrophysics Data System (ADS)

    Bonifazi, Giuseppe; Serranti, Silvia; Volpe, Fabio; Zuco, Riccardo

    2001-11-01

    It is well known and well recognised that flotation is a process that is complex to monitor and study if a classical approach based on the evaluation of the signals resulting from sensors is adopted. Sensors are usually strategically positioned in the bank cells and detect global process variables such as pH, reagent addition, froth level, on-stream chemical analysis, particle size distribution, etc. In the last ten years several studies have been carried out with the main goal to utilise imaging techniques to detect froth bubbles characteristics and to evaluate the flotation process performance. In this paper an approach of this type is described. More specifically, image processing techniques to automatically measure the colour and the structure of the froth bubbles are presented and the results are discussed. All the investigations are carried out on digital sample images collected in an industrial flotation plant operating in steady-state conditions. The colour analysis is performed on the whole surface of the froth images considering different colour reference systems (RGB, HSV, HSI); the morphological measurements are obtained after the application of selected enhancement and segmentation techniques, necessary to consider the bubbles as separate domains. The multiple correlation analysis performed between froth mineral concentrations (Cu, MgO, Zn and Pb content) and the extracted colour and structure parameters are good in most situations.

  13. The use of colour difference vectors in diagnosing congenital colour vision deficiencies with the Farnsworth-Munsell 100-hue test.

    PubMed

    Vingrys, A J; Atchison, D A; Bowman, K J

    1992-01-01

    Colour difference vector analysis provides useful and meaningful information in scoring the Farnsworth-Munsell (FM) 100-hue test. However, the FM 100-hue test is limited in its ability to diagnose type and severity of congenital colour vision defect. Type classification for all subjects is incorrect in 21% of cases, and for deuteranomals the misclassification rate is 38%. Visual inspection of the plots yields a similar misclassification rate and classification of plots with few errors (under 180) is generally less reliable. The FM 100-hue test has a limited ability to separate dichromats from anomalous trichromats. A test protocol based on joint D15 and FM 100-hue tests should pass 36% of anomalous trichromats and 26% of all colour defectives yet fail all dichromatic observers. We conclude that administering the FM 100-hue test is of less value than a combination of D15 panels (Standard D15 and L'Anthony's desaturated D15) in the clinical diagnosis of congenital colour defective observers. Our results for the FM 100-hue panel are similar to those reported previously by other investigators.

  14. A complex carotenoid palette tunes avian colour vision

    PubMed Central

    Toomey, Matthew B.; Collins, Aaron M.; Frederiksen, Rikard; Cornwall, M. Carter; Timlin, Jerilyn A.; Corbo, Joseph C.

    2015-01-01

    The brilliantly coloured cone oil droplets of the avian retina function as long-pass cut-off filters that tune the spectral sensitivity of the photoreceptors and are hypothesized to enhance colour discrimination and improve colour constancy. Although it has long been known that these droplets are pigmented with carotenoids, their precise composition has remained uncertain owing to the technical challenges of measuring these very small, dense and highly refractile optical organelles. In this study, we integrated results from high-performance liquid chromatography, hyperspectral microscopy and microspectrophotometry to obtain a comprehensive understanding of oil droplet carotenoid pigmentation in the chicken (Gallus gallus). We find that each of the four carotenoid-containing droplet types consists of a complex mixture of carotenoids, with a single predominant carotenoid determining the wavelength of the spectral filtering cut-off. Consistent with previous reports, we find that the predominant carotenoid type in the oil droplets of long-wavelength-sensitive, medium-wavelength-sensitive and short-wavelength-sensitive type 2 cones are astaxanthin, zeaxanthin and galloxanthin, respectively. In addition, the oil droplet of the principal member of the double cone contains a mixture of galloxanthin and two hydroxycarotenoids (lutein and zeaxanthin). Short-wavelength-absorbing apocarotenoids are present in all of the droplet types, providing filtering of light in a region of the spectrum where filtering by hydroxy- and ketocarotenoids may be incomplete. Thus, birds rely on a complex palette of carotenoid pigments within their cone oil droplets to achieve finely tuned spectral filtering. PMID:26446559

  15. A complex carotenoid palette tunes avian colour vision.

    PubMed

    Toomey, Matthew B; Collins, Aaron M; Frederiksen, Rikard; Cornwall, M Carter; Timlin, Jerilyn A; Corbo, Joseph C

    2015-10-06

    The brilliantly coloured cone oil droplets of the avian retina function as long-pass cut-off filters that tune the spectral sensitivity of the photoreceptors and are hypothesized to enhance colour discrimination and improve colour constancy. Although it has long been known that these droplets are pigmented with carotenoids, their precise composition has remained uncertain owing to the technical challenges of measuring these very small, dense and highly refractile optical organelles. In this study, we integrated results from high-performance liquid chromatography, hyperspectral microscopy and microspectrophotometry to obtain a comprehensive understanding of oil droplet carotenoid pigmentation in the chicken (Gallus gallus). We find that each of the four carotenoid-containing droplet types consists of a complex mixture of carotenoids, with a single predominant carotenoid determining the wavelength of the spectral filtering cut-off. Consistent with previous reports, we find that the predominant carotenoid type in the oil droplets of long-wavelength-sensitive, medium-wavelength-sensitive and short-wavelength-sensitive type 2 cones are astaxanthin, zeaxanthin and galloxanthin, respectively. In addition, the oil droplet of the principal member of the double cone contains a mixture of galloxanthin and two hydroxycarotenoids (lutein and zeaxanthin). Short-wavelength-absorbing apocarotenoids are present in all of the droplet types, providing filtering of light in a region of the spectrum where filtering by hydroxy- and ketocarotenoids may be incomplete. Thus, birds rely on a complex palette of carotenoid pigments within their cone oil droplets to achieve finely tuned spectral filtering.

  16. Loss of form vision impairs spatial imagery

    PubMed Central

    Occelli, Valeria; Lin, Jonathan B.; Lacey, Simon; Sathian, K.

    2014-01-01

    Previous studies have reported inconsistent results when comparing spatial imagery performance in the blind and the sighted, with some, but not all, studies demonstrating deficits in the blind. Here, we investigated the effect of visual status and individual preferences (“cognitive style”) on performance of a spatial imagery task. Participants with blindness resulting in the loss of form vision at or after age 6, and age- and gender-matched sighted participants, performed a spatial imagery task requiring memorization of a 4 × 4 lettered matrix and subsequent mental construction of shapes within the matrix from four-letter auditory cues. They also completed the Santa Barbara Sense of Direction Scale (SBSoDS) and a self-evaluation of cognitive style. The sighted participants also completed the Object-Spatial Imagery and Verbal Questionnaire (OSIVQ). Visual status affected performance on the spatial imagery task: the blind performed significantly worse than the sighted, independently of the age at which form vision was completely lost. Visual status did not affect the distribution of preferences based on self-reported cognitive style. Across all participants, self-reported verbalizer scores were significantly negatively correlated with accuracy on the spatial imagery task. There was a positive correlation between the SBSoDS score and accuracy on the spatial imagery task, across all participants, indicating that a better sense of direction is related to a more proficient spatial representation and that the imagery task indexes ecologically relevant spatial abilities. Moreover, the older the participants were, the worse their performance was, indicating a detrimental effect of age on spatial imagery performance. Thus, spatial skills represent an important target for rehabilitative approaches to visual impairment, and individual differences, which can modulate performance, should be taken into account in such approaches. PMID:24678294

  17. Psychophysical Evaluation of Congenital Colour Vision Deficiency: Discrimination between Protans and Deutans Using Mollon-Reffin’s Ellipses and the Farnsworth-Munsell 100-Hue Test

    PubMed Central

    Bento-Torres, Natáli Valim Oliver; Rodrigues, Anderson Raiol; Côrtes, Maria Izabel Tentes; Bonci, Daniela Maria de Oliveira; Ventura, Dora Fix

    2016-01-01

    We have used the Farnsworth-Munsell 100-hue (FM 100) test and Mollon-Reffin (MR) test to evaluate the colour vision of 93 subjects, 30.4 ± 9.7 years old, who had red-green congenital colour vision deficiencies. All subjects lived in Belém (State of Pará, Brazil) and were selected by the State of Pará Traffic Department. Selection criteria comprised the absence of visual dysfunctions other than Daltonism and no history of systemic diseases that could impair the visual system performance. Results from colour vision deficient were compared with those from 127 normal trichromats, 29.3 ± 10.3 years old. For the MR test, measurements were taken around five points of the CIE 1976 colour space, along 20 directions irradiating from each point, in order to determine with high-resolution the corresponding colour discrimination ellipses (MacAdam ellipses). Three parameters were used to compare results obtained from different subjects: diameter of circle with same ellipse area, ratio between ellipse’s long and short axes, and ellipse long axis angle. For the FM 100 test, the parameters were: logarithm of the total number of mistakes and positions of mistakes in the FM diagram. Data were also simultaneously analysed in two or three dimensions as well as by using multidimensional cluster analysis. For the MR test, Mollon-Reffin Ellipse #3 (u’ = 0.225, v’ = 0.415) discriminated more efficiently than the other four ellipses between protans and deutans once it provided larger angular difference in the colour space between protan and deutan confusion lines. The MR test was more sensitive than the FM 100 test. It separated individuals by dysfunctional groups with greater precision, provided a more sophisticated quantitative analysis, and its use is appropriate for a more refined evaluation of different phenotypes of red-green colour vision deficiencies. PMID:27101124

  18. Psychophysical Evaluation of Congenital Colour Vision Deficiency: Discrimination between Protans and Deutans Using Mollon-Reffin's Ellipses and the Farnsworth-Munsell 100-Hue Test.

    PubMed

    Bento-Torres, Natáli Valim Oliver; Rodrigues, Anderson Raiol; Côrtes, Maria Izabel Tentes; Bonci, Daniela Maria de Oliveira; Ventura, Dora Fix; Silveira, Luiz Carlos de Lima

    2016-01-01

    We have used the Farnsworth-Munsell 100-hue (FM 100) test and Mollon-Reffin (MR) test to evaluate the colour vision of 93 subjects, 30.4 ± 9.7 years old, who had red-green congenital colour vision deficiencies. All subjects lived in Belém (State of Pará, Brazil) and were selected by the State of Pará Traffic Department. Selection criteria comprised the absence of visual dysfunctions other than Daltonism and no history of systemic diseases that could impair the visual system performance. Results from colour vision deficient were compared with those from 127 normal trichromats, 29.3 ± 10.3 years old. For the MR test, measurements were taken around five points of the CIE 1976 colour space, along 20 directions irradiating from each point, in order to determine with high-resolution the corresponding colour discrimination ellipses (MacAdam ellipses). Three parameters were used to compare results obtained from different subjects: diameter of circle with same ellipse area, ratio between ellipse's long and short axes, and ellipse long axis angle. For the FM 100 test, the parameters were: logarithm of the total number of mistakes and positions of mistakes in the FM diagram. Data were also simultaneously analysed in two or three dimensions as well as by using multidimensional cluster analysis. For the MR test, Mollon-Reffin Ellipse #3 (u' = 0.225, v' = 0.415) discriminated more efficiently than the other four ellipses between protans and deutans once it provided larger angular difference in the colour space between protan and deutan confusion lines. The MR test was more sensitive than the FM 100 test. It separated individuals by dysfunctional groups with greater precision, provided a more sophisticated quantitative analysis, and its use is appropriate for a more refined evaluation of different phenotypes of red-green colour vision deficiencies.

  19. The molecular genetics and evolution of colour and polarization vision in stomatopod crustaceans.

    PubMed

    Cronin, T W; Porter, M L; Bok, M J; Wolf, J B; Robinson, P R

    2010-09-01

    Stomatopod crustaceans have the most complex assemblage of visual receptor classes known; retinas of many species are thought to express up to 16 different visual pigments. Physiological studies indicate that stomatopods contain up to six distinct middle-wavelength-sensitive (MWS) photoreceptor classes, suggesting that no more than six different MWS opsin gene copies exist per species. However, we previously reported the unexpected expression of 6-15 different MWS genes in retinas of each of five stomatopod species (Visual Neurosci 26: 255-266, 2009). Here, we present a review of the results reported in this publication, plus new results that shed light on the origins of the diverse colour and polarization visual capabilities of stomatopod crustaceans. Using in situ hybridization of opsins in photoreceptor cells, we obtained new results that support the hypothesis of an ancient functional division separating spatial and polarizational vision from colour vision in the stomatopods. Since evolutionary trace analysis indicates that stomatopod MWS opsins have diverged both with respect to spectral tuning and to cytoplasmic interactions, we have now further analyzed these data in an attempt to uncover the origins, diversity and potential specializations among clades for specific visual functions. The presence of many clusters of highly similar transcripts suggests exuberant opsin gene duplication has occurred in the stomatopods, together with more conservative, ancient gene duplication events within the stem crustacean lineage. Phylogenetic analysis of opsin relatedness suggests that opsins specialized for colour vision have diverged from those devoted to polarization vision, and possibly motion and spatial vision.

  20. The nature of sound and vision in relation to colour

    NASA Astrophysics Data System (ADS)

    Greated, Marianne

    2011-03-01

    The increasing role of sound within the visual arts context and the trend in postmodernism towards interdisciplinary artworks has demanded a heightened awareness of the audio-visual. This paper explores some of the fundamental physical properties of both sound and colour, their similarities and differences and how the audio and visual senses are related. Ways in which soundscapes have been combined with paintings in exhibitions by the author will be used to illustrate how the two media can be combined to enhance the overall artistic experience.

  1. Dichromatic Colour Vision in Wallabies as Characterised by Three Behavioural Paradigms

    PubMed Central

    Ebeling, Wiebke; Hemmi, Jan M.

    2014-01-01

    Despite lacking genetic evidence of a third cone opsin in the retina of any Australian marsupial, most species tested so far appear to be trichromatic. In the light of this, we have re-examined colour vision of the tammar wallaby which had previously been identified as a dichromat. Three different psychophysical tests, based on an operant conditioning paradigm, were used to confirm that colour perception in the wallaby can be predicted and conclusively explained by the existence of only two cone types. Firstly, colour-mixing experiments revealed a Confusion Point between the three primary colours of a LCD monitor that can be predicted by the cone excitation ratio of the short- and middle-wavelength sensitive cones. Secondly, the wavelength discrimination ability in the wallaby, when tested with monochromatic stimuli, was found to be limited to a narrow range between 440 nm and 500 nm. Lastly, an experiment designed to test the wallaby’s ability to discriminate monochromatic lights from a white light provided clear evidence for a Neutral Point around 485 nm where discrimination consistently failed. Relative colour discrimination seemed clearly preferred but it was possible to train a wallaby to perform absolute colour discriminations. The results confirm the tammar wallaby as a dichromat, and so far the only behaviourally confirmed dichromat among the Australian marsupials. PMID:24489742

  2. Dichromatic colour vision in wallabies as characterised by three behavioural paradigms.

    PubMed

    Ebeling, Wiebke; Hemmi, Jan M

    2014-01-01

    Despite lacking genetic evidence of a third cone opsin in the retina of any Australian marsupial, most species tested so far appear to be trichromatic. In the light of this, we have re-examined colour vision of the tammar wallaby which had previously been identified as a dichromat. Three different psychophysical tests, based on an operant conditioning paradigm, were used to confirm that colour perception in the wallaby can be predicted and conclusively explained by the existence of only two cone types. Firstly, colour-mixing experiments revealed a Confusion Point between the three primary colours of a LCD monitor that can be predicted by the cone excitation ratio of the short- and middle-wavelength sensitive cones. Secondly, the wavelength discrimination ability in the wallaby, when tested with monochromatic stimuli, was found to be limited to a narrow range between 440 nm and 500 nm. Lastly, an experiment designed to test the wallaby's ability to discriminate monochromatic lights from a white light provided clear evidence for a Neutral Point around 485 nm where discrimination consistently failed. Relative colour discrimination seemed clearly preferred but it was possible to train a wallaby to perform absolute colour discriminations. The results confirm the tammar wallaby as a dichromat, and so far the only behaviourally confirmed dichromat among the Australian marsupials.

  3. Mineralized rods and cones suggest colour vision in a 300 Myr-old fossil fish.

    PubMed

    Tanaka, Gengo; Parker, Andrew R; Hasegawa, Yoshikazu; Siveter, David J; Yamamoto, Ryoichi; Miyashita, Kiyoshi; Takahashi, Yuichi; Ito, Shosuke; Wakamatsu, Kazumasa; Mukuda, Takao; Matsuura, Marie; Tomikawa, Ko; Furutani, Masumi; Suzuki, Kayo; Maeda, Haruyoshi

    2014-12-23

    Vision, which consists of an optical system, receptors and image-processing capacity, has existed for at least 520 Myr. Except for the optical system, as in the calcified lenses of trilobite and ostracod arthropods, other parts of the visual system are not usually preserved in the fossil record, because the soft tissue of the eye and the brain decay rapidly after death, such as within 64 days and 11 days, respectively. The Upper Carboniferous Hamilton Formation (300 Myr) in Kansas, USA, yields exceptionally well-preserved animal fossils in an estuarine depositional setting. Here we show that the original colour, shape and putative presence of eumelanin have been preserved in the acanthodii fish Acanthodes bridgei. We also report on the tissues of its eye, which provides the first record of mineralized rods and cones in a fossil and indicates that this 300 Myr-old fish likely possessed colour vision.

  4. Molecular logic behind the three-way stochastic choices that expand butterfly colour vision.

    PubMed

    Perry, Michael; Kinoshita, Michiyo; Saldi, Giuseppe; Huo, Lucy; Arikawa, Kentaro; Desplan, Claude

    2016-07-14

    Butterflies rely extensively on colour vision to adapt to the natural world. Most species express a broad range of colour-sensitive Rhodopsin proteins in three types of ommatidia (unit eyes), which are distributed stochastically across the retina. The retinas of Drosophila melanogaster use just two main types, in which fate is controlled by the binary stochastic decision to express the transcription factor Spineless in R7 photoreceptors. We investigated how butterflies instead generate three stochastically distributed ommatidial types, resulting in a more diverse retinal mosaic that provides the basis for additional colour comparisons and an expanded range of colour vision. We show that the Japanese yellow swallowtail (Papilio xuthus, Papilionidae) and the painted lady (Vanessa cardui, Nymphalidae) butterflies have a second R7-like photoreceptor in each ommatidium. Independent stochastic expression of Spineless in each R7-like cell results in expression of a blue-sensitive (Spineless(ON)) or an ultraviolet (UV)-sensitive (Spineless(OFF)) Rhodopsin. In P. xuthus these choices of blue/blue, blue/UV or UV/UV sensitivity in the two R7 cells are coordinated with expression of additional Rhodopsin proteins in the remaining photoreceptors, and together define the three types of ommatidia. Knocking out spineless using CRISPR/Cas9 (refs 5, 6) leads to the loss of the blue-sensitive fate in R7-like cells and transforms retinas into homogeneous fields of UV/UV-type ommatidia, with corresponding changes in other coordinated features of ommatidial type. Hence, the three possible outcomes of Spineless expression define the three ommatidial types in butterflies. This developmental strategy allowed the deployment of an additional red-sensitive Rhodopsin in P. xuthus, allowing for the evolution of expanded colour vision with a greater variety of receptors. This surprisingly simple mechanism that makes use of two binary stochastic decisions coupled with local coordination may prove

  5. Vision impairment and dual sensory problems in middle age

    PubMed Central

    Dawes, Piers; Dickinson, Christine; Emsley, Richard; Bishop, Paul; Cruickshanks, Karen; Edmondson-Jones, Mark; McCormack, Abby; Fortnum, Heather; Moore, David R.; Norman, Paul; Munro, Kevin

    2014-01-01

    Purpose Vision and hearing impairments are known to increase in middle age. In this study we describe the prevalence of vision impairment and dual sensory impairment in UK adults aged 40 to 69 years in a very large and recently ascertained data set. The associations between vision impairment, age, sex, socioeconomic status, and ethnicity are reported. Methods This research was conducted using the UK Biobank Resource, with subsets of UK Biobank data analysed with respect to self-report of eye problems and glasses use. Better-eye visual acuity with habitually worn refractive correction was assessed with a logMAR chart (n = 116,682). Better-ear speech reception threshold was measured with an adaptive speech in noise test, the Digit Triplet Test (n = 164,770). Prevalence estimates were weighted with respect to UK 2001 Census data. Results Prevalence of mild visual impairment and low vision was estimated at 15.2% (95% CI 14.9–15.5%) and 0.9% (95% CI 0.8–1.0%), respectively. Use of glasses was 88.0% (95% CI 87.9–88.1%). The prevalence of dual sensory impairment was 3.1% (95% CI 3.0–3.2%) and there was a nine-fold increase in the prevalence of dual sensory problems between the youngest and oldest age groups. Older adults, those from low socioeconomic and ethnic minority backgrounds were most at risk for vision problems. Conclusions Mild vision impairment is common in middle aged UK adults, despite widespread use of spectacles. Possible barriers to optometric care for those from low socioeconomic and ethnic minority backgrounds may require attention. A higher than expected prevalence of dual impairment suggests that hearing and vision problems share common causes. Optometrists should consider screening for hearing problems, particularly among older adults. PMID:24888710

  6. The intensity threshold of colour vision in two species of parrot.

    PubMed

    Lind, Olle; Kelber, Almut

    2009-11-01

    We have used behavioural tests to determine the intensity thresholds of colour vision in Bourke's parrots (Neopsephotus bourkii) and budgerigars (Melopsittacus undulatus). We have also examined the relationship between these thresholds and the optical sensitivities of single photoreceptors using morphological methods. Bourke's parrots lose colour vision in brighter light (0.4 cd m(-2)) than budgerigars (0.1 cd m(-2)) and both birds lose colour vision in brighter light (;end of civil twilight') than humans (0.02 cd m(-2), ;moonlight'). The optical sensitivities of single cones are similar in both birds (budgerigar 0.27 microm(2) sr, Bourke's parrot 0.25 microm(2) sr) but Bourke's parrots have more (cone to rod ratio, 1.2:1.0), thinner (2.8 microm) and longer rods (18.5 microm) than budgerigars (2.1:1.0, 3.4 microm, 13.3 microm). Bourke's parrots thus have an eye type that, with a flexible pooling mechanism, allows for high resolution or high absolute sensitivity depending on the light conditions. The results nicely agree with the activity patterns of the birds, Bourke's parrots being active during the day and in twilight while budgerigars are not normally active before sunrise and after sunset. However, Bourke's parrots have fewer cones than budgerigars, which implies that a smaller number of cones are pooled within each retinal integration area. That could explain why Bourke's parrots have a higher intensity threshold of colour vision than budgerigars. Furthermore, the study emphasises the need to expand the sensitivity measure so that photoreceptor integration units are used rather than single receptors.

  7. Bank note recognition for the vision impaired.

    PubMed

    Hinwood, A; Preston, P; Suaning, G J; Lovell, N H

    2006-06-01

    Blind Australians find great difficulty in recognising bank notes. Each note has the same feel, with no Braille markings, irregular edges or other tangible features. In Australia, there is only one device available that can assist blind people recognise their notes. Internationally, there are devices available; however they are expensive, complex and have not been developed to cater for Australian currency. This paper discusses a new device, the MoneyTalker that takes advantage of the largely different colours and patterns on each Australian bank note and recognises the notes electronically, using the reflection and transmission properties of light. Different coloured lights are transmitted through the inserted note and the corresponding sensors detect distinct ranges of values depending on the colour of the note. Various classification algorithms were studied and the final algorithm was chosen based on accuracy and speed of recognition. The MoneyTalker has shown an accuracy of more than 99%. A blind subject has tested the device and believes that it is usable, compact and affordable. Based on the devices that are available currently in Australia, the MoneyTalker is an effective alternative in terms of accuracy and usability.

  8. Highly polymorphic colour vision in a New World monkey with red facial skin, the bald uakari (Cacajao calvus)

    PubMed Central

    Corso, Josmael; Roos, Christian

    2016-01-01

    Colour vision is highly variable in New World monkeys (NWMs). Evidence for the adaptive basis of colour vision in this group has largely centred on environmental features such as foraging benefits for differently coloured foods or predator detection, whereas selection on colour vision for sociosexual communication is an alternative hypothesis that has received little attention. The colour vision of uakaris (Cacajao) is of particular interest because these monkeys have the most dramatic red facial skin of any primate, as well as a unique fission/fusion social system and a specialist diet of seeds. Here, we investigate colour vision in a wild population of the bald uakari, C. calvus, by genotyping the X-linked opsin locus. We document the presence of a polymorphic colour vision system with an unprecedented number of functional alleles (six), including a novel allele with a predicted maximum spectral sensitivity of 555 nm. This supports the presence of strong balancing selection on different alleles at this locus. We consider different hypotheses to explain this selection. One possibility is that trichromacy functions in sexual selection, enabling females to choose high-quality males on the basis of red facial coloration. In support of this, there is some evidence that health affects facial coloration in uakaris, as well as a high prevalence of blood-borne parasitism in wild uakari populations. Alternatively, the low proportion of heterozygous female trichromats in the population may indicate selection on different dichromatic phenotypes, which might be related to cryptic food coloration. We have uncovered unexpected diversity in the last major lineage of NWMs to be assayed for colour vision, which will provide an interesting system to dissect adaptation of polymorphic trichromacy. PMID:27053753

  9. Colour vision and contrast sensitivity losses of mercury intoxicated industry workers in Brazil.

    PubMed

    Ventura, D F; Simões, A L; Tomaz, S; Costa, M F; Lago, M; Costa, M T V; Canto-Pereira, L H M; de Souza, J M; Faria, M A M; Silveira, L C L

    2005-05-01

    We evaluated vision loss in workers from fluorescent lamp industries (n=39) who had retired due to intoxication with mercury vapour and had been away from the work situation for several years (mean=6.32 years). An age-matched control group was submitted to the same tests for comparison. The luminance contrast sensitivity (CSF) was measured psychophysically and with the sweep visual evoked potential (sVEP) method. Chromatic red-green and blue-yellow CSFs were measured psychophysically. Colour discrimination was assessed with the Farnsworth-Munsell 100-hue test, Lanthony D-15d test and Cambridge Colour Vision Test. Patient data showed significantly lower scores in all colour tests compared to controls (p<.001). The behavioural luminance CSF of the patients was lower than that of controls (p<.001 at all frequencies tested). This result was confirmed by the electrophysiologically measured sweep VEP luminance CSF except at the highest frequencies-a difference that might be related to stimulus differences in the two situations. Chromatic CSFs were also statistically significantly lower for the patients than for the controls, for both chromatic equiluminant stimuli: red-green (p<.005) and blue-yellow (p<.04 for all frequencies, except 2 cycles per degree (cpd), the highest spatial frequency tested) spatial gratings. We conclude that exposure to elemental mercury vapour is associated with profound and lasting losses in achromatic and chromatic visual functions, affecting the magno-, parvo- and koniocellular visual pathways.

  10. Spotting fruit versus picking fruit as the selective advantage of human colour vision.

    PubMed

    Bompas, Aline; Kendall, Grace; Sumner, Petroc

    2013-01-01

    The spatiochromatic properties of the red-green dimension of human colour vision appear to be optimized for picking fruit in leaves at about arms' reach. However, other evidence suggests that the task of spotting fruit from a distance might be more important. This discrepancy may arise because the task a system (e.g. human trichromacy) is best at is not necessarily the same task where the largest advantage occurs over the evolutionary alternatives (dichromacy or anomalous trichromacy). We tested human dichromats, anomalous trichromats and "normal" trichromats in a naturalistic visual search task in which they had to find fruit pieces in a bush at 1, 4, 8 or 12 m viewing distance. We found that the largest advantage (in terms of either performance ratio or performance difference) of normal trichromacy over both types of colour deficiency was for the largest viewing distance. We infer that in the evolution of human colour vision, spotting fruit from a distance was a more important selective advantage than picking fruit at arms' reach.

  11. Global cost of correcting vision impairment from uncorrected refractive error

    PubMed Central

    Fricke, TR; Wilson, DA; Schlenther, G; Naidoo, KS; Resnikoff, S; Frick, KD

    2012-01-01

    Abstract Objective To estimate the global cost of establishing and operating the educational and refractive care facilities required to provide care to all individuals who currently have vision impairment resulting from uncorrected refractive error (URE). Methods The global cost of correcting URE was estimated using data on the population, the prevalence of URE and the number of existing refractive care practitioners in individual countries, the cost of establishing and operating educational programmes for practitioners and the cost of establishing and operating refractive care facilities. The assumptions made ensured that costs were not underestimated and an upper limit to the costs was derived using the most expensive extreme for each assumption. Findings There were an estimated 158 million cases of distance vision impairment and 544 million cases of near vision impairment caused by URE worldwide in 2007. Approximately 47 000 additional full-time functional clinical refractionists and 18 000 ophthalmic dispensers would be required to provide refractive care services for these individuals. The global cost of educating the additional personnel and of establishing, maintaining and operating the refractive care facilities needed was estimated to be around 20 000 million United States dollars (US$) and the upper-limit cost was US$ 28 000 million. The estimated loss in global gross domestic product due to distance vision impairment caused by URE was US$ 202 000 million annually. Conclusion The cost of establishing and operating the educational and refractive care facilities required to deal with vision impairment resulting from URE was a small proportion of the global loss in productivity associated with that vision impairment. PMID:23109740

  12. Shades of red: bird-pollinated flowers target the specific colour discrimination abilities of avian vision.

    PubMed

    Shrestha, Mani; Dyer, Adrian G; Boyd-Gerny, Skye; Wong, Bob B M; Burd, Martin

    2013-04-01

    Colour signals are a major cue in putative pollination syndromes. There is evidence that the reflectance spectra of many flowers target the distinctive visual discrimination abilities of hymenopteran insects, but far less is known about bird-pollinated flowers. Birds are hypothesized to exert different selective pressures on floral colour compared with hymenopterans because of differences in their visual systems. We measured the floral reflectance spectra of 206 Australian angiosperm species whose floral visitors are known from direct observation rather than inferred from floral characteristics. We quantified the match between these spectra and the hue discrimination abilities of hymenopteran and avian vision, and analysed these metrics in a phylogenetically informed comparison of flowers in different pollination groups. We show that bird-visited flowers and insect-visited flowers differ significantly from each other in the chromatic cues they provide, and that the differences are concentrated near wavelengths of optimal colour discrimination by whichever class of pollinator visits the flowers. Our results indicate that angiosperms have evolved the spectral signals most likely to reinforce their pollinators' floral constancy (the tendency of individual pollinators to visit flowers of the same species) in communities of similarly coloured floral competitors.

  13. Fear of falling in vision impairment.

    PubMed

    White, Ursula E; Black, Alex A; Wood, Joanne M; Delbaere, Kim

    2015-06-01

    Falls are the leading cause of injury-related morbidity and mortality among older adults. In addition to the resulting physical injury and potential disability after a fall, there are also important psychological consequences, including depression, anxiety, activity restriction, and fear of falling. Fear of falling affects 20 to 43% of community-dwelling older adults and is not limited to those who have previously experienced a fall. About half of older adults who experience fear of falling subsequently restrict their physical and everyday activities, which can lead to functional decline, depression, increased falls risk, and reduced quality of life. Although there is clear evidence that older adults with visual impairment have higher falls risk, only a limited number of studies have investigated fear of falling in older adults with visual impairment and the findings have been mixed. Recent studies suggest increased levels of fear of falling among older adults with various eye conditions, including glaucoma and age-related macular degeneration, whereas other studies have failed to find differences. Interventions, which are still in their infancy in the general population, are also largely unexplored in those with visual impairment. The major aims of this review were to provide an overview of the literature on fear of falling, its measurement, and risk factors among older populations, with specific focus on older adults with visual impairment, and to identify directions for future research in this area.

  14. Resource Guide for Persons with Vision Impairments.

    ERIC Educational Resources Information Center

    IBM, Atlanta, GA. National Support Center for Persons with Disabilities.

    The resource guide identifies products which assist visually impaired individuals in accessing IBM (International Business Machine) Personal Computers or the IBM Personal System/2 family of products. An introduction provides a general overview of ways computers can help persons with visual handicaps. The document then provides descriptions of…

  15. The Impact of Vision Impairment on Students' Self-Concept

    ERIC Educational Resources Information Center

    Datta, Poulomee; Talukdar, Joy

    2016-01-01

    This study investigated the self-concept of students with vision impairment who were placed in specialist and mainstream educational settings in South Australia. Self-Concept was explored across six dimensions, namely Physical, Moral, Personal, Family, Social and Academic Self-Concepts and the Total Self-Concept. The "Tennessee Self-Concept…

  16. Schooling through the Eyes of a Student with Vision Impairment

    ERIC Educational Resources Information Center

    Opie, Jill; Southcott, Jane

    2015-01-01

    This article focuses on the school experience of a year 12 student with vision impairment. Few studies have looked at school experiences from a student's perspective, although the belief is that through research focusing on listening to students with disabilities their perspectives will become part of the solution to provide equity and quality in…

  17. Insights into the Support Services for Students with Vision Impairment

    ERIC Educational Resources Information Center

    Datta, Poulomee; Palmer, Carolyn

    2015-01-01

    There is a general need for research in Australia on whether the support services provided in schools prove useful for students with disabilities (Datta, 2015; O'Rourke & Houghton, 2006), especially students with vision impairment. This qualitative study aimed to provide insights into the influence of the support services delivered in South…

  18. Associations between platelet monoamine oxidase-B activity and acquired colour vision loss in a fish-eating population.

    PubMed

    Stamler, Christopher John; Mergler, Donna; Abdelouahab, Nadia; Vanier, Claire; Chan, Hing Man

    2006-01-01

    Platelet monoamine oxidase-B (MAO-B) has been considered a surrogate biochemical marker of neurotoxicity, as it may reflect changes in the monoaminergic system in the brain. Colour vision discrimination, in part a dopamine dependent process, has been used to identify early neurological effects of some environmental and industrial neurotoxicants. The objective of this cross-sectional study was to explore the relationship between platelet MAO-B activity and acquired colour discrimination capacity in fish-consumers from the St. Lawrence River region of Canada. Assessment of acquired dyschromatopsia was determined using the Lanthony D-15 desaturated panel test. Participants classified with dyschromatopsia (n=81) had significantly lower MAO-B activity when compared to those with normal colour vision (n=32) (26.5+/-9.6 versus 31.0+/-9.9 nmol/min/20 microg, P=0.030)). Similarly, Bowman's Colour Confusion Index (CCI) was inversely correlated with MAO-B activity when the vision test was performed with the worst eye only (r=-0.245, P=0.009), the best eye only (r=-0.188, P=0.048) and with both eyes together (r=-0.309, P=0.001). Associations remained significant after adjustment for age and gender when both eyes (P=0.003) and the worst eye (P=0.045) were tested. Adjustment for heavy smoking weakened the association between MAO-B and CCI in the worst eye (P=0.140), but did not alter this association for both eyes (P=0.006). Adjustment for blood-mercury concentrations did not change the association. This study suggests a relationship between reduced MAO-B activity and acquired colour vision loss and both are associated with tobacco smoking. Therefore, results show that platelet MAO-B may be used as a surrogate biochemical marker of acquired colour vision loss.

  19. Computer vision-based analysis of foods: a non-destructive colour measurement tool to monitor quality and safety.

    PubMed

    Mogol, Burçe Ataç; Gökmen, Vural

    2014-05-01

    Computer vision-based image analysis has been widely used in food industry to monitor food quality. It allows low-cost and non-contact measurements of colour to be performed. In this paper, two computer vision-based image analysis approaches are discussed to extract mean colour or featured colour information from the digital images of foods. These types of information may be of particular importance as colour indicates certain chemical changes or physical properties in foods. As exemplified here, the mean CIE a* value or browning ratio determined by means of computer vision-based image analysis algorithms can be correlated with acrylamide content of potato chips or cookies. Or, porosity index as an important physical property of breadcrumb can be calculated easily. In this respect, computer vision-based image analysis provides a useful tool for automatic inspection of food products in a manufacturing line, and it can be actively involved in the decision-making process where rapid quality/safety evaluation is needed.

  20. Blue-yellow colour vision in an onchocercal area of northern Nigeria

    PubMed Central

    Landers, A; Murdoch, I; Birch, J; Cousens, S; Babalola, O; Lawal, B; Abiose, A; Jones, B

    1998-01-01

    AIM—To determine if the City University Tritan Test is a useful addition to visual function assessment in rural communities in northern Nigeria.
METHODS—The study was a cross sectional survey. The participants were 8394 people, aged 5 years and over, living in 37 rural communities, mesoendemic and non-endemic for onchocerciasis, in Kaduna State in northern Nigeria. The main outcome measures were the detection of a defect in blue-yellow colour vision by two criteria: (1) failure with the City University tritan screening plates; (2) failure with the City University grading plates to identify severe tritan defects.
RESULTS—91% of those aged 10 years and above could perform the test. Below this age, there were difficulties in comprehension. The test showed good inter- and intraobserver agreement. After adjustment for confounders the odds of failing the screening plates were significantly increased in the presence of optic atrophy or glaucoma (3.55 (2.48-5.08) and 15.9 (4.22-60.2) respectively). There was a greater increase in the adjusted odds of failing the grading plates in the presence of optic atrophy or glaucoma (5.30 (2.97-9.45) and 8.87 (1.61-48.7) respectively). Cataract had a smaller effect on the screening plates, adjusted odds 1.63 (0.95-2.80).
CONCLUSION—Blue-yellow colour vision testing is a useful addition to visual function assessment in those aged 10 years and above in rural northern Nigeria, particularly in the detection of optic nerve disease.

 Keywords: tritan defects; optic nerve disease; onchocerciasis; visual function assessment PMID:9713057

  1. Use of the Farnsworth-Munsell 100-Hue test in the examination of congenital colour vision defects.

    PubMed

    Birch, J

    1989-04-01

    Results for the Farnsworth-Munsell 100-Hue test are reported for 238 male subjects with congenital colour vision defects (47 protanopes, 17 protanomalous trichromats, 57 deuteranopes and 117 deuteranomalous trichromats). The results are analysed in terms of the error score and the presence of an axis of confusion. A wide range of results is obtained in each diagnostic group and the error score cannot be used to distinguish between dichromats and anomalous trichromats. Approximately 50% of subjects with anomalous trichromatism obtain error scores less than 100 without an axis of confusion. These subjects could be mistakenly identified as having normal colour vision if pseudoisochromatic and colour matching tests are not employed. The prime use of the F-M 100 Hue test is in vocational guidance.

  2. Advanced IT Education for the Vision Impaired via e-Learning

    ERIC Educational Resources Information Center

    Armstrong, Helen L.

    2009-01-01

    Lack of accessibility in the design of e-learning courses continues to hinder students with vision impairment. E-learning materials are predominantly vision-centric, incorporating images, animation, and interactive media, and as a result students with acute vision impairment do not have equal opportunity to gain tertiary qualifications or skills…

  3. A randomised comparison between an inexpensive, general-purpose headlight and a purpose-built surgical headlight on users' visual acuity and colour vision.

    PubMed

    Street, I; Sayles, M; Nistor, M; McRae, A R

    2014-02-01

    To determine if there are any differences in near visual acuity and colour vision between an inexpensive general-purpose light emitting diode (LED) headlight and a purpose-built surgical LED headlight. A prospective study was conducted sequentially comparing near visual acuity and colour vision, the headlights being tested in random order, in a testing room with a constant minimal amount of background light. The participants were NHS employee volunteers, with self-declared normal (or corrected) vision, working in occupations requiring full literacy. For visual acuity, outcome was measured by recording the smallest font legible when using each headlight when the subject read a near visual acuity test card. For colour vision, the outcome was passing or failing the Ishihara test. There was no statistically significant difference between the general-purpose and the purpose-built headlights in users' near visual acuity or colour vision.

  4. The Reliability of the CVI Range: A Functional Vision Assessment for Children with Cortical Visual Impairment

    ERIC Educational Resources Information Center

    Newcomb, Sandra

    2010-01-01

    Children who are identified as visually impaired frequently have a functional vision assessment as one way to determine how their visual impairment affects their educational performance. The CVI Range is a functional vision assessment for children with cortical visual impairment. The purpose of the study presented here was to examine the…

  5. [A biotechnical system for diagnosis and treatment of binocular vision impairments].

    PubMed

    Korzhuk, N L; Shcheglova, M V

    2008-01-01

    Automation of the binocular vision biorhythm diagnosis and improvement of the efficacy of treatment of vision impairments are important medical problems. In authors' opinion, to solve these problems, it is necessary to take into account the correlation between the binocular vision and the electrical activity of the brain. A biotechnical system for diagnosis and treatment of binocular vision impairments was developed to implement diagnostic and treatment procedures based on the detection of this correlation.

  6. Operational Colour Vision in the Modern Aviation Environment (la Vision des couleurs dans l’environnement aeronautique operationnel d’ aujourd hui)

    DTIC Science & Technology

    2001-03-01

    dominant optic atrophy senile macular glaucoma degeneration Caveat: normal ageing of the retinal pigment epithelium and retina may give similar...cases of such entities as retinitis, choroidoretinitis, central haemorrhaging, myopic choroid atrophy and macular degeneration in old age. Detrimental...causes include illnesses such as macular degeneration and cataracts, which, may not affect just colour vision. Table 5.2 that follows this chapter

  7. A computer-controlled color vision test for children based on the Cambridge Colour Test.

    PubMed

    Goulart, Paulo R K; Bandeira, Marcio L; Tsubota, Daniela; Oiwa, Nestor N; Costa, Marcelo F; Ventura, Dora F

    2008-01-01

    The present study aimed at providing conditions for the assessment of color discrimination in children using a modified version of the Cambridge Colour Test (CCT, Cambridge Research Systems Ltd., Rochester, UK). Since the task of indicating the gap of the Landolt C used in that test proved counterintuitive and/or difficult for young children to understand, we changed the target stimulus to a patch of color approximately the size of the Landolt C gap (about 7 degrees of visual angle at 50 cm from the monitor). The modifications were performed for the CCT Trivector test which measures color discrimination for the protan, deutan and tritan confusion lines. Experiment 1 sought to evaluate the correspondence between the CCT and the child-friendly adaptation with adult subjects (n = 29) with normal color vision. Results showed good agreement between the two test versions. Experiment 2 tested the child-friendly software with children 2 to 7 years old (n = 25) using operant training techniques for establishing and maintaining the subjects' performance. Color discrimination thresholds were progressively lower as age increased within the age range tested (2 to 30 years old), and the data--including those obtained for children--fell within the range of thresholds previously obtained for adults with the CCT. The protan and deutan thresholds were consistently lower than tritan thresholds, a pattern repeatedly observed in adults tested with the CCT. The results demonstrate that the test is fit for assessment of color discrimination in young children and may be a useful tool for the establishment of color vision thresholds during development.

  8. Computerised scoring and graphing of the Farnsworth-Munsell 100 Hue test of colour vision--a program written in Pascal.

    PubMed

    Balakrishnan, V; Chew, P T

    1992-04-01

    The Farnsworth Munsell 100 Hue test is the best test for diagnosing and assessing colour vision defects. A computer program written in Pascal which automatically scores, plots and analyses the results of the Farnsworth Munsell 100 Hue test is presented.

  9. The Impact of Residual Vision in Spatial Skills of Individuals with Visual Impairments

    ERIC Educational Resources Information Center

    Papadopoulos, Konstantinos; Koustriava, Eleni; Kartasidou, Lefkothea

    2011-01-01

    Loss of vision is believed to have a great impact on the acquisition of spatial knowledge. The aims of the present study are to examine the performance of individuals with visual impairments on spatial tasks and the impact of residual vision on processing these tasks. In all, 28 individuals with visual impairments--blindness or low…

  10. The Perspectives of Singapore Secondary School Students with Vision Impairments towards Their Inclusion in Mainstream Education

    ERIC Educational Resources Information Center

    West, John; Houghton, Stephen; Taylor, Myra; Ling, Phua Kia

    2004-01-01

    Students with vision impairments in Singapore are educated in segregated settings from an early age. On completing primary school these students continue their education in mainstream secondary school settings. This transition requires considerable adjustment on the part of students with vision impairments. The present research explored the social…

  11. The Potential Impact of Undiagnosed Vision Impairment on Reading Development in the Early Years of School

    ERIC Educational Resources Information Center

    Thurston, Allen

    2014-01-01

    This article presents a critical review of the literature surrounding the potential impact of undiagnosed and untreated vision impairment on reading development in the early years of primary school. Despite pre-school screening programmes, it is still possible for children to enter school with undiagnosed, uncorrected vision impairments. This can…

  12. Falls Among Persons Aged ≥65 Years With and Without Severe Vision Impairment - United States, 2014.

    PubMed

    Crews, John E; Chou, Chiu-Fung; Stevens, Judy A; Saaddine, Jinan B

    2016-05-06

    In 2014, an estimated 2.8 million persons aged ≥65 years in the United States reported severe vision impairment* defined as being blind or having severe difficulty seeing, even with eyeglasses. Good vision is important for maintaining balance as well as for identifying low-contrast hazards, estimating distances, and discerning spatial relationships. Conversely, having poor vision increases the risk for falls (1,2). Falls among older adults are common and can cause serious injuries, disabilities, and premature death (1,3). To date, no state-level investigations have examined the annual prevalence of falls among persons with and without severe vision impairment. CDC analyzed data from the 2014 Behavioral Risk Factor Surveillance System (BRFSS) to estimate the state-specific annual prevalence of falls among persons aged ≥65 years with and without self-reported severe vision impairment. Overall, 46.7% of persons with, and 27.7% of older adults without, self-reported severe vision impairment reported having fallen during the previous year. The state-specific annual prevalence of falls among persons aged ≥65 years with severe vision impairment ranged from 30.8% (Hawaii) to 59.1% (California). In contrast, the prevalence of falls among persons aged ≥65 years without severe vision impairment ranged from 20.4% (Hawaii) to 32.4% (Alaska). Developing fall-prevention interventions intended for persons with severe vision impairment will help states manage the impact of vision impairment and falls on health care resources, and can inform state-specific fall prevention initiatives.

  13. Parallel evolution of angiosperm colour signals: common evolutionary pressures linked to hymenopteran vision

    PubMed Central

    Dyer, Adrian G.; Boyd-Gerny, Skye; McLoughlin, Stephen; Rosa, Marcello G. P.; Simonov, Vera; Wong, Bob B. M.

    2012-01-01

    Flowering plants in Australia have been geographically isolated for more than 34 million years. In the Northern Hemisphere, previous work has revealed a close fit between the optimal discrimination capabilities of hymenopteran pollinators and the flower colours that have most frequently evolved. We collected spectral data from 111 Australian native flowers and tested signal appearance considering the colour discrimination capabilities of potentially important pollinators. The highest frequency of flower reflectance curves is consistent with data reported for the Northern Hemisphere. The subsequent mapping of Australian flower reflectances into a bee colour space reveals a very similar distribution of flower colour evolution to the Northern Hemisphere. Thus, flowering plants in Australia are likely to have independently evolved spectral signals that maximize colour discrimination by hymenoptera. Moreover, we found that the degree of variability in flower coloration for particular angiosperm species matched the range of reflectance colours that can only be discriminated by bees that have experienced differential conditioning. This observation suggests a requirement for plasticity in the nervous systems of pollinators to allow generalization of flowers of the same species while overcoming the possible presence of non-rewarding flower mimics. PMID:22673351

  14. Mapping the timecourse of goal-directed attention to location and colour in human vision.

    PubMed

    Adams, Rachel C; Chambers, Christopher D

    2012-03-01

    Goal-directed attention prioritises perception of task-relevant stimuli according to location, features, or onset time. In this study we compared the behavioural timecourse of goal-directed selection to locations and colours by varying the stimulus-onset asynchrony (SOA) between cue and target in a strategic cueing paradigm. Participants reported the presence or absence of a target following prior information regarding its location or colour. Results revealed that preparatory selection by colour is more effective at enhancing perceptual sensitivity than selection by location, even though both types of cue provided equivalent overall information. More detailed analysis revealed that this advantage arose due a limitation of spatial attention in maintaining a sufficiently broad focus (>2°) for target detection across multiple stimuli. In contrast, when target stimuli fell within 2° of the spatial attention spotlight, the strategic advantages and speed of spatial and colour attention were equated. Our findings are consistent with the conclusion that, under spatially optimal conditions, prior spatial and colour information are equally proficient at guiding top-down selection. When spatial locations are ambiguous, however, colour-based selection is the more efficient mechanism.

  15. Is colour cognitive?

    NASA Astrophysics Data System (ADS)

    Skorupski, Peter; Chittka, Lars

    2011-03-01

    In recent years, colour-vision abilities have been rather generously ascribed to various invertebrates and even bacteria. This uncertainty of when to diagnose colour vision stems in part from confusing what colour vision can do with what it is. What colour vision can do is discriminate wavelength independent of intensity. However, if we take this as a definition of what colour vision is, then we might be obliged to conclude that some plants and bacteria have colour vision. Moreover, there is a similar confusion of what are necessary and what are sufficient mechanisms and behavioural abilities for colour vision. To humans, seeing in colour means seeing an image in which objects/lights have chromatic attributes—in contrast to the sensation that we have when viewing monochrome movies, or our experience in dim light when only rod vision is possible. The necessary basic equipment for this is to have at least two types of photoreceptors that differ in spectral sensitivity, and at least one type of spectrally opponent cell to compare the signals from the photoreceptors. Clearly, however, a necessary additional prerequisite for colour vision is to have vision, which entails the identification of shapes, sizes and locations of objects in the world. Thus, if an animal has colour vision, it should see an image in which distinct objects/lights have colour attributes. This distinguishes colour vision from wavelength discrimination, but also from what has historically been called wavelength-specific behaviour: a type of behaviour triggered by fixed configurations of spectral receptor signals; however, we discuss difficulties in diagnosing wavelength-specific behaviour as an indicator of the absence of colour vision. Finally, we discuss whether colour vision, by definition, contains a cognitive dimension for ordering and classifying perceptual experience.

  16. Exercise and Drinking May Play a Role in Vision Impairment Risk

    MedlinePlus

    ... May Play a Role in Vision Impairment Risk Mar. 20, 2014 In 2020, the number of people ... 2004;122:477–85. Related Stories Drusen Diagnosis Mar 01, 2017 Stargardt Disease Symptoms Mar 01, 2017 ...

  17. Audible vision for the blind and visually impaired in indoor open spaces.

    PubMed

    Yu, Xunyi; Ganz, Aura

    2012-01-01

    In this paper we introduce Audible Vision, a system that can help blind and visually impaired users navigate in large indoor open spaces. The system uses computer vision to estimate the location and orientation of the user, and enables the user to perceive his/her relative position to a landmark through 3D audio. Testing shows that Audible Vision can work reliably in real-life ever-changing environment crowded with people.

  18. [Acute bilateral impaired vision with central scotoma in an 11-year-old boy].

    PubMed

    Pollithy, S; Ach, T; Schaal, K B; Dithmar, S

    2012-09-01

    This article presents a case of acute bilateral impaired vision and central scotoma in an 11-year-old boy. Looking directly into a laser beam of a laser pointer for only a few seconds can cause retinal damage in the form of lesions of the retinal pigment epithelium and the photoreceptor layer, up to retinal hemorrhage. Patients often complain about impaired vision and a central scotoma of the affected eye.

  19. High complexity of aquatic irradiance may have driven the evolution of four-dimensional colour vision in shallow-water fish.

    PubMed

    Sabbah, Shai; Troje, Nikolaus F; Gray, Suzanne M; Hawryshyn, Craig W

    2013-05-01

    Humans use three cone photoreceptor classes for colour vision, yet many birds, reptiles and shallow-water fish are tetrachromatic and use four cone classes. Screening pigments, which narrow the spectrum of photoreceptors in birds and diurnal reptiles, render visual systems with four cone classes more efficient. To date, however, the question of tetrachromacy in shallow-water fish that, like humans, lack screening pigments, is still unsolved. We raise the possibility that tetrachromacy in fish has evolved in response to higher spectral complexity of underwater light. We compared the dimensionality of colour vision in humans and fish by examining the spectral complexity of the colour signal reflected from objects into their eyes. We show that fish require four to six cone classes to reconstruct the colour signal of aquatic objects at the accuracy level achieved by humans viewing terrestrial objects. This is because environmental light, which alters the colour signals, is more complex and contains more spectral fluctuations underwater than on land. We further show that fish cones are better suited than human cones to detect these spectral fluctuations, suggesting that the capability of fish cones to detect high-frequency fluctuations in the colour signal confers an advantage. Taken together, we propose that tetrachromacy in fish has evolved to enhance the reconstruction of complex colour signals in shallow aquatic environments. Of course, shallow-water fish might possess fewer than four cone classes; however, this would come with the inevitable loss in accuracy of signal reconstruction.

  20. The relationship between visual function and performance in rifle shooting for athletes with vision impairment

    PubMed Central

    Myint, Joy; Latham, Keziah; Mann, David; Gomersall, Phil; Wilkins, Arnold J; Allen, Peter M

    2016-01-01

    Background Paralympic sports provide opportunities for those who have an impairment that might otherwise be a barrier to participation in regular sporting competition. Rifle shooting represents an ideal sport for persons with vision impairment (VI) because the direction of the rifle can be guided by auditory information when vision is impaired. However, it is unknown whether those with some remaining vision when shooting with auditory guidance would be at an advantage when compared with those with no vision at all. If this were the case then it would be necessary for those with and without remaining vision to compete in separate classes of competition. Materials and method The associations between shooting performance and 3 measures of visual function thought important for shooting were assessed for 10 elite VI shooters currently classified as VI. A conventional audiogram was also obtained. Results The sample size, though small, included the majority of European VI shooters competing at this level. The relationships between visual functions and performance confirmed that individuals with residual vision had no advantage over those without vision when auditory guidance was available. Auditory function was within normal limits for age, and showed no relationship with performance. Summary The findings suggest that rifle-shooting athletes with VI are able to use auditory information to overcome their impairment and optimise performance. Paralympic competition should be structured in a way that ensures that all shooters who qualify to compete in VI shooting participate within the same class irrespective of their level of VI. PMID:27900160

  1. Use of the Simplified Color Video Magnifier by Young Children with Severely Impaired Vision.

    ERIC Educational Resources Information Center

    Muranaka, Yoshio; And Others

    1985-01-01

    A new image magnifier system that enlarges color picture images for visually impaired children consists of home video components following the closed-circuit television model. The technique seems especially effective in enriching visual experience of children with severely impaired vision and bridging the interest development gap between picture…

  2. Health Outcomes Associated with Self-Reported Vision Impairment in Older Adults

    ERIC Educational Resources Information Center

    Steinman, Bernard A.

    2016-01-01

    Introduction: To compare the health status of older adults with and without vision impairment, this study employed a disability framework consisting of four stages, progressing from risk factors; through pathology and impairments that result in declining functioning; and eventually to disability. Methods: Data from five rounds (1999 to 2008) of…

  3. Colour Perception in ADHD

    ERIC Educational Resources Information Center

    Banaschewski, Tobias; Ruppert, Sinje; Tannock, Rosemary; Albrecht, Bjorn; Becker, Andreas; Uebel, Henrik; Sergeant, Joseph A.; Rothenberger, Aribert

    2006-01-01

    Attention-deficit/hyperactivity disorder (ADHD) is associated with unexplained impairments on speeded naming of coloured stimuli. These deficits may reflect hypofunctioning retinal dopaminergic mechanisms impairing particularly blue-yellow colour discrimination. Colour perception and rapid colour naming ability were investigated in 14 children…

  4. Towards Understanding the Role of Colour Information in Scene Perception using Night Vision Device

    DTIC Science & Technology

    2009-06-01

    example orange flare smoke and fog, or camouflage and vegetation . Under very low light conditions the device uses the infrared band. The colour imagery... fruit (Mollon, 1989; Orsorio and Voryobyev, 1996). Recent ecological studies have shown that the primate red and green photopigments are in fact more...useful for distinguishing young leaves than ripe fruit . The latter are generally brighter and yellower than the surrounding foliage (Dominy and

  5. The Effect of Gender and Level of Vision on the Physical Activity Level of Children and Adolescents with Visual Impairment

    ERIC Educational Resources Information Center

    Aslan, Ummuhan Bas; Calik, Bilge Basakci; Kitis, Ali

    2012-01-01

    This study was planned in order to determine physical activity levels of visually impaired children and adolescents and to investigate the effect of gender and level of vision on physical activity level in visually impaired children and adolescents. A total of 30 visually impaired children and adolescents (16 low vision and 14 blind) aged between…

  6. Visual Impairment Secondary to Congenital Glaucoma in Children: Visual Responses, Optical Correction and Use of Low Vision Aids

    PubMed Central

    Haddad, Maria Aparecida Onuki; Sampaio, Marcos Wilson; Oltrogge, Ernst Werner; Kara-José, Newton; Betinjane, Alberto Jorge

    2009-01-01

    INTRODUCTION Congenital glaucoma is frequently associated with visual impairment due to optic nerve damage, corneal opacities, cataracts and amblyopia. Poor vision in childhood is related to global developmental problems, and referral to vision habilitation/rehabilitation services should be without delay to promote efficient management of the impaired vision. OBJECTIVE To analyze data concerning visual response, the use of optical correction and prescribed low vision aids in a population of children with congenital glaucoma. METHOD The authors analyzed data from 100 children with congenital glaucoma to assess best corrected visual acuity, prescribed optical correction and low vision aids. RESULTS Fifty-five percent of the sample were male, 43% female. The mean age was 6.3 years. Two percent presented normal visual acuity levels, 29% mild visual impairment, 28% moderate visual impairment, 15% severe visual impairment, 11% profound visual impairment, and 15% near blindness. Sixty-eight percent received optical correction for refractive errors. Optical low vision aids were adopted for distance vision in 34% of the patients and for near vision in 6%. A manual monocular telescopic system with 2.8 × magnification was the most frequently prescribed low vision aid for distance, and for near vision a +38 diopter illuminated stand magnifier was most frequently prescribed. DISCUSSION AND CONCLUSION Careful low vision assessment and the appropriate prescription of optical corrections and low vision aids are mandatory in children with congenital glaucoma, since this will assist their global development, improving efficiency in daily life activities and promoting social and educational inclusion. PMID:19690654

  7. The Level of Vision Necessary for Competitive Performance in Rifle Shooting: Setting the Standards for Paralympic Shooting with Vision Impairment

    PubMed Central

    Allen, Peter M.; Latham, Keziah; Mann, David L.; Ravensbergen, Rianne H. J. C.; Myint, Joy

    2016-01-01

    The aim of this study was to investigate the level of vision impairment (VI) that would reduce performance in shooting; to guide development of entry criteria to visually impaired (VI) shooting. Nineteen international-level shooters without VI took part in the study. Participants shot an air rifle, while standing, toward a regulation target placed at the end of a 10 m shooting range. Cambridge simulation glasses were used to simulate six different levels of VI. Visual acuity (VA) and contrast sensitivity (CS) were assessed along with shooting performance in each of seven conditions of simulated impairment and compared to that with habitual vision. Shooting performance was evaluated by calculating each individual’s average score in every level of simulated VI and normalizing this score by expressing it as a percentage of the baseline performance achieved with habitual vision. Receiver Operating Characteristic curves were constructed to evaluate the ability of different VA and CS cut-off criteria to appropriately classify these athletes as achieving ‘expected’ or ‘below expected’ shooting results based on their performance with different levels of VA and CS. Shooting performance remained relatively unaffected by mild decreases in VA and CS, but quickly deteriorated with more moderate losses. The ability of visual function measurements to classify shooting performance was good, with 78% of performances appropriately classified using a cut-off of 0.53 logMAR and 74% appropriately classified using a cut-off of 0.83 logCS. The current inclusion criteria for VI shooting (1.0 logMAR) is conservative, maximizing the chance of including only those with an impairment that does impact performance, but potentially excluding some who do have a genuine impairment in the sport. A lower level of impairment would include more athletes who do have a genuine impairment but would potentially include those who do not actually have an impairment that impacts performance in the

  8. The Level of Vision Necessary for Competitive Performance in Rifle Shooting: Setting the Standards for Paralympic Shooting with Vision Impairment.

    PubMed

    Allen, Peter M; Latham, Keziah; Mann, David L; Ravensbergen, Rianne H J C; Myint, Joy

    2016-01-01

    The aim of this study was to investigate the level of vision impairment (VI) that would reduce performance in shooting; to guide development of entry criteria to visually impaired (VI) shooting. Nineteen international-level shooters without VI took part in the study. Participants shot an air rifle, while standing, toward a regulation target placed at the end of a 10 m shooting range. Cambridge simulation glasses were used to simulate six different levels of VI. Visual acuity (VA) and contrast sensitivity (CS) were assessed along with shooting performance in each of seven conditions of simulated impairment and compared to that with habitual vision. Shooting performance was evaluated by calculating each individual's average score in every level of simulated VI and normalizing this score by expressing it as a percentage of the baseline performance achieved with habitual vision. Receiver Operating Characteristic curves were constructed to evaluate the ability of different VA and CS cut-off criteria to appropriately classify these athletes as achieving 'expected' or 'below expected' shooting results based on their performance with different levels of VA and CS. Shooting performance remained relatively unaffected by mild decreases in VA and CS, but quickly deteriorated with more moderate losses. The ability of visual function measurements to classify shooting performance was good, with 78% of performances appropriately classified using a cut-off of 0.53 logMAR and 74% appropriately classified using a cut-off of 0.83 logCS. The current inclusion criteria for VI shooting (1.0 logMAR) is conservative, maximizing the chance of including only those with an impairment that does impact performance, but potentially excluding some who do have a genuine impairment in the sport. A lower level of impairment would include more athletes who do have a genuine impairment but would potentially include those who do not actually have an impairment that impacts performance in the sport. An

  9. Colour agnosia impairs the recognition of natural but not of non-natural scenes.

    PubMed

    Nijboer, Tanja C W; Van Der Smagt, Maarten J; Van Zandvoort, Martine J E; De Haan, Edward H F

    2007-03-01

    Scene recognition can be enhanced by appropriate colour information, yet the level of visual processing at which colour exerts its effects is still unclear. It has been suggested that colour supports low-level sensory processing, while others have claimed that colour information aids semantic categorization and recognition of objects and scenes. We investigated the effect of colour on scene recognition in a case of colour agnosia, M.A.H. In a scene identification task, participants had to name images of natural or non-natural scenes in six different formats. Irrespective of scene format, M.A.H. was much slower on the natural than on the non-natural scenes. As expected, neither M.A.H. nor control participants showed any difference in performance for the non-natural scenes. However, for the natural scenes, appropriate colour facilitated scene recognition in control participants (i.e., shorter reaction times), whereas M.A.H.'s performance did not differ across formats. Our data thus support the hypothesis that the effect of colour occurs at the level of learned associations.

  10. Controllable liquid colour-changing lenses with microfluidic channels for vision protection, camouflage and optical filtering based on soft lithography fabrication.

    PubMed

    Zhang, Min; Li, Songjing

    2016-01-01

    In this work, liquid colour-changing lenses for vision protection, camouflage and optical filtering are developed by circulating colour liquids through microfluidic channels on the lenses manually. Soft lithography technology is applied to fabricate the silicone liquid colour-changing layers with microfluidic channels on the lenses instead of mechanical machining. To increase the hardness and abrasion resistance of the silicone colour-changing layers on the lenses, proper fabrication parameters such as 6:1 (mass ration) mixing proportion and 100 °C curing temperature for 2 h are approved for better soft lithography process of the lenses. Meanwhile, a new surface treatment for the irreversible bonding of silicone colour-changing layer with optical resin (CR39) substrate lens by using 5 % (volume ratio) 3-Aminopropyltriethoxysilane solution is proposed. Vision protection, camouflage and optical filtering functions of the lenses are investigated with different designs of the channels and multi-layer structures. Each application can not only well achieve their functional demands, but also shows the advantages of functional flexibility, rapid prototyping and good controllability compared with traditional ways. Besides optometry, some other designs and applications of the lenses are proposed for potential utility in the future.

  11. Establishing Equity and Quality: The Experience of Schooling from the Perspective of a Student with Vision Impairment

    ERIC Educational Resources Information Center

    Southcott, Jane; Opie, Jill

    2016-01-01

    A single participant phenomenological study using Interpretative Phenomenological Analysis can give voice to a student with vision impairment, exploring and developing our understanding of the experience of schooling. This article focuses on the school experience of a senior school student with vision impairment. Few studies have looked at school…

  12. 14 CFR 382.119 - What information must carriers give individuals with vision or hearing impairment on aircraft?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false What information must carriers give individuals with vision or hearing impairment on aircraft? 382.119 Section 382.119 Aeronautics and Space... carriers give individuals with vision or hearing impairment on aircraft? (a) As a carrier, you must...

  13. 14 CFR 382.53 - What information must carriers give individuals with a vision or hearing impairment at airports?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false What information must carriers give individuals with a vision or hearing impairment at airports? 382.53 Section 382.53 Aeronautics and Space... information must carriers give individuals with a vision or hearing impairment at airports? (a)(1) As a...

  14. 14 CFR 382.53 - What information must carriers give individuals with a vision or hearing impairment at airports?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false What information must carriers give individuals with a vision or hearing impairment at airports? 382.53 Section 382.53 Aeronautics and Space... information must carriers give individuals with a vision or hearing impairment at airports? (a)(1) As a...

  15. 14 CFR 382.53 - What information must carriers give individuals with a vision or hearing impairment at airports?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false What information must carriers give individuals with a vision or hearing impairment at airports? 382.53 Section 382.53 Aeronautics and Space... information must carriers give individuals with a vision or hearing impairment at airports? (a)(1) As a...

  16. 14 CFR 382.119 - What information must carriers give individuals with vision or hearing impairment on aircraft?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false What information must carriers give individuals with vision or hearing impairment on aircraft? 382.119 Section 382.119 Aeronautics and Space... carriers give individuals with vision or hearing impairment on aircraft? (a) As a carrier, you must...

  17. 14 CFR 382.53 - What information must carriers give individuals with a vision or hearing impairment at airports?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false What information must carriers give individuals with a vision or hearing impairment at airports? 382.53 Section 382.53 Aeronautics and Space... information must carriers give individuals with a vision or hearing impairment at airports? (a)(1) As a...

  18. 14 CFR 382.119 - What information must carriers give individuals with vision or hearing impairment on aircraft?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false What information must carriers give individuals with vision or hearing impairment on aircraft? 382.119 Section 382.119 Aeronautics and Space... carriers give individuals with vision or hearing impairment on aircraft? (a) As a carrier, you must...

  19. 14 CFR 382.119 - What information must carriers give individuals with vision or hearing impairment on aircraft?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false What information must carriers give individuals with vision or hearing impairment on aircraft? 382.119 Section 382.119 Aeronautics and Space... carriers give individuals with vision or hearing impairment on aircraft? (a) As a carrier, you must...

  20. Students with Low Vision Describe Their Visual Impairments and Visual Functioning

    ERIC Educational Resources Information Center

    Guerette, Amy R.; Lewis, Sandra; Mattingly, Cameron

    2011-01-01

    In the study reported here, the responses to a survey that was designed to determine the knowledge of their visual impairment of 51 students with low vision were analyzed. Although the students described their visual weaknesses and strengths, they had limited knowledge of, and difficulty communicating about, the medical aspects of their…

  1. Test Anxiety Research: Students with Vision Impairments and Students with Mild Intellectual Disabilities

    ERIC Educational Resources Information Center

    Datta, Poulomee

    2014-01-01

    There is an absence of research on test anxiety in students with disabilities although such testing is taken for granted among students without disabilities. This study investigated the test anxiety of the students in each of the two disability groups, those with vision impairments and those with intellectual disabilities who are placed in…

  2. An Overview of a UK Paediatric Visual Impaired Population and Low Vision Aid Provision

    ERIC Educational Resources Information Center

    Theodorou, Nana; Shipman, Tracey

    2013-01-01

    A retrospective study was carried out to evaluate the paediatric visual impaired population attending the Low Vision Clinic at Sheffield Teaching Hospitals NHS Foundation Trust, over a period of 14 years. Data were collected and analysed for children less than 17 years for prevalence, demographics, registration status, aetiologies, and types of…

  3. Understanding the Graphical Challenges Faced by Vision-Impaired Students in Australian Universities

    ERIC Educational Resources Information Center

    Butler, Matthew; Holloway, Leona; Marriott, Kim; Goncu, Cagatay

    2017-01-01

    Information graphics such as plots, maps, plans, charts, tables and diagrams form an integral part of the student learning experience in many disciplines. However, for a vision impaired student accessing such graphical materials can be problematic. This research seeks to understand the current state of accessible graphics provision in Australian…

  4. Audio from Orbit: The Future of Libraries for Individuals Who Are Blind or Vision Impaired

    ERIC Educational Resources Information Center

    Steer, Michael; Cheetham, Leonie

    2005-01-01

    Free library service is a component of the foundations of democracy, citizenship, economic and social development, scholarship and education, in progressive societies. The evolution of libraries for people who are blind or vision impaired is briefly discussed and an innovative project, a talking book and daily newspaper delivery system that…

  5. Space Vision: Making Astronomy Accessible to Visually Impaired Students

    NASA Astrophysics Data System (ADS)

    Ries, J. G.; Baguio, M. R.; Jurgens, T. D.; Pruett, K. M.

    2004-05-01

    Astronomy, with good reason, is thought of as a visual science. Spectacular images of deep space objects or other worlds of our solar system inspire public interest in Astronomy. People encounter news about the universe during their daily life. Developing concepts about celestial objects presents an extra challenge of abstraction for people with visual impairments. The Texas Space Grant Consortium with educators at the Texas School for the Blind and Visually Impaired have developed a 2 day workshop to be held in April 2004 to help students with visual impairments understand these concepts. Hands-on activities and experiments will emphasize non-visual senses. For example, students will learn about: - Constellations as historical ways of finding one's way across the sky. - The size and structure of the Solar System by building a scale model on a running track. They will also: - Plan a planetary exploration mission. - Explore wave phenomenon using heat and sound waves. In preparation for the workshop we worked with teens involved in the countywide 4-H Teens Leading with Character (TLC) program to create the tactile materials necessary for the activities. The teens attended solar system education training so they would have the skills necessary to make the tactile displays to be used during the workshop. The results and evaluation of the workshop will be presented at the meeting. Touch the Universe: A NASA Braille Book of Astronomy inspired this workshop, and it is supported by HST Grant HST-ED-90255.01-A.

  6. Seroepidemiology of Toxocara Infection in Patients With Vision Impairment and Blindness in Durango, Mexico

    PubMed Central

    Alvarado-Esquivel, Cosme; Hernandez-Tinoco, Jesus; Sanchez-Anguiano, Luis Francisco

    2015-01-01

    Background Toxocara infection is a cause of vision impairment and blindness. We aimed to determine the seroprevalence and correlates of Toxocara infection in patients suffering from vision impairment and blindness in Durango City, Mexico. Methods Through a cross-sectional seroprevalence study, 204 patients with vision impairment and 19 blind patients were studied for the presence of anti-Toxocara IgG antibodies in Durango City, Mexico. Seroprevalence association with socio-demographic, housing, clinical, and behavioral characteristics of participants was also investigated. Results Five (2.5%) of the 204 patients with vision impairment, and none of the 19 patients with blindness were positive for anti-Toxocara IgG antibodies. In total, five of the 223 (2.2%) patients were positive for anti-Toxocara IgG antibodies. Seropositivity to Toxocara was not associated with age, sex, educational level, socio-economic status, presence of underlying diseases or behavioral characteristics of the patients. In contrast, multivariate analysis showed that Toxocara seropositivity was associated with living in a house with soil floor (odds ratio (OR) = 11.14; 95% confidence interval (CI): 1.57 - 78.74; P = 0.01). Conclusions This is the first report of Toxocara exposure in patients with vision impairment and blindness in Mexico, and of an association of Toxocara exposure with living in a house with soil floors. Results suggest a low Toxocara exposure in these patients in Durango, Mexico. The risk factor associated with Toxocara exposure identified in this study warrants for further investigation. PMID:25584103

  7. Impact of correcting visual impairment and low vision in deaf-mute students in Pune, India

    PubMed Central

    Gogate, Parikshit; Bhusan, Shashi; Ray, Shantanu; Shinde, Amit

    2016-01-01

    Aim: The aim of this study was to evaluate visual acuity and vision function before and after providing spectacles and low vision devices (LVDs) in deaf-mute students. Settings: Schools for deaf-mute in West Maharashtra. Methods: Hearing-impaired children in all special schools in Pune district underwent detailed visual acuity testing (with teachers' help), refraction, external ocular examination, and fundoscopy. Students with refractive errors and low vision were provided with spectacles and LVD. The LV Prasad-Functional Vision Questionnaire consisting of twenty items was administered to each subject before and after providing spectacles, LVDs. Statistical Analysis: Wilcoxon matched-pairs signed-ranks test. Results: 252/929 (27.1%) students had a refractive error. 794 (85.5%) were profound deaf. Two-hundred and fifty students were dispensed spectacles and LVDs. Mean LogMAR visual acuity before introduction of spectacles and LVDs were 0.33 ± 0.36 which improved to 0.058 (P < 0.0001) after intervention. It was found that difference in functional vision pre- and post-intervention was statistically significant (P < 0.0001) for questions 1–19. The most commonly reported difficulties were for performing distance task like reading the bus destination (58.7%), making out the bus number (51.1%), copying from blackboard (47.7%), and seeing whether somebody is waving hand from across the road (45.5%). In response to question number 20, 57.4% of students felt that their vision was much worse than their friend's vision, which was reduced to 17.6% after dispensing spectacles and LVDs. Conclusion: Spectacle and LVD reduced visual impairment and improved vision function in deaf-mute students, augmenting their ability to negotiate in and out of school. PMID:28112130

  8. Do visually impaired children and their parents agree on the child's vision-related quality of life and functional vision?

    PubMed Central

    Tadić, Valerija; Cumberland, Phillippa M; Lewando-Hundt, Gillian; Rahi, Jugnoo S

    2017-01-01

    Aims To investigate agreement between children with visual impairment (VI) and their parents on their ratings of the child's vision-related quality of life (VQoL) and functional vision (FV) using two novel self-report patient-reported outcome measures developed for this population. Methods 99 children aged 10–15 years (mean age=12.2, SD=1.9) with VI (best corrected acuity (logarithm of the minimum angle of resolution) 0.50 or worse in better eye) and their parents participated in a national postal survey, completing the child and proxy versions of our novel instruments assessing VQoL and FV of children with VI—the vision-related quality of life instrument for children and young people (VQoL_CYP) and the functional vision questionnaire for children and young people (FVQ_CYP), respectively. Parent-child agreement was investigated using the Bland-Altman (BA) method. Variation across key sociodemographic and clinical characteristics was examined using the Intraclass Correlation Coefficient. Results Average parental ratings of their child's VQoL and FV were significantly lower than the children's own ratings, but the range of disagreement was wide, with parents both overestimating and underestimating their child's VQoL (mean score difference=5.7, BA limits of agreement (LOA): lower −22.10 (CI 95% −24.61 to 19.59) and upper 33.50 (CI 95% 30.99 to 36.01)), but more consistently underestimating the child's FV (mean score difference=−11.8, BA LOA: lower −39.60 (CI 95% −42.12 to 37.08) and upper 16 (CI 95% 13.48 to 18.52)). There was variation in agreement by some child characteristics, including vision level, time of onset and course of VI progression. Conclusions Visually impaired children and their parents perceive the broader impact of living with VI very differently. There is value in routine capture of information independently from children and their parents for comprehensively gauging the impact of childhood VI and tailoring appropriate interventions

  9. Comorbid Cognitive Impairment and Functional Trajectories in Low Vision Rehabilitation for Macular Disease

    PubMed Central

    Whitson, Heather E.; Ansah, Deidra; Sanders, Linda L; Whitaker, Diane; Potter, Guy G.; Cousins, Scott W.; Steffens, David C.; Landerman, Lawrence R.; Pieper, Carl F.; Cohen, Harvey Jay

    2011-01-01

    Background and Aims Comorbid cognitive impairment is common among visually impaired older adults. This study investigated whether baseline cognitive status predicts functional trajectories among older adults in low vision rehabilitation (LVR) for macular disease. Methods The Telephone Interview for Cognitive Status – modified (TICS-m) was administered to macular disease patients aged ≥ 65 years receiving outpatient LVR. Mixed models assessed the rate of change in instrumental activities of daily living and visual function measures over a mean follow-up of 115 days. Results Of 91 participants, 17 (18.7%) had cognitive impairment (TICS-m score ≤ 27) and 23 (25.3%) had marginal impairment (TICS-m scores 28 to 30). Controlling for age and gender, baseline cognitive status did not predict most functional outcomes. However, participants with marginal cognitive impairment experienced worse functional trajectories in ability to prepare meals (p=0.03).and activities that require distance vision (p = 0.05). Conclusion Patients with mild to moderate cognitive impairment should not be excluded from LVR, but programs should be prepared to detect and accommodate a range of cognitive ability. PMID:22526069

  10. The effects of simulated vision impairments on the cone of gaze.

    PubMed

    Hecht, Heiko; Hörichs, Jenny; Sheldon, Sarah; Quint, Jessilin; Bowers, Alex

    2015-10-01

    Detecting the gaze direction of others is critical for many social interactions. We explored factors that may make the perception of mutual gaze more difficult, including the degradation of the stimulus and simulated vision impairment. To what extent do these factors affect the complex assessment of mutual gaze? Using an interactive virtual head whose eye direction could be manipulated by the subject, we conducted two experiments to assess the effects of simulated vision impairments on mutual gaze. Healthy subjects had to demarcate the center and the edges of the cone of gaze-that is, the range of gaze directions that are accepted for mutual gaze. When vision was impaired by adding a semitransparent white contrast reduction mask to the display (Exp. 1), judgments became more variable and more influenced by the head direction (indicative of a compensation strategy). When refractive blur was added (Exp. 1), the gaze cone shrank from 12.9° (no blur) to 11.3° (3-diopter lens), which cannot be explained by a low-level process but might reflect a tightening of the criterion for mutual gaze as a response to the increased uncertainty. However, the overall effects of the impairments were relatively modest. Elderly subjects (Exp. 2) produced more variability but did not differ qualitatively from the younger subjects. In the face of artificial vision impairments, compensation mechanisms and criterion changes allow us to perform better in mutual gaze perception than would be predicted by a simple extrapolation from the losses in basic visual acuity and contrast sensitivity.

  11. The Influence of Manifest Strabismus and Stereoscopic Vision on Non-Verbal Abilities of Visually Impaired Children

    ERIC Educational Resources Information Center

    Gligorovic, Milica; Vucinic, Vesna; Eskirovic, Branka; Jablan, Branka

    2011-01-01

    This research was conducted in order to examine the influence of manifest strabismus and stereoscopic vision on non-verbal abilities of visually impaired children aged between 7 and 15. The sample included 55 visually impaired children from the 1st to the 6th grade of elementary schools for visually impaired children in Belgrade. RANDOT stereotest…

  12. High Tech Aids Low Vision: A Review of Image Processing for the Visually Impaired

    PubMed Central

    Moshtael, Howard; Aslam, Tariq; Underwood, Ian; Dhillon, Baljean

    2015-01-01

    Recent advances in digital image processing provide promising methods for maximizing the residual vision of the visually impaired. This paper seeks to introduce this field to the readership and describe its current state as found in the literature. A systematic search revealed 37 studies that measure the value of image processing techniques for subjects with low vision. The techniques used are categorized according to their effect and the principal findings are summarized. The majority of participants preferred enhanced images over the original for a wide range of enhancement types. Adapting the contrast and spatial frequency content often improved performance at object recognition and reading speed, as did techniques that attenuate the image background and a technique that induced jitter. A lack of consistency in preference and performance measures was found, as well as a lack of independent studies. Nevertheless, the promising results should encourage further research in order to allow their widespread use in low-vision aids. PMID:26290777

  13. High Tech Aids Low Vision: A Review of Image Processing for the Visually Impaired.

    PubMed

    Moshtael, Howard; Aslam, Tariq; Underwood, Ian; Dhillon, Baljean

    2015-08-01

    Recent advances in digital image processing provide promising methods for maximizing the residual vision of the visually impaired. This paper seeks to introduce this field to the readership and describe its current state as found in the literature. A systematic search revealed 37 studies that measure the value of image processing techniques for subjects with low vision. The techniques used are categorized according to their effect and the principal findings are summarized. The majority of participants preferred enhanced images over the original for a wide range of enhancement types. Adapting the contrast and spatial frequency content often improved performance at object recognition and reading speed, as did techniques that attenuate the image background and a technique that induced jitter. A lack of consistency in preference and performance measures was found, as well as a lack of independent studies. Nevertheless, the promising results should encourage further research in order to allow their widespread use in low-vision aids.

  14. The relative impact of vision impairment and cardiovascular disease on quality of life: the example of pseudoxanthoma elasticum

    PubMed Central

    2011-01-01

    Objective To investigate the impact of pseudoxanthoma elasticum (PXE), a rare hereditary disease of concurrent vision impairment (VI) and cardiovascular complications (CVCs), on vision-related (VRQoL) and health-related quality of life (HRQoL). Methods VRQoL and HRQoL were assessed using the Impact of Vision Impairment (IVI) questionnaire and the Short Form Health Survey (SF-36) in 107 PXE patients. Patients were stratified into four groups: A = no VI or CVC; B = CVCs only; C = VI only; and D = both VI and CVCs. Results Following Rasch analysis, the IVI was found to function as a vision-specific functioning and emotional well-being subscale, and the SF-36 as a health-related physical functioning and mental health subscale. The presence of VI and CVC were significant predictors of vision-specific functioning and emotional well-being (p < 0.001), with a clinically meaningful decrement in vision-specific functioning in patients with VI. No associations were found for the SF-36 Physical Functioning and Mental Health scores between any groups. Conclusions Vision impaired patients with PXE report significantly poorer vision-specific functioning than PXE patients without VI. In contrast, the relative impact of PXE on reported general HRQoL was much less. Our results suggest that vision impairment has the larger impact on QoL in this sample. PMID:22152229

  15. The Use of a Tactile-Vision Sensory Substitution System as an Augmentative Tool for Individuals with Visual Impairments

    ERIC Educational Resources Information Center

    Williams, Michael D.; Ray, Christopher T.; Griffith, Jennifer; De l'Aune, William

    2011-01-01

    The promise of novel technological strategies and solutions to assist persons with visual impairments (that is, those who are blind or have low vision) is frequently discussed and held to be widely beneficial in countless applications and daily activities. One such approach involving a tactile-vision sensory substitution modality as a mechanism to…

  16. No rainbow for grey bamboo sharks: evidence for the absence of colour vision in sharks from behavioural discrimination experiments.

    PubMed

    Schluessel, V; Rick, I P; Plischke, K

    2014-11-01

    Despite convincing data collected by microspectrophotometry and molecular biology, rendering sharks colourblind cone monochromats, the question of whether sharks can perceive colour had not been finally resolved in the absence of any behavioural experiments compensating for the confounding factor of brightness. The present study tested the ability of juvenile grey bamboo sharks to perceive colour in an experimental design based on a paradigm established by Karl von Frisch using colours in combination with grey distractor stimuli of equal brightness. Results showed that contrasts but no colours could be discriminated. Blue and yellow stimuli were not distinguished from a grey distractor stimulus of equal brightness but could be distinguished from distractor stimuli of varying brightness. In addition, different grey stimuli were distinguished significantly above chance level from one another. In conclusion, the behavioural results support the previously collected physiological data on bamboo sharks, which mutually show that the grey bamboo shark, like several marine mammals, is a cone monochromate and colourblind.

  17. Color vision impairment in multiple sclerosis points to retinal ganglion cell damage.

    PubMed

    Lampert, E J; Andorra, M; Torres-Torres, R; Ortiz-Pérez, S; Llufriu, S; Sepúlveda, M; Sola, N; Saiz, A; Sánchez-Dalmau, B; Villoslada, P; Martínez-Lapiscina, Elena H

    2015-11-01

    Multiple Sclerosis (MS) results in color vision impairment regardless of optic neuritis (ON). The exact location of injury remains undefined. The objective of this study is to identify the region leading to dyschromatopsia in MS patients' NON-eyes. We evaluated Spearman correlations between color vision and measures of different regions in the afferent visual pathway in 106 MS patients. Regions with significant correlations were included in logistic regression models to assess their independent role in dyschromatopsia. We evaluated color vision with Hardy-Rand-Rittler plates and retinal damage using Optical Coherence Tomography. We ran SIENAX to measure Normalized Brain Parenchymal Volume (NBPV), FIRST for thalamus volume and Freesurfer for visual cortex areas. We found moderate, significant correlations between color vision and macular retinal nerve fiber layer (rho = 0.289, p = 0.003), ganglion cell complex (GCC = GCIP) (rho = 0.353, p < 0.001), thalamus (rho = 0.361, p < 0.001), and lesion volume within the optic radiations (rho = -0.230, p = 0.030). Only GCC thickness remained significant (p = 0.023) in the logistic regression model. In the final model including lesion load and NBPV as markers of diffuse neuroaxonal damage, GCC remained associated with dyschromatopsia [OR = 0.88 95 % CI (0.80-0.97) p = 0.016]. This association remained significant when we also added sex, age, and disease duration as covariates in the regression model. Dyschromatopsia in NON-eyes is due to damage of retinal ganglion cells (RGC) in MS. Color vision can serve as a marker of RGC damage in MS.

  18. Device for diagnosis and treatment of impairments on binocular vision and stereopsis

    NASA Astrophysics Data System (ADS)

    Bahn, Jieun; Choi, Yong-Jin; Son, Jung-Young; Kodratiev, N. V.; Elkhov, Victor A.; Ovechkis, Yuri N.; Chung, Chan-sup

    2001-06-01

    Strabismus and amblyopia are two main impairments of our visual system, which are responsible for the loss of stereovision. A device is developed for diagnosis and treatment of strabismus and amblyopia, and for training and developing stereopsis. This device is composed of a liquid crystal glasses (LCG), electronics for driving LCG and synchronizing with an IBM PC, and a special software. The software contains specially designed patterns and graphics for enabling to train and develop stereopsis, and do objective measurement of some stereoscopic vision parameters such as horizontal and vertical phoria, fusion, fixation disparity, and stereoscopic visual threshold.

  19. The adaptation dynamics of chronic functional impairment: what we can learn from older adults with vision loss.

    PubMed

    Schilling, Oliver K; Wahl, Hans-Werner; Horowitz, Amy; Reinhardt, Joann P; Boerner, Kathrin

    2011-03-01

    This study used vision loss due to age-related macular degeneration to learn about adaptation processes related to chronic functional impairment, focusing on Horowitz and Reinhardt's (1998) concept of Adaptation to Age-related Vision Loss (AVL) as the outcome. We hypothesized that impacts of visual acuity on AVL are mediated by perceived functional vision losses and functional abilities, and tested for "adaptive" weakening of this impact with ongoing loss. Longitudinal data covering a one-year interval from samples with age-related macular degeneration gathered in New York (N = 361) and Heidelberg (Germany, N = 90) were used. We analyzed the hypothesized causal structure by modeling latent change scores, and checked if those with low, medium, and high levels of vision loss at baseline differ in the relations between one-year change scores. Results confirmed that impacts of vision loss on AVL are mediated by decline in functional ability. However, under the most severe levels of vision loss at baseline, functional decline showed only a minor impact on AVL change not explained by a lack of further decline in vision. Findings confirm the effectiveness of adaptation in terms of reduced reactivity to functional losses across increasing level of chronic impairment. Thus, adaptation, weakening the impact of chronic functional impairment on psychological outcomes over time with disease progression, deserves consideration in the study of psychological consequences of chronic physical health conditions in old age.

  20. Eye Diseases and Impaired Vision as Possible Risk Factors for Recurrent Falls in the Aged: A Systematic Review

    PubMed Central

    Salonen, Liisa; Kivelä, Sirkka-Liisa

    2012-01-01

    Background. Recurrent falls are common among the aged. Vision is needed in maintaining balance, and impaired vision may be an intrinsic risk factor of recurrent falls. The aim was to perform a systematic review about the relationships between eye diseases or impaired vision and the risk of recurrent falls in the aged. Material and Methods. MEDLINE and CINAHL databases were searched in order to find longitudinal epidemiological studies about the associations between eye diseases or impaired vision and the risk of recurrent falls. Altogether 19 studies were found. A qualitative systematic analysis of these studies was performed. Results and Conclusions. The evidence about poor depth perception/stereoacuity and poor low-contrast visual acuity as risk factors of recurrent falls is quite convincing. Discrepant vision, a decrease in visual acuity, and loss of visual field may be risk factors, but more studies are needed. The results concerning the relationships between poor visual acuity and poor contrast sensitivity and the risk of recurrent falls are controversial. More studies about the relationships between different measures of vision and the risk of recurrent falls are needed before final conclusions about poor vision as a risk factor for recurrent falling can be done. PMID:22927843

  1. Self-reported visual impairment and impact on vision-related activities in an elderly Nigerian population: report from the Ibadan Study of Ageing

    PubMed Central

    Bekibele, CO; Gureje, Oye

    2010-01-01

    Background Studies have shown an association between visual impairment and poor overall function. Studies from Africa and developing countries show high prevalence of visual impairment. More information is needed on the community prevalence and impact of visual impairment among elderly Africans. Methods A multi-stage stratified sampling of households was implemented to select persons aged 65 years and over in the south-western and north-central parts of Nigeria. Impairments of distant and near vision were based on subjective self-reports obtained with the use of items derived from the World Health Organization multi-country World Health Survey questionnaire. Impairment was defined as reporting much difficulty to questions on distant and near vision. Disabilities in activities of daily living (ADL) and instrumental activities of daily living (IADL) were evaluated by interview, using standardized scales. Results A total of 2054 subjects 957 (46.6%) males and 1097 (53.4) females responded to the questions on vision. 22% (n=453) of the respondents reported distant vision impairment, and 18% (n=377) reported near vision impairment (not mutually exclusive). 15% (n= 312) however reported impairment for both far and near vision. Impairment of distant vision increased progressively with age (P < 0.01). Persons with self reported near vision impairment had elevated risk of functional disability in several IADLs and ADLs than those with out. Distant vision impairment was less associated with role limitations in both ADLs and IADLs. Conclusion The prevalence of self reported distant visual impairment was high but that for near visual impairment was less than expected in this elderly African population. Impairment of near vision was found to carry with it a higher burden of functional disability than that of distant vision. PMID:18780258

  2. Retinal Structures and Visual Cortex Activity are Impaired Prior to Clinical Vision Loss in Glaucoma

    PubMed Central

    Murphy, Matthew C.; Conner, Ian P.; Teng, Cindy Y.; Lawrence, Jesse D.; Safiullah, Zaid; Wang, Bo; Bilonick, Richard A.; Kim, Seong-Gi; Wollstein, Gadi; Schuman, Joel S.; Chan, Kevin C.

    2016-01-01

    Glaucoma is the second leading cause of blindness worldwide and its pathogenesis remains unclear. In this study, we measured the structure, metabolism and function of the visual system by optical coherence tomography and multi-modal magnetic resonance imaging in healthy subjects and glaucoma patients with different degrees of vision loss. We found that inner retinal layer thinning, optic nerve cupping and reduced visual cortex activity occurred before patients showed visual field impairment. The primary visual cortex also exhibited more severe functional deficits than higher-order visual brain areas in glaucoma. Within the visual cortex, choline metabolism was perturbed along with increasing disease severity in the eye, optic radiation and visual field. In summary, this study showed evidence that glaucoma deterioration is already present in the eye and the brain before substantial vision loss can be detected clinically using current testing methods. In addition, cortical cholinergic abnormalities are involved during trans-neuronal degeneration and can be detected non-invasively in glaucoma. The current results can be of impact for identifying early glaucoma mechanisms, detecting and monitoring pathophysiological events and eye-brain-behavior relationships, and guiding vision preservation strategies in the visual system, which may help reduce the burden of this irreversible but preventable neurodegenerative disease. PMID:27510406

  3. Oculopharyngeal Weakness, Hypophrenia, Deafness, and Impaired Vision: A Novel Autosomal Dominant Myopathy with Rimmed Vacuoles

    PubMed Central

    Chen, Ting; Lu, Xiang-Hui; Wang, Hui-Fang; Ban, Rui; Liu, Hua-Xu; Shi, Qiang; Wang, Qian; Yin, Xi; Pu, Chuan-Qiang

    2016-01-01

    Background: Myopathies with rimmed vacuoles are a heterogeneous group of muscle disorders with progressive muscle weakness and varied clinical manifestations but similar features in muscle biopsies. Here, we describe a novel autosomal dominant myopathy with rimmed vacuoles in a large family with 11 patients of three generations affected. Methods: A clinical study including family history, obstetric, pediatric, and development history was recorded. Clinical examinations including physical examination, electromyography (EMG), serum creatine kinase (CK), bone X-rays, and brain magnetic resonance imaging (MRI) were performed in this family. Open muscle biopsies were performed on the proband and his mother. To find the causative gene, the whole-exome sequencing was carried out. Results: Disease onset was from adolescence to adulthood, but the affected patients of the third generation presented an earlier onset and more severe clinical manifestations than the older generations. Clinical features were characterized as dysarthria, dysphagia, external ophthalmoplegia, limb weakness, hypophrenia, deafness, and impaired vision. However, not every patient manifested all symptoms. Serum CK was mildly elevated and EMG indicated a myopathic pattern. Brain MRI showed cerebellum and brain stem mildly atrophy. Rimmed vacuoles and inclusion bodies were observed in muscle biopsy. The whole-exome sequencing was performed, but the causative gene has not been found. Conclusions: We reported a novel autosomal dominant myopathy with rimmed vacuoles characterized by dysarthria, dysphagia, external ophthalmoplegia, limb weakness, hypophrenia, deafness, and impaired vision, but the causative gene has not been found and needs further study. PMID:27453229

  4. Object knowledge modulates colour appearance

    PubMed Central

    Witzel, Christoph; Valkova, Hanna; Hansen, Thorsten; Gegenfurtner, Karl R

    2011-01-01

    We investigated the memory colour effect for colour diagnostic artificial objects. Since knowledge about these objects and their colours has been learned in everyday life, these stimuli allow the investigation of the influence of acquired object knowledge on colour appearance. These investigations are relevant for questions about how object and colour information in high-level vision interact as well as for research about the influence of learning and experience on perception in general. In order to identify suitable artificial objects, we developed a reaction time paradigm that measures (subjective) colour diagnosticity. In the main experiment, participants adjusted sixteen such objects to their typical colour as well as to grey. If the achromatic object appears in its typical colour, then participants should adjust it to the opponent colour in order to subjectively perceive it as grey. We found that knowledge about the typical colour influences the colour appearance of artificial objects. This effect was particularly strong along the daylight axis. PMID:23145224

  5. Impairing the useful field of view in natural scenes: Tunnel vision versus general interference.

    PubMed

    Ringer, Ryan V; Throneburg, Zachary; Johnson, Aaron P; Kramer, Arthur F; Loschky, Lester C

    2016-01-01

    A fundamental issue in visual attention is the relationship between the useful field of view (UFOV), the region of visual space where information is encoded within a single fixation, and eccentricity. A common assumption is that impairing attentional resources reduces the size of the UFOV (i.e., tunnel vision). However, most research has not accounted for eccentricity-dependent changes in spatial resolution, potentially conflating fixed visual properties with flexible changes in visual attention. Williams (1988, 1989) argued that foveal loads are necessary to reduce the size of the UFOV, producing tunnel vision. Without a foveal load, it is argued that the attentional decrement is constant across the visual field (i.e., general interference). However, other research asserts that auditory working memory (WM) loads produce tunnel vision. To date, foveal versus auditory WM loads have not been compared to determine if they differentially change the size of the UFOV. In two experiments, we tested the effects of a foveal (rotated L vs. T discrimination) task and an auditory WM (N-back) task on an extrafoveal (Gabor) discrimination task. Gabor patches were scaled for size and processing time to produce equal performance across the visual field under single-task conditions, thus removing the confound of eccentricity-dependent differences in visual sensitivity. The results showed that although both foveal and auditory loads reduced Gabor orientation sensitivity, only the foveal load interacted with retinal eccentricity to produce tunnel vision, clearly demonstrating task-specific changes to the form of the UFOV. This has theoretical implications for understanding the UFOV.

  6. Frequency of colour vision deficiencies in melanoma patients: results of a prospective comparative screening study with the Farnsworth panel D 15 test including 300 melanoma patients and 100 healthy controls.

    PubMed

    Pföhler, Claudia; Tschöp, Sabine; König, Jochem; Rass, Knuth; Tilgen, Wolfgang

    2006-10-01

    Patients with melanoma may experience a variety of different vision symptoms, in part associated with melanoma-associated retinopathy. For several melanoma patients with or without melanoma-associated retinopathy, colour vision deficiencies, especially involving the tritan system, have been reported. The frequency of colour vision deficiencies in a larger cohort of melanoma patients has not yet been investigated. The aim of this study was to investigate the frequency of colour vision deficiencies in melanoma patients subject to stage of disease, prognostic factors such as tumour thickness or Clark level, S100-beta and predisposing diseases that may have an impact on colour vision (hypertension, diabetes mellitus, glaucoma or cataract). Three hundred melanoma patients in different tumour stages and 100 healthy age-matched and sex-matched controls were examined with the saturated Farnsworth panel D 15 test. Seventy out of 300 (23.3%) melanoma patients and 12/100 (12%) controls showed pathologic results in colour testing. This discrepancy was significant (P < 0.016; odds ratio = 2.23, 95% confidence interval 1.15-4.32). Increasing age was identified as a highly significant (P = 0.0005) risk factor for blue vision deficiency. Adjusting for the age and predisposing diseases, we could show that melanoma was associated with the risk of blue vision deficiency. The frequency of blue vision deficiency in 52/260 melanoma patients without predisposing diseases (20%) compared with 4/78 controls without predisposing diseases (5.1%) differed significantly (odds ratio 4.441; confidence interval 1.54-12.62; P < 0.004). In 260 melanoma patients without predisposing diseases, blue vision deficiency, as graded on a 6-point scale, showed a weak positive correlation (Spearman) with tumour stage (r = 0.147; P < 0.01), tumour thickness (r = 0.10; P = 0.0035), Clark level (r = 0.12; P = 0.04) and a weak negative correlation with time since initial diagnosis (r = -0.11; P = 0.0455). Blue

  7. Prevalence and patterns of comorbid cognitive impairment in low vision rehabilitation (LVR) for macular disease

    PubMed Central

    Whitson, Heather E.; Ansah, Deidra; Whitaker, Diane; Potter, Guy; Cousins, Scott W.; MacDonald, Heather; Pieper, Carl F.; Landerman, Lawrence; Steffens, David C.; Cohen, Harvey J.

    2009-01-01

    The prevalence of comorbid cognitive impairment among older adults referred to LVR for macular disease is unknown. We performed cognitive testing on 101 adults aged 65 years or older with macular disease who were referred to The Duke LVR Clinic between September 2007 and March 2008. Scores on the telephone interview for cognitive status-modified (TICS-m) ranged from 7 to 44, with 18.8% of scores below an established cutoff for cognitive impairment (≤ 27) and an additional 27.7% of scores considered marginal (28-30). On letter fluency, 46% of participants scored at least 1 × S.D. below the mean for their age, gender, race, and education level, and 18% of participants scored at least 2 × S.D. below their demographic mean. On logical memory, 26% of participants scored at least 1 × S.D. below the mean for their age group and race and 6% scored at least 2 × S.D. below their demographic mean. High prevalence of cognitive impairment, with particular difficulty in verbal fluency and verbal memory, may compromise the success of low vision rehabilitation interventions among macular disease patients. Additional work is needed to develop strategies to maximize function in older adults with this common comorbidity. PMID:19427045

  8. Crowded visual search in children with normal vision and children with visual impairment.

    PubMed

    Huurneman, Bianca; Cox, Ralf F A; Vlaskamp, Björn N S; Boonstra, F Nienke

    2014-03-01

    This study investigates the influence of oculomotor control, crowding, and attentional factors on visual search in children with normal vision ([NV], n=11), children with visual impairment without nystagmus ([VI-nys], n=11), and children with VI with accompanying nystagmus ([VI+nys], n=26). Exclusion criteria for children with VI were: multiple impairments and visual acuity poorer than 20/400 or better than 20/50. Three search conditions were presented: a row with homogeneous distractors, a matrix with homogeneous distractors, and a matrix with heterogeneous distractors. Element spacing was manipulated in 5 steps from 2 to 32 minutes of arc. Symbols were sized 2 times the threshold acuity to guarantee visibility for the VI groups. During simple row and matrix search with homogeneous distractors children in the VI+nys group were less accurate than children with NV at smaller spacings. Group differences were even more pronounced during matrix search with heterogeneous distractors. Search times were longer in children with VI compared to children with NV. The more extended impairments during serial search reveal greater dependence on oculomotor control during serial compared to parallel search.

  9. An averaging method for the interpretation of the Farnsworth-Munsell 100-Hue Test--II. Colour vision defects acquired in diabetic retinopathy.

    PubMed

    Birch, J; Dain, S J

    1987-01-01

    The Farnsworth-Munsell 100-Hue test is frequently used to assess acquired colour vision defects. In diabetic retinopathy the acquired defect is a mild or severe type III (Tritan) defect which may be coupled with poor overall hue discrimination. In consequence, error scores are often high and the 100-Hue polar diagram is difficult to interpret. In this study the averaging method of analysis proposed by Dain and Birch is used to examine 120 100-Hue plots obtained by patients with proliferative diabetic retinopathy. These plots have either moderate (150-300) or high error scores (greater than 300). The method of analysis is found to be effective in determining whether a Tritan defect is present or not.

  10. Retinal Image Quality Assessment for Spaceflight-Induced Vision Impairment Study

    NASA Technical Reports Server (NTRS)

    Vu, Amanda Cadao; Raghunandan, Sneha; Vyas, Ruchi; Radhakrishnan, Krishnan; Taibbi, Giovanni; Vizzeri, Gianmarco; Grant, Maria; Chalam, Kakarla; Parsons-Wingerter, Patricia

    2015-01-01

    Long-term exposure to space microgravity poses significant risks for visual impairment. Evidence suggests such vision changes are linked to cephalad fluid shifts, prompting a need to directly quantify microgravity-induced retinal vascular changes. The quality of retinal images used for such vascular remodeling analysis, however, is dependent on imaging methodology. For our exploratory study, we hypothesized that retinal images captured using fluorescein imaging methodologies would be of higher quality in comparison to images captured without fluorescein. A semi-automated image quality assessment was developed using Vessel Generation Analysis (VESGEN) software and MATLAB® image analysis toolboxes. An analysis of ten images found that the fluorescein imaging modality provided a 36% increase in overall image quality (two-tailed p=0.089) in comparison to nonfluorescein imaging techniques.

  11. Global Vision Impairment and Blindness Due to Uncorrected Refractive Error, 1990-2010.

    PubMed

    Naidoo, Kovin S; Leasher, Janet; Bourne, Rupert R; Flaxman, Seth R; Jonas, Jost B; Keeffe, Jill; Limburg, Hans; Pesudovs, Konrad; Price, Holly; White, Richard A; Wong, Tien Y; Taylor, Hugh R; Resnikoff, Serge

    2016-03-01

    The purpose of this systematic review was to estimate worldwide the number of people with moderate and severe visual impairment (MSVI; presenting visual acuity <6/18, ≥3/60) or blindness (presenting visual acuity <3/60) due to uncorrected refractive error (URE), to estimate trends in prevalence from 1990 to 2010, and to analyze regional differences. The review focuses on uncorrected refractive error which is now the most common cause of avoidable visual impairment globally. : The systematic review of 14,908 relevant manuscripts from 1990 to 2010 using Medline, Embase, and WHOLIS yielded 243 high-quality, population-based cross-sectional studies which informed a meta-analysis of trends by region. The results showed that in 2010, 6.8 million (95% confidence interval [CI]: 4.7-8.8 million) people were blind (7.9% increase from 1990) and 101.2 million (95% CI: 87.88-125.5 million) vision impaired due to URE (15% increase since 1990), while the global population increased by 30% (1990-2010). The all-age age-standardized prevalence of URE blindness decreased 33% from 0.2% (95% CI: 0.1-0.2%) in 1990 to 0.1% (95% CI: 0.1-0.1%) in 2010, whereas the prevalence of URE MSVI decreased 25% from 2.1% (95% CI: 1.6-2.4%) in 1990 to 1.5% (95% CI: 1.3-1.9%) in 2010. In 2010, URE contributed 20.9% (95% CI: 15.2-25.9%) of all blindness and 52.9% (95% CI: 47.2-57.3%) of all MSVI worldwide. The contribution of URE to all MSVI ranged from 44.2 to 48.1% in all regions except in South Asia which was at 65.4% (95% CI: 62-72%). : We conclude that in 2010, uncorrected refractive error continues as the leading cause of vision impairment and the second leading cause of blindness worldwide, affecting a total of 108 million people or 1 in 90 persons.

  12. Epidemiological assessment of lens opacifications that impaired vision in patients injected with radium-224

    SciTech Connect

    Chmelevsky, D.; Mays, C.W.; Spiess, H.; Stefani, F.H.; Kellerer, A.M.

    1988-08-01

    The incidence of lens opacifications that impaired vision (cataract) was analyzed among 831 patients who were injected with known dosages of /sup 224/Ra in Germany shortly after World War II. The dependence of the incidence on dosage, i.e., injected activity per unit body weight, and on time after treatment was determined. The observations are equally consistent with proportionality of the incidence of cataract to the square of dosage or with a linear dependence beyond a threshold of 0.5 MBq/kg. The possibility of a linear dependence without threshold was strongly rejected (P less than 0.001). The analysis of temporal dependences yielded a component that was correlated with the injected amount of /sup 224/Ra and a component that was uncorrelated. The former was inferred by a maximum likelihood analysis to increase approximately as the square of the time after treatment. The component unrelated to the treatment was found to increase steeply with age and to become dominant within the collective of patients between age 50 and 60. The relative magnitudes of the two components were such that a fraction of 55 to 60% of the total of 58 cataracts had to be ascribed to the dose-related incidence. Impaired vision due to cataract was diagnosed before age 54 in 25 cases. In terms of injected activity per unit body weight no dependence of the sensitivity on age was found; specifically there was no indication of a faster occurrence of the treatment-related cataracts in patients treated at older ages.

  13. Association between Val66Met polymorphism of Brain-Derived Neurotrophic Factor (BDNF) gene and a deficiency of colour vision in alcohol-dependent male patients.

    PubMed

    Serý, Omar; Sťastný, František; Zvolský, Petr; Hlinomazová, Zuzana; Balcar, Vladimir J

    2011-07-25

    Brain-derived neurotrophic factor (BDNF) is a protein encoded, in humans, by BDNF gene on chromosome 11. BDNF protects adult neurons and promotes growth and differentiation during ontogenetic development but the nature and magnitude of its effects could be influenced by functional polymorphisms. The BDNF polymorphism Val66Met (rs6265) has been studied in the context of etiology of mental diseases including alcoholism. Alcoholism - a complex disorder known to be linked to several genes - has multiple manifestations, including sensory deficits such as those affecting vision. In the present study we examined a relationship between the Val66Met polymorphism, alcohol dependence and colour vision deficiency (CVD) in 167 alcohol-dependent men and 289 control male subjects. Statistical analysis revealed that almost half (about 48%) of the alcohol dependent men had a CVD. In addition we found that CVD was significantly associated (P=0.005) with the Val66Met polymorphism. The A allele containing 66Met promotes BDNF expression and this may protect humans against CVD induced by long-term excessive alcohol intake. The present findings indicate that alcohol-induced CVD does not depend solely on excessive alcohol consumption but is significantly influenced by genetic predisposition in the form of a specific BDNF polymorphism.

  14. 14 CFR 382.119 - What information must carriers give individuals with vision or hearing impairment on aircraft?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false What information must carriers give individuals with vision or hearing impairment on aircraft? 382.119 Section 382.119 Aeronautics and Space... NONDISCRIMINATION ON THE BASIS OF DISABILITY IN AIR TRAVEL Services on Aircraft § 382.119 What information...

  15. 14 CFR 382.53 - What information must carriers give individuals with a vision or hearing impairment at airports?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false What information must carriers give individuals with a vision or hearing impairment at airports? 382.53 Section 382.53 Aeronautics and Space... NONDISCRIMINATION ON THE BASIS OF DISABILITY IN AIR TRAVEL Accessibility of Airport Facilities § 382.53...

  16. The Impact of Vision Impairment (IVI) Questionnaire; Validation of the Thai-Version and the Implementation on Vision-Related Quality of Life in Thai Rural Community.

    PubMed

    Ratanasukon, Mansing; Tongsomboon, Jongjit; Bhurayanontachai, Patama; Jirarattanasopa, Pichai

    2016-01-01

    The objective of this study is to validate the Thai-version of the impact of vision impairment (IVI) questionnaire and to evaluate its impact on vision-related quality of life (VRQoL) in southern Thailand. The IVI questionnaire was translated into Thai according to WHO translation guidelines. In addition to the routine ophthalmological examinations, a Thai version of the IVI questionnaire was administered to all participants. A total of 120 patients with visual impairment who presented at Songklanagarind hospital, Songkhla province, were enrolled in the study; 30 had age-related macular degeneration (AMD), 30 had cataract, 30 had diabetic retinopathy, 30 had glaucoma, and 30 non-visually impaired individuals comprised the control group. Statistical analysis demonstrated the Thai-version IVI questionnaire is valid and reliable to evaluate the VRQoL of the Thai patients through three subscales: (i) mobility and independence, (ii) reading and accessing information, and (iii) emotional well-being. The results demonstrated high consistency in all subscales with Cronbach's alpha ranging from 0.787 to 0.849. Rasch analysis revealed the validity of the Thai-version IVI to assess VRQoL through all three subscales. Test-retest reliability was also high (intraclass correlation coefficient = 0.96). The composite score of the IVI was significantly higher in participants with visual impairment compared with healthy participants. Moreover, the subscale scores of reading and accessing information, and emotional well-being were highest in participants with AMD. While the subscale scores of mobility and independence were highest among those with either cataracts or diabetic retinopathy. The symptoms of the common vision impairment diseases are associated with an adverse impact on VRQoL in a clinic-based population as demonstrated in this study.

  17. The Impact of Vision Impairment (IVI) Questionnaire; Validation of the Thai-Version and the Implementation on Vision-Related Quality of Life in Thai Rural Community

    PubMed Central

    Ratanasukon, Mansing; Tongsomboon, Jongjit; Bhurayanontachai, Patama; Jirarattanasopa, Pichai

    2016-01-01

    The objective of this study is to validate the Thai-version of the impact of vision impairment (IVI) questionnaire and to evaluate its impact on vision-related quality of life (VRQoL) in southern Thailand. The IVI questionnaire was translated into Thai according to WHO translation guidelines. In addition to the routine ophthalmological examinations, a Thai version of the IVI questionnaire was administered to all participants. A total of 120 patients with visual impairment who presented at Songklanagarind hospital, Songkhla province, were enrolled in the study; 30 had age-related macular degeneration (AMD), 30 had cataract, 30 had diabetic retinopathy, 30 had glaucoma, and 30 non-visually impaired individuals comprised the control group. Statistical analysis demonstrated the Thai-version IVI questionnaire is valid and reliable to evaluate the VRQoL of the Thai patients through three subscales: (i) mobility and independence, (ii) reading and accessing information, and (iii) emotional well-being. The results demonstrated high consistency in all subscales with Cronbach’s alpha ranging from 0.787 to 0.849. Rasch analysis revealed the validity of the Thai-version IVI to assess VRQoL through all three subscales. Test-retest reliability was also high (intraclass correlation coefficient = 0.96). The composite score of the IVI was significantly higher in participants with visual impairment compared with healthy participants. Moreover, the subscale scores of reading and accessing information, and emotional well-being were highest in participants with AMD. While the subscale scores of mobility and independence were highest among those with either cataracts or diabetic retinopathy. The symptoms of the common vision impairment diseases are associated with an adverse impact on VRQoL in a clinic-based population as demonstrated in this study. PMID:27191960

  18. Candidate genes for colour and vision exhibit signals of selection across the pied flycatcher (Ficedula hypoleuca) breeding range.

    PubMed

    Lehtonen, P K; Laaksonen, T; Artemyev, A V; Belskii, E; Berg, P R; Both, C; Buggiotti, L; Bureš, S; Burgess, M D; Bushuev, A V; Krams, I; Moreno, J; Mägi, M; Nord, A; Potti, J; Ravussin, P-A; Sirkiä, P M; Sætre, G-P; Winkel, W; Primmer, C R

    2012-04-01

    The role of natural selection in shaping adaptive trait differentiation in natural populations has long been recognized. Determining its molecular basis, however, remains a challenge. Here, we search for signals of selection in candidate genes for colour and its perception in a passerine bird. Pied flycatcher plumage varies geographically in both its structural and pigment-based properties. Both characteristics appear to be shaped by selection. A single-locus outlier test revealed 2 of 14 loci to show significantly elevated signals of divergence. The first of these, the follistatin gene, is expressed in the developing feather bud and is found in pathways with genes that determine the structure of feathers and may thus be important in generating variation in structural colouration. The second is a gene potentially underlying the ability to detect this variation: SWS1 opsin. These two loci were most differentiated in two Spanish pied flycatcher populations, which are also among the populations that have the highest UV reflectance. The follistatin and SWS1 opsin genes thus provide strong candidates for future investigations on the molecular basis of adaptively significant traits and their co-evolution.

  19. Book4All: A Tool to Make an e-Book More Accessible to Students with Vision/Visual-Impairments

    NASA Astrophysics Data System (ADS)

    Calabrò, Antonello; Contini, Elia; Leporini, Barbara

    Empowering people who are blind or otherwise visually impaired includes ensuring that products and electronic materials incorporate a broad range of accessibility features and work well with screen readers and other assistive technology devices. This is particularly important for students with vision impairments. Unfortunately, authors and publishers often do not include specific criteria when preparing the contents. Consequently, e-books can be inadequate for blind and low vision users, especially for students. In this paper we describe a semi-automatic tool developed to support operators who adapt e-documents for visually impaired students. The proposed tool can be used to convert a PDF e-book into a more suitable accessible and usable format readable on desktop computer or on mobile devices.

  20. Colour constancy in insects.

    PubMed

    Chittka, Lars; Faruq, Samia; Skorupski, Peter; Werner, Annette

    2014-06-01

    Colour constancy is the perceptual phenomenon that the colour of an object appears largely unchanged, even if the spectral composition of the illuminating light changes. Colour constancy has been found in all insect species so far tested. Especially the pollinating insects offer a remarkable opportunity to study the ecological significance of colour constancy since they spend much of their adult lives identifying and choosing between colour targets (flowers) under continuously changing ambient lighting conditions. In bees, whose colour vision is best studied among the insects, the compensation provided by colour constancy is only partial and its efficiency depends on the area of colour space. There is no evidence for complete 'discounting' of the illuminant in bees, and the spectral composition of the light can itself be used as adaptive information. In patchy illumination, bees adjust their spatial foraging to minimise transitions between variously illuminated zones. Modelling allows the quantification of the adaptive benefits of various colour constancy mechanisms in the economy of nature. We also discuss the neural mechanisms and cognitive operations that might underpin colour constancy in insects.

  1. Vision problems

    MedlinePlus

    ... shade or curtain hanging across part of your visual field. Optic neuritis : inflammation of the optic nerve ... Impaired vision; Blurred vision Images Crossed eyes Eye Visual acuity test Slit-lamp exam Visual field test ...

  2. Vision screening in children: Is 7-9 years of age a threshold for visual impairment?

    PubMed Central

    Ertekin, Yusuf Haydar; Tekin, Murat; Uludag, Aysegul; Arikan, Sedat; Sahin, Erkan Melih

    2016-01-01

    Objective: The present study aimed to assess the prevalence of decreased visual acuity, strabismus, and spectacle wear in children aged 5 to 13 years. Methods: A cross-sectional study was performed in primary education schools. A total of 1938 participants, including 940 females (48.5%) and 998 males (51.5%) with a mean age 8.96 ± 2.31 (5-13 years old), were screened. The comparisons were performed with gender, age, and age groups. The children attended to vision screening were assigned to three age groups as 5-6 years, 7-9 years, and 10-13 years. Results: The prevalence of the parameters was detected as decreased visual acuity 12.4%, strabismus 2.2%, and spectacle wear 6.9%. The prevalence of decreased visual acuity was significantly higher in girls and in children aged 7-9 years old (p = 0.013, p < 0.001). The prevalence of spectacle wear was significantly higher in girls and in children aged 7-9 years old (p = 0.019, p < 0.001). There was a visual acuity decrease in 33 of 106 (31.1%) children despite wearing own spectacle. There was no significant difference among three age groups for strabismus. Conclusion: Increased prevalence of decreased visual acuity, as well as the higher frequency of spectacle wear in children at ages of 7-9 years old may point out a threshold for visual impairment. PMID:27882020

  3. Braille Reading Accuracy of Students Who Are Visually Impaired: The Effects of Gender, Age at Vision Loss, and Level of Education

    ERIC Educational Resources Information Center

    Argyropoulos, Vassilis; Papadimitriou, Vassilios

    2015-01-01

    Introduction: The present study assesses the performance of students who are visually impaired (that is, those who are blind or have low vision) in braille reading accuracy and examines potential correlations among the error categories on the basis of gender, age at loss of vision, and level of education. Methods: Twenty-one visually impaired…

  4. A case study of cortical colour "blindness" with relatively intact achromatic discrimination.

    PubMed

    Heywood, C A; Wilson, B; Cowey, A

    1987-01-01

    A patient is described whose most striking visual disorder was a grossly impaired ability to discriminate between different colours (hues) that were matched for brightness. In contrast his ability to discriminate between different neutral greys presented in the same fashion was much less abnormal, even though the greys were perceptually difficult. Although visual acuity was reduced and visual fields were constricted, and the patient's memory was moderately impaired, these associated symptoms could not themselves be the cause of his unusual colour vision. The patient had the symptoms of cerebral achromatopsia, and the relative preservation of his form vision (when his reduced acuity is taken into account) and his achromatic vision supports the view that the many different visual cortical areas recently demonstrated in the brains of monkeys, and presumed to exist in man, have a perceptual specialisation that matches their physiological differences.

  5. Colour detection thresholds in faces and colour patches.

    PubMed

    Tan, Kok Wei; Stephen, Ian D

    2013-01-01

    Human facial skin colour reflects individuals' underlying health (Stephen et al 2011 Evolution & Human Behavior 32 216-227); and enhanced facial skin CIELab b* (yellowness), a* (redness), and L* (lightness) are perceived as healthy (also Stephen et al 2009a International Journal of Primatology 30 845-857). Here, we examine Malaysian Chinese participants' detection thresholds for CIELab L* (lightness), a* (redness), and b* (yellowness) colour changes in Asian, African, and Caucasian faces and skin coloured patches. Twelve face photos and three skin coloured patches were transformed to produce four pairs of images of each individual face and colour patch with different amounts of red, yellow, or lightness, from very subtle (deltaE = 1.2) to quite large differences (deltaE = 9.6). Participants were asked to decide which of sequentially displayed, paired same-face images or colour patches were lighter, redder, or yellower. Changes in facial redness, followed by changes in yellowness, were more easily discriminated than changes in luminance. However, visual sensitivity was not greater for redness and yellowness in nonface stimuli, suggesting red facial skin colour special salience. Participants were also significantly better at recognizing colour differences in own-race (Asian) and Caucasian faces than in African faces, suggesting the existence of cross-race effect in discriminating facial colours. Humans' colour vision may have been selected for skin colour signalling (Changizi et al 2006 Biology Letters 2 217-221), enabling individuals to perceive subtle changes in skin colour, reflecting health and emotional status.

  6. Television, computer and portable display device use by people with central vision impairment

    PubMed Central

    Woods, Russell L; Satgunam, PremNandhini

    2011-01-01

    Purpose To survey the viewing experience (e.g. hours watched, difficulty) and viewing metrics (e.g. distance viewed, display size) for television (TV), computers and portable visual display devices for normally-sighted (NS) and visually impaired participants. This information may guide visual rehabilitation. Methods Survey was administered either in person or in a telephone interview on 223 participants of whom 104 had low vision (LV, worse than 6/18, age 22 to 90y, 54 males), and 94 were NS (visual acuity 6/9 or better, age 20 to 86y, 50 males). Depending on their situation, NS participants answered up to 38 questions and LV participants answered up to a further 10 questions. Results Many LV participants reported at least “some” difficulty watching TV (71/103), reported at least “often” having difficulty with computer displays (40/76) and extreme difficulty watching videos on handheld devices (11/16). The average daily TV viewing was slightly, but not significantly, higher for the LV participants (3.6h) than the NS (3.0h). Only 18% of LV participants used visual aids (all optical) to watch TV. Most LV participants obtained effective magnification from a reduced viewing distance for both TV and computer display. Younger LV participants also used a larger display when compared to older LV participants to obtain increased magnification. About half of the TV viewing time occurred in the absence of a companion for both the LV and the NS participants. The mean number of TVs at home reported by LV participants (2.2) was slightly but not significantly (p=0.09) higher than NS participants (2.0). LV participants were equally likely to have a computer but were significantly (p=0.004) less likely to access the internet (73/104) compared to NS participants (82/94). Most LV participants expressed an interest in image enhancing technology for TV viewing (67/104) and for computer use (50/74), if they used a computer. Conclusion In this study, both NS and LV participants

  7. Validity and suitability of the Bayley-III Low Motor/Vision version: a comparative study among young children with and without motor and/or visual impairments.

    PubMed

    Visser, Linda; Ruiter, Selma A J; Van der Meulen, Bieuwe F; Ruijssenaars, Wied A J J M; Timmerman, Marieke E

    2013-11-01

    The aim of the present study was to examine the validity of the Bayley-III Low Motor/Vision version, and its suitability for children with motor and/or visual impairment(s). This version contains accommodated items, that is, adaptations to minimize impairment bias, without altering what the test measures. We hypothesized that the accommodations would not affect the item scores of children without impairment, and that children with impairment(s) would benefit from the accommodations. We tested 41 children without impairment and 63 children with impairment with both the standard Bayley-III and the Low Motor/Vision versions, in randomly counterbalanced order. The test administrators filled in an evaluation form. Results showed that the accommodations did not affect the test scores of children without impairment and did improve the test scores of children with impairment on the Cognition scale, while no improvement was found for the other scales. The test administrators indicated that the vast majority of the children with impairment had been able to show their abilities on the test and that the accommodations were beneficial in 29 out of these 52 cases. For some children, the accommodated instrument appeared to be unsuitable because the impairment was too severe. The conclusion is that the accommodations improve the validity of the Bayley-III when used with children with mild to moderate motor and/or visual impairment, especially with regard to the Cognition scale.

  8. Profound vision loss impairs psychological well-being in young and middle-aged individuals

    PubMed Central

    Garcia, Giancarlo A; Khoshnevis, Matin; Gale, Jesse; Frousiakis, Starleen E; Hwang, Tiffany J; Poincenot, Lissa; Karanjia, Rustum; Baron, David; Sadun, Alfredo A

    2017-01-01

    Purpose The aim of this study was to evaluate the effects of profound vision loss on psychological well-being in adolescents, young adults, and middle-aged adults with regard to mood, interpersonal interactions, and career-related goals. In addition, we assessed the significance of the resources that may be used to enhance psychological well-being in cases of profound vision loss, and in particular, examined the utility of low vision aids and the role of the ophthalmologist as a provider of emotional support. Methods A questionnaire was issued to individuals aged 13–65 years with profound vision loss resulting from Leber’s hereditary optic neuropathy (LHON). Depression prevalence was evaluated with questions regarding major depressive disorder symptomatology. Participants appraised the effects of vision loss on their interpersonal interactions and career goals by providing an impact rating (IR) on a 21-point psychometric scale from −10 to +10. Social well-being index was defined as the average of interpersonal IR and career IR. Subjects were additionally asked about the use of low vision aids and sources of emotional support. Results A total of 103 participants (mean age =26.4±11.2 years at LHON diagnosis; mean ± standard deviation) completed the questionnaire. Nearly half (49.5%) met the depression criteria after vision loss. Negative impacts on interpersonal interactions (median IR = −5) and career goals (median IR = −6) were observed; both ratings were worse (P<0.001) for depressed versus nondepressed subjects. Older age at diagnosis corresponded to higher depression prevalence and increased incidence of negative interpersonal IR and career IR. Sixty-eight percent of subjects used electronic vision aids; controlling for age, social well-being index was higher among these individuals than for those who did not use electronic aids (P=0.03). Over half of the participants (52.4%) asserted that they derived emotional support from their ophthalmologist

  9. Adaptive colouration in amphibians.

    PubMed

    Rudh, Andreas; Qvarnström, Anna

    2013-01-01

    Amphibians, i.e. salamanders, frogs and caecilians show a wide range of bright colours in combination with contrasting patterns. There is variation among species, populations and also within species and populations. Furthermore, individuals often change colours during developmental stages or in response to environmental factors. This extraordinary variation means that there are excellent opportunities to test hypotheses of the adaptive significance of colours using amphibian species as models. We review the present view of functions of colouration in amphibians with the main focus on relatively unexplored topics. Variation in colouration has been found to play a role in thermoregulation, UV protection, predator avoidance and sexual signalling. However, many proposed cases of adaptive functions of colouration in amphibians remain virtually scientifically unexplored and surprisingly few genes influencing pigmentation or patterning have been detected. We would like to especially encourage more studies that take advantage of recent developments in measurement of visual properties of several possible signalling receivers (e.g. predators, competitors or mates). Future investigations on interactions between behaviour, ecology and vision have the potential to challenge our current view of the adaptive function of colouration in amphibians.

  10. Changes in quality of life in visually impaired patients after low-vision rehabilitation.

    PubMed

    Renieri, Giulia; Pitz, Susanne; Pfeiffer, Norbert; Beutel, Manfred E; Zwerenz, Rüdiger

    2013-03-01

    The objective of the study was to assess the impact of low-vision aids on quality of life. Interviews included a modified version of the National Eye Institute Visual Functioning Questionnaire (Modified German NEI VFQ-25), the Hospital Anxiety and Depression Scale, the Mini-Mental State Examination Blind, and Indicators of the Rehabilitation Status. These were conducted before and 5 months after low-vision rehabilitation that involved recommendation of devices and instructing patients on how to use them. Of a total of 88 patients interviewed before low-vision rehabilitation, 50 patients could be reached for the follow-up interview. A huge proportion of the sample reported clinically significant depression (30%) or anxiety (30%). There were no differences between participants or dropouts. After fitting of low-vision devices, patients reported a significant improvement in perceived near tasks (P<0.01), social functioning (P<0.01), and reading ability (P<0.001). The magnitude of change was moderate. No significant changes were found in Hospital Anxiety and Depression Scale, Mini-Mental State Examination Blind, and Indicators of the Rehabilitation Status. Low-vision rehabilitation appears to have a broader effect than simply improving visual performance, as it may positively influence social functioning. Even though this study had no control group, the influence of low-vision aids on social functioning has not been reported before and should encourage their use.

  11. "They Think They Know What's Best for Me": An Interpretative Phenomenological Analysis of the Experience of Inclusion and Support in High School for Vision-Impaired Students with Albinism

    ERIC Educational Resources Information Center

    Thurston, Mhairi

    2014-01-01

    The challenges of social inclusion and access to the curriculum facing students with visual impairment in schools are well documented. The refreshed UK Vision Strategy (2013) seeks to improve education for students with vision impairment. In order to do this, it is important to understand how students with visual impairment experience education.…

  12. Extending Our Vision: Access to Inclusive Dance Education for People with Visual Impairment

    ERIC Educational Resources Information Center

    Seham, Jenny; Yeo, Anna J.

    2015-01-01

    Environmental, organizational and attitudinal obstacles continue to prevent people with vision loss from meaningfully engaging in dance education and performance. This article addresses the societal disabilities that handicap access to dance education for the blind. Although much of traditional dance instruction relies upon visual cuing and…

  13. Changes in Quality of Life in Visually Impaired Patients after Low-Vision Rehabilitation

    ERIC Educational Resources Information Center

    Renieri, Giulia; Pitz, Susanne; Pfeiffer, Norbert; Beutel, Manfred E.; Zwerenz, Rudiger

    2013-01-01

    The objective of the study was to assess the impact of low-vision aids on quality of life. Interviews included a modified version of the National Eye Institute Visual Functioning Questionnaire (Modified German NEI VFQ-25), the Hospital Anxiety and Depression Scale, the Mini-Mental State Examination Blind, and Indicators of the Rehabilitation…

  14. The Use of Visual Feedback during Signing: Evidence from Signers with Impaired Vision

    ERIC Educational Resources Information Center

    Emmorey, Karen; Korpics, Franco; Petronio, Karen

    2009-01-01

    The role of visual feedback during the production of American Sign Language was investigated by comparing the size of signing space during conversations and narrative monologues for normally sighted signers, signers with tunnel vision due to Usher syndrome, and functionally blind signers. The interlocutor for all groups was a normally sighted deaf…

  15. Assistive obstacle detection and navigation devices for vision-impaired users.

    PubMed

    Ong, S K; Zhang, J; Nee, A Y C

    2013-09-01

    Quality of life for the visually impaired is an urgent worldwide issue that needs to be addressed. Obstacle detection is one of the most important navigation tasks for the visually impaired. In this research, a novel range sensor placement scheme is proposed in this paper for the development of obstacle detection devices. Based on this scheme, two prototypes have been developed targeting at different user groups. This paper discusses the design issues, functional modules and the evaluation tests carried out for both prototypes. Implications for Rehabilitation Visual impairment problem is becoming more severe due to the worldwide ageing population. Individuals with visual impairment require assistance from assistive devices in daily navigation tasks. Traditional assistive devices that assist navigation may have certain drawbacks, such as the limited sensing range of a white cane. Obstacle detection devices applying the range sensor technology can identify road conditions with a higher sensing range to notify the users of potential dangers in advance.

  16. Visual Impairment

    MedlinePlus

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Visual Impairment KidsHealth > For Teens > Visual Impairment Print A ... with the brain, making vision impossible. What Is Visual Impairment? Many people have some type of visual ...

  17. Colour Terms Affect Detection of Colour and Colour-Associated Objects Suppressed from Visual Awareness.

    PubMed

    Forder, Lewis; Taylor, Olivia; Mankin, Helen; Scott, Ryan B; Franklin, Anna

    2016-01-01

    The idea that language can affect how we see the world continues to create controversy. A potentially important study in this field has shown that when an object is suppressed from visual awareness using continuous flash suppression (a form of binocular rivalry), detection of the object is differently affected by a preceding word prime depending on whether the prime matches or does not match the object. This may suggest that language can affect early stages of vision. We replicated this paradigm and further investigated whether colour terms likewise influence the detection of colours or colour-associated object images suppressed from visual awareness by continuous flash suppression. This method presents rapidly changing visual noise to one eye while the target stimulus is presented to the other. It has been shown to delay conscious perception of a target for up to several minutes. In Experiment 1 we presented greyscale photos of objects. They were either preceded by a congruent object label, an incongruent label, or white noise. Detection sensitivity (d') and hit rates were significantly poorer for suppressed objects preceded by an incongruent label compared to a congruent label or noise. In Experiment 2, targets were coloured discs preceded by a colour term. Detection sensitivity was significantly worse for suppressed colour patches preceded by an incongruent colour term as compared to a congruent term or white noise. In Experiment 3 targets were suppressed greyscale object images preceded by an auditory presentation of a colour term. On congruent trials the colour term matched the object's stereotypical colour and on incongruent trials the colour term mismatched. Detection sensitivity was significantly poorer on incongruent trials than congruent trials. Overall, these findings suggest that colour terms affect awareness of coloured stimuli and colour- associated objects, and provide new evidence for language-perception interaction in the brain.

  18. Colour Terms Affect Detection of Colour and Colour-Associated Objects Suppressed from Visual Awareness

    PubMed Central

    Forder, Lewis; Taylor, Olivia; Mankin, Helen; Scott, Ryan B.; Franklin, Anna

    2016-01-01

    The idea that language can affect how we see the world continues to create controversy. A potentially important study in this field has shown that when an object is suppressed from visual awareness using continuous flash suppression (a form of binocular rivalry), detection of the object is differently affected by a preceding word prime depending on whether the prime matches or does not match the object. This may suggest that language can affect early stages of vision. We replicated this paradigm and further investigated whether colour terms likewise influence the detection of colours or colour-associated object images suppressed from visual awareness by continuous flash suppression. This method presents rapidly changing visual noise to one eye while the target stimulus is presented to the other. It has been shown to delay conscious perception of a target for up to several minutes. In Experiment 1 we presented greyscale photos of objects. They were either preceded by a congruent object label, an incongruent label, or white noise. Detection sensitivity (d’) and hit rates were significantly poorer for suppressed objects preceded by an incongruent label compared to a congruent label or noise. In Experiment 2, targets were coloured discs preceded by a colour term. Detection sensitivity was significantly worse for suppressed colour patches preceded by an incongruent colour term as compared to a congruent term or white noise. In Experiment 3 targets were suppressed greyscale object images preceded by an auditory presentation of a colour term. On congruent trials the colour term matched the object’s stereotypical colour and on incongruent trials the colour term mismatched. Detection sensitivity was significantly poorer on incongruent trials than congruent trials. Overall, these findings suggest that colour terms affect awareness of coloured stimuli and colour- associated objects, and provide new evidence for language-perception interaction in the brain. PMID:27023274

  19. A grayscale pneumatic micro-valve for use in a reconfigurable tactile tablet for vision-impaired individuals

    NASA Astrophysics Data System (ADS)

    Schneider, Joseph Devin; Rebolledo-Mendez, Jovan David; McNamara, Shamus

    2015-01-01

    The design, fabrication, and characterization of a strained bilayer film for use in a micro-valve for a reconfigurable tactile tablet for vision-impaired individuals is presented. The bilayer film consists of a compressive and tensile layer to cause the film to coil and retract from the gas channel when the micro-valve is in the open position. A novel support structure that improves yield and controls the direction of coiling is demonstrated. An array of 225 strained bilayer films was designed and fabricated. Each strained bilayer film was able to be actuated individually with a voltage that ranged between 60 and 70 V. The relationship between the applied voltage and the percentage open of the micro-valve is found to be linear over an extended voltage range, enabling the reconfigurable tactile tablet to produce the equivalent of a grayscale image.

  20. Evaluation of a gaze-controlled vision enhancement system for reading in visually impaired people.

    PubMed

    Aguilar, Carlos; Castet, Eric

    2017-01-01

    People with low vision, especially those with Central Field Loss (CFL), need magnification to read. The flexibility of Electronic Vision Enhancement Systems (EVES) offers several ways of magnifying text. Due to the restricted field of view of EVES, the need for magnification is conflicting with the need to navigate through text (panning). We have developed and implemented a real-time gaze-controlled system whose goal is to optimize the possibility of magnifying a portion of text while maintaining global viewing of the other portions of the text (condition 1). Two other conditions were implemented that mimicked commercially available advanced systems known as CCTV (closed-circuit television systems)-conditions 2 and 3. In these two conditions, magnification was uniformly applied to the whole text without any possibility to specifically select a region of interest. The three conditions were implemented on the same computer to remove differences that might have been induced by dissimilar equipment. A gaze-contingent artificial 10° scotoma (a mask continuously displayed in real time on the screen at the gaze location) was used in the three conditions in order to simulate macular degeneration. Ten healthy subjects with a gaze-contingent scotoma read aloud sentences from a French newspaper in nine experimental one-hour sessions. Reading speed was measured and constituted the main dependent variable to compare the three conditions. All subjects were able to use condition 1 and they found it slightly more comfortable to use than condition 2 (and similar to condition 3). Importantly, reading speed results did not show any significant difference between the three systems. In addition, learning curves were similar in the three conditions. This proof of concept study suggests that the principles underlying the gaze-controlled enhanced system might be further developed and fruitfully incorporated in different kinds of EVES for low vision reading.

  1. Visualizing without Vision at the Microscale: Students with Visual Impairments Explore Cells with Touch

    ERIC Educational Resources Information Center

    Jones, M. Gail; Minogue, James; Oppewal, Tom; Cook, Michelle P.; Broadwell, Bethany

    2006-01-01

    Science instruction is typically highly dependent on visual representations of scientific concepts that are communicated through textbooks, teacher presentations, and computer-based multimedia materials. Little is known about how students with visual impairments access and interpret these types of visually-dependent instructional materials. This…

  2. The Impact of Support Services on Students' Test Anxiety and/or Their Ability to Submit Assignments: A Focus on Vision Impairment and Intellectual Disability

    ERIC Educational Resources Information Center

    Datta, Poulomee; Talukdar, Joy

    2017-01-01

    This study investigated the influence of the support services on the test anxiety of students and/or their ability to submit assignments in each of the two disability groups, those with vision impairment and those with intellectual disability, who were placed in specialist and mainstream educational settings in South Australia. Interviews were…

  3. The Sound of Vision Project: On the Feasibility of an Audio-Haptic Representation of the Environment, for the Visually Impaired

    PubMed Central

    Jóhannesson, Ómar I.; Balan, Oana; Unnthorsson, Runar; Moldoveanu, Alin; Kristjánsson, Árni

    2016-01-01

    The Sound of Vision project involves developing a sensory substitution device that is aimed at creating and conveying a rich auditory representation of the surrounding environment to the visually impaired. However, the feasibility of such an approach is strongly constrained by neural flexibility, possibilities of sensory substitution and adaptation to changed sensory input. We review evidence for such flexibility from various perspectives. We discuss neuroplasticity of the adult brain with an emphasis on functional changes in the visually impaired compared to sighted people. We discuss effects of adaptation on brain activity, in particular short-term and long-term effects of repeated exposure to particular stimuli. We then discuss evidence for sensory substitution such as Sound of Vision involves, while finally discussing evidence for adaptation to changes in the auditory environment. We conclude that sensory substitution enterprises such as Sound of Vision are quite feasible in light of the available evidence, which is encouraging regarding such projects. PMID:27355966

  4. Auditory localization and precedence effect: an exploratory study in infants and toddlers with visual impairment and normal vision.

    PubMed

    Hüg, Mercedes X; Arias, Claudia; Tommasini, Fabián C; Ramos, Oscar A

    2014-09-01

    The precedence effect is a spatial hearing phenomenon implicated in sound localization on reverberant environments. It occurs when a pair of sounds, with a brief delay between them, is presented from different directions; listeners give greater perceptual weight to localization cues coming from the first-arriving sound, called lead, and suppress localization cues from the later-arriving reflection, called lag. Developmental studies with sighted infants show that the first responses to precedence effect stimuli are observed at 4-5 months of life. In this exploratory study, we use the minimum audible angle (MAA) paradigm in conjunction with the observer-based psychophysical procedure to test the ability of infants and toddlers, with visual impairment and normal vision, to discriminate changes in the azimuthal position of sounds configured under precedence effect conditions. The results indicated that similar and, in some conditions, higher performances were obtained by blind toddlers when compared to sighted children of similar age, and revealed that the observer-based psychophysical procedure is a valuable method to measure auditory localization acuity in infants and toddlers with visual impairment. The video records showed auditory orienting behaviors specific of the blind children group.

  5. Construction of an Evaluating System of Tactile Walking Surface Indicators for Persons with Vision Impairments

    NASA Astrophysics Data System (ADS)

    Sueda, Osamu; Fujisawa, Shoichiro; Xin, Wang

    An experiment to evaluate a tactile walking surface indicator for visually impaired persons was usually carried out in the outdoor environment, and the weather and the seasons affected on the schedule and the result. We constructed the evaluation system within the building so we could conduct walking experiments that were unaffected by the weather regardless of the four seasons. The subjects of this system were not only a visually impaired person and a sighted deaf person but also general person. The laboratory provided a soundproof and shaded structure consisting of the walls and the ceiling. External sound and light were blocked. The hue could be adjusted by three-color fluorescent lamps, and the light could be adjusted from daytime brightness to a dim moon light. Research into the walking of visually impaired persons at nighttime is a pressing problem as the barrier-free transportation law has been enacted in Japan. An international standard has been discussed, and a scientific basis for that standard is now required.

  6. Applying colour science in colour design

    NASA Astrophysics Data System (ADS)

    Luo, Ming Ronnier

    2006-06-01

    Although colour science has been widely used in a variety of industries over the years, it has not been fully explored in the field of product design. This paper will initially introduce the three main application fields of colour science: colour specification, colour-difference evaluation and colour appearance modelling. By integrating these advanced colour technologies together with modern colour imaging devices such as display, camera, scanner and printer, some computer systems have been recently developed to assist designers for designing colour palettes through colour selection by means of a number of widely used colour order systems, for creating harmonised colour schemes via a categorical colour system, for generating emotion colours using various colour emotional scales and for facilitating colour naming via a colour-name library. All systems are also capable of providing accurate colour representation on displays and output to different imaging devices such as printers.

  7. Integrated vision-based robotic arm interface for operators with upper limb mobility impairments.

    PubMed

    Jiang, Hairong; Wachs, Juan P; Duerstock, Bradley S

    2013-06-01

    An integrated, computer vision-based system was developed to operate a commercial wheelchair-mounted robotic manipulator (WMRM). In this paper, a gesture recognition interface system developed specifically for individuals with upper-level spinal cord injuries (SCIs) was combined with object tracking and face recognition systems to be an efficient, hands-free WMRM controller. In this test system, two Kinect cameras were used synergistically to perform a variety of simple object retrieval tasks. One camera was used to interpret the hand gestures to send as commands to control the WMRM and locate the operator's face for object positioning. The other sensor was used to automatically recognize different daily living objects for test subjects to select. The gesture recognition interface incorporated hand detection, tracking and recognition algorithms to obtain a high recognition accuracy of 97.5% for an eight-gesture lexicon. An object recognition module employing Speeded Up Robust Features (SURF) algorithm was performed and recognition results were sent as a command for "coarse positioning" of the robotic arm near the selected daily living object. Automatic face detection was also provided as a shortcut for the subjects to position the objects to the face by using a WMRM. Completion time tasks were conducted to compare manual (gestures only) and semi-manual (gestures, automatic face detection and object recognition) WMRM control modes. The use of automatic face and object detection significantly increased the completion times for retrieving a variety of daily living objects.

  8. Chromatic induction in neon colour spreading.

    PubMed

    da Pos, Osvaldo; Bressan, Paola

    2003-03-01

    Neon colour spreading occurs when sections of a lattice are replaced by segments of a different colour. This colour appears to diffuse out of the segments, and produce a slightly tinted transparent surface floating above the lattice. In two of the four experiments reported here, observers varied the colour of an area in a test display, until it matched the neon colour perceived in a corresponding (illusory) area in a comparison display. We found that the neon colour is an additive mixture of the colour of the segments and the colour complementary to the lattice, as suggested by Bressan (Vision Research 35 (1995) 375). In the other two experiments, we separately manipulated the presence and alignment of lattice and segments, to test whether the neon effect is fully predicted by a combination of colour diffusion and simultaneous colour contrast. We found that the colour induced in a neon figure is more saturated than the colour induced in a comparable non-neon figure. We discuss the implications of these results on our current understanding of the mechanisms of neon colour spreading.

  9. Pseudoisochromatic test plate colour representation dependence on printing technology

    NASA Astrophysics Data System (ADS)

    Luse, K.; Fomins, S.; Ozolinsh, M.

    2012-08-01

    The aim of the study is to determine best printing technology for creation of colour vision deficiency tests. Valid tests for protanopia and deuteranopia were created from perceived colour matching experiments from printed colour samples by colour deficient individuals. Calibrated EpsonStylus Pro 7800 printer for ink prints and Noritsu HD 3701 digital printer for photographic prints were used. Multispectral imagery (by tunable liquid crystal filters system CRI Nuance Vis 07) data analysis show that in case of ink prints, the measured pixel colour coordinate dispersion (in the CIExy colour diagram) of similar colour arrays is smaller than in case of photographic printing. The print quality in terms of colour coordinate dispersion for printing methods used is much higher than in case of commercially available colour vision deficiency tests.

  10. Spatial resolution for feature binding is impaired in peripheral and amblyopic vision.

    PubMed

    Neri, Peter; Levi, Dennis M

    2006-07-01

    We measured spatial resolution for discriminating targets that differed from nearby distractors in either color or orientation or their conjunction. In the fovea of normal human observers, whenever both attributes are big enough to be individually visible, their conjunction is also visible. In the periphery, the two attributes may be visible, but their conjunction may be invisible. We found a similar impairment in resolving conjunctions for the fovea of deprived eyes of humans with abnormal visual development (amblyopia). These results are quantitatively explained by a model of primary visual cortex (V1) in which orientation and color maps are imperfectly co-registered topographically. Our results in persons with amblyopia indicate that the ability of the fovea to compensate for this poor co-registration is consolidated by visual experience during postnatal development.

  11. Robust colour calibration of an imaging system using a colour space transform and advanced regression modelling.

    PubMed

    Jackman, Patrick; Sun, Da-Wen; Elmasry, Gamal

    2012-08-01

    A new algorithm for the conversion of device dependent RGB colour data into device independent L*a*b* colour data without introducing noticeable error has been developed. By combining a linear colour space transform and advanced multiple regression methodologies it was possible to predict L*a*b* colour data with less than 2.2 colour units of error (CIE 1976). By transforming the red, green and blue colour components into new variables that better reflect the structure of the L*a*b* colour space, a low colour calibration error was immediately achieved (ΔE(CAL) = 14.1). Application of a range of regression models on the data further reduced the colour calibration error substantially (multilinear regression ΔE(CAL) = 5.4; response surface ΔE(CAL) = 2.9; PLSR ΔE(CAL) = 2.6; LASSO regression ΔE(CAL) = 2.1). Only the PLSR models deteriorated substantially under cross validation. The algorithm is adaptable and can be easily recalibrated to any working computer vision system. The algorithm was tested on a typical working laboratory computer vision system and delivered only a very marginal loss of colour information ΔE(CAL) = 2.35. Colour features derived on this system were able to safely discriminate between three classes of ham with 100% correct classification whereas colour features measured on a conventional colourimeter were not.

  12. Knockdown of poc1b causes abnormal photoreceptor sensory cilium and vision impairment in zebrafish.

    PubMed

    Zhang, Conghui; Zhang, Qi; Wang, Fang; Liu, Qin

    2015-10-02

    Proteomic analysis of the mouse photoreceptor sensory cilium identified a set of cilia proteins, including Poc1 centriolar protein b (Poc1b). Previous functional studies in human cells and zebrafish embryos implicated that Poc1b plays important roles in centriole duplication and length control, as well as ciliogenesis. To study the function of Poc1b in photoreceptor sensory cilia and other primary cilia, we expressed a tagged recombinant Poc1b protein in cultured renal epithelial cells and rat retina. Poc1b was localized to the centrioles and spindle bundles during cell cycle progression, and to the basal body of photoreceptor sensory cilia. A morpholino knockdown and complementation assay of poc1b in zebrafish showed that loss of poc1b led to a range of morphological anomalies of cilia commonly associated with human ciliopathies. In the retina, the development of retinal laminae was significantly delayed and the length of photoreceptor outer segments was shortened. Visual behavior studies revealed impaired visual function in the poc1b morphants. In addition, ciliopathy-associated developmental defects, such as small eyes, curved body axis, heart defects, and shortened cilia in Kupffer's vesicle, were observed as well. These data suggest that poc1b is required for normal development and ciliogenesis of retinal photoreceptor sensory cilia and other cilia. Furthermore, this conclusion is supported by recent findings that mutations in POC1B gene have been identified in patients with inherited retinal dystrophy and syndromic retinal ciliopathy.

  13. A Navigation System for the Visually Impaired: A Fusion of Vision and Depth Sensor

    PubMed Central

    Kanwal, Nadia; Bostanci, Erkan; Currie, Keith; Clark, Adrian F.

    2015-01-01

    For a number of years, scientists have been trying to develop aids that can make visually impaired people more independent and aware of their surroundings. Computer-based automatic navigation tools are one example of this, motivated by the increasing miniaturization of electronics and the improvement in processing power and sensing capabilities. This paper presents a complete navigation system based on low cost and physically unobtrusive sensors such as a camera and an infrared sensor. The system is based around corners and depth values from Kinect's infrared sensor. Obstacles are found in images from a camera using corner detection, while input from the depth sensor provides the corresponding distance. The combination is both efficient and robust. The system not only identifies hurdles but also suggests a safe path (if available) to the left or right side and tells the user to stop, move left, or move right. The system has been tested in real time by both blindfolded and blind people at different indoor and outdoor locations, demonstrating that it operates adequately. PMID:27057135

  14. The “voice” has it: screen reader adoption and switching behavior among vision impaired persons in India

    PubMed Central

    Pal, Joyojeet; Cutrell, Edward

    2013-01-01

    We present results from a mixed methods study of screen reader use and switching behavior among people with vision impairments in India. We examine loyalty and experimentation with screen readers and find that the main drivers of adoption for early users differ significantly from the factors that drive continued use by advanced users. We discuss the factor that emerges as one of the strongest stated drivers of early adoption, TTS “voice” quality, particularly a “human-sounding voice” as one of the key features differentiating free/open source (FOSS) products from more expensive proprietary products. While the initial preferences are driven by voice quality, application support becomes more important over time as users speed up their sound settings and become more comfortable with the resultant non-human-sounding speech. We discuss these findings from two theoretical perspectives – first, through the application of the economics of behavior switching, and second, vis-à-vis novice and expert approaches toward new product adoption. We argue that these findings further our understanding of initial user comfort related to assistive technology adoption, and the impact of early technology choices on long-term technology switching behavior. PMID:24620705

  15. Cav1.4 IT mouse as model for vision impairment in human congenital stationary night blindness type 2.

    PubMed

    Knoflach, Dagmar; Kerov, Vasily; Sartori, Simone B; Obermair, Gerald J; Schmuckermair, Claudia; Liu, Xiaoni; Sothilingam, Vithiyanjali; Garcia Garrido, Marina; Baker, Sheila A; Glösmann, Martin; Schicker, Klaus; Seeliger, Mathias; Lee, Amy; Koschak, Alexandra

    2013-01-01

    Mutations in the CACNA1F gene encoding the Cav1.4 Ca (2+) channel are associated with X-linked congenital stationary night blindness type 2 (CSNB2). Despite the increasing knowledge about the functional behavior of mutated channels in heterologous systems, the pathophysiological mechanisms that result in vision impairment remain to be elucidated. This work provides a thorough functional characterization of the novel IT mouse line that harbors the gain-of-function mutation I745T reported in a New Zealand CSNB2 family. (1) Electroretinographic recordings in IT mice permitted a direct comparison with human data. Our data supported the hypothesis that a hyperpolarizing shift in the voltage-dependence of channel activation-as seen in the IT gain-of-function mutant (2)-may reduce the dynamic range of photoreceptor activity. Morphologically, the retinal outer nuclear layer in adult IT mutants was reduced in size and cone outer segments appeared shorter. The organization of the outer plexiform layer was disrupted, and synaptic structures of photoreceptors had a variable, partly immature, appearance. The associated visual deficiency was substantiated in behavioral paradigms. The IT mouse line serves as a specific model for the functional phenotype of human CSNB2 patients with gain-of-function mutations and may help to further understand the dysfunction in CSNB.

  16. Cav1.4 IT mouse as model for vision impairment in human congenital stationary night blindness type 2

    PubMed Central

    Knoflach, Dagmar; Kerov, Vasily; Sartori, Simone B; Obermair, Gerald J; Schmuckermair, Claudia; Liu, Xiaoni; Sothilingam, Vithiyanjali; Garrido, Marina Garcia; Baker, Sheila A; Glösmann, Martin; Schicker, Klaus; Seeliger, Mathias; Lee, Amy; Koschak, Alexandra

    2013-01-01

    Mutations in the CACNA1F gene encoding the Cav1.4 Ca2+ channel are associated with X-linked congenital stationary night blindness type 2 (CSNB2). Despite the increasing knowledge about the functional behavior of mutated channels in heterologous systems, the pathophysiological mechanisms that result in vision impairment remain to be elucidated. This work provides a thorough functional characterization of the novel IT mouse line that harbors the gain-of-function mutation I745T reported in a New Zealand CSNB2 family.1 Electroretinographic recordings in IT mice permitted a direct comparison with human data. Our data supported the hypothesis that a hyperpolarizing shift in the voltage-dependence of channel activation—as seen in the IT gain-of-function mutant2—may reduce the dynamic range of photoreceptor activity. Morphologically, the retinal outer nuclear layer in adult IT mutants was reduced in size and cone outer segments appeared shorter. The organization of the outer plexiform layer was disrupted, and synaptic structures of photoreceptors had a variable, partly immature, appearance. The associated visual deficiency was substantiated in behavioral paradigms. The IT mouse line serves as a specific model for the functional phenotype of human CSNB2 patients with gain-of-function mutations and may help to further understand the dysfunction in CSNB. PMID:24051672

  17. Monitor, a Vibrotactile Aid for Environmental Perception: A Field Evaluation by Four People with Severe Hearing and Vision Impairment

    PubMed Central

    Stenström, Ingeborg

    2013-01-01

    Monitor is a portable vibrotactile aid to improve the ability of people with severe hearing impairment or deafblindness to detect, identify, and recognize the direction of sound-producing events. It transforms and adapts sounds to the frequency sensitivity range of the skin. The aid was evaluated in the field. Four females (44–54 years) with Usher Syndrome I (three with tunnel vision and one with only light perception) tested the aid at home and in traffic in three different field studies: without Monitor, with Monitor with an omnidirectional microphone, and with Monitor with a directional microphone. The tests were video-documented, and the two field studies with Monitor were initiated after five weeks of training. The detection scores with omnidirectional and directional microphones were 100% for three participants and above 57% for one, both in their home and traffic environments. In the home environment the identification scores with the omnidirectional microphone were 70%–97% and 58%–95% with the directional microphone. The corresponding values in traffic were 29%–100% and 65%–100%, respectively. Their direction perception was improved to some extent by both microphones. Monitor improved the ability of people with deafblindness to detect, identify, and recognize the direction of events producing sounds. PMID:23861651

  18. Colour-space distortion in women who are heterozygous for colour deficiency.

    PubMed

    Bimler, David; Kirkland, John

    2009-03-01

    We examined colour perception among a group of women heterozygous for colour vision deficiency. Judgements of colour dissimilarity were collected by presenting colour stimuli in groups of three for odd-one-out decisions. The judgements were summarised as one consensus colour space for the heterozygotes and another for age-matched controls. Individual differences MDS was also applied, resulting in a single colour space which can be adjusted to fit each subject's responses individually by compressing it along its axes. Heterozygous women showed a trend towards colour-space compression in a red-green dimension, or reduced salience of that dimension compared to controls, though less extreme than found in overt colour deficiency.

  19. Low vision due to cerebral visual impairment: differentiating between acquired and genetic causes

    PubMed Central

    2014-01-01

    Background To gain more insight into genetic causes of cerebral visual impairment (CVI) in children and to compare ophthalmological findings between genetic and acquired forms of CVI. Methods The clinical data of 309 individuals (mainly children) with CVI, and a visual acuity ≤0.3 were analyzed for etiology and ocular variables. A differentiation was made between acquired and genetic causes. However, in persons with West syndrome or hydrocephalus, it might be impossible to unravel whether CVI is caused by the seizure disorder or increased intracranial pressure or by the underlying disorder (that in itself can be acquired or genetic). In two subgroups, individuals with ‘purely’ acquired CVI and with ‘purely’ genetic CVI, the ocular variables (such as strabismus, pale optic disc and visual field defects) were compared. Results It was possible to identify a putative cause for CVI in 60% (184/309) of the cohort. In the remaining 40% the etiology could not be determined. A ‘purely’ acquired cause was identified in 80 of the patients (26%). West syndrome and/or hydrocephalus was identified in 21 patients (7%), and in 17 patients (6%) both an acquired cause and West and/or hydrocephalus was present. In 66 patients (21%) a genetic diagnosis was obtained, of which 38 (12%) had other possible risk factor (acquired, preterm birth, West syndrome or hydrocephalus), making differentiation between acquired and genetic not possible. In the remaining 28 patients (9%) a ‘purely’ genetic cause was identified. CVI was identified for the first time in several genetic syndromes, such as ATR-X, Mowat-Wilson, and Pitt Hopkins syndrome. In the subgroup with ‘purely’ acquired causes (N = 80) strabismus (88% versus 64%), pale optic discs (65% versus 27%) and visual field defects (72% versus 30%) could be observed more frequent than in the subgroup with ‘purely’ genetic disorders (N = 28). Conclusions We conclude that CVI can be part of a genetic syndrome and

  20. Colour in the eye of the beholder: receptor sensitivities and neural circuits underlying colour opponency and colour perception.

    PubMed

    Kelber, Almut

    2016-12-01

    Colour vision-the ability to discriminate spectral differences irrespective of variations in intensity-has two basic requirements: (1) photoreceptors with different spectral sensitivities, and (2) neural comparison of signals from these photoreceptors. Major progress has been made understanding the evolution of the basic stages of colour vision-opsin pigments, screening pigments, and the first neurons coding chromatic opponency, and similarities between mammals and insects point to general mechanisms. However, much work is still needed to unravel full colour pathways in various animals. While primates may have brain regions entirely dedicated to colour coding, animals with small brains, such as insects, likely combine colour information directly in parallel multisensory pathways controlling various behaviours.

  1. `Flight of colours' in lesions of the visual system 1

    PubMed Central

    Feldman, Martin; Todman, Leo; Bender, Morris B.

    1974-01-01

    A bright pocket flashlight was directed into one eye for 10 seconds; the subject then closed the eyelids and reported the sequence of after-image colours observed. Lesions of the visual system which compromised bilateral central colour vision also reduced or abolished the `flight of colours'. This simple bedside test of each eye independently is of value in detecting mild defects of central vision. PMID:4457619

  2. Evaluation of Tactile Situation Awareness System as an Aid for Improving Aircraft Control During Periods of Impaired Vision

    DTIC Science & Technology

    2009-06-01

    Standardization NVG Night Vision Goggles OPNAVINST Operational Naval Instruction POM Program Objective Memorandum SEC Seconds TSAS Tactile...pioneering work of Dr. Rupert. The Netherlands used the TSAS in a study to reduce side drift while training pilots in the use of night vision ...H.A.H.C., Oving, A.B. (2002). Tactile Torso Display as Countermeasure to Reduce Night Vision Goggles Induced Drift, TNO Human Factors Soesterberg

  3. Vision Changes in Space

    NASA Video Gallery

    This Human Research Program 'Research to Outreach' video featuring NASA Clinical Translational Scientist Jennifer Fogarty explains the risk of vision impairment both during and after spaceflight, i...

  4. Prevalences and causes of vision impairment in elderly Chinese: a socioeconomic perspective of a comparative report nested in Jiangsu Eye Study

    PubMed Central

    Zhu, Rong-Rong; Shi, Jian; Yang, Mei; Guan, Huai-Jin

    2016-01-01

    AIM To survey the prevalence and causes of visual impairment/blindness among elderly Chinese from different socioeconomic status in community-based design. METHODS Cluster-sampling randomly selected residents from Binhu and Funing District, two areas representing different socioeconomic levels in China with Binhu in an advanced status and Funing in less-developed area. The participants subjected to ophthalmic examination. The presenting visual acuity (PVA) and best-corrected visual acuity (BCVA) were recorded. Visual impairment and blindness were defined according to World Health Organization criteria. The causes of visual impairment/blindness were identified by ophthalmic examination and/or questionnaire. The socioeconomic status included the per capita gross domestic product, numbers of hospital with ophthalmic service and the number of ophthalmologists per 1 million residents. RESULTS We successfully included 12 867 participants form 2 areas in this study. The prevalence of PVA impairment (<20/63 to ≥20/400) in the better eye was 5.4% in Binhu and 23.6% in Funing, while the prevalence of blindness (<20/400) was 0.9% in Binhu and 2.3% in Funing. With BCVA, the prevalence of visual impairment was 2.4% in Binhu and 6.4% in Funing, while the prevalence of blindness was 0.8% in Binhu and 1.6% in Funing. The participants with older age and female gender had higher prevalence in visual impairment and blindness. The highest prevalences of vision impairment and blindness evaluated by BCVA at >80y age group reached 20.4% and 6.3% respectively. The prevalences of vision impairment and blindness evaluated by BCVA were 3.5% and 1.0% in male and 5.0% and 1.3% in female. The above differences were statistically significant (P<0.05). The predominant causes of visual impairment and blindness were cataract, retinal disorders and uncorrected refractive error in both areas. The socioeconomic status was associated with visual impairment and blindness. CONCLUSION This community

  5. Colour discrimination and categorisation in Williams syndrome.

    PubMed

    Farran, Emily K; Cranwell, Matthew B; Alvarez, James; Franklin, Anna

    2013-10-01

    Individuals with Williams syndrome (WS) present with impaired functioning of the dorsal visual stream relative to the ventral visual stream. As such, little attention has been given to ventral stream functions in WS. We investigated colour processing, a predominantly ventral stream function, for the first time in nineteen individuals with Williams syndrome. Colour discrimination was assessed using the Farnsworth-Munsell 100 hue test. Colour categorisation was assessed using a match-to-sample test and a colour naming task. A visual search task was also included as a measure of sensitivity to the size of perceptual colour difference. Results showed that individuals with WS have reduced colour discrimination relative to typically developing participants matched for chronological age; performance was commensurate with a typically developing group matched for non-verbal ability. In contrast, categorisation was typical in WS, although there was some evidence that sensitivity to the size of perceptual colour differences was reduced in this group.

  6. Covert colour processing in colour agnosia.

    PubMed

    Nijboer, Tanja C W; van Zandvoort, Martine J E; de Haan, Edward H F

    2006-01-01

    Patients with colour agnosia can perceive colours and are able to match coloured patches on hue, but are unable to identify or categorise colours. It is a rare condition and there is as yet no agreement on the clinical definition or a generally accepted explanation. In line with observations from object agnosia and prosopagnosia, we hypothesised that (some of) these patients might still be able to process colour information at an implicit level. In this study, we investigated this possibility of implicit access to colour semantics and colour names in a man (MAH) who suffers from developmental colour agnosia. We designed two experimental computer tasks: an associative colour priming task with a lexical decision response and a reversed Stroop task. The results of these experiments suggest that there is indeed automatic processing of colour, although MAH was unable to explicitly use colour information.

  7. X-linked cone dystrophy and colour vision deficiency arising from a missense mutation in a hybrid L/M cone opsin gene

    PubMed Central

    McClements, Michelle; Davies, Wayne I L; Michaelides, Michel; Carroll, Joseph; Rha, Jungate; Mollon, John D; Neitz, Maureen; MacLaren, Robert E; Moore, Anthony T; Hunt, David M

    2013-01-01

    In this report, we describe a male subject who presents with a complex phenotype of myopia associated with cone dysfunction and a protan vision deficiency. Retinal imaging demonstrates extensive cone disruption, including the presence of non-waveguiding cones, an overall thinning of the retina, and an irregular mottled appearance of the hyper reflective band associated with the inner segment ellipsoid portion of the photoreceptor. Mutation screening revealed a novel p.Glu41Lys missense mutation in a hybrid L/M opsin gene. Spectral analysis shows that the mutant opsin fails to form a pigment in vitro and fails to be trafficked to the cell membrane in transfected Neuro2a cells. Extensive sequence and quantitative PCR analysis identifies this mutant gene as the only gene present in the affected subject’s L/M opsin gene array, yet the presence of protanopia indicates that the mutant opsin must retain some activity in vivo. To account for this apparent contradiction, we propose that a limited amount of functional pigment is formed within the normal cellular environment of the intact photoreceptor, and that this requires the presence of chaperone proteins that promote stability and normal folding of the mutant protein. PMID:23337435

  8. X-linked cone dystrophy and colour vision deficiency arising from a missense mutation in a hybrid L/M cone opsin gene.

    PubMed

    McClements, Michelle; Davies, Wayne I L; Michaelides, Michel; Carroll, Joseph; Rha, Jungtae; Mollon, John D; Neitz, Maureen; MacLaren, Robert E; Moore, Anthony T; Hunt, David M

    2013-03-22

    In this report, we describe a male subject who presents with a complex phenotype of myopia associated with cone dysfunction and a protan vision deficiency. Retinal imaging demonstrates extensive cone disruption, including the presence of non-waveguiding cones, an overall thinning of the retina, and an irregular mottled appearance of the hyper-reflective band associated with the inner segment ellipsoid portion of the photoreceptor. Mutation screening revealed a novel p.Glu41Lys missense mutation in a hybrid L/M opsin gene. Spectral analysis shows that the mutant opsin fails to form a pigment in vitro and fails to be trafficked to the cell membrane in transfected Neuro2a cells. Extensive sequence and quantitative PCR analysis identifies this mutant gene as the only gene present in the affected subject's L/M opsin gene array, yet the presence of protanopia indicates that the mutant opsin must retain some activity in vivo. To account for this apparent contradiction, we propose that a limited amount of functional pigment is formed within the normal cellular environment of the intact photoreceptor, and that this requires the presence of chaperone proteins that promote stability and normal folding of the mutant protein.

  9. Present Vision--Future Vision.

    ERIC Educational Resources Information Center

    Fitterman, L. Jeffrey

    This paper addresses issues of current and future technology use for and by individuals with visual impairments and blindness in Florida. Present technology applications used in vision programs in Florida are individually described, including video enlarging, speech output, large inkprint, braille print, paperless braille, and tactual output…

  10. Colour thresholds in a coral reef fish

    PubMed Central

    Vorobyev, M.; Marshall, N. J.

    2016-01-01

    Coral reef fishes are among the most colourful animals in the world. Given the diversity of lifestyles and habitats on the reef, it is probable that in many instances coloration is a compromise between crypsis and communication. However, human observation of this coloration is biased by our primate visual system. Most animals have visual systems that are ‘tuned’ differently to humans; optimized for different parts of the visible spectrum. To understand reef fish colours, we need to reconstruct the appearance of colourful patterns and backgrounds as they are seen through the eyes of fish. Here, the coral reef associated triggerfish, Rhinecanthus aculeatus, was tested behaviourally to determine the limits of its colour vision. This is the first demonstration of behavioural colour discrimination thresholds in a coral reef species and is a critical step in our understanding of communication and speciation in this vibrant colourful habitat. Fish were trained to discriminate between a reward colour stimulus and series of non-reward colour stimuli and the discrimination thresholds were found to correspond well with predictions based on the receptor noise limited visual model and anatomy of the eye. Colour discrimination abilities of both reef fish and a variety of animals can therefore now be predicted using the parameters described here. PMID:27703704

  11. Colour thresholds in a coral reef fish.

    PubMed

    Champ, C M; Vorobyev, M; Marshall, N J

    2016-09-01

    Coral reef fishes are among the most colourful animals in the world. Given the diversity of lifestyles and habitats on the reef, it is probable that in many instances coloration is a compromise between crypsis and communication. However, human observation of this coloration is biased by our primate visual system. Most animals have visual systems that are 'tuned' differently to humans; optimized for different parts of the visible spectrum. To understand reef fish colours, we need to reconstruct the appearance of colourful patterns and backgrounds as they are seen through the eyes of fish. Here, the coral reef associated triggerfish, Rhinecanthus aculeatus, was tested behaviourally to determine the limits of its colour vision. This is the first demonstration of behavioural colour discrimination thresholds in a coral reef species and is a critical step in our understanding of communication and speciation in this vibrant colourful habitat. Fish were trained to discriminate between a reward colour stimulus and series of non-reward colour stimuli and the discrimination thresholds were found to correspond well with predictions based on the receptor noise limited visual model and anatomy of the eye. Colour discrimination abilities of both reef fish and a variety of animals can therefore now be predicted using the parameters described here.

  12. Floral colour diversity in plant communities, bee colour space and a null model

    PubMed Central

    Gumbert, A.; Kunze, J.; Chittka, L.

    1999-01-01

    Evolutionary biologists have long hypothesized that the diversity of flower colours we see is in part a strategy to promote memorization by pollinators, pollinator constancy, and therefore, a directed and efficient pollen transfer between plants. However, this hypothesis has never been tested against a biologically realistic null model, nor were colours assessed in the way pollinators see them. Our intent here is to fill these gaps. Throughout one year, we sampled floral species compositions at five ecologically distinct sites near Berlin, Germany. Bee-subjective colours were quantified for all 168 species. A model of colour vision was used to predict how similar the colours of sympatric and simultaneously blooming flowers were for bees. We then compared flower colour differences in the real habitats with those of random plant communities. We did not find pronounced deviations from chance when we considered common plants. When we examined rare plants, however, we found significant divergence in two of the five plant communities. At one site, similarly coloured species were found to be more frequent than expected, and at the other two locations, flower colours were indistinguishable from a random distribution. These results fit theoretical considerations that rare plants are under stronger selective pressure to secure pollination than common plants. Our study illustrates the power of linking such distinct biological traditions as community ecology and the neuroethology of bee vision.

  13. Colour blindness in Italian art high school students.

    PubMed

    Grassivaro Gallo, P; Oliva, S; Lantieri, P B; Viviani, F

    2002-12-01

    To highlight the link between colour blindness and school achievement, the Ishihara and Farnsworth tests were administered to 3,565 high school art students (2,545 girls and 1,020 boys). Analysis showed colour defective students were discriminated against in theoretical subject matter, relative to orthochromate students, but not in the art-related subjects. This emphasizes the need to recognize youth with colour defective vision early.

  14. Is binocular vision worth considering in people with low vision?

    PubMed

    Uzdrowska, Marta; Crossland, Michael; Broniarczyk-Loba, Anna

    2014-01-01

    In someone with good vision, binocular vision provides benefits which could not be obtained by monocular viewing only. People with visual impairment often have abnormal binocularity. However, they often use both eyes simultaneously in their everyday activities. Much remains to be known about binocular vision in people with visual impairment. As the binocular status of people with low vision strongly influences their treatment and rehabilitation, it should be evaluated and considered before diagnosis and further recommendations.

  15. Low Vision Training in Sweden.

    ERIC Educational Resources Information Center

    Inde, Krister

    1978-01-01

    The article describes the team work approach used in Sweden to provide services to the four main categories of visual impairment: central scotoma, nystagmus, loss of peripheral vision while retaining central vision, and amblyopia. (Author/PHR)

  16. Developmental colour agnosia.

    PubMed

    van Zandvoort, Martine J E; Nijboer, Tanja C W; de Haan, Edward

    2007-08-01

    Colour agnosia concerns the inability to recognise colours despite intact colour perception, semantic memory for colour information, and colour naming. Patients with selective colour agnosia have been described and the deficit is associated with left hemisphere damage. Here we report a case study of a 43-year-old man who was referred to us with a stroke in his right cerebellar hemisphere. During the standard assessment it transpired that he was unable to name coloured patches. Detailed assessment of his colour processing showed that he suffers from a selective colour agnosia. As he claimed to have had this problem all his life, and the fact that the infratentorial infarct that he had incurred was in an area far away from the brain structures that are known to be involved in colour processing, we suggest that he is the first reported case of developmental colour agnosia.

  17. Prevalence of colour blindness in young Jordanians.

    PubMed

    Al-Aqtum, M T; Al-Qawasmeh, M H

    2001-01-01

    Colour blindness is one of the common genetic disorders observed in all human populations. It is a sex-linked recessive trait. The genes are located on the X chromosome within the Xq28 band. 1,418 university students (1,200 female and 218 male) from Zarka Private University and the Hashemite University were randomly selected and tested for congenital red/green colour blindness, by using Ishihara pseudo-isochromatic colour plates. A total of 23 individuals were found to be colour blind. In females, 4 students (0.33%) were colour blind: 1 of them showed protanomalia, 1 protanopia and 2 deuteranomalia. In males, 19 students (8.72%) were colour blind: 4 showed protanomalia, 3 protanopia, 8 deuteranomalia and 4 deuteranopia. The allelic frequencies of the colour vision gene were found to be 0.087 in males, 0.003 in females and 0.016 in the total population. Studies on colour blindness in Jordan are very few; this population-based investigation is meant to fill a gap in this field.

  18. Interactions between colour and synaesthetic colour: an effect of simultaneous colour contrast on synaesthetic colours.

    PubMed

    Nijboer, Tanja C W; Gebuis, Titia; te Pas, Susan F; van der Smagt, Maarten J

    2011-01-01

    We investigated whether simultaneous colour contrast affects the synaesthetic colour experience and normal colour percept in a similar manner. We simultaneously presented a target stimulus (i.e. grapheme) and a reference stimulus (i.e. hash). Either the grapheme or the hash was presented on a saturated background of the same or opposite colour category as the synaesthetic colour and the other stimulus on a grey background. In both conditions, grapheme-colour synaesthetes were asked to colour the hash in a colour similar to the synaesthetic colour of the grapheme. Controls that were pair-matched to the synaesthetes performed the same experiment, but for them, the grapheme was presented in the colour induced by the grapheme in synaesthetes. When graphemes were presented on a grey and the hash on a coloured background, a traditional simultaneous colour-contrast effect was found for controls as well as synaesthetes. When graphemes were presented on colour and the hash on grey, the controls again showed a traditional simultaneous colour-contrast effect, whereas the synaesthetes showed the opposite effect. Our results show that synaesthetic colour experiences differ from normal colour perception; both are susceptible to different surrounding colours, but not in a comparable manner.

  19. [Vision and car driving ability].

    PubMed

    Wilhelm, Helmut

    2011-05-01

    Visual functions relevant for car driving are: Visual acuity, contrast and twilight vision, visual field, ocular motility and alignment and colour vision. Generally accepted and standardized tests are available for visual acuity and visual field. Maximum permissible values have been defined arbitrarily and are hardly supported by studies. European standards have been published comprising also contrast and twilight vision. When examining driving ability progressive and treatable ocular disorders such as cataract and glaucoma have to be considered.

  20. Colour is more than hue: preferences for compiled colour traits in the stingless bees Melipona mondury and M. quadrifasciata.

    PubMed

    Koethe, Sebastian; Bossems, Jessica; Dyer, Adrian G; Lunau, Klaus

    2016-10-01

    The colour vision of bees has been extensively analysed in honeybees and bumblebees, but few studies consider the visual perception of stingless bees (Meliponini). In a five-stage experiment the preference for colour intensity and purity, and the preference for the dominant wavelength were tested by presenting four colour stimuli in each test to freely flying experienced workers of two stingless bee species, Melipona mondury and Melipona quadrifasciata. The results with bee-blue, bee-UV-blue and bee-green colours offered in four combinations of varying colour intensity and purity suggest a complex interaction between these colour traits for the determination of colour choice. Specifically, M. mondury preferred bee-UV-blue colours over bee-green, bee-blue and bee-blue-green colours while M. quadrifasciata preferred bee-green colour stimuli. Moreover in M. mondury the preferences were different if the background colour was changed from grey to green. There was a significant difference between species where M. mondury preferred UV-reflecting over UV-absorbing bee-blue-green colour stimuli, whereas M. quadrifasciata showed an opposite preference. The different colour preferences of the free flying bees in identical conditions may be caused by the bees' experience with natural flowers precedent to the choice tests, suggesting reward partitioning between species.

  1. Synaesthesia and colour constancy.

    PubMed

    Erskine, Holly; Mattingley, Jason B; Arnold, Derek H

    2013-04-01

    Grapheme-colour synaesthesia is an atypical condition characterized by the perception of colours when reading achromatic text. We investigated the level of colour processing responsible for these experiences. To do so, we tapped a central characteristic of colour perception. In different lighting conditions the same wavelength of light can prompt the perception of different colours. This helps humans recognize distinctive coloured objects despite changes in illumination. We wanted to see if synaesthetic colours were generated at a neural locus that was susceptible to colour constancy analyses. We used colour matching and naming tasks to examine interactions between simulated coloured illuminants and synaesthetic colours. Neither synaesthetic colour matching or naming was impacted. This contrasted with non-synaesthetic control participants, who performed the colour-matching task with graphemes physically coloured to mimic synaesthesia. Our data suggest that synaesthetic colour signals are not generated at lower-levels of colour processing, but are introduced at higher levels of analysis and are therefore not impacted by the processes responsible for perceptual constancy.

  2. Holmes and Horrax (1919) revisited: impaired binocular fusion as a cause of "flat vision" after right parietal brain damage - a case study.

    PubMed

    Schaadt, Anna-Katharina; Brandt, Stephan A; Kraft, Antje; Kerkhoff, Georg

    2015-03-01

    The complete loss of binocular depth perception ("flat vision") was first thoroughly described by Holmes and Horrax (1919), and has been occasionally reported thereafter in patients with bilateral posterior-parietal lesions. Though partial spontaneous recovery occurred in some cases, the precise cause(s) of this condition remained obscure for almost a century. Here, we describe a unique patient (EH) with a large right-sided occipito-parietal hemorrhage showing a complete loss of visual depth perception for several months post-stroke. EH could well simultaneously describe multiple visual objects - hence did not show simultanagnosia - but at the same time was completely unable to estimate their distance from him. In every 3-D visual scene objects appeared equidistant to him, thus experiencing a total loss of depth perception ("flat vision"). Neurovisual assessments revealed normal functions of the eyes. EH showed bilateral lower field loss and a severely impaired binocular convergent fusion, but preserved stereopsis. Perceptual re-training of binocular fusion resulted in a progressive and finally complete recovery of objective binocular fusion values and subjective binocular depth perception in a far-to-near-space, gradient-like manner. In parallel, visual depth estimation of relative distances improved, whereas stereopsis remained unchanged. Our results show that a complete loss of 3-D depth perception can result from an isolated impairment in binocular fusion. On a neuroanatomical level, this connection could be explained by a selective lesion of area V6/V6A in the medial occipito-parietal cortex that has been associated with the integration of visual space coordinates and sustained eye-positions into a cyclopean visual 3-D percept.

  3. Colour Vision: Random Retina of Butterflies Explained.

    PubMed

    Kelber, Almut

    2016-10-10

    Butterfly eyes are random mosaics built of three ommatidia types, each with a different set of photoreceptors and pigments. What defines the combined features in each ommatidium? A new study has solved the puzzle.

  4. In the Palm of Your Hand: A Vision of the Future of Technology for People with Visual Impairments.

    ERIC Educational Resources Information Center

    Fruchterman, James R.

    2003-01-01

    This article discusses future directions for wireless cell phones, including personal computer capabilities, multiple input and output modalities, and open source platforms, and the benefits for people with visual impairments. The use of cell phones for increased accessibility of the Internet and for electronic books is also discussed. (Contains…

  5. Light Vision Color

    NASA Astrophysics Data System (ADS)

    Valberg, Arne

    2005-04-01

    Light Vision Color takes a well-balanced, interdisciplinary approach to our most important sensory system. The book successfully combines basics in vision sciences with recent developments from different areas such as neuroscience, biophysics, sensory psychology and philosophy. Originally published in 1998 this edition has been extensively revised and updated to include new chapters on clinical problems and eye diseases, low vision rehabilitation and the basic molecular biology and genetics of colour vision. Takes a broad interdisciplinary approach combining basics in vision sciences with the most recent developments in the area Includes an extensive list of technical terms and explanations to encourage student understanding Successfully brings together the most important areas of the subject in to one volume

  6. Why do seals have cones? Behavioural evidence for colour-blindness in harbour seals.

    PubMed

    Scholtyssek, Christine; Kelber, Almut; Dehnhardt, Guido

    2015-03-01

    All seals and cetaceans have lost at least one of two ancestral cone classes and should therefore be colour-blind. Nevertheless, earlier studies showed that these marine mammals can discriminate colours and a colour vision mechanism has been proposed which contrasts signals from cones and rods. However, these earlier studies underestimated the brightness discrimination abilities of these animals, so that they could have discriminated colours using brightness only. Using a psychophysical discrimination experiment, we showed that a harbour seal can solve a colour discrimination task by means of brightness discrimination alone. Performing a series of experiments in which two harbour seals had to discriminate the brightness of colours, we also found strong evidence for purely scotopic (rod-based) vision at light levels that lead to mesopic (rod-cone-based) vision in other mammals. This finding speaks against rod-cone-based colour vision in harbour seals. To test for colour-blindness, we used a cognitive approach involving a harbour seal trained to use a concept of same and different. We tested this seal with pairs of isoluminant stimuli that were either same or different in colour. If the seal had perceived colour, it would have responded to colour differences between stimuli. However, the seal responded with "same", providing strong evidence for colour-blindness.

  7. Tetrachromacy, oil droplets and bird plumage colours.

    PubMed

    Vorobyev, M; Osorio, D; Bennett, A T; Marshall, N J; Cuthill, I C

    1998-11-01

    There is a growing body of data on avian eyes, including measurements of visual pigment and oil droplet spectral absorption, and of receptor densities and their distributions across the retina. These data are sufficient to predict psychophysical colour discrimination thresholds for light-adapted eyes, and hence provide a basis for relating eye design to visual needs. We examine the advantages of coloured oil droplets, UV vision and tetrachromacy for discriminating a diverse set of avian plumage spectra under natural illumination. Discriminability is enhanced both by tetrachromacy and coloured oil droplets. Oil droplets may also improve colour constancy. Comparison of the performance of a pigeon's eye, where the shortest wavelength receptor peak is at 410 nm, with that of the passerine Leiothrix, where the ultraviolet-sensitive peak is at 365 nm, generally shows a small advantage to the latter, but this advantage depends critically on the noise level in the sensitivity mechanism and on the set of spectra being viewed.

  8. Rethinking Colour Constancy.

    PubMed

    Logvinenko, Alexander D; Funt, Brian; Mirzaei, Hamidreza; Tokunaga, Rumi

    2015-01-01

    Colour constancy needs to be reconsidered in light of the limits imposed by metamer mismatching. Metamer mismatching refers to the fact that two objects reflecting metameric light under one illumination may reflect non-metameric light under a second; so two objects appearing as having the same colour under one illuminant can appear as having different colours under a second. Yet since Helmholtz, object colour has generally been believed to remain relatively constant. The deviations from colour constancy registered in experiments are usually thought to be small enough that they do not contradict the notion of colour constancy. However, it is important to determine how the deviations from colour constancy relate to the limits metamer mismatching imposes on constancy. Hence, we calculated metamer mismatching's effect for the 20 Munsell papers and 8 pairs of illuminants employed in the colour constancy study by Logvinenko and Tokunaga and found it to be so extensive that the two notions-metamer mismatching and colour constancy-must be mutually exclusive. In particular, the notion of colour constancy leads to some paradoxical phenomena such as the possibility of 20 objects having the same colour under chromatic light dispersing into a hue circle of colours under neutral light. Thus, colour constancy refers to a phenomenon, which because of metamer mismatching, simply cannot exist. Moreover, it obscures the really important visual phenomenon; namely, the alteration of object colours induced by illumination change. We show that colour is not an independent, intrinsic attribute of an object, but rather an attribute of an object/light pair, and then define a concept of material colour in terms of equivalence classes of such object/light pairs. We suggest that studying the shift in material colour under a change in illuminant will be more fruitful than pursuing colour constancy's false premise that colour is an intrinsic attribute of an object.

  9. Rethinking Colour Constancy

    PubMed Central

    Logvinenko, Alexander D.; Funt, Brian; Mirzaei, Hamidreza; Tokunaga, Rumi

    2015-01-01

    Colour constancy needs to be reconsidered in light of the limits imposed by metamer mismatching. Metamer mismatching refers to the fact that two objects reflecting metameric light under one illumination may reflect non-metameric light under a second; so two objects appearing as having the same colour under one illuminant can appear as having different colours under a second. Yet since Helmholtz, object colour has generally been believed to remain relatively constant. The deviations from colour constancy registered in experiments are usually thought to be small enough that they do not contradict the notion of colour constancy. However, it is important to determine how the deviations from colour constancy relate to the limits metamer mismatching imposes on constancy. Hence, we calculated metamer mismatching’s effect for the 20 Munsell papers and 8 pairs of illuminants employed in the colour constancy study by Logvinenko and Tokunaga and found it to be so extensive that the two notions—metamer mismatching and colour constancy—must be mutually exclusive. In particular, the notion of colour constancy leads to some paradoxical phenomena such as the possibility of 20 objects having the same colour under chromatic light dispersing into a hue circle of colours under neutral light. Thus, colour constancy refers to a phenomenon, which because of metamer mismatching, simply cannot exist. Moreover, it obscures the really important visual phenomenon; namely, the alteration of object colours induced by illumination change. We show that colour is not an independent, intrinsic attribute of an object, but rather an attribute of an object/light pair, and then define a concept of material colour in terms of equivalence classes of such object/light pairs. We suggest that studying the shift in material colour under a change in illuminant will be more fruitful than pursuing colour constancy’s false premise that colour is an intrinsic attribute of an object. PMID:26356217

  10. Functional analysis of human CNGA3 mutations associated with colour blindness suggests impaired surface expression of channel mutants A3(R427C) and A3(R563C).

    PubMed

    Koeppen, Katja; Reuter, Peggy; Kohl, Susanne; Baumann, Britta; Ladewig, Thomas; Wissinger, Bernd

    2008-05-01

    Mutations in the CNGA3 gene have been associated with complete and incomplete forms of total colour blindness (achromatopsia), a disorder characterized by reduced visual acuity, lack of colour discrimination, photophobia and nystagmus. CNGA3 encodes the A-subunit of the cone photoreceptor cyclic nucleotide-gated (CNG) channel, an essential component of the phototransduction cascade. Here we report the identification of three new CNGA3 mutations in patients with achromatopsia. To assess the pathogenicity of these newly identified and four previously reported mutations, mutant CNGA3 channels were heterologously expressed in a human embryonic kidney cell line (HEK293 cells) and functionally analysed using calcium imaging. Channels with the mutations R427C and R563C showed a response in imaging experiments and were subsequently characterized in-depth with the patch-clamp technique. The mutant channels were analysed as homooligomers and also as heterooligomers with the wild-type B-subunit present in native channels. Overall, cyclic guanosine monophosphate (cGMP) maximum currents of mutant channels were profoundly reduced in homo- and heteromers. Treatment with the chemical chaperone glycerol effectively increased macroscopic currents, presumably by enhancing surface expression of mutant channels as confirmed by immunocytochemistry. These results suggest decreased channel density in the cell membrane due to impaired folding or trafficking of the channel protein as the main pathogenic effect of the mutations R427C and R563C. Moreover, A3(R427C) homomers showed distinctly increased cGMP and cyclic adenosine monophosphate (cAMP) sensitivities as well as cAMP fractional currents that were raised to over 90% of cGMP maximum currents. Co-expression of A3(R427C) with the B3 subunit compensated for most of these aberrant properties, apart from the reduced cGMP maximum currents.

  11. Low Vision

    MedlinePlus

    ... USAJobs Home > Statistics and Data > Low Vision Low Vision Low Vision Defined: Low Vision is defined as the best- ... 2010 U.S. Age-Specific Prevalence Rates for Low Vision by Age, and Race/Ethnicity Table for 2010 ...

  12. Seasonal Changes in Colour: A Comparison of Structural, Melanin- and Carotenoid-Based Plumage Colours

    PubMed Central

    Delhey, Kaspar; Burger, Claudia; Fiedler, Wolfgang; Peters, Anne

    2010-01-01

    Background Plumage coloration is important for bird communication, most notably in sexual signalling. Colour is often considered a good quality indicator, and the expression of exaggerated colours may depend on individual condition during moult. After moult, plumage coloration has been deemed fixed due to the fact that feathers are dead structures. Still, many plumage colours change after moult, although whether this affects signalling has not been sufficiently assessed. Methodology/Principal Findings We studied changes in coloration after moult in four passerine birds (robin, Erithacus rubecula; blackbird, Turdus merula; blue tit, Cyanistes caeruleus; and great tit, Parus major) displaying various coloration types (melanin-, carotenoid-based and structural). Birds were caught regularly during three years to measure plumage reflectance. We used models of avian colour vision to derive two variables, one describing chromatic and the other achromatic variation over the year that can be compared in magnitude among different colour types. All studied plumage patches but one (yellow breast of the blue tit) showed significant chromatic changes over the year, although these were smaller than for a typical dynamic trait (bill colour). Overall, structural colours showed a reduction in relative reflectance at shorter wavelengths, carotenoid-based colours the opposite pattern, while no general pattern was found for melanin-based colours. Achromatic changes were also common, but there were no consistent patterns of change for the different types of colours. Conclusions/Significance Changes of plumage coloration independent of moult are probably widespread; they should be perceivable by birds and have the potential to affect colour signalling. PMID:20644723

  13. Colour spaces in ecology and evolutionary biology.

    PubMed

    Renoult, Julien P; Kelber, Almut; Schaefer, H Martin

    2017-02-01

    The recognition that animals sense the world in a different way than we do has unlocked important lines of research in ecology and evolutionary biology. In practice, the subjective study of natural stimuli has been permitted by perceptual spaces, which are graphical models of how stimuli are perceived by a given animal. Because colour vision is arguably the best-known sensory modality in most animals, a diversity of colour spaces are now available to visual ecologists, ranging from generalist and basic models allowing rough but robust predictions on colour perception, to species-specific, more complex models giving accurate but context-dependent predictions. Selecting among these models is most often influenced by historical contingencies that have associated models to specific questions and organisms; however, these associations are not always optimal. The aim of this review is to provide visual ecologists with a critical perspective on how models of colour space are built, how well they perform and where their main limitations are with regard to their most frequent uses in ecology and evolutionary biology. We propose a classification of models based on their complexity, defined as whether and how they model the mechanisms of chromatic adaptation and receptor opponency, the nonlinear association between the stimulus and its perception, and whether or not models have been fitted to experimental data. Then, we review the effect of modelling these mechanisms on predictions of colour detection and discrimination, colour conspicuousness, colour diversity and diversification, and for comparing the perception of colour traits between distinct perceivers. While a few rules emerge (e.g. opponent log-linear models should be preferred when analysing very distinct colours), in general model parameters still have poorly known effects. Colour spaces have nonetheless permitted significant advances in ecology and evolutionary biology, and more progress is expected if ecologists

  14. [Anamnesis of brain-originated vision disorders].

    PubMed

    Kerkhoff, G; Schaub, J; Zihl, J

    1990-12-01

    A questionnaire for the subjective assessment of cerebral visual disorders was administered to 269 brain damaged patients. The patients' subjective complaints were correlated with the outcome of objective diagnostic procedures (visual perimetry, visual search, spatial contrast sensitivity, visual evoked potentials, depth perception, light- and dark-adaptation, reading, colour vision). A significant correlation was found between subjective complaints and objective diagnostic results for all fields. The prediction of visual impairments on the basis of subjective complaints and verified by objective tests was correct in 80 to 98% of the brain damaged patients tested. Interrater reliability was about 0.84. Thus, the questionnaire is suitable for the assessment of cerebral visual disorders because of its simplicity, short administration time (10-15 min) and high predictive value.

  15. Does Colour Preference Have a Role in Colour Term Acquisition?

    ERIC Educational Resources Information Center

    Pitchford, Nicola J.; Davis, Emma E.; Scerif, Gaia

    2009-01-01

    A developmental association exists between colour preference and emerging colour term acquisition in young children. Colour preference might influence colour term acquisition by directing attention towards or away from a particular colour, making it more or less memorable. To investigate the role that colour preference may have in the acquisition…

  16. Diplostomum spathaceum metacercarial infection and colour change in salmonid fish.

    PubMed

    Rintamäki-Kinnunen, P; Karvonen, A; Anttila, P; Valtonen, E T

    2004-05-01

    Colour changes in two salmonid fish, the salmon (Salmo salar) and sea trout (S. trutta), were examined in relation to infection with the trematode Diplostomum spathaceum. This parasite had no effect on the rate of colour change in these fish, although species specific differences in colour adjustment times were observed. Increasing asymmetry in parasite numbers between the right and left eye, which could lead to the retention of vision in one eye, nevertheless tended to reduce the colour change time in salmon with moderate infection (P=0.08). This first experimental attempt to examine colour changes in fish in relation to eye fluke infections provides grounds for future investigations. The darker appearance of the heavily infected fish described in the literature suggests that a high parasite burden actually causes colour changes. We emphasise that detailed quantitative studies using fish with higher parasite loads, especially from the tail of the aggregated parasite distribution, are needed to describe these relationships in detail.

  17. Specific deficit of colour-colour short-term memory binding in sporadic and familial Alzheimer's disease.

    PubMed

    Parra, Mario A; Sala, Sergio Della; Abrahams, Sharon; Logie, Robert H; Méndez, Luis Guillermo; Lopera, Francisco

    2011-06-01

    Short-term memory binding of visual features which are processed across different dimensions (shape-colour) is impaired in sporadic Alzheimer's disease, familial Alzheimer's disease, and in asymptomatic carriers of familial Alzheimer's disease. This study investigated whether Alzheimer's disease also impacts on within-dimension binding processes. The study specifically explored whether visual short-term memory binding of features of the same type (colour-colour) is sensitive to Alzheimer's disease. We used a neuropsychological battery and a short-term memory binding task to assess patients with sporadic Alzheimer's disease (Experiment 1), familial Alzheimer's disease (Experiment 2) due to the mutation E280A of the Presenilin-1 gene and asymptomatic carriers of the mutation. The binding task assessed change detection within arrays of unicoloured objects (Colour Only) or bicoloured objects the colours of which had to be remembered separately (Unbound Colours) or together (Bound Colours). Performance on the Bound Colours condition (1) explained the largest proportion of variance between patients (sporadic and familial Alzheimer's disease), (2) combined more sensitivity and specificity for the disease than other more traditional neuropsychological tasks, (3) identified asymptomatic carriers of the mutation even when traditional neuropsychological measures and other measures of short-term memory did not and, (4) contrary to shape-colour binding, correlated with measures of hippocampal functions. Colour-colour binding and shape-colour binding both appear to be sensitive to AD even though they seem to rely on different brain mechanisms.

  18. Colour and lighting in hospital design

    NASA Astrophysics Data System (ADS)

    Dalke, Hilary; Little, Jenny; Niemann, Elga; Camgoz, Nilgun; Steadman, Guillaume; Hill, Sarah; Stott, Laura

    2006-06-01

    Little information or guidance has been available to assist the development of a hospital's visual environment. A report on lighting and colour design schemes, accessible to non professionals with responsibility for refurbishment strategies, was required by NHS Estates. Firstly, 20 hospitals were audited to establish a picture of current practice and to identify key issues where colour design could broadly enhance the environment for patients, staff and visitors. Critical areas were outlined in this report, where colour design can be utilised and applied, for the benefit of all users, from ambience to essential legal requirements such as colour contrast for the visually impaired. Provision of staff relaxation rooms that are different in terms of colour and lux levels from immediate work spaces, or thoughtfully designed areas for patients awaiting intensive treatment, have been shown to have some beneficial effects on a sense of well being. Colour and design have not been established as a definite cure for sickness and ill health, but certainly monotony and poor conditions in premises that have not been refurbished with any care, have had a detrimental affect on recovery rates and staff morale. The realisation that a well balanced and attractive environment is of major importance to patients' health is, in no way new; Florence Nightingale observed that 'a variety of form and brilliance of colour in the objects presented to patients are an actual means of recovery'.

  19. Chromatic Discrimination in a Cortically Colour Blind Observer.

    PubMed

    Heywood, C. A.; Cowey, A.; Newcombe, F.

    1991-01-01

    We tested the ability of a subject with cerebral achromatopsia to discriminate between colours and to detect chromatic borders. He was unable to identify colours or to arrange them in an orderly series or choose the odd colour out of an array or even to pick out a colour embedded in an array of greys. Nevertheless, he could select the odd colour when the colours were contiguous, even when they were isoluminant, and could discriminate an ordered from a disordered chromatic series as long as the colours in each row abutted one other. His verbal replies showed that he did so by detecting an edge between two stimuli that were, to him, perceptually identical. Introducing a narrow isoluminant grey stripe between adjacent colours abolished or greatly impaired this ability. As long as isoluminant colours were contiguous the patient could identify the orientation of the chromatic borders. Photopic spectral sensitivity showed evidence both for activity of three cone channels and for chromatic opponent processing, indicating that postreceptoral chromatic processing is occurring despite the absence of any conscious awareness of colour. The results indicate that both parvocellular colour opponent and magnocellular broad-band channels are active and that the cortical brain damage has selectively disrupted the appreciation of colour but not the ability to detect even isoluminant chromatic borders, which would be invisible to a retinal achromat. The subject's performance on non-colour tasks involving the discrimination of shape, texture, greyness and position was excellent. His disorder is therefore not like that of macaque monkeys in which cortical area V4 has been removed, and which are much more severely impaired at discriminating shape than colour.

  20. Practical colour management

    NASA Astrophysics Data System (ADS)

    Williams, Susan

    2006-06-01

    Spectrophotometers have been successfully used for colour measurement. This paper addresses digital imaging as a complementary and alternative method of colour measurement and appearance and an effective communication tool as part of a practical colour management programme within the supply chain of a textile retailer. The specific needs—to measure and communicate textured dyed material and printed fabric—are discussed, as well as the colour specification and quality control (QC) of currently un-measurable fabrics and accessories. A unique method of using digital imaging for the assessment of colour fastness will also be discussed.

  1. Cognitive Impairment and Age-Related Vision Disorders: Their Possible Relationship and the Evaluation of the Use of Aspirin and Statins in a 65 Years-and-Over Sardinian Population

    PubMed Central

    Mandas, Antonella; Mereu, Rosa Maria; Catte, Olga; Saba, Antonio; Serchisu, Luca; Costaggiu, Diego; Peiretti, Enrico; Caminiti, Giulia; Vinci, Michela; Casu, Maura; Piludu, Stefania; Fossarello, Maurizio; Manconi, Paolo Emilio; Dessí, Sandra

    2014-01-01

    Neurological disorders (Alzheimer’s disease, vascular and mixed dementia) and visual loss (cataract, age-related macular degeneration, glaucoma, and diabetic retinopathy) are among the most common conditions that afflict people of at least 65 years of age. An increasing body of evidence is emerging, which demonstrates that memory and vision impairment are closely, significantly, and positively linked and that statins and aspirin may lessen the risk of developing age-related visual and neurological problems. However, clinical studies have produced contradictory results. Thus, the intent of the present study was to reliably establish whether a relationship exist between various types of dementia and age-related vision disorders, and to establish whether statins and aspirin may or may not have beneficial effects on these two types of disorders. We found that participants with dementia and/or vision problems were more likely to be depressed and displayed worse functional ability in basic and instrumental activities of daily living than controls. Mini mental state examination scores were significantly lower in patients with vision disorders compared to subjects without vision disorders. A closer association with macular degeneration was found in subjects with Alzheimer’s disease than in subjects without dementia or with vascular dementia, mixed dementia, or other types of age-related vision disorders. When we considered the associations between different types of dementia and vision disorders and the use of statins and aspirin, we found a significant positive association between Alzheimer’s disease and statins on their own or in combination with aspirin, indicating that these two drugs do not appear to reduce the risk of Alzheimer’s disease or improve its clinical evolution and may, on the contrary, favor its development. No significant association in statin use alone, aspirin use alone, or the combination of these was found in subjects without vision

  2. Colour Measurements and Modeling

    NASA Astrophysics Data System (ADS)

    Jha, Shyam N.

    The most common property to measure quality of any material is its appearance. Appearance includes colour, shape, size and surface conditions. The analysis of colour is especially an important consideration when determining the efficacy of variety of postharvest treatments. Consumers can easily be influenced by preconceived ideas of how a particular fruit or vegetable or a processed food should appear, and marketers often attempt to improve upon what nature has painted. Recently colour measurements have also been used as quality parameters and indicator of some inner constituents of the material. In spite of the significance of colour in food industries, many continue to analyze it inadequately. This chapter deals with theory of colour, colour scales and its measurement, sampling techniques, and modeling of colour values for correlating them with some internal quality parameters of selected fruits.

  3. Minimum Perceptible Differences in the Colour Reproduction of Photographic Prints.

    NASA Astrophysics Data System (ADS)

    Wood, Carol Ann

    Available from UMI in association with The British Library. Electronic simulations of the Macbeth Color Checker Chart were prepared such that each of the eighteen colour patches could be varied independently from the rest of the chart. The output was in the form of photographic colour prints which comprised a ring-around set of 168 prints for each of the colour patches, where each print was a colour perturbation from a standard print. Twelve observers, with normal colour vision, judged the prints in each set to be perceptibly different or not perceptibly different from the standard print, for each patch. The experimental results, in the form of hue-orientated and non hue-orientated ellipses, were compared with MacAdam type ellipses, CIELAB unit ellipses and ellipses derived from the CMC(1:c) colour difference formula: the comparisons were made in the 1976 CIELAB colour space. Colour reproduction indices were calculated for the end points of the semi-major and semi-minor axes of the CMC ellipses, for each of the eighteen colour patches. The coefficient of variation was very small for the combined hue index, the combined chroma index and the overall combined index, indicating that the mean values for these indices could be assigned to any of the ellipses as a measure of the minimum perceptible difference in terms of colour appearance.

  4. Topographic Mapping of Residual Vision by Computer

    ERIC Educational Resources Information Center

    MacKeben, Manfred

    2008-01-01

    Many persons with low vision have diseases that damage the retina only in selected areas, which can lead to scotomas (blind spots) in perception. The most frequent of these diseases is age-related macular degeneration (AMD), in which foveal vision is often impaired by a central scotoma that impairs vision of fine detail and causes problems with…

  5. Optimality of the basic colour categories for classification

    PubMed Central

    Griffin, Lewis D

    2005-01-01

    Categorization of colour has been widely studied as a window into human language and cognition, and quite separately has been used pragmatically in image-database retrieval systems. This suggests the hypothesis that the best category system for pragmatic purposes coincides with human categories (i.e. the basic colours). We have tested this hypothesis by assessing the performance of different category systems in a machine-vision task. The task was the identification of the odd-one-out from triples of images obtained using a web-based image-search service. In each triple, two of the images had been retrieved using the same search term, the other a different term. The terms were simple concrete nouns. The results were as follows: (i) the odd-one-out task can be performed better than chance using colour alone; (ii) basic colour categorization performs better than random systems of categories; (iii) a category system that performs better than the basic colours could not be found; and (iv) it is not just the general layout of the basic colours that is important, but also the detail. We conclude that (i) the results support the plausibility of an explanation for the basic colours as a result of a pressure-to-optimality and (ii) the basic colours are good categories for machine vision image-retrieval systems. PMID:16849219

  6. Rockpool Gobies Change Colour for Camouflage

    PubMed Central

    Stevens, Martin; Lown, Alice E.; Denton, Alexander M.

    2014-01-01

    Camouflage is found in a wide range of species living in numerous habitat types, offering protection from visually guided predators. This includes many species from the intertidal zone, which must cope with background types diverse in appearance and with multiple predator groups foraging at high and low tide. Many animals are capable of either relatively slow (hours, days, weeks) or rapid (seconds and minutes) colour change in order to better resemble the background against which they are found, but most work has been restricted to a few species or taxa. It is often suggested that many small intertidal fish are capable of colour change for camouflage, yet little experimental work has addressed this. Here, we test rock gobies (Gobius paganellus) for colour change abilities, and whether they can tune their appearance to match the background. In two experiments, we place gobies on backgrounds of different brightness (black or white), and of different colours (red and blue) and use digital image analysis and modelling of predator (avian) vision to quantify colour and luminance (perceived lightness) changes and camouflage. We find that gobies are capable of rapid colour change (occurring within one minute), and that they can change their luminance on lighter or darker backgrounds. When presented on backgrounds of different colours, gobies also change their colour (hue and saturation) while keeping luminance the same. These changes lead to predicted improvements in camouflage match to the background. Our study shows that small rockpool fish are capable of rapid visual change for concealment, and that this may be an important mechanism in many species to avoid predation, especially in complex heterogeneous environments. PMID:25333382

  7. Increased Burden of Vision Impairment and Eye Diseases in Persons with Chronic Kidney Disease — A Population-Based Study

    PubMed Central

    Wong, Chee Wai; Lamoureux, Ecosse L.; Cheng, Ching-Yu; Cheung, Gemmy Chui Ming; Tai, E. Shyong; Wong, Tien Y.; Sabanayagam, Charumathi

    2016-01-01

    Background Chronic kidney disease (CKD) has been shown to be associated with diabetic retinopathy (DR) and age-related macular degeneration (AMD), leading causes of blindness in elderly adults in previous studies. However, the association of CKD with visual impairment (VI) is not clear. We aimed to examine the association of CKD with VI and other age-related ocular diseases in a population-based sample of Asian adults. Methods We analyzed data from 10,033 adults aged 40–80 years who participated in the Singapore Epidemiology of Eye Diseases (SEED, 2004–11) Study. CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2 from serum creatinine. VI was defined as best-corrected visual acuity < 20/40 in the better eye. Cataract, retinopathy, DR, glaucoma and AMD were assessed using standardized ocular examination, retinal photography and visual field assessments. The associations of CKD with VI and ocular conditions were examined using logistic regression models adjusted for age, sex, race, smoking, alcohol intake, education status, body mass index, systolic blood pressure, diabetes mellitus, cholesterol levels and cardiovascular disease. Findings The prevalence of VI and ocular disease were significantly higher in participants with CKD (36.1% and 84.7%) than in those without (12.9% and 54.3%, both p < 0.001). In multivariable models, CKD was significantly associated with VI (odds ratio [95% confidence interval] = 1.34 [1.14–1.58]), any ocular disease (1.28 [1.03–1.61]), cataract (1.24 [1.01–1.52]), any retinopathy (1.77 [1.45–2.15]), and DR (1.94 [1.47–2.54]). Interpretation The burden of VI and eye diseases is high among persons with CKD. Our findings suggest that it may be useful to screen for ocular disease and VI in persons with CKD. PMID:27077127

  8. The involvement of the temporal lobes in colour discrimination.

    PubMed

    Heywood, C A; Shields, C; Cowey, A

    1988-01-01

    Monkeys with ablation of lateral striate, prestriate or inferotemporal cortex were compared with unoperated controls in their ability to discriminate Munsell colours, or greys, of increasing difficulty. Whereas lateral striate or prestriate lesions centred on visual area V4 mildly impaired only the most difficult discriminations, inferotemporal ablation resulted in a severe impairment in the acquisition of colour discriminations. However, the ability to discriminate greys was much less affected.

  9. A colour image reproduction framework for 3D colour printing

    NASA Astrophysics Data System (ADS)

    Xiao, Kaida; Sohiab, Ali; Sun, Pei-li; Yates, Julian M.; Li, Changjun; Wuerger, Sophie

    2016-10-01

    In this paper, the current technologies in full colour 3D printing technology were introduced. A framework of colour image reproduction process for 3D colour printing is proposed. A special focus was put on colour management for 3D printed objects. Two approaches, colorimetric colour reproduction and spectral based colour reproduction are proposed in order to faithfully reproduce colours in 3D objects. Two key studies, colour reproduction for soft tissue prostheses and colour uniformity correction across different orientations are described subsequently. Results are clear shown that applying proposed colour image reproduction framework, performance of colour reproduction can be significantly enhanced. With post colour corrections, a further improvement in colour process are achieved for 3D printed objects.

  10. Colour harmony of two colour combinations in clothes matching

    NASA Astrophysics Data System (ADS)

    Wicaksono, Sungging Haryo; Fu, Tzu-Hao; Chen, Liang-Ya; Hou, Chien-Yu; Ou, Li-Chen

    2015-01-01

    There are many definitions and theories about colour harmony. But no consistent rules and definitions can be determined. Some previous researches show that there are many factors that influence the colour harmony. Colour harmony is highly depends on the external factors, including the context of colour besides their colour combinations. In the current research an experiment conducted by observing two colour combinations which applied in shirt and trousers. Twenty observers involved in the experiment, consist of ten male and ten female. Each observer predict colour harmony score in 58 samples of shirt and trouser pairs, the colour combination then applied upside down. Based on the experimental results, male and female group has similar tendency in colour harmony score prediction in the same colour samples (correlation coefficient, r=0.84). Upside down colour combinations will change the impression of observer about colour harmony and yields a different value of colour harmony prediction score which indicated from correlation coefficient results of 0.53.

  11. The colour preference control based on two-colour combinations

    NASA Astrophysics Data System (ADS)

    Hong, Ji Young; Kwak, Youngshin; Park, Du-Sik; Kim, Chang Yeong

    2008-02-01

    This paper proposes a framework of colour preference control to satisfy the consumer's colour related emotion. A colour harmony algorithm based on two-colour combinations is developed for displaying the images with several complementary colour pairs as the relationship of two-colour combination. The colours of pixels belonging to complementary colour areas in HSV colour space are shifted toward the target hue colours and there is no colour change for the other pixels. According to the developed technique, dynamic emotions by the proposed hue conversion can be improved and the controlled output image shows improved colour emotions in the preference of the human viewer. The psychophysical experiments are conducted to investigate the optimal model parameters to produce the most pleasant image to the users in the respect of colour emotions.

  12. Dynamic plasmonic colour display

    NASA Astrophysics Data System (ADS)

    Duan, Xiaoyang; Kamin, Simon; Liu, Na

    2017-02-01

    Plasmonic colour printing based on engineered metasurfaces has revolutionized colour display science due to its unprecedented subwavelength resolution and high-density optical data storage. However, advanced plasmonic displays with novel functionalities including dynamic multicolour printing, animations, and highly secure encryption have remained in their infancy. Here we demonstrate a dynamic plasmonic colour display technique that enables all the aforementioned functionalities using catalytic magnesium metasurfaces. Controlled hydrogenation and dehydrogenation of the constituent magnesium nanoparticles, which serve as dynamic pixels, allow for plasmonic colour printing, tuning, erasing and restoration of colour. Different dynamic pixels feature distinct colour transformation kinetics, enabling plasmonic animations. Through smart material processing, information encoded on selected pixels, which are indiscernible to both optical and scanning electron microscopies, can only be read out using hydrogen as a decoding key, suggesting a new generation of information encryption and anti-counterfeiting applications.

  13. Dynamic plasmonic colour display

    PubMed Central

    Duan, Xiaoyang; Kamin, Simon; Liu, Na

    2017-01-01

    Plasmonic colour printing based on engineered metasurfaces has revolutionized colour display science due to its unprecedented subwavelength resolution and high-density optical data storage. However, advanced plasmonic displays with novel functionalities including dynamic multicolour printing, animations, and highly secure encryption have remained in their infancy. Here we demonstrate a dynamic plasmonic colour display technique that enables all the aforementioned functionalities using catalytic magnesium metasurfaces. Controlled hydrogenation and dehydrogenation of the constituent magnesium nanoparticles, which serve as dynamic pixels, allow for plasmonic colour printing, tuning, erasing and restoration of colour. Different dynamic pixels feature distinct colour transformation kinetics, enabling plasmonic animations. Through smart material processing, information encoded on selected pixels, which are indiscernible to both optical and scanning electron microscopies, can only be read out using hydrogen as a decoding key, suggesting a new generation of information encryption and anti-counterfeiting applications. PMID:28232722

  14. Plasmonic colour generation

    NASA Astrophysics Data System (ADS)

    Kristensen, Anders; Yang, Joel K. W.; Bozhevolnyi, Sergey I.; Link, Stephan; Nordlander, Peter; Halas, Naomi J.; Mortensen, N. Asger

    2016-11-01

    Plasmonic colours are structural colours that emerge from resonant interactions between light and metallic nanostructures. The engineering of plasmonic colours is a promising, rapidly emerging research field that could have a large technological impact. We highlight basic properties of plasmonic colours and recent nanofabrication developments, comparing technology-performance indicators for traditional and nanophotonic colour technologies. The structures of interest include diffraction gratings, nanoaperture arrays, thin films, and multilayers and structures that support Mie resonances and whispering-gallery modes. We discuss plasmonic colour nanotechnology based on localized surface plasmon resonances, such as gap plasmons and hybridized disk-hole plasmons, which allow for colour printing with sub-diffraction resolution. We also address a range of fabrication approaches that enable large-area printing and nanoscale lithography compatible with complementary metal-oxide semiconductor technologies, including nanoimprint lithography and self-assembly. Finally, we review recent developments in dynamically reconfigurable plasmonic colours and in the laser-induced post-processing of plasmonic colour surfaces.

  15. 77 FR 38379 - Qualification of Drivers; Exemption Applications; Vision

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-27

    ... were not recently developed. Six of the applicants were either born with their vision impairments or... a record of safety while driving with their vision impairment, demonstrating the likelihood that... Federal Motor Carrier Safety Administration Qualification of Drivers; Exemption Applications;...

  16. Colour helps to solve the binocular matching problem.

    PubMed

    den Ouden, H E M; van Ee, R; de Haan, E H F

    2005-09-01

    The spatial differences between the two retinal images, called binocular disparities, can be used to recover the three-dimensional (3D) aspects of a scene. The computation of disparity depends upon the correct identification of corresponding features in the two images. Understanding what image features are used by the brain to solve this binocular matching problem is an important issue in research on stereoscopic vision. The role of colour in binocular vision is controversial and it has been argued that colour is ineffective in achieving binocular vision. In the current experiment subjects were required to indicate the amount of perceived depth. The stimulus consisted of an array of fronto-parallel bars uniformly distributed in a constant sized volume. We studied the perceived depth in those 3D stimuli by manipulating both colour (monochrome, trichrome) and luminance (congruent, incongruent). Our results demonstrate that the amount of perceived depth was influenced by colour, indicating that the visual system uses colour to achieve binocular matching. Physiological data have revealed cortical cells in macaque V2 that are tuned both to binocular disparity and to colour. We suggest that one of the functional roles of these cells may be to help solve the binocular matching problem.

  17. Colour contribution to children's wayfinding in school environments

    NASA Astrophysics Data System (ADS)

    Helvacıoǧlu, Elif; Olguntürk, Nilgün

    2011-03-01

    The purpose of this study was to explore the contribution of colour to children's wayfinding ability in school environments and to examine the differences between colours in terms of their remembrance and usability in route learning process. The experiment was conducted with three different sample groups for each of three experiment sets differentiated by their colour arrangement. The participants totalled 100 primary school children aged seven and eight years old. The study was conducted in four phases. In the first phase, the participants were tested for familiarity with the experiment site and also for colour vision deficiencies by using Ishihara's tests for colour-blindness. In the second phase, they were escorted on the experiment route by the tester one by one, from one starting point to one end point and were asked to lead the tester to the end point by the same route. In the third phase, they were asked to describe verbally the route. In the final phase, they were asked to remember the specific colours at their correct locations. It was found that colour has a significant effect on children's wayfinding performances in school environments. However, there were no differences between different colours in terms of their remembrances in route finding tasks. In addition, the correct identifications of specific colours and landmarks were dependent on their specific locations. Contrary to the literature, gender differences were not found to be significant in the accuracy of route learning performances.

  18. Evidence for a role of action in colour perception.

    PubMed

    Bompas, Aline; O'Regan, J Kevin

    2006-01-01

    Action is not usually considered to play a role in colour perception. However, sensorimotor theories of perception (eg O'Regan and Noë, 2001 Behavior and Brain Science 24 939-1011) suggest that, on the contrary, the transformations created by action in the sensory input are a necessary condition for all perception. In the case of colour vision, eye movements may explain how a retina with significant irregularities in resolution and cone arrangement (Roorda and Williams, 1999 Nature 397 520-522) could permit the perception of a richly coloured world (Clark and O'Regan, 2000 15th International Conference on Pattern Recognition volume 2: Pattern Recognition and Neural Networks pp 503-506; Skaff et al, 2002 16th International Conference on Pattern Recognition volume 2, pp 681-684). We provide evidence that perception of colour is modified when an artificial coupling is introduced linking eye movements and colour changes. After 40 min of wearing left-field-blue/right-field-yellow spectacles, observers' colour vision adapts so that, after removing the spectacles, white patches seem to become bluer when the eyes move rightwards and yellower when the eyes move leftwards. This induced dependence of colour perception on the direction of eye saccade is shown to be related to the amount of eye movements during exposure. This result, which cannot be explained either by retinal adaptation, or by a conditioned association between colour and side, constitutes first clear evidence for a role of eye movements in perceived colour and argues for the involvement in colour perception of neural mechanisms continuously tuned to sensorimotor contingencies.

  19. The unsuitability of html-based colour charts for estimating animal colours – a comment on Berggren and Merilä (2004)

    PubMed Central

    Stevens, Martin; Cuthill, Innes C

    2005-01-01

    Background A variety of techniques are used to study the colours of animal signals, including the use of visual matching to colour charts. This paper aims to highlight why they are generally an unsatisfactory tool for the measurement and classification of animal colours and why colour codes based on HTML (really RGB) standards, as advocated in a recent paper, are particularly inappropriate. There are many theoretical arguments against the use of colour charts, not least that human colour vision differs markedly from that of most other animals. However, the focus of this paper is the concern that, even when applied to humans, there is no simple 1:1 mapping from an RGB colour space to the perceived colours in a chart (the results are both printer- and illumination-dependent). We support our criticisms with data from colour matching experiments with humans, involving self-made, printed colour charts. Results Colour matching experiments with printed charts involving 11 subjects showed that the choices made by individuals were significantly different between charts that had exactly the same RGB values, but were produced from different printers. Furthermore, individual matches tended to vary under different lighting conditions. Spectrophotometry of the colour charts showed that the reflectance spectra of the charts varied greatly between printers and that equal steps in RGB space were often far from equal in terms of reflectance on the printed charts. Conclusion In addition to outlining theoretical criticisms of the use of colour charts, our empirical results show that: individuals vary in their perception of colours, that different printers produce strikingly different results when reproducing what should be the same chart, and that the characteristics of the light irradiating the surface do affect colour perception. Therefore, we urge great caution in the use of colour charts to study animal colour signals. They should be used only as a last resort and in full

  20. (Computer) Vision without Sight

    PubMed Central

    Manduchi, Roberto; Coughlan, James

    2012-01-01

    Computer vision holds great promise for helping persons with blindness or visual impairments (VI) to interpret and explore the visual world. To this end, it is worthwhile to assess the situation critically by understanding the actual needs of the VI population and which of these needs might be addressed by computer vision. This article reviews the types of assistive technology application areas that have already been developed for VI, and the possible roles that computer vision can play in facilitating these applications. We discuss how appropriate user interfaces are designed to translate the output of computer vision algorithms into information that the user can quickly and safely act upon, and how system-level characteristics affect the overall usability of an assistive technology. Finally, we conclude by highlighting a few novel and intriguing areas of application of computer vision to assistive technology. PMID:22815563

  1. Vision and Driving

    PubMed Central

    Owsley, Cynthia; McGwin, Gerald

    2010-01-01

    Driving is the primary means of personal travel in many countries and is relies heavily on vision for its successful execution. Research over the past few decades has addressed the role of vision in driver safety (motor vehicle collision involvement) and in driver performance (both on-road and using interactive simulators in the laboratory). Here we critically review what is currently known about the role of various aspects of visual function in driving. We also discuss translational research issues on vision screening for licensure and re-licensure and rehabilitation of visually impaired persons who want to drive. PMID:20580907

  2. Double cones are used for colour discrimination in the reef fish, Rhinecanthus aculeatus

    PubMed Central

    Pignatelli, Vincenzo; Champ, Conor; Marshall, Justin; Vorobyev, Misha

    2010-01-01

    Double cones (DCs) are the most common cone types in fish, reptiles and birds. It has been suggested that DCs are used for achromatic tasks such as luminance, motion and polarization vision. Here we show that a reef fish Rhinecanthus aculeatus can discriminate colours on the basis of the difference between the signals of individual members of DCs. This is the first direct evidence that individual members of DCs are used in colour vision as independent spectral channels. PMID:20129950

  3. Colour and pattern change against visually heterogeneous backgrounds in the tree frog Hyla japonica.

    PubMed

    Kang, Changku; Kim, Ye Eun; Jang, Yikweon

    2016-03-02

    Colour change in animals can be adaptive phenotypic plasticity in heterogeneous environments. Camouflage through background colour matching has been considered a primary force that drives the evolution of colour changing ability. However, the mechanism to which animals change their colour and patterns under visually heterogeneous backgrounds (i.e. consisting of more than one colour) has only been identified in limited taxa. Here, we investigated the colour change process of the Japanese tree frog (Hyla japonica) against patterned backgrounds and elucidated how the expression of dorsal patterns changes against various achromatic/chromatic backgrounds with/without patterns. Our main findings are i) frogs primarily responded to the achromatic differences in background, ii) their contrasting dorsal patterns were conditionally expressed dependent on the brightness of backgrounds, iii) against mixed coloured background, frogs adopted intermediate forms between two colours. Using predator (avian and snake) vision models, we determined that colour differences against different backgrounds yielded perceptible changes in dorsal colours. We also found substantial individual variation in colour changing ability and the levels of dorsal pattern expression between individuals. We discuss the possibility of correlational selection on colour changing ability and resting behaviour that maintains the high variation in colour changing ability within population.

  4. Colour and pattern change against visually heterogeneous backgrounds in the tree frog Hyla japonica

    PubMed Central

    Kang, Changku; Kim, Ye Eun; Jang, Yikweon

    2016-01-01

    Colour change in animals can be adaptive phenotypic plasticity in heterogeneous environments. Camouflage through background colour matching has been considered a primary force that drives the evolution of colour changing ability. However, the mechanism to which animals change their colour and patterns under visually heterogeneous backgrounds (i.e. consisting of more than one colour) has only been identified in limited taxa. Here, we investigated the colour change process of the Japanese tree frog (Hyla japonica) against patterned backgrounds and elucidated how the expression of dorsal patterns changes against various achromatic/chromatic backgrounds with/without patterns. Our main findings are i) frogs primarily responded to the achromatic differences in background, ii) their contrasting dorsal patterns were conditionally expressed dependent on the brightness of backgrounds, iii) against mixed coloured background, frogs adopted intermediate forms between two colours. Using predator (avian and snake) vision models, we determined that colour differences against different backgrounds yielded perceptible changes in dorsal colours. We also found substantial individual variation in colour changing ability and the levels of dorsal pattern expression between individuals. We discuss the possibility of correlational selection on colour changing ability and resting behaviour that maintains the high variation in colour changing ability within population. PMID:26932675

  5. Increased conspicuousness can explain the match between visual sensitivities and blue plumage colours in fairy-wrens

    PubMed Central

    Delhey, Kaspar; Hall, Michelle; Kingma, Sjouke A.; Peters, Anne

    2013-01-01

    Colour signals are expected to match visual sensitivities of intended receivers. In birds, evolutionary shifts from violet-sensitive (V-type) to ultraviolet-sensitive (U-type) vision have been linked to increased prevalence of colours rich in shortwave reflectance (ultraviolet/blue), presumably due to better perception of such colours by U-type vision. Here we provide the first test of this widespread idea using fairy-wrens and allies (Family Maluridae) as a model, a family where shifts in visual sensitivities from V- to U-type eyes are associated with male nuptial plumage rich in ultraviolet/blue colours. Using psychophysical visual models, we compared the performance of both types of visual systems at two tasks: (i) detecting contrast between male plumage colours and natural backgrounds, and (ii) perceiving intraspecific chromatic variation in male plumage. While U-type outperforms V-type vision at both tasks, the crucial test here is whether U-type vision performs better at detecting and discriminating ultraviolet/blue colours when compared with other colours. This was true for detecting contrast between plumage colours and natural backgrounds (i), but not for discriminating intraspecific variability (ii). Our data indicate that selection to maximize conspicuousness to conspecifics may have led to the correlation between ultraviolet/blue colours and U-type vision in this clade of birds. PMID:23118438

  6. Impaired Waters and TMDLs: New Vision for the CWA 303(d) Program – An Updated Framework for Implementing the CWA 303(d) Program Responsibilities

    EPA Pesticide Factsheets

    A vision detailing enhancements made to the Clean Water Act 303(d) Program informed by the experience gained over the past two decades in assessing and reporting on water quality and in developing approximately 65,000 TMDLs.

  7. Tunable structural colour

    NASA Astrophysics Data System (ADS)

    Graham-Rowe, Duncan

    2009-10-01

    Strain gauges that change colour when stressed, bright backlight-free displays and highly sensitive biological sensors are all potential applications of tunable photonic crystal materials, reports Duncan Graham-Rowe.

  8. Colour Mixing Based on Daylight

    ERIC Educational Resources Information Center

    Meyn, Jan-Peter

    2008-01-01

    Colour science is based on the sensation of monochromatic light. In contrast to that, surface colours are caused by reflection of wide sections of the daylight spectrum. Non-spectral colours like magenta and purple appear homologous to colours with spectral hue, if the approach of mixing monochromatic light is abandoned. It is shown that a large…

  9. Colour reconnections in Herwig++

    NASA Astrophysics Data System (ADS)

    Gieseke, Stefan; Röhr, Christian; Siódmok, Andrzej

    2012-11-01

    We describe the implementation details of the colour reconnection model in the event generator Herwig++. We study the impact on final-state observables in detail and confirm the model idea from colour preconfinement on the basis of studies within the cluster hadronization model. Moreover, we show that the description of minimum bias and underlying event data at the LHC is improved with this model and present results of a tune to available data.

  10. Can colours be used to segment words when reading?

    PubMed

    Perea, Manuel; Tejero, Pilar; Winskel, Heather

    2015-07-01

    Rayner, Fischer, and Pollatsek (1998, Vision Research) demonstrated that reading unspaced text in Indo-European languages produces a substantial reading cost in word identification (as deduced from an increased word-frequency effect on target words embedded in the unspaced vs. spaced sentences) and in eye movement guidance (as deduced from landing sites closer to the beginning of the words in unspaced sentences). However, the addition of spaces between words comes with a cost: nearby words may fall outside high-acuity central vision, thus reducing the potential benefits of parafoveal processing. In the present experiment, we introduced a salient visual cue intended to facilitate the process of word segmentation without compromising visual acuity: each alternating word was printed in a different colour (i.e., ). Results only revealed a small reading cost of unspaced alternating colour sentences relative to the spaced sentences. Thus, present data are a demonstration that colour can be useful to segment words for readers of spaced orthographies.

  11. Tetrachromatic colour space

    NASA Astrophysics Data System (ADS)

    Restrepo, Alfredo

    2012-03-01

    We derive colour spaces of the hue-colourfulness-luminance type, on the basis of a four-dimensional hypercube I4 (I = [0, 1]). The hypercube corresponds to a tetrachromatic colour system, analogous to the three-dimensional RGB cube. In the first derived space the colourfulness is chromatic saturation while in the second one, colourfulness refers to the vividness of the colour, even if it is achromatic. The hue is defined on the basis of an icositetrahedron of 24 triangles that is embedded in the boundary of the hypercube. The boundary of the hypercube is the polytope {4 3 3} (in Sclafli notation) that is a topological 3-sphere. Out of the 24 square faces in the boundary of the hypercube, 6 meet the black vertex and 6 meet the white vertex; the remaining 12 faces form a dodecahedron which is a topological 2-sphere. This equatorial or chromatic dodecahedron is used to define a hue for each point in the hypercube that is not on the achromatic segment; the icositetrahedron results from a division of each of the square faces of the dodecahedron into two triangles. In addition, a hexdecahedron of 16 square faces with the topology of a torus that is also embedded in the boundary of the hypercube, is used to define an alternate two-dimensional hue space.

  12. Plasmonic colour laser printing

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaolong; Vannahme, Christoph; Højlund-Nielsen, Emil; Mortensen, N. Asger; Kristensen, Anders

    2016-04-01

    Colour generation by plasmonic nanostructures and metasurfaces has several advantages over dye technology: reduced pixel area, sub-wavelength resolution and the production of bright and non-fading colours. However, plasmonic colour patterns need to be pre-designed and printed either by e-beam lithography (EBL) or focused ion beam (FIB), both expensive and not scalable processes that are not suitable for post-processing customization. Here we show a method of colour printing on nanoimprinted plasmonic metasurfaces using laser post-writing. Laser pulses induce transient local heat generation that leads to melting and reshaping of the imprinted nanostructures. Depending on the laser pulse energy density, different surface morphologies that support different plasmonic resonances leading to different colour appearances can be created. Using this technique we can print all primary colours with a speed of 1 ns per pixel, resolution up to 127,000 dots per inch (DPI) and power consumption down to 0.3 nJ per pixel.

  13. Quantitative studies of animal colour constancy: using the chicken as model.

    PubMed

    Olsson, Peter; Wilby, David; Kelber, Almut

    2016-05-11

    Colour constancy is the capacity of visual systems to keep colour perception constant despite changes in the illumination spectrum. Colour constancy has been tested extensively in humans and has also been described in many animals. In humans, colour constancy is often studied quantitatively, but besides humans, this has only been done for the goldfish and the honeybee. In this study, we quantified colour constancy in the chicken by training the birds in a colour discrimination task and testing them in changed illumination spectra to find the largest illumination change in which they were able to remain colour-constant. We used the receptor noise limited model for animal colour vision to quantify the illumination changes, and found that colour constancy performance depended on the difference between the colours used in the discrimination task, the training procedure and the time the chickens were allowed to adapt to a new illumination before making a choice. We analysed literature data on goldfish and honeybee colour constancy with the same method and found that chickens can compensate for larger illumination changes than both. We suggest that future studies on colour constancy in non-human animals could use a similar approach to allow for comparison between species and populations.

  14. [Screening of early color vision loss in diabetic patients].

    PubMed

    Peduzzi, M; Longanesi, L; Ascari, A; Cascione, S; Galletti, M; Roncaia, R; Pacchioni, C; Maione, M

    1989-01-01

    Colour vision defects have been claimed to appear in diabetes before any retinopathy is visible. In the present study diabetic patients and non diabetic control subjects were screened with two different colour vision tests which include both red-green and blue-yellow parts, and are suitable for quantitative analysis of scores. The Lanthony 40 Hue test and the Tokyo Medical College--T.M.C. tables were used to assess colour vision in 106 diabetic (50 insulin dependent and 56 non insulin dependent) patients and in 99 non diabetic control subjects. Diabetic patients without visible retinopathy, familiar colour vision defects and/or lens changes, had significantly higher scores than control subjects in both eyes. The differences were more evident in non insulin dependent patients. Statistical analysis showed that early loss of colour vision was correlated with age and duration of diabetes for older patients, while correlation with glycosylated hemoglobin was moderately positive only for younger patients. Both tests (especially the Lanthony 40 Hue) resulted to be highly specific and could be used for the clinical study of colour vision losses in diabetic patients.

  15. Gene therapy for red-green colour blindness in adult primates.

    PubMed

    Mancuso, Katherine; Hauswirth, William W; Li, Qiuhong; Connor, Thomas B; Kuchenbecker, James A; Mauck, Matthew C; Neitz, Jay; Neitz, Maureen

    2009-10-08

    Red-green colour blindness, which results from the absence of either the long- (L) or the middle- (M) wavelength-sensitive visual photopigments, is the most common single locus genetic disorder. Here we explore the possibility of curing colour blindness using gene therapy in experiments on adult monkeys that had been colour blind since birth. A third type of cone pigment was added to dichromatic retinas, providing the receptoral basis for trichromatic colour vision. This opened a new avenue to explore the requirements for establishing the neural circuits for a new dimension of colour sensation. Classic visual deprivation experiments have led to the expectation that neural connections established during development would not appropriately process an input that was not present from birth. Therefore, it was believed that the treatment of congenital vision disorders would be ineffective unless administered to the very young. However, here we show that the addition of a third opsin in adult red-green colour-deficient primates was sufficient to produce trichromatic colour vision behaviour. Thus, trichromacy can arise from a single addition of a third cone class and it does not require an early developmental process. This provides a positive outlook for the potential of gene therapy to cure adult vision disorders.

  16. Colour preferences of UK garden birds at supplementary seed feeders.

    PubMed

    Rothery, Luke; Scott, Graham W; Morrell, Lesley J

    2017-01-01

    Supplementary feeding of garden birds generally has benefits for both bird populations and human wellbeing. Birds have excellent colour vision, and show preferences for food items of particular colours, but research into colour preferences associated with artificial feeders is limited to hummingbirds. Here, we investigated the colour preferences of common UK garden birds foraging at seed-dispensing artificial feeders containing identical food. We presented birds simultaneously with an array of eight differently coloured feeders, and recorded the number of visits made to each colour over 370 30-minute observation periods in the winter of 2014/15. In addition, we surveyed visitors to a garden centre and science festival to determine the colour preferences of likely purchasers of seed feeders. Our results suggest that silver and green feeders were visited by higher numbers of individuals of several common garden bird species, while red and yellow feeders received fewer visits. In contrast, people preferred red, yellow, blue and green feeders. We suggest that green feeders may be simultaneously marketable and attractive to foraging birds.

  17. Colour preferences of UK garden birds at supplementary seed feeders

    PubMed Central

    Rothery, Luke; Scott, Graham W.

    2017-01-01

    Supplementary feeding of garden birds generally has benefits for both bird populations and human wellbeing. Birds have excellent colour vision, and show preferences for food items of particular colours, but research into colour preferences associated with artificial feeders is limited to hummingbirds. Here, we investigated the colour preferences of common UK garden birds foraging at seed-dispensing artificial feeders containing identical food. We presented birds simultaneously with an array of eight differently coloured feeders, and recorded the number of visits made to each colour over 370 30-minute observation periods in the winter of 2014/15. In addition, we surveyed visitors to a garden centre and science festival to determine the colour preferences of likely purchasers of seed feeders. Our results suggest that silver and green feeders were visited by higher numbers of individuals of several common garden bird species, while red and yellow feeders received fewer visits. In contrast, people preferred red, yellow, blue and green feeders. We suggest that green feeders may be simultaneously marketable and attractive to foraging birds. PMID:28212435

  18. Colour in flux: describing and printing colour in art

    NASA Astrophysics Data System (ADS)

    Parraman, Carinna

    2008-01-01

    This presentation will describe artists, practitioners and scientists, who were interested in developing a deeper psychological, emotional and practical understanding of the human visual system who were working with wavelength, paint and other materials. From a selection of prints at The Prints and Drawings Department at Tate London, the presentation will refer to artists who were motivated by issues relating to how colour pigment was mixed and printed, to interrogate and explain colour perception and colour science, and in art, how artists have used colour to challenge the viewer and how a viewer might describe their experience of colour. The title Colour in Flux refers, not only to the perceptual effect of the juxtaposition of one colour pigment with another, but also to the changes and challenges for the print industry. In the light of screenprinted examples from the 60s and 70s, the presentation will discuss 21 st century ideas on colour and how these notions have informed the Centre for Fine Print Research's (CFPR) practical research in colour printing. The latter part of this presentation will discuss the implications for the need to change methods in mixing inks that moves away from existing colour spaces, from non intuitive colour mixing to bespoke ink sets, colour mixing approaches and colour mixing methods that are not reliant on RGB or CMYK.

  19. The measurement of vision disability.

    PubMed

    Massof, Robert W

    2002-08-01

    The American Medical Association's (AMA) visual efficiency scale, a vision disability metric based on visual impairment measurements, was adopted in 1925. That scale was based on a 30-year history of theoretical models in vision economics, a misinterpretation of Snellen notation for visual acuity, and an erroneous application of Weber's psychophysical law. The AMA visual efficiency scale survived uncontested for 75 years. In 2001, the AMA adopted a new vision disability scale based on logarithmic transformations of visual acuity and visual field diameter. Like the earlier visual efficiency scale, the new scale is theoretical-it is not supported by any data that speak to the relationship between vision disability and visual impairments. Attempts to measure vision disability date to the early 1980s with the development of self-assessment visual function rating scale questionnaires. Nearly all of the questionnaires developed over the last 20 years use Likert scales, but use them incorrectly. The development of a vision disability metric based on Likert scaling parallels the historical development of other forms of measurement. A tutorial review of psychometrics-classical test theory, item response theory, and Rasch analysis-shows how vision disability measurement scales can be estimated from Likert-type visual function rating scales. We conclude that preliminary data relating measures of vision disability to measures of visual acuity and visual fields support the new AMA vision disability scale.

  20. Flower Colour: How Bumblebees Handle Colours with Perceptually Changing Hues.

    PubMed

    Lunau, Klaus

    2016-03-21

    Colours are floral signals enabling bees to detect, inspect and discriminate flowers in a multitasking world. Behavioural tests now show that trained bumblebees find iridescent coloured targets more quickly and that weak iridescence does not corrupt target identification.

  1. Colour image segmentation using unsupervised clustering technique for acute leukemia images

    NASA Astrophysics Data System (ADS)

    Halim, N. H. Abd; Mashor, M. Y.; Nasir, A. S. Abdul; Mustafa, N.; Hassan, R.

    2015-05-01

    Colour image segmentation has becoming more popular for computer vision due to its important process in most medical analysis tasks. This paper proposes comparison between different colour components of RGB(red, green, blue) and HSI (hue, saturation, intensity) colour models that will be used in order to segment the acute leukemia images. First, partial contrast stretching is applied on leukemia images to increase the visual aspect of the blast cells. Then, an unsupervised moving k-means clustering algorithm is applied on the various colour components of RGB and HSI colour models for the purpose of segmentation of blast cells from the red blood cells and background regions in leukemia image. Different colour components of RGB and HSI colour models have been analyzed in order to identify the colour component that can give the good segmentation performance. The segmented images are then processed using median filter and region growing technique to reduce noise and smooth the images. The results show that segmentation using saturation component of HSI colour model has proven to be the best in segmenting nucleus of the blast cells in acute leukemia image as compared to the other colour components of RGB and HSI colour models.

  2. Can Impaired Vision be Easily, Quickly and Safely Restored toward Health and Maintained Wellness, Using McLeod's Patent Pending Naturoptics Methods?

    NASA Astrophysics Data System (ADS)

    Courtmanche, Amanda; McLeod, Roger; McLeod, David

    2006-10-01

    A healthy eye has its large set of diffraction patterns, generated by the viewed scene, spread across the visible spectrum. Only the two of these simultaneously coincident with foveal cones, and rods, or with extra-foveal cones, are visually useful. This fact and pupil diameter changes with illumination, which cause proportional wavelength changes, drives the healthy visual state. A quasi-monochromatic interval is coincident with foveal cones, and rods. A shorter, partially overlapping interval aligns with extrafoveal cones, with about twenty nanometers separation. Wavelengths follow the Airy disk radius formula. An unhealthy eye is an eyeball deformed by self- induced vision abuse. Incorrect and effectively static stresses in the large external eye muscles displace and distort the patterns. Rebalancing the proper vision and muscle state are safely, quickly and rapidly restored by mimicking natural eye and head movements with naturoptics.

  3. Fun with Colour

    ERIC Educational Resources Information Center

    Rennie, Richard

    2015-01-01

    The Australian Curriculum: Science for Year 5 includes "recognising that the colour of an object depends on the properties of the object and the color of the light source". This article shows how much more can be done with color in the science laboratory. Activities include using a prism to explore white light, using a hand lens to…

  4. Low Vision Aids and Low Vision Rehabilitation

    MedlinePlus

    ... Vision Resources Low Vision Rehabilitation and Low Vision Aids Written by: David Turbert Edited by: Robert H ... covers most services, but not devices.) Low vision aids There are many low vision aids and devices ...

  5. Colour perception in pathologists: the Farnsworth-Munsell 100-hue test.

    PubMed

    Rigby, H S; Warren, B F; Diamond, J; Carter, C; Bradfield, J W

    1991-09-01

    The value of many histological stains depends on the ability of the observer to differentiate colour. This ability was assessed in 30 histopathologists and cytopathologists of varying experience using the Farnsworth-Munsell 100-hue test. As a group, the pathologists performed better than a reference population. Twenty eight subjects showed a wide ranging ability to differentiate colour: none was colour blind. Three of the 30 pathologists, however, fell below the twentieth centile for normal subjects and only one was aware of this deficiency! They may unknowingly misinterpret subtle stains. Two of these three had specific and major defects which could affect their ability to interpret a wide range of less subtle stains. Those with the poorest colour discrimination were not those with the least experience of microscopy. Pathologists should be apprised of the importance of their ability to discriminate colour, and that formal colour vision testing of prospective histopathologists may be appropriate.

  6. Mimicry, colour forms and spectral sensitivity of the bluestriped fangblenny, Plagiotremus rhinorhynchos.

    PubMed

    Cheney, Karen L; Skogh, Charlotta; Hart, Nathan S; Marshall, N Justin

    2009-05-07

    Animals change their body coloration for a variety of purposes including communication, thermoregulation and crypsis. The cues that trigger adaptive colour change are often unclear, and the role of colour vision remains largely untested. Here, we investigated the bluestriped fangblenny (Plagiotremus rhinorhynchos), an aggressive mimic that changes its body coloration to impersonate a variety of coral reef fishes. In this field, we determined the fish species that the fangblenny associated with and measured the spectral reflectance of mimics and their models. We measured the spectral absorbance characteristics of the retinal photoreceptor visual pigments in the bluestriped fangblenny using microspectrophotometry and found it to have rod photoreceptors (lambda(max) 498 nm), single cones (449 nm) and double cones (561 nm principal member; 520 nm accessory member). Using theoretical vision models, fangblennies could discriminate between the colours they adopted and the colours of the fish they associated with. Potential signal receivers (Abudefduf abdominalis and Ctenochaetus strigosus) perceived colours of most mimics to closely resemble fishes they associated with. However, fishes with ultraviolet-sensitive visual pigments were better at discriminating between mimics and models. Therefore, colour vision could be used by fangblennies when initiating colour change enabling them to accurately resemble fishes they associate with and to avoid detection by signal receivers.

  7. 21 CFR 886.5900 - Electronic vision aid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Identification. An electronic vision aid is an AC-powered or battery-powered device that consists of an electronic sensor/transducer intended for use by a patient who has impaired vision or blindness to...

  8. 21 CFR 886.5900 - Electronic vision aid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) Identification. An electronic vision aid is an AC-powered or battery-powered device that consists of an electronic sensor/transducer intended for use by a patient who has impaired vision or blindness to...

  9. 21 CFR 886.5910 - Image intensification vision aid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... aid. (a) Identification. An image intensification vision aid is a battery-powered device intended for use by a patient who has limited dark adaptation or impaired vision to amplify ambient light....

  10. 21 CFR 886.5910 - Image intensification vision aid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... aid. (a) Identification. An image intensification vision aid is a battery-powered device intended for use by a patient who has limited dark adaptation or impaired vision to amplify ambient light....

  11. Low Vision FAQs

    MedlinePlus

    ... USAJobs Home > Low Vision > Low Vision FAQs Healthy Vision Diabetes Diabetes Home How Much Do You Know? ... los Ojos Cómo hablarle a su oculista Low Vision FAQs What is low vision? Low vision is ...

  12. Colouration in crab spiders: substrate choice and prey attraction.

    PubMed

    Heiling, Astrid M; Chittka, Lars; Cheng, Ken; Herberstein, Marie E

    2005-05-01

    Australian crab spiders Thomisus spectabilis ambush pollinating insects, such as honeybees (Apis mellifera) on flowers, and can change their body colour between yellow and white. It is traditionally assumed that the spiders change their colour to match the flower colour, thus rendering them cryptic to insect prey. Here, we test this assumption combining state-of-the-art knowledge of bee vision and behavioural experiments. In the field, yellow spiders are only found on yellow daisies (Chrysanthemum frutescens), whereas white spiders are found on yellow and white daisies. These field patterns were confirmed in the laboratory. When given the choice between white and yellow daisies, yellow spiders preferred yellow daisies, whereas white spiders showed only a slight but non-significant preference for white flowers. Thus, T. spectabilis select background colours according to their own body colour. When viewed from a distance, bees use an achromatic signal produced by their green receptors for target detection. Through this visual channel, white spiders on white flowers, and yellow spiders on yellow flowers are virtually undetectable. From a closer distance of a few centimetres, when bees evaluate colour contrast, the combination of spider colour against different flower backgrounds affected the response of honeybees, but not in ways predicted by a classical crypsis/conspicuousness interpretation. Yellow spiders on yellow flowers are not perfectly matched when interpreted through the colour vision of a honeybee. Nevertheless, honeybees showed indifference to the presence of a spider, equally landing on vacant or spider-occupied flowers. Likewise, white spiders are poorly hidden on white flowers, as white spiders reflect ultraviolet light strongly, while white flowers do not. Surprisingly, bees are attracted to this contrast, and significantly more honeybees preferred white flowers occupied by white spiders. White spiders on yellow flowers produce the highest colour

  13. Colour and translucency of tooth-coloured orthodontic brackets.

    PubMed

    Lee, Yong-Keun

    2008-04-01

    The objective of this study was to determine the reflected and transmitted colours and the diffuse light transmittance of tooth-coloured brackets. Four ceramic and four plastic brands were evaluated and five brackets of each brand were tested. Reflected colour and spectral reflectance of the labial surface of the brackets were measured according to the Commission Internationale de l'Eclairage (CIE) colour scale and transmitted colour and diffuse spectral transmittance measured with a spectrophotometer. One-way analyses of variance were performed for the reflected and transmitted colour co-ordinates (CIE L*, a*, and b*) and for light transmittance according to bracket brand. The range for CIE L* (lightness) was 36.2-50.3, for a* (red-green parameter) -1.3-3.8 and for b* (yellow-blue parameter) -2.9-11.2. All these colour co-ordinates were influenced by bracket brand (P < 0.05). Diffuse light transmittance was also influenced by bracket brand and ranged from 44.9 to 75.9 per cent (P < 0.05). Colour and transmittance varied by bracket brand. Variations in optical properties influenced the aesthetic performance of the brackets and the degree of cure of the adhesive that is possible through the brackets. Further studies on the clinical implications of colour matching of tooth-coloured brackets with teeth should now be performed.

  14. Quantifying Variability of Avian Colours: Are Signalling Traits More Variable?

    PubMed Central

    Delhey, Kaspar; Peters, Anne

    2008-01-01

    Background Increased variability in sexually selected ornaments, a key assumption of evolutionary theory, is thought to be maintained through condition-dependence. Condition-dependent handicap models of sexual selection predict that (a) sexually selected traits show amplified variability compared to equivalent non-sexually selected traits, and since males are usually the sexually selected sex, that (b) males are more variable than females, and (c) sexually dimorphic traits more variable than monomorphic ones. So far these predictions have only been tested for metric traits. Surprisingly, they have not been examined for bright coloration, one of the most prominent sexual traits. This omission stems from computational difficulties: different types of colours are quantified on different scales precluding the use of coefficients of variation. Methodology/Principal Findings Based on physiological models of avian colour vision we develop an index to quantify the degree of discriminable colour variation as it can be perceived by conspecifics. A comparison of variability in ornamental and non-ornamental colours in six bird species confirmed (a) that those coloured patches that are sexually selected or act as indicators of quality show increased chromatic variability. However, we found no support for (b) that males generally show higher levels of variability than females, or (c) that sexual dichromatism per se is associated with increased variability. Conclusions/Significance We show that it is currently possible to realistically estimate variability of animal colours as perceived by them, something difficult to achieve with other traits. Increased variability of known sexually-selected/quality-indicating colours in the studied species, provides support to the predictions borne from sexual selection theory but the lack of increased overall variability in males or dimorphic colours in general indicates that sexual differences might not always be shaped by similar selective

  15. Colour based fire detection method with temporal intensity variation filtration

    NASA Astrophysics Data System (ADS)

    Trambitckii, K.; Anding, K.; Musalimov, V.; Linß, G.

    2015-02-01

    Development of video, computing technologies and computer vision gives a possibility of automatic fire detection on video information. Under that project different algorithms was implemented to find more efficient way of fire detection. In that article colour based fire detection algorithm is described. But it is not enough to use only colour information to detect fire properly. The main reason of this is that in the shooting conditions may be a lot of things having colour similar to fire. A temporary intensity variation of pixels is used to separate them from the fire. These variations are averaged over the series of several frames. This algorithm shows robust work and was realised as a computer program by using of the OpenCV library.

  16. Measuring changes in internal meat colour, colour lightness and colour opacity as predictors of cooking time.

    PubMed

    Pakula, Christiane; Stamminger, Rainer

    2012-03-01

    Consumers and cooks often assess the degree of doneness of roasted beef by the internal meat colour. Real-time colour measurement of the cooking process is therefore developed in order to determine the degree of doneness, and thus the end of the cooking process, by the internal meat colour. The colour values (X, Y, Z) provided by the true colour sensor show significant variation within initial values and end values. Change in colour lightness caused by the increase of meat colour opacity is dominant. Calculating the first deviation of the Y values (dY/dt) indicates that most rapid changes in lightness are within a temperature range of 42°C and 56°C. At this temperature, the degree of meat doneness is still assumed to be rare, but it is possible to predict the time needed from this point until the desired degree of doneness is reached.

  17. Colour cues proved to be more informative for dogs than brightness.

    PubMed

    Kasparson, Anna A; Badridze, Jason; Maximov, Vadim V

    2013-09-07

    The results of early studies on colour vision in dogs led to the conclusion that chromatic cues are unimportant for dogs during their normal activities. Nevertheless, the canine retina possesses two cone types which provide at least the potential for colour vision. Recently, experiments controlling for the brightness information in visual stimuli demonstrated that dogs have the ability to perform chromatic discrimination. Here, we show that for eight previously untrained dogs colour proved to be more informative than brightness when choosing between visual stimuli differing both in brightness and chromaticity. Although brightness could have been used by the dogs in our experiments (unlike previous studies), it was not. Our results demonstrate that under natural photopic lighting conditions colour information may be predominant even for animals that possess only two spectral types of cone photoreceptors.

  18. A study of women heterozygous for colour deficiencies.

    PubMed

    Jordan, G; Mollon, J D

    1993-07-01

    We have examined the colour vision of 43 female subjects in the age range 30-59 yr of whom 31 were obligate carriers of various forms of colour deficiency and the rest were women who had no known colour-deficient relatives. In the case of all the carriers we established the phenotypes of their colour-deficient sons. As a group, carriers made significantly more errors on the Ishihara plates and showed enlarged matching ranges on the Nagel anomaloscope, but we could not replicate earlier reports of increased error scores on the Farnsworth-Munsell 100-Hue test or of systematic shifts in Rayleigh match mid-points. We did find that the colour matches of carriers of deuteranomaly were significantly displaced from those of normals in a ratio-matching task in which a mixture of 546 and 600 nm was matched with a mixture of 570 and 690 nm. Owing to X-chromosome inactivation, women who are heterozygous for anomalous trichromacy ought to have at least four types of cone in their retinae and we ask whether this affords them an extra dimension of colour vision, by analogy to New World monkeys where heterozygous females gain trichromacy in a basically dichromatic species. Many carriers of anomalous trichromacy exhibited no evidence for tetrachromacy, in that they accepted large-field Rayleigh matches following a rod bleach and they were unable to set unique matches in our ratio-matching task. However, eight carriers of anomalous trichromacy--and no other subject--refused large-field Rayleigh matches; and we found one carrier of deuteranomaly who was apparently able to make unique matches in the ratio-matching task.

  19. Perceiving colour at a glimpse: the relevance of where one fixates.

    PubMed

    Brenner, Eli; Granzier, Jeroen J M; Smeets, Jeroen B J

    2007-09-01

    We used classification images to examine whether certain parts of a surface are particularly important when judging its colour, such as its centre, its edges, or where one is looking. The scene consisted of a regular pattern of square tiles with random colours from along a short line in colour space. Targets defined by a square array of brighter tiles were presented for 200ms. The colours of the tiles within the target were biased by an amount that led to about 70% of the responses being correct. Subjects fixated a point that fell within the target's lower left quadrant and reported each target's colour. They tended to report the colour of the tiles near the fixation point. The influence of the tiles' colour reversed at the target's border and was weaker outside the target. The colour at the border itself was not particularly important. When coloured tiles were also presented before (and after) target presentation they had an opposite (but weaker) effect, indicating that the change in colour is important. Comparing the influence of tiles outside the target with that of tiles at the position at which the target would soon appear suggests that when judging surface colours during the short "glimpses" between saccades, temporal comparisons can be at least as important as spatial ones. We conclude that eye movements are important for colour vision, both because they determine which part of the surface of interest will be given most weight and because the perceived colour of such a surface also depends on what one looked at last.

  20. Distinctive convergence in Australian floral colours seen through the eyes of Australian birds.

    PubMed

    Burd, Martin; Stayton, C Tristan; Shrestha, Mani; Dyer, Adrian G

    2014-04-22

    We used a colour-space model of avian vision to assess whether a distinctive bird pollination syndrome exists for floral colour among Australian angiosperms. We also used a novel phylogenetically based method to assess whether such a syndrome represents a significant degree of convergent evolution. About half of the 80 species in our sample that attract nectarivorous birds had floral colours in a small, isolated region of colour space characterized by an emphasis on long-wavelength reflection. The distinctiveness of this 'red arm' region was much greater when colours were modelled for violet-sensitive (VS) avian vision than for the ultraviolet-sensitive visual system. Honeyeaters (Meliphagidae) are the dominant avian nectarivores in Australia and have VS vision. Ancestral state reconstructions suggest that 31 lineages evolved into the red arm region, whereas simulations indicate that an average of five or six lineages and a maximum of 22 are likely to have entered in the absence of selection. Thus, significant evolutionary convergence on a distinctive floral colour syndrome for bird pollination has occurred in Australia, although only a subset of bird-pollinated taxa belongs to this syndrome. The visual system of honeyeaters has been the apparent driver of this convergence.

  1. Distinctive convergence in Australian floral colours seen through the eyes of Australian birds

    PubMed Central

    Burd, Martin; Stayton, C. Tristan; Shrestha, Mani; Dyer, Adrian G.

    2014-01-01

    We used a colour-space model of avian vision to assess whether a distinctive bird pollination syndrome exists for floral colour among Australian angiosperms. We also used a novel phylogenetically based method to assess whether such a syndrome represents a significant degree of convergent evolution. About half of the 80 species in our sample that attract nectarivorous birds had floral colours in a small, isolated region of colour space characterized by an emphasis on long-wavelength reflection. The distinctiveness of this ‘red arm’ region was much greater when colours were modelled for violet-sensitive (VS) avian vision than for the ultraviolet-sensitive visual system. Honeyeaters (Meliphagidae) are the dominant avian nectarivores in Australia and have VS vision. Ancestral state reconstructions suggest that 31 lineages evolved into the red arm region, whereas simulations indicate that an average of five or six lineages and a maximum of 22 are likely to have entered in the absence of selection. Thus, significant evolutionary convergence on a distinctive floral colour syndrome for bird pollination has occurred in Australia, although only a subset of bird-pollinated taxa belongs to this syndrome. The visual system of honeyeaters has been the apparent driver of this convergence. PMID:24573847

  2. Grey leaves in an alpine plant: a cryptic colouration to avoid attack?

    PubMed

    Niu, Yang; Chen, Gao; Peng, De-Li; Song, Bo; Yang, Yang; Li, Zhi-Min; Sun, Hang

    2014-08-01

    Cryptic colouration is a common predation-avoidance strategy in animals that is postulated to occur in plants, but few experimental studies have rigorously tested this hypothesis. We investigated the colouration of Corydalis benecincta, an alpine plant with remarkably dimorphic leaf colours (grey and green), based on a cost-benefit analysis. First we tested the premise that herbivores (Parnassius butterflies) cannot distinguish grey leaves from a scree background by spectrographic measurements and by estimating discriminability between leaves and scree using a butterfly colour vision model. Then we estimated the potential costs of inconspicuousness by comparing the photosynthetic performance and visual attractiveness to flower visitors of the two colour morphs. Finally, we examined the potential benefits of inconspicuousness by comparing damage, survivorship and female reproductive success. It is difficult for herbivores to distinguish grey-coloured morphs against the background. This grey colour originates in a combination of anthocyanins and chlorophylls. The two colour morphs had similar photosynthetic performance, visual attractiveness and female reproductive success. However, grey morphs had significantly lower herbivore damage and higher survivorship. Grey leaves benefit C. benecincta by reducing herbivory with low investment in anthocyanin synthesis, and little cost on photosynthesis and mating opportunity. This cryptic colouration may have evolved through selection pressure imposed by visually foraging herbivores.

  3. Class separation improvements in pixel classification using colour injection.

    PubMed

    Blanco, Edward; Mazo, Manuel; Bergasa, Luis; Palazuelos, Sira; Rodríguez, Jose; Losada, Cristina; Martín, Jose

    2010-01-01

    This paper presents an improvement in the colour image segmentation in the Hue Saturation (HS) sub-space. The authors propose to inject (add) a colour vector in the Red Green Blue (RGB) space to increase the class separation in the HS plane. The goal of the work is the development of an algorithm to obtain the optimal colour vector for injection that maximizes the separation between the classes in the HS plane. The chromatic Chrominace-1 Chrominance-2 sub-space (of the Luminance Chrominace-1 Chrominance-2 (YC(1)C(2)) space) is used to obtain the optimal vector to add. The proposal is applied on each frame of a colour image sequence in real-time. It has been tested in applications with reduced contrast between the colours of the background and the object, and particularly when the size of the object is very small in comparison with the size of the captured scene. Numerous tests have confirmed that this proposal improves the segmentation process, considerably reducing the effects of the variation of the light intensity of the scene. Several tests have been made in skin segmentation in applications for sign language recognition via computer vision, where an accurate segmentation of hands and face is required.

  4. Colour invariant target recognition in multiple camera CCTV surveillance

    NASA Astrophysics Data System (ADS)

    Soori, Umair; Yuen, P. W. T.; Ibrahim, I.; Han, J.; Tsitiridis, A.; Hong, K.; Chen, T.; Jackman, J.; James, D.; Richardson, M.

    2011-11-01

    People tracking in crowded scene have been a popular, and at the same time a very difficult topic in computer vision. It is mainly because of the difficulty for the acquisition of intrinsic signatures of targets from a single view of the scene. Many factors, such as variable illumination conditions and viewing angles, will induce illusive modification of intrinsic signatures of targets. The objective of this paper is to verify if colour constancy (CC) approach really helps people tracking in CCTV network system. We have testified a number of CC algorithms together with various colour descriptors, to assess the efficiencies of people recognitions from multi-camera i-LIDS data set via receiver operation characteristics (ROC). It is found that when CC is applied together with some form of colour restoration mechanisms such as colour transfer, it does improve people recognition by at least a factor of 2. An elementary luminance based CC coupled with a pixel based colour transfer algorithm have been developed and it is reported in this paper.

  5. Computer vision

    NASA Technical Reports Server (NTRS)

    Gennery, D.; Cunningham, R.; Saund, E.; High, J.; Ruoff, C.

    1981-01-01

    The field of computer vision is surveyed and assessed, key research issues are identified, and possibilities for a future vision system are discussed. The problems of descriptions of two and three dimensional worlds are discussed. The representation of such features as texture, edges, curves, and corners are detailed. Recognition methods are described in which cross correlation coefficients are maximized or numerical values for a set of features are measured. Object tracking is discussed in terms of the robust matching algorithms that must be devised. Stereo vision, camera control and calibration, and the hardware and systems architecture are discussed.

  6. Detecting gradual visual changes in colour and brightness agnosia: a double dissociation.

    PubMed

    Nijboer, Tanja C W; te Pas, Susan F; van der Smagt, Maarten J

    2011-03-09

    Two patients, one with colour agnosia and one with brightness agnosia, performed a task that required the detection of gradual temporal changes in colour and brightness. The results for these patients, who showed anaverage or an above-average performance on several tasks designed to test low-level colour and luminance (contrast) perception in the spatial domain, yielded a double dissociation; the brightness agnosic patient was within the normal range for the coloured stimuli, but much slower to detect brightness differences, whereas the colour agnosic patient was within the normal range for the achromatic stimuli, but much slower for the coloured stimuli. These results suggest that a modality-specific impairment in the detection of gradual temporal changes might be related to, if not underlie, the phenomenon of visual agnosia.

  7. Across light: through colour

    NASA Astrophysics Data System (ADS)

    Azevedo, Isabel; Richardson, Martin; Bernardo, Luis Miguel

    2012-03-01

    The speed at which our world is changing is reflected in the shifting way artistic images are created and produced. Holography can be used as a medium to express the perception of space with light and colour and to make the material and the immaterial experiments with optical and digital holography. This paper intends to be a reflection on the final product of that process surrounding a debate of ideas for new experimental methodologies applied to holographic images. Holography is a time-based medium and the irretrievable linear flow of time is responsible for a drama, unique to traditional cinematography. If the viewers move to left or right, they see glimpses of the next scene or the previous one perceived a second ago. This interaction of synthetic space arises questions such as: can we see, in "reality", two forms in the same space? Trying to answer this question, a series of works has been created. These concepts are embryonic to a series of digital art holograms and lenticulars technique's titled "Across Light: Through Colour". They required some technical research and comparison between effects from different camera types, using Canon IS3 and Sony HDR CX105.

  8. The colours of cloaks

    NASA Astrophysics Data System (ADS)

    Guenneau, Sébastien; McPhedran, Ross C.; Enoch, Stefan; Movchan, Alexander B.; Farhat, Mohamed; Nicorovici, Nicolae-Alexandru P.

    2011-02-01

    We present a survey of results from various research groups under the unifying viewpoint of transformational physics, which has been recently introduced for the design of metamaterials in optics and acoustics. We illustrate the versatility of underlying geometric transforms in order to bridge wave phenomena (the different 'colours' of waves) ranging from transverse electric waves, to linear surface water waves at an air-fluid interface, to pressure waves in fluids and out-of-plane shear waves in elastic media: these waves are all governed by a second order scalar partial differential equation (PDE) invariant under geometric transform. Moreover, flexural waves propagating in thin plates represent a very peculiar situation whereby the displacement field satisfies a fourth order scalar PDE which also retains its form under geometric transform (unlike for the Navier equation in elastodynamics). Control of flexural wave trajectories is illustrated with a multilayered cloak and a carpet. Interestingly, the colours of waves can be revealed through an analysis of the band spectra of invisibility cloaks. In the context of acoustics, this suggests one can hear the shape of a drum. Alternative avenues towards cloaking based upon anomalous resonances of a negatively refracting coating (which can be seen as the result of folding the space back onto itself), and even plasmonic shells reducing the scattering cross-section of nano-objects are also addressed.

  9. Disruptive Colouration and Perceptual Grouping

    PubMed Central

    Espinosa, Irene; Cuthill, Innes C.

    2014-01-01

    Camouflage is the primary defence of many animals and includes multiple strategies that interfere with figure-ground segmentation and object recognition. While matching background colours and textures is widespread and conceptually straightforward, less well explored are the optical ‘tricks’, collectively called disruptive colouration, that exploit perceptual grouping mechanisms. Adjacent high contrast colours create false edges, but this is not sufficient for an object’s shape to be broken up; some colours must blend with the background. We test the novel hypothesis that this will be particularly effective when the colour patches on the animal appear to belong to, not merely different background colours, but different background objects. We used computer-based experiments where human participants had to find cryptic targets on artificial backgrounds. Creating what appeared to be bi-coloured foreground objects on bi-coloured backgrounds, we generated colour boundaries that had identical local contrast but either lay within or between (illusory) objects. As predicted, error rates for targets matching what appeared to be different background objects were higher than for targets which had otherwise identical local contrast to the background but appeared to belong to single background objects. This provides evidence for disruptive colouration interfering with higher-level feature integration in addition to previously demonstrated low-level effects involving contour detection. In addition, detection was impeded in treatments where targets were on or in close proximity to multiple background colour or tone boundaries. This is consistent with other studies which show a deleterious influence of visual ‘clutter’ or background complexity on search. PMID:24466337

  10. Disruptive colouration and perceptual grouping.

    PubMed

    Espinosa, Irene; Cuthill, Innes C

    2014-01-01

    Camouflage is the primary defence of many animals and includes multiple strategies that interfere with figure-ground segmentation and object recognition. While matching background colours and textures is widespread and conceptually straightforward, less well explored are the optical 'tricks', collectively called disruptive colouration, that exploit perceptual grouping mechanisms. Adjacent high contrast colours create false edges, but this is not sufficient for an object's shape to be broken up; some colours must blend with the background. We test the novel hypothesis that this will be particularly effective when the colour patches on the animal appear to belong to, not merely different background colours, but different background objects. We used computer-based experiments where human participants had to find cryptic targets on artificial backgrounds. Creating what appeared to be bi-coloured foreground objects on bi-coloured backgrounds, we generated colour boundaries that had identical local contrast but either lay within or between (illusory) objects. As predicted, error rates for targets matching what appeared to be different background objects were higher than for targets which had otherwise identical local contrast to the background but appeared to belong to single background objects. This provides evidence for disruptive colouration interfering with higher-level feature integration in addition to previously demonstrated low-level effects involving contour detection. In addition, detection was impeded in treatments where targets were on or in close proximity to multiple background colour or tone boundaries. This is consistent with other studies which show a deleterious influence of visual 'clutter' or background complexity on search.

  11. Efficacy of a Low Vision Patient Consultation

    ERIC Educational Resources Information Center

    Siemsen, Dennis W.; Bergstrom, A. Ren?e; Hathaway, Julie C.

    2005-01-01

    A variety of obstacles can prevent persons or individuals with low vision from deriving the greatest possible benefit from the rehabilitation process, including inadequate understanding of their visual impairment, lack of knowledge about available services, and misconceptions about low vision devices. This study explores the use of a…

  12. Color Vision Deficits and Literacy Acquisition.

    ERIC Educational Resources Information Center

    Hurley, Sandra Rollins

    1994-01-01

    Shows that color blindness, whether partial or total, inhibits literacy acquisition. Offers a case study of a third grader with impaired color vision. Presents a review of literature on the topic. Notes that people with color vision deficits are often unaware of the handicap. (RS)

  13. A Low Vision Reading Comprehension Test.

    ERIC Educational Resources Information Center

    Watson, G. R.; And Others

    1996-01-01

    Fifty adults (ages 28-86) with macular degeneration were given the Low Vision Reading Comprehension Assessment (LVRCA) to test its reliability and validity in evaluating the reading comprehension of those with vision impairments. The LVRCA was found to take only nine minutes to administer and was a valid and reliable tool. (CR)

  14. Improving Vision

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Many people are familiar with the popular science fiction series Star Trek: The Next Generation, a show featuring a blind character named Geordi La Forge, whose visor-like glasses enable him to see. What many people do not know is that a product very similar to Geordi's glasses is available to assist people with vision conditions, and a NASA engineer's expertise contributed to its development. The JORDY(trademark) (Joint Optical Reflective Display) device, designed and manufactured by a privately-held medical device company known as Enhanced Vision, enables people with low vision to read, write, and watch television. Low vision, which includes macular degeneration, diabetic retinopathy, and glaucoma, describes eyesight that is 20/70 or worse, and cannot be fully corrected with conventional glasses.

  15. Vision Underwater.

    ERIC Educational Resources Information Center

    Levine, Joseph S.

    1980-01-01

    Provides information regarding underwater vision. Includes a discussion of optically important interfaces, increased eye size of organisms at greater depths, visual peculiarities regarding the habitat of the coastal environment, and various pigment visual systems. (CS)

  16. [Central vision].

    PubMed

    Fahle, M

    2004-07-01

    The clinical assessment of vision by means of optotypes does by no means test just two-point resolution, since a correct naming of the letters or digits requires a preceding visual object recognition. Cortical lesions can massively deteriorate vision up to a "Seelenblindheit" in spite of intact optics and retina. There are different processing levels involved in the analysis which can be individually defective, leading to disorders from visual indiscrimination to agnosia or anomia.

  17. Colour constancy and conscious perception of changes of illuminant.

    PubMed

    Barbur, John L; Spang, Karoline

    2008-02-12

    A sudden change in illuminant (e.g., the outcome of turning on a tungsten light in a room illuminated with dim, natural daylight) causes a "global" change in perceived colour which subjects often recognise as a change of illuminant. In spite of this distinct, global change in the perceptual appearance of the scene caused by significant changes in the wavelength composition of the light reflected from different objects under the new illuminant, the perceived colour of the objects remains largely unchanged and this cornerstone property of human vision is often described as instantaneous colour constancy (ICC). ICC mechanisms are often difficult to study. The generation of appropriate stimuli to isolate ICC mechanisms remains a difficult task since the extraction of colour signals is also confounded in the processing of spatial chromatic context that leads to ICC. The extraction of differences in chromaticity that describe spatial changes in the wavelength composition of the light on the retina is a necessary operation that must precede colour constancy computations. A change of illuminant or changes in the spectral reflectance of the elements that make up the scene under a constant illuminant cause spatial changes in chromatic context and are likely to drive colour constancy mechanisms, but not exclusively. The same stimulus changes also cause differences in local luminance contrast and overall light flux changes, stimulus attributes that can activate different areas of the visual cortex. In order to address this problem we carried out a series of dichoptic experiments designed to investigate how the colour signals from the two eyes are combined in dichoptically viewed Mondrians and the extent to which the processing of chromatic context in monocularly driven neurons contributes to ICC. The psychophysical findings show that normal levels of ICC can be achieved in dichoptic experiments, even when the subject remains unaware of any changes of illuminant. Functional MRI

  18. Reversible colour change in Arthropoda.

    PubMed

    Umbers, Kate D L; Fabricant, Scott A; Gawryszewski, Felipe M; Seago, Ainsley E; Herberstein, Marie E

    2014-11-01

    The mechanisms and functions of reversible colour change in arthropods are highly diverse despite, or perhaps due to, the presence of an exoskeleton. Physiological colour changes, which have been recorded in 90 arthropod species, are rapid and are the result of changes in the positioning of microstructures or pigments, or in the refractive index of layers in the integument. By contrast, morphological colour changes, documented in 31 species, involve the anabolism or catabolism of components (e.g. pigments) directly related to the observable colour. In this review we highlight the diversity of mechanisms by which reversible colour change occurs and the evolutionary context and diversity of arthropod taxa in which it has been observed. Further, we discuss the functions of reversible colour change so far proposed, review the limited behavioural and ecological data, and argue that the field requires phylogenetically controlled approaches to understanding the evolution of reversible colour change. Finally, we encourage biologists to explore new model systems for colour change and to engage scientists from other disciplines; continued cross-disciplinary collaboration is the most promising approach to this nexus of biology, physics, and chemistry.

  19. Colourful Semantics: A Clinical Investigation

    ERIC Educational Resources Information Center

    Bolderson, Sarah; Dosanjh, Christine; Milligan, Claudine; Pring, Tim; Chiat, Shula

    2011-01-01

    Children with language difficulties often omit verbs and grammatical elements and fail to complete sentences. Bryan (1997) described "colourful semantics", a therapy she used to treat a 5-year-old boy. The therapy uses colour coding to highlight the predicate argument structure of sentences. This study further tested the therapy's…

  20. The colour of gender stereotyping.

    PubMed

    Cunningham, Sheila J; Macrae, C Neil

    2011-08-01

    Despite legislative attempts to eliminate gender stereotyping from society, the propensity to evaluate people on the basis of their sex remains a pernicious social problem. Noting the critical interplay between cultural and cognitive factors in the establishment of stereotypical beliefs, the current investigation explored the extent to which culturally transmitted colour-gender associations (i.e., pink is for girls, blue is for boys) set the stage for the automatic activation and expression of gender stereotypes. Across six experiments, the results demonstrated that (1) consumer choice for children's goods is dominated by gender-stereotyped colours (Experiment 1); (2) colour-based stereotypic associations guide young children's behaviour (Experiment 2); (3) colour-gender associations automatically activate associated stereotypes in adulthood (Experiments 3-5); and (4) colour-based stereotypic associations bias impressions of male and female targets (Experiment 6). These findings indicate that, despite prohibitions against stereotyping, seemingly innocuous societal practices may continue to promote this mode of thought.

  1. Genetics of colouration in birds.

    PubMed

    Roulin, Alexandre; Ducrest, Anne-Lyse

    2013-01-01

    Establishing the links between phenotype and genotype is of great importance for resolving key questions about the evolution, maintenance and adaptive function of phenotypic variation. Bird colouration is one of the most studied systems to investigate the role of natural and sexual selection in the evolution of phenotypic diversity. Given the recent advances in molecular tools that allow discovering genetic polymorphisms and measuring gene and protein expression levels, it is timely to review the literature on the genetics of bird colouration. The present study shows that melanin-based colour phenotypes are often associated with mutations at melanogenic genes. Differences in melanin-based colouration are caused by switches of eumelanin to pheomelanin production or by changes in feather keratin structure, melanoblast migration and differentiation, as well as melanosome structure. Similar associations with other types of colourations are difficult to establish, because our knowledge about the molecular genetics of carotenoid-based and structural colouration is quasi inexistent. This discrepancy stems from the fact that only melanin-based colouration shows pronounced heritability estimates, i.e. the resemblance between related individuals is usually mainly explained by genetic factors. In contrast, the expression of carotenoid-based colouration is phenotypically plastic with a high sensitivity to variation in environmental conditions. It therefore appears that melanin-based colour traits are prime systems to understand the genetic basis of phenotypic variation. In this context, birds have a great potential to bring us to new frontiers where many exciting discoveries will be made on the genetics of phenotypic traits, such as colouration. In this context, a major goal of our review is to suggest a number of exciting future avenues.

  2. Teaching Visually Impaired Children. Second Edition.

    ERIC Educational Resources Information Center

    Bishop, Virginia E.

    Intended for either the general educator or the specialist, this text offers principles and teaching strategies for teaching students with visual impairments including both blind students and those with low vision. The book is organized into three sections: "Vision,""Learning," and "Testing and Transitions." The four chapters in the "Vision"…

  3. A 14-year-old girl who regained normal vision after bilateral visual impairment following hot water injury to the eyes

    PubMed Central

    Monsudi, Kehinde F.; Ayanniyi, Abdulkabir A.

    2010-01-01

    A 14-year-old girl presented with bilateral visual impairment following hot water injury to the eyes. The patient was admitted for a week and managed with guttae tropicamide 0.5% 8 h, diclofenac sodium 0.1% 4 h, and fluoroquinolone 0.3% 6 h and ointment chloramphenicol 8 h. Also, the patient was managed with capsule doxycycline 100 mg 12 h for 10 days, tablet cataflam 50 mg 12 h for 7 days and intramuscular tetanus toxoid 0.5 mg stat and dermacine cream for facial scald. The visual acuities improved from 3/60 (right eye) and 6/24 (left eye) to 6/6 in both eyes. There were resolutions of facial/eye pain, tearing, photophobia, lid edema, blepharospasm, and conjunctival hyperemia. There was complete healing of facial wounds and corneal ulcers. She was discharged from hospital on the 7th day of admission. Prompt presentation, degree of scald sustained, and appropriate medical intervention enhanced visual recovery and wound healing in the patient. PMID:23960925

  4. Cone opsins, colour blindness and cone dystrophy: Genotype-phenotype correlations.

    PubMed

    Gardner, J C; Michaelides, M; Hardcastle, A J

    2016-05-25

    X-linked cone photoreceptor disorders caused by mutations in the OPN1LW (L) and OPN1MW (M) cone opsin genes on chromosome Xq28 include a range of conditions from mild stable red-green colour vision deficiencies to severe cone dystrophies causing progressive loss of vision and blindness. Advances in molecular genotyping and functional analyses of causative variants, combined with deep retinal phenotyping, are unravelling genetic mechanisms underlying the variability of cone opsin disorders.

  5. Generating colour and texture verniers.

    PubMed

    Brelstaff, G J; Wilson, J B

    1994-05-01

    This paper describes computer graphics techniques for presenting visual stimuli in a vernier format composed out of coloured texture patterns. Such stimuli can be used to investigate the performance at the task of localising boundaries mediated by changes in colour and/or texture. We summarise the contents as follows: (1) Techniques for presenting visual stimuli are reviewed with a view to how they might be used to present colour and texture verniers. (2) The design of the vernier stimuli for the localisation task is considered. (3) Significant elements of this design are: (a) the use of non-isoplanatic textures to avoid interference effects at boundaries, (b) the modulation of the texture patterns along axes in MacLeod-Boynton colour space so that relative retinal cone contributions are controlled, and (c) the use of double-buffering, colour map manipulation, and contrast randomisation techniques to avoid problems commonly encountered when presenting computer graphics stimuli on colour monitors. (4) Results of a psychophysical experiment that presents colour and texture verniers are reported elsewhere.

  6. Age-Related Psychophysical Changes and Low Vision

    PubMed Central

    Dagnelie, Gislin

    2013-01-01

    When considering the burden of visual impairment on aging individuals and society at large, it is important to bear in mind that vision changes are a natural aspect of aging. In this article, we consider vision changes that are part of normal aging, the prevalence of abnormal vision changes caused by disorders of the visual system, and the anticipated incidence and impact of visual impairment as the US population ages. We then discuss the services available to reduce the impact of vision loss, and the extent to which those services can and should be improved, not only to be better prepared for the anticipated increase in low vision over the coming decades, but also to increase the awareness of interactions between visual impairment and comorbidities that are common among the elderly. Finally, we consider how to promote improved quality, availability, and acceptance of low vision care to lessen the impact of visual impairment on individuals, and its burden on society. PMID:24335074

  7. [Usefulness of color vision test for early detection of neurological damages by neurotoxic substances].

    PubMed

    Lee, Eun-Hee; Choi, Kyungho; Chae, Hong Jae; Paek, Domyung

    2008-11-01

    This paper reviews the published literature that is concerned with color vision impairment from industrial and environmental exposure to neurotoxic substances, and we evaluated whether testing for color vision impairment could be an affordable procedure for assessing these neurotoxic effects. In general, most cases of congenital color vision impairment are red-green, and blue-yellow impairment is extremely rare. However, most of the acquired color vision impairment that is related to age, alcohol or environmental factors is blue-yellow impairment. Therefore, many studies have been performed to identify this relationship between exposure to neurotoxic substances, such as organic solvents and heavy metals, and the prevalence of blue-yellow color vision impairment. The test for color vision impairment is known to be very sensitive to the early signs of nervous system dysfunction and this can be useful for making the early diagnosis of neurotoxic effects from exposure to very low concentrations of toxic substances.

  8. Colour Reconnection in WW Events

    NASA Astrophysics Data System (ADS)

    D'Hondt, J.

    2003-07-01

    Preliminary results are presented for a measurement of the κ parameter used in the JETSET SK-I model of Colour Reconnection in {W}+{W}^- -> qbar {q}'bar {q}q^' events at LEP2. An update on the investigation of Colour Reconnection effects in hadronic decays of W pairs, using the particle flow in DELPHI is presented. A second method is based on the observation that two different mW estimators have different sensitivity to the parametrised Colour Reconnection effect. Hence the difference between them is an observable with information content about κ.

  9. Alternative to colour feature classification using colour contrast ocurrence matrix

    NASA Astrophysics Data System (ADS)

    Martínez, R. A.; Richard, N.; Fernandez, C.

    2015-04-01

    Texture discrimination was the second more important task studied after colour perception and characterization. Nevertheless, colour texture assessment and characterization was few studied and no vector processing was proposed to assess this important visual information. In this work we show the construction of a new vector that integrates fully the information of texture and color. This vector is based on Julesz psico-physics conjectures and the Haralick cooccurrence matrix. A colour texture image in the CIEL*a* b* colour space is characterizing in a 3D matrix, from which it is possible to visually some variations in chromaticity. The performance of this vector had evaluated in tasks of classification in front of other developments that mix the texture and colour information. The colour contrast occurrence matrix (C2O) has the best classification rates in three of the four image database evaluated as OUTEX, VISTEX, STEX and ALOT. C2O texture classification was evaluated in front of co-occurrence matrix (GLMC), run-length matrix (RLM) and local binary patterns (LBP) approaches.

  10. Optimal colour quality of LED clusters based on memory colours.

    PubMed

    Smet, Kevin; Ryckaert, Wouter R; Pointer, Michael R; Deconinck, Geert; Hanselaer, Peter

    2011-03-28

    The spectral power distributions of tri- and tetrachromatic clusters of Light-Emitting-Diodes, composed of simulated and commercially available LEDs, were optimized with a genetic algorithm to maximize the luminous efficacy of radiation and the colour quality as assessed by the memory colour quality metric developed by the authors. The trade-off of the colour quality as assessed by the memory colour metric and the luminous efficacy of radiation was investigated by calculating the Pareto optimal front using the NSGA-II genetic algorithm. Optimal peak wavelengths and spectral widths of the LEDs were derived, and over half of them were found to be close to Thornton's prime colours. The Pareto optimal fronts of real LED clusters were always found to be smaller than those of the simulated clusters. The effect of binning on designing a real LED cluster was investigated and was found to be quite large. Finally, a real LED cluster of commercially available AlGaInP, InGaN and phosphor white LEDs was optimized to obtain a higher score on memory colour quality scale than its corresponding CIE reference illuminant.

  11. The dual rod system of amphibians supports colour discrimination at the absolute visual threshold

    PubMed Central

    Yovanovich, Carola A. M.; Koskela, Sanna M.; Nevala, Noora; Kondrashev, Sergei L.

    2017-01-01

    The presence of two spectrally different kinds of rod photoreceptors in amphibians has been hypothesized to enable purely rod-based colour vision at very low light levels. The hypothesis has never been properly tested, so we performed three behavioural experiments at different light intensities with toads (Bufo) and frogs (Rana) to determine the thresholds for colour discrimination. The thresholds of toads were different in mate choice and prey-catching tasks, suggesting that the differential sensitivities of different spectral cone types as well as task-specific factors set limits for the use of colour in these behavioural contexts. In neither task was there any indication of rod-based colour discrimination. By contrast, frogs performing phototactic jumping were able to distinguish blue from green light down to the absolute visual threshold, where vision relies only on rod signals. The remarkable sensitivity of this mechanism comparing signals from the two spectrally different rod types approaches theoretical limits set by photon fluctuations and intrinsic noise. Together, the results indicate that different pathways are involved in processing colour cues depending on the ecological relevance of this information for each task. This article is part of the themed issue ‘Vision in dim light’. PMID:28193811

  12. The dual rod system of amphibians supports colour discrimination at the absolute visual threshold.

    PubMed

    Yovanovich, Carola A M; Koskela, Sanna M; Nevala, Noora; Kondrashev, Sergei L; Kelber, Almut; Donner, Kristian

    2017-04-05

    The presence of two spectrally different kinds of rod photoreceptors in amphibians has been hypothesized to enable purely rod-based colour vision at very low light levels. The hypothesis has never been properly tested, so we performed three behavioural experiments at different light intensities with toads (Bufo) and frogs (Rana) to determine the thresholds for colour discrimination. The thresholds of toads were different in mate choice and prey-catching tasks, suggesting that the differential sensitivities of different spectral cone types as well as task-specific factors set limits for the use of colour in these behavioural contexts. In neither task was there any indication of rod-based colour discrimination. By contrast, frogs performing phototactic jumping were able to distinguish blue from green light down to the absolute visual threshold, where vision relies only on rod signals. The remarkable sensitivity of this mechanism comparing signals from the two spectrally different rod types approaches theoretical limits set by photon fluctuations and intrinsic noise. Together, the results indicate that different pathways are involved in processing colour cues depending on the ecological relevance of this information for each task.This article is part of the themed issue 'Vision in dim light'.

  13. On Colour, Category Effects, and Alzheimer's Disease: A Critical Review of Studies and Further Longitudinal Evidence.

    PubMed

    Moreno-Martínez, F Javier; Rodríguez-Rojo, Inmaculada C

    2015-01-01

    The role of colour in object recognition is controversial; in this study, a critical review of previous studies, as well as a longitudinal study, was conducted. We examined whether colour benefits the ability of Alzheimer's disease (AD) patients and normal controls (NC) when naming items differing in colour diagnosticity: living things (LT) versus nonliving things (NLT). Eleven AD patients were evaluated twice with a temporal interval of 3 years; 26 NC were tested once. The participants performed a naming task (colour and greyscale photographs); the impact of nuisance variables (NVs) and potential ceiling effects were also controlled. Our results showed that (i) colour slightly favoured processing of items with higher colour diagnosticity (i.e., LT) in both groups; (ii) AD patients used colour information similarly to NC, retaining this ability over time; (iii) NVs played a significant role as naming predictors in all the participants, relegating domain to a minor plane; and (iv) category effects (better processing of NLT) were present in both groups. Finally, although patients underwent semantic longitudinal impairment, this was independent of colour deterioration. This finding provides better support to the view that colour is effective at the visual rather than at the semantic level of object processing.

  14. On Colour, Category Effects, and Alzheimer's Disease: A Critical Review of Studies and Further Longitudinal Evidence

    PubMed Central

    Moreno-Martínez, F. Javier; Rodríguez-Rojo, Inmaculada C.

    2015-01-01

    The role of colour in object recognition is controversial; in this study, a critical review of previous studies, as well as a longitudinal study, was conducted. We examined whether colour benefits the ability of Alzheimer's disease (AD) patients and normal controls (NC) when naming items differing in colour diagnosticity: living things (LT) versus nonliving things (NLT). Eleven AD patients were evaluated twice with a temporal interval of 3 years; 26 NC were tested once. The participants performed a naming task (colour and greyscale photographs); the impact of nuisance variables (NVs) and potential ceiling effects were also controlled. Our results showed that (i) colour slightly favoured processing of items with higher colour diagnosticity (i.e., LT) in both groups; (ii) AD patients used colour information similarly to NC, retaining this ability over time; (iii) NVs played a significant role as naming predictors in all the participants, relegating domain to a minor plane; and (iv) category effects (better processing of NLT) were present in both groups. Finally, although patients underwent semantic longitudinal impairment, this was independent of colour deterioration. This finding provides better support to the view that colour is effective at the visual rather than at the semantic level of object processing. PMID:26074675

  15. Presidential Visions.

    ERIC Educational Resources Information Center

    Gallin, Alice, Ed.

    1992-01-01

    This journal issue is devoted to the theme of university presidents and their visions of the future. It presents the inaugural addresses and speeches of 16 Catholic college and university presidents focusing on their goals, ambitions, and reasons for choosing to become higher education leaders at this particular time in the history of education in…

  16. Visions 2001.

    ERIC Educational Resources Information Center

    Rivero, Victor; Norman, Michele

    2001-01-01

    Reports on the views of 18 educational leaders regarding their vision on the future of education in an information age. Topics include people's diverse needs; relationships between morality, ethics, values, and technology; leadership; parental involvement; online courses from multiple higher education institutions; teachers' role; technology…

  17. The Gradual Transformation of Historical Situations: Understanding "Change and Continuity" through Colours and Timelines

    ERIC Educational Resources Information Center

    Vella, Yosanne

    2011-01-01

    The small-scale research that Yosanne Vella reports in this article was driven by concern to help pupils develop "big picture" visions of the past and to engage effectively with the idea of change as a process rather than an event. The strategy that she adopts--asking groups of students to colour in a timeline recording their judgement…

  18. The Effect of an On-Site Vision Examination on Adherence to Vision Screening Recommendations

    ERIC Educational Resources Information Center

    Chu, Raymond; Huang, Kristine; Barnhardt, Carmen; Chen, Angela

    2015-01-01

    Vision screenings are intended to efficiently identify students with possible visual impairment and initiate a referral for diagnosis and treatment. In many cases, at-risk students do not access the recommended care or experience delays in receiving care. The purpose of this article is to report the effect on adherence to vision screening…

  19. BRIEF REPORT: The colour relaxation equation

    NASA Astrophysics Data System (ADS)

    Xiaofei, Zhang; Jiarong, Li

    1996-03-01

    Colour diffusion in quark - gluon plasma (QGP) is investigated from the transport equations of QGP. The pure non-Abelian collision term describing the colour diffusion in QGP is obtained, the expression for colour relaxation time is derived and the physical picture of the colour diffusion in QGP is shown.

  20. Resurgence of natural colourants: a holistic view.

    PubMed

    Kumar, J K; Sinha, A K

    2004-02-01

    Today, natural colourants are emerging globally, leaving synthetic colourants behind in the race, due to the realisation that are safer and ecofriendly in nature. In this context, a brief review of natural colourant sources, their classification, chemical constituents responsible for producing different colours, its activities and effect of different mordants on the hue is discussed.

  1. What Colour Is a Shadow?

    ERIC Educational Resources Information Center

    Hughes, S. W.

    2009-01-01

    What colour is a shadow? Black, grey, or some other colour? This article describes how to use a digital camera to test the hypothesis that a shadow under a clear blue sky has a blue tint. A white sheet of A4 paper was photographed in full sunlight and in shadow under a clear blue sky. The images were analysed using a shareware program called…

  2. Healthy Vision Tips

    MedlinePlus

    ... NEI for Kids > Healthy Vision Tips All About Vision About the Eye Ask a Scientist Video Series ... Links to More Information Optical Illusions Printables Healthy Vision Tips Healthy vision starts with you! Use these ...

  3. Blindness and vision loss

    MedlinePlus

    ... eye ( chemical burns or sports injuries) Diabetes Glaucoma Macular degeneration The type of partial vision loss may differ, ... tunnel vision and missing areas of vision With macular degeneration, the side vision is normal but the central ...

  4. Accuracy of shade matching performed by colour blind and normal dental students using 3D Master and Vita Lumin shade guides.

    PubMed

    Vafaee, F; Rakhshan, V; Vafaei, M; Khoshhal, M

    2012-03-01

    The purpose of this study was to investigate whether 3D Master or VitaLumin shade guides could improve colour selection in individuals with normal and defective colour vision. First, colour perception of 260 dental students was evaluated. Afterwards, 9 colour blind and 9 matched normal subjects tried to detect colours of 10 randomly selected tabs from each kit and the correct/false answers were counted. Of the colour-defective subjects, 47.8% and 33.3% correctly detected the shade using 3D Master and VitaLumin, respectively. These statistics were 62.2% and 42.2% in normal subjects. In normal participants, but not in colour blind ones, 3D Master significantly improved shade matching accuracy compared to VitaLumin.

  5. The Role of Organizations in Reaching Older Adults about Vision Loss

    ERIC Educational Resources Information Center

    Sussman-Skalka, Carol J.; Cimarolli, Verena R.; Stuen, Cynthia

    2006-01-01

    Vision impairment affects approximately 17% of Americans age 45 and older. Yet, 94% of adults with self-reported vision loss did not receive any type of vision rehabilitation services to help them retain independence. These findings underscore the need for promoting awareness about what can be done when vision fails. A national dissemination…

  6. Computer vision

    SciTech Connect

    Not Available

    1982-01-01

    This paper discusses material from areas such as artificial intelligence, psychology, computer graphics, and image processing. The intent is to assemble a selection of this material in a form that will serve both as a senior/graduate-level academic text and as a useful reference to those building vision systems. This book has a strong artificial intelligence flavour, emphasising the belief that both the intrinsic image information and the internal model of the world are important in successful vision systems. The book is organised into four parts, based on descriptions of objects at four different levels of abstraction. These are: generalised images-images and image-like entities; segmented images-images organised into subimages that are likely to correspond to interesting objects; geometric structures-quantitative models of image and world structures; relational structures-complex symbolic descriptions of image and world structures. The book contains author and subject indexes.

  7. Pleiades Visions

    NASA Astrophysics Data System (ADS)

    Whitehouse, M.

    2016-01-01

    Pleiades Visions (2012) is my new musical composition for organ that takes inspiration from traditional lore and music associated with the Pleiades (Seven Sisters) star cluster from Australian Aboriginal, Native American, and Native Hawaiian cultures. It is based on my doctoral dissertation research incorporating techniques from the fields of ethnomusicology and cultural astronomy; this research likely represents a new area of inquiry for both fields. This large-scale work employs the organ's vast sonic resources to evoke the majesty of the night sky and the expansive landscapes of the homelands of the above-mentioned peoples. Other important themes in Pleiades Visions are those of place, origins, cosmology, and the creation of the world.

  8. Cartesian visions.

    PubMed

    Fara, Patricia

    2008-12-01

    Few original portraits exist of René Descartes, yet his theories of vision were central to Enlightenment thought. French philosophers combined his emphasis on sight with the English approach of insisting that ideas are not innate, but must be built up from experience. In particular, Denis Diderot criticised Descartes's views by describing how Nicholas Saunderson--a blind physics professor at Cambridge--relied on touch. Diderot also made Saunderson the mouthpiece for some heretical arguments against the existence of God.

  9. Lambda Vision

    NASA Astrophysics Data System (ADS)

    Czajkowski, Michael

    2014-06-01

    There is an explosion in the quantity and quality of IMINT data being captured in Intelligence Surveillance and Reconnaissance (ISR) today. While automated exploitation techniques involving computer vision are arriving, only a few architectures can manage both the storage and bandwidth of large volumes of IMINT data and also present results to analysts quickly. Lockheed Martin Advanced Technology Laboratories (ATL) has been actively researching in the area of applying Big Data cloud computing techniques to computer vision applications. This paper presents the results of this work in adopting a Lambda Architecture to process and disseminate IMINT data using computer vision algorithms. The approach embodies an end-to-end solution by processing IMINT data from sensors to serving information products quickly to analysts, independent of the size of the data. The solution lies in dividing up the architecture into a speed layer for low-latent processing and a batch layer for higher quality answers at the expense of time, but in a robust and fault-tolerant way. This approach was evaluated using a large corpus of IMINT data collected by a C-130 Shadow Harvest sensor over Afghanistan from 2010 through 2012. The evaluation data corpus included full motion video from both narrow and wide area field-of-views. The evaluation was done on a scaled-out cloud infrastructure that is similar in composition to those found in the Intelligence Community. The paper shows experimental results to prove the scalability of the architecture and precision of its results using a computer vision algorithm designed to identify man-made objects in sparse data terrain.

  10. Machine vision

    SciTech Connect

    Horn, D.

    1989-06-01

    To keep up with the speeds of modern production lines, most machine vision applications require very powerful computers (often parallel-processing machines), which process millions of points of data in real time. The human brain performs approximately 100 billion logical floating-point operations each second. That is 400 times the speed of a Cray-1 supercomputer. The right software must be developed for parallel-processing computers. The NSF has awarded Rensselaer Polytechnic Institute (Troy, N.Y.) a $2 million grant for parallel- and image-processing software research. Over the last 15 years, Rensselaer has been conducting image-processing research, including work with high-definition TV (HDTV) and image coding and understanding. A similar NSF grant has been awarded to Michigan State University (East Lansing, Mich.) Neural networks are supposed to emulate human learning patterns. These networks and their hardware implementations (neurocomputers) show a great deal of promise for machine vision systems because they allow the systems to understand the use sensory data input more effectively. Neurocomputers excel at pattern-recognition tasks when input data are fuzzy or the vision algorithm is not optimal and is difficult to ascertain.

  11. Differentiating Biological Colours with Few and Many Sensors: Spectral Reconstruction with RGB and Hyperspectral Cameras

    PubMed Central

    Garcia, Jair E.; Girard, Madeline B.; Kasumovic, Michael; Petersen, Phred; Wilksch, Philip A.; Dyer, Adrian G.

    2015-01-01

    Background The ability to discriminate between two similar or progressively dissimilar colours is important for many animals as it allows for accurately interpreting visual signals produced by key target stimuli or distractor information. Spectrophotometry objectively measures the spectral characteristics of these signals, but is often limited to point samples that could underestimate spectral variability within a single sample. Algorithms for RGB images and digital imaging devices with many more than three channels, hyperspectral cameras, have been recently developed to produce image spectrophotometers to recover reflectance spectra at individual pixel locations. We compare a linearised RGB and a hyperspectral camera in terms of their individual capacities to discriminate between colour targets of varying perceptual similarity for a human observer. Main Findings (1) The colour discrimination power of the RGB device is dependent on colour similarity between the samples whilst the hyperspectral device enables the reconstruction of a unique spectrum for each sampled pixel location independently from their chromatic appearance. (2) Uncertainty associated with spectral reconstruction from RGB responses results from the joint effect of metamerism and spectral variability within a single sample. Conclusion (1) RGB devices give a valuable insight into the limitations of colour discrimination with a low number of photoreceptors, as the principles involved in the interpretation of photoreceptor signals in trichromatic animals also apply to RGB camera responses. (2) The hyperspectral camera architecture provides means to explore other important aspects of colour vision like the perception of certain types of camouflage and colour constancy where multiple, narrow-band sensors increase resolution. PMID:25965264

  12. Colour blindness of the movement-detecting system of the spider Cupiennius salei.

    PubMed

    Orlando, Eva; Schmid, Axel

    2011-02-15

    The nocturnal wandering spider Cupiennius salei has one pair of principal eyes and three pairs of secondary eyes located on the prosoma, which differ in both morphology and function. Their spectral sensitivity, measured with intracellular recordings, is due to three different types of photoreceptors with absorbance maxima in the mid-range of the spectrum, at 480 nm and 520 nm and in the UV at 360 nm. Based on these physiological data colour vision might be possible. In the present study, the ability to discriminate coloured moving stimuli from grey backgrounds was tested. The perception of moving coloured stripes in front of backgrounds with 29 different grey levels was measured by using extracellular recordings from the anterior median eye muscles as a monitoring system. Each of these eyes has two muscles, which increase their activity when moving stimuli are presented in front of a secondary eye. This variation in eye muscle activity can be recorded extracellulary in a living spider using a single channel telemetry device. If colour perception exists, the animal should be able to detect a moving coloured stripe in front of any grey level. Blue, green and red stripes were used as moving stimuli, in front of all 29 grey backgrounds. The results indicate that C. salei is not able to discriminate the coloured stimuli from distinct shades of grey. It is therefore evident that the movement-detecting system in this spider appears to be colour blind.

  13. Reading aids for adults with low vision

    PubMed Central

    Virgili, Gianni; Acosta, Ruthy; Grover, Lori L; Bentley, Sharon A; Giacomelli, Giovanni

    2014-01-01

    Background The purpose of low-vision rehabilitation is to allow people to resume or to continue to perform daily living tasks, with reading being one of the most important. This is achieved by providing appropriate optical devices and special training in the use of residual-vision and low-vision aids, which range from simple optical magnifiers to high-magnification video magnifiers. Objectives To assess the effects of reading aids for adults with low vision. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 1), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE, (January 1950 to January 2013), EMBASE (January 1980 to January 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2013), OpenGrey (System for Information on Grey Literature in Europe) (www.opengrey.eu/), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov/) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 31 January 2013. We searched the reference lists of relevant articles and used the Science Citation Index to find articles that cited the included studies and contacted investigators and manufacturers of low-vision aids. We handsearched the British Journal of Visual Impairment from 1983 to 1999 and the Journal of Visual Impairment and Blindness from 1976 to 1991. Selection criteria This review includes randomised and quasi-randomised trials in which any device or aid used for reading had been compared to another device or aid in people aged 16 or over with low vision as defined by the study investigators. Data collection and analysis At least two authors independently

  14. Colour knowledge in semantic dementia: it is not all black and white.

    PubMed

    Rogers, Timothy T; Patterson, Karalyn; Graham, Kim

    2007-11-05

    In three experiments we assessed the colour knowledge of patients with semantic dementia, a neuro-degenerative condition that gradually erodes conceptual knowledge. In Experiment 1, the patients' colour naming performance correlated strongly with their object naming for frequency-matched items, with no patient showing better-than-expected naming of colours relative to objects. In Experiment 2, where patients were asked to colour black-and-white line drawings of common objects, all patients were impaired relative to controls, and performance correlated strongly with degree of semantic deficit. The fact that patients often erroneously selected green for fruits or vegetables, and brown for animals, suggests some preservation of general knowledge about the colours that typify a given domain. In Experiment 3, patients were given pairs of identical line drawings of familiar animals, fruits and vegetables--one of each pair coloured correctly, and one incorrectly--and were asked to choose the correct one. When the target's colour was characteristic of the domain, patients scored well; but when the distractor had a typical hue and the target's colour was unusual (e.g. a green versus an orange carrot), performance was far poorer. The results are discussed with reference to alternative theories about the neural basis of conceptual knowledge.

  15. The colour of an avifauna: A quantitative analysis of the colour of Australian birds

    PubMed Central

    Delhey, Kaspar

    2015-01-01

    Animal coloration is a poorly-understood aspect of phenotypic variability. Here I expand initial studies of the colour gamut of birds by providing the first quantitative description of the colour variation of an entire avifauna: Australian landbirds (555 species). The colour of Australian birds occupies a small fraction (19%) of the entire possible colour space and colour variation is extremely uneven. Most colours are unsaturated, concentrated in the centre of colour space and based on the deposition of melanins. Other mechanisms of colour production are less common but account for larger portions of colour space and for most saturated colours. Male colours occupy 45–25% more colour space than female colours, indicating that sexual dichromatism translates into a broader range of male colours. Male-exclusive colours are often saturated, at the edge of chromatic space, and have most likely evolved for signalling. While most clades of birds occupy expected or lower-than-expected colour volumes, parrots and cockatoos (Order Psittaciformes) occupy a much larger volume than expected. This uneven distribution of colour variation across mechanisms of colour production, sexes and clades is probably shared by avifaunas in other parts of the world, but this remains to be tested with comparable data. PMID:26679370

  16. The colour of an avifauna: A quantitative analysis of the colour of Australian birds.

    PubMed

    Delhey, Kaspar

    2015-12-18

    Animal coloration is a poorly-understood aspect of phenotypic variability. Here I expand initial studies of the colour gamut of birds by providing the first quantitative description of the colour variation of an entire avifauna: Australian landbirds (555 species). The colour of Australian birds occupies a small fraction (19%) of the entire possible colour space and colour variation is extremely uneven. Most colours are unsaturated, concentrated in the centre of colour space and based on the deposition of melanins. Other mechanisms of colour production are less common but account for larger portions of colour space and for most saturated colours. Male colours occupy 45-25% more colour space than female colours, indicating that sexual dichromatism translates into a broader range of male colours. Male-exclusive colours are often saturated, at the edge of chromatic space, and have most likely evolved for signalling. While most clades of birds occupy expected or lower-than-expected colour volumes, parrots and cockatoos (Order Psittaciformes) occupy a much larger volume than expected. This uneven distribution of colour variation across mechanisms of colour production, sexes and clades is probably shared by avifaunas in other parts of the world, but this remains to be tested with comparable data.

  17. [Vision-impaired patients. Nursing diagnoses].

    PubMed

    García-Carpintero Muñoz, M A

    2001-10-01

    The author analyzes the most habitual problems one encounters in patients suffering a visual deficit, using the NANDA diagnostic taxonomy. The author formulates and classifies these problems as well as the specific nursing treatments which should be carried out when dealing with each one of these problems.

  18. Incorporating Colour Information for Computer-Aided Diagnosis of Melanoma from Dermoscopy Images: A Retrospective Survey and Critical Analysis

    PubMed Central

    Drew, Mark S.

    2016-01-01

    Cutaneous melanoma is the most life-threatening form of skin cancer. Although advanced melanoma is often considered as incurable, if detected and excised early, the prognosis is promising. Today, clinicians use computer vision in an increasing number of applications to aid early detection of melanoma through dermatological image analysis (dermoscopy images, in particular). Colour assessment is essential for the clinical diagnosis of skin cancers. Due to this diagnostic importance, many studies have either focused on or employed colour features as a constituent part of their skin lesion analysis systems. These studies range from using low-level colour features, such as simple statistical measures of colours occurring in the lesion, to availing themselves of high-level semantic features such as the presence of blue-white veil, globules, or colour variegation in the lesion. This paper provides a retrospective survey and critical analysis of contributions in this research direction. PMID:28096807

  19. Where have all the blue flowers gone: pollinator responses and selection on flower colour in New Zealand Wahlenbergia albomarginata.

    PubMed

    Campbell, D R; Bischoff, M; Lord, J M; Robertson, A W

    2012-02-01

    Although pollinators are thought to select on flower colour, few studies have experimentally decoupled effects of colour from correlated traits on pollinator visitation and pollen transfer. We combined selection analysis and phenotypic manipulations to measure the effect of petal colour on visitation and pollen export at two spatial scales in Wahlenbergia albomarginata. This species is representative of many New Zealand alpine herbs that have secondarily evolved white or pale flowers. The major pollinators, solitary bees, exerted phenotypic selection on flower size but not colour, quantified by bee vision. When presented with manipulated flowers, bees visited flowers painted blue to resemble a congener over white flowers in large, but not small, experimental arrays. Pollen export was higher for blue flowers in large arrays. Pollinator preference does not explain the pale colouration of W. albomarginata, as commonly hypothesized. Absence of bright blue could be driven instead by indirect selection of correlated characters.

  20. Methods for describing illumination colour uniformities

    NASA Astrophysics Data System (ADS)

    Rotscholl, Ingo; Trampert, Klaus; Herrmann, Franziska; Neumann, Cornelius

    2015-02-01

    Optimizing angular or spatial colour homogeneity has become an important task in many general lighting applications and first requires a valid description of illumination colour homogeneity. We analyse different frequently used methods to describe colour distributions in theory and with measurement data. It is described why information about chromaticity coordinates, correlated colour temperature and global chromaticity coordinate distances are not sufficient for describing colour homogeneity perception of light distributions. We present local chromaticity coordinate distances as expandable and easy implementable method for describing colour homogeneity distributions that is adaptable to the field of view by only one intuitive, physiological meaningful parameter.

  1. Evaluating the Visually Impaired: Neuropsychological Techniques.

    ERIC Educational Resources Information Center

    Price, J. R.; And Others

    1987-01-01

    Assessment of nonvisual neuropsychological impairments in visually impaired persons can be achieved through modification of existing intelligence, memory, sensory-motor, personality, language, and achievement tests so that they do not require vision or penalize visually impaired persons. The Halstead-Reitan and Luria-Nebraska neuropsychological…

  2. Colour and inclusivity: a visual communication design project with older people.

    PubMed

    da Silva, Fernando Moreira

    2012-01-01

    In an ideal world, inclusive products and services would be the standard and not the exception. This paper presents a systematic approach to an overlap between Visual Communication Design, Printed Colour and Inclusive Design, for older people, with the aim to develop of a set of research-based ageing and ergonomics-centred communication design guidelines and recommendations for printed material (analogical displays). The approach included an initial extensive literature review in the area of colour, older people and ergonomics issues and vision common diseases, communication design. The second phase was the implementation of an experiment to measure the different colour experiences of the participants in two sample groups (one in UK and another one in Portugal), using printed material, to find out the colours one should use in analogical communication material, being aware of the colour contrast importance (foreground versus background) and the difficulties experienced by older people to read and understand lettering, signs. As main contribution of this research project, we developed a set of guidelines and recommendations based on the reviewed literature and the sample groups' findings, trying to demonstrate the importance of these guidelines when conceiving a new communicational design project in a way this project will achieve vision comfort and understandability, especially for older people, in an inclusive design perspective.

  3. Floral colours in a world without birds and bees: the plants of Macquarie Island.

    PubMed

    Shrestha, M; Lunau, K; Dorin, A; Schulze, B; Bischoff, M; Burd, M; Dyer, A G

    2016-09-01

    We studied biotically pollinated angiosperms on Macquarie Island, a remote site in the Southern Ocean with a predominately or exclusively dipteran pollinator fauna, in an effort to understand how flower colour affects community assembly. We compared a distinctive group of cream-green Macquarie Island flowers to the flora of likely source pools of immigrants and to a continental flora from a high latitude in the northern hemisphere. We used both dipteran and hymenopteran colour models and phylogenetically informed analyses to explore the chromatic component of community assembly. The species with cream-green flowers are very restricted in colour space models of both fly vision and bee vision and represent a distinct group that plays a very minor role in other communities. It is unlikely that such a community could form through random immigration from continental source pools. Our findings suggest that fly pollination has imposed a strong ecological filter on Macquarie Island, favouring floral colours that are rare in continental floras. This is one of the strongest demonstrations that plant-pollinator interactions play an important role in plant community assembly. Future work exploring colour choices by dipteran flower visitors would be valuable.

  4. Vision Therapy News Backgrounder.

    ERIC Educational Resources Information Center

    American Optometric Association, St. Louis, MO.

    The booklet provides an overview on vision therapy to aid writers, editors, and broadcasters help parents, teachers, older adults, and all consumers learn more about vision therapy. Following a description of vision therapy or vision training, information is provided on how and why vision therapy works. Additional sections address providers of…

  5. Ophthalmology. Screening and treatment of age-related and pathologic vision changes.

    PubMed

    Rosenthal, B P

    2001-12-01

    In the older adult, deterioration of normal vision is caused by age-related physiologic and pathologic changes. Vision impairment undermines quality of life by reducing independence, mobility, and the enjoyment that goes with seeing clearly. The most common causes of vision impairment are age-related macular degeneration (AMD), glaucoma, cataract, and diabetic retinopathy. Key to successful management of vision impairment is early detection of signs and symptoms, patient education regarding preventive strategies, and swift medical or surgical intervention for established or emerging conditions. Vision rehabilitation is an important management option.

  6. Altered vision destabilizes gait in older persons.

    PubMed

    Helbostad, Jorunn L; Vereijken, Beatrix; Hesseberg, Karin; Sletvold, Olav

    2009-08-01

    This study assessed the effects of dim light and four experimentally induced changes in vision on gait speed and footfall and trunk parameters in older persons walking on level ground. Using a quasi-experimental design, gait characteristics were assessed in full light, dim light, and in dim light combined with manipulations resulting in reduced depth vision, double vision, blurred vision, and tunnel vision, respectively. A convenience sample of 24 home-dwelling older women and men (mean age 78.5 years, SD 3.4) with normal vision for their age and able to walk at least 10 m without assistance participated. Outcome measures were gait speed and spatial and temporal parameters of footfall and trunk acceleration, derived from an electronic gait mat and accelerometers. Dim light alone had no effect. Vision manipulations combined with dim light had effect on most footfall parameters but few trunk parameters. The largest effects were found regarding double and tunnel vision. Men increased and women decreased gait speed following manipulations (p=0.017), with gender differences also in stride velocity variability (p=0.017) and inter-stride medio-lateral trunk acceleration variability (p=0.014). Gender effects were related to differences in body height and physical functioning. Results indicate that visual problems lead to a more cautious and unstable gait pattern even under relatively simple conditions. This points to the importance of assessing vision in older persons and correcting visual impairments where possible.

  7. Neuronal morphology of biological vision: a basis for machine vision (Proceedings Only)

    NASA Astrophysics Data System (ADS)

    Gupta, Madan M.

    1992-03-01

    In this paper, we are concerned with the study of the biological vision system and the emulation of some of its mathematical functions, in both the retinal and visual cortex, for the development of a robust computer vision system. This field of research is not only intriguing, but offers a great challenge to systems scientists in the development of functional algorithms. These functional algorithms can be generalized for further studies for fields such as signal processing, control systems and image processing. Our studies are heavily dependent on the use of neuronal layers and the generalized receptive fields. Building blocks of such neuronal layers and receptive fields may lead to the design of better sensors and better computer vision systems. It is hoped that these studies will lead to the development of better artificial vision systems with applications to vision prosthesis for visually impaired persons, robotic vision, medical imaging, medical sensors, industrial automation, remote sensing, space stations and ocean exploration.

  8. Hypoxia, color vision deficiencies, and blood oxygen saturation.

    PubMed

    Hovis, Jeffery K; Milburn, Nelda J; Nesthus, Thomas E

    2012-02-01

    Chromatic thresholds were measured using the Cambridge Colour Test (CCT), the Colour Assessment and Diagnosis (CAD) test, and the Cone Specific Contrast Test (CSCT) at ground and 3780 m (12,400 ft) for subjects with normal color vision and red-green color vision defects. The CAD revealed a small (~10%) increase in the red-green thresholds for the trichromatic subjects and a similar increase in the blue-yellow thresholds for the dichromats. The other two color vision tests did not reveal any significant change in chromatic thresholds. The CAD results for the trichromats were consistent with a rotation of the discrimination ellipse counterclockwise with little change in the elliptical area. This alteration in the color discrimination ellipse can occur when retinal illumination is lowered.

  9. Vision Loss in Older Adults.

    PubMed

    Pelletier, Allen L; Rojas-Roldan, Ledy; Coffin, Janis

    2016-08-01

    Vision loss affects 37 million Americans older than 50 years and one in four who are older than 80 years. The U.S. Preventive Services Task Force concludes that current evidence is insufficient to assess the balance of benefits and harms of screening for impaired visual acuity in adults older than 65 years. However, family physicians play a critical role in identifying persons who are at risk of vision loss, counseling patients, and referring patients for disease-specific treatment. The conditions that cause most cases of vision loss in older patients are age-related macular degeneration, glaucoma, ocular complications of diabetes mellitus, and age-related cataracts. Vitamin supplements can delay the progression of age-related macular degeneration. Intravitreal injection of a vascular endothelial growth factor inhibitor can preserve vision in the neovascular form of macular degeneration. Medicated eye drops reduce intraocular pressure and can delay the progression of vision loss in patients with glaucoma, but adherence to treatment is poor. Laser trabeculoplasty also lowers intraocular pressure and preserves vision in patients with primary open-angle glaucoma, but long-term studies are needed to identify who is most likely to benefit from surgery. Tight glycemic control in adults with diabetes slows the progression of diabetic retinopathy, but must be balanced against the risks of hypoglycemia and death in older adults. Fenofibrate also slows progression of diabetic retinopathy. Panretinal photocoagulation is the mainstay of treatment for diabetic retinopathy, whereas vascular endothelial growth factor inhibitors slow vision loss resulting from diabetic macular edema. Preoperative testing before cataract surgery does not improve outcomes and is not recommended.

  10. Structural colour in Chondrus crispus

    NASA Astrophysics Data System (ADS)

    Chandler, Chris J.; Wilts, Bodo D.; Vignolini, Silvia; Brodie, Juliet; Steiner, Ullrich; Rudall, Paula J.; Glover, Beverley J.; Gregory, Thomas; Walker, Rachel H.

    2015-07-01

    The marine world is incredibly rich in brilliant and intense colours. Photonic structures are found in many different species and provide extremely complex optical responses that cannot be achieved solely by pigments. In this study we examine the cuticular structure of the red alga Chondrus crispus (Irish Moss) using anatomical and optical approaches. We experimentally measure the optical response of the multilayer structure in the cuticle. Using finite-difference time-domain modelling, we demonstrate conclusively for the first time that the dimensions and organisation of lamellae are responsible for the blue structural colouration on the surface of the fronds. Comparison of material along the apical-basal axis of the frond demonstrates that structural colour is confined to the tips of the thalli and show definitively that a lack of structural colour elsewhere corresponds with a reduction in the number of lamellae and the regularity of their ordering. Moreover, by studying the optical response for different hydration conditions, we demonstrate that the cuticular structure is highly porous and that the presence of water plays a critical role in its ability to act as a structural light reflector.

  11. Structural colour in Chondrus crispus

    PubMed Central

    Chandler, Chris J.; Wilts, Bodo D.; Vignolini, Silvia; Brodie, Juliet; Steiner, Ullrich; Rudall, Paula J.; Glover, Beverley J.; Gregory, Thomas; Walker, Rachel H.

    2015-01-01

    The marine world is incredibly rich in brilliant and intense colours. Photonic structures are found in many different species and provide extremely complex optical responses that cannot be achieved solely by pigments. In this study we examine the cuticular structure of the red alga Chondrus crispus (Irish Moss) using anatomical and optical approaches. We experimentally measure the optical response of the multilayer structure in the cuticle. Using finite-difference time-domain modelling, we demonstrate conclusively for the first time that the dimensions and organisation of lamellae are responsible for the blue structural colouration on the surface of the fronds. Comparison of material along the apical-basal axis of the frond demonstrates that structural colour is confined to the tips of the thalli and show definitively that a lack of structural colour elsewhere corresponds with a reduction in the number of lamellae and the regularity of their ordering. Moreover, by studying the optical response for different hydration conditions, we demonstrate that the cuticular structure is highly porous and that the presence of water plays a critical role in its ability to act as a structural light reflector. PMID:26139470

  12. Colour Reconnection at LEP2

    NASA Astrophysics Data System (ADS)

    Abreu, P.

    2002-03-01

    The preliminary results on the search of colour reconnection effects (CR) from the four experiments at LEP, Aleph, Delphi, L3 and Opal, are reviewed. Extreme models are excluded by studies of standard variables, and on going studies of a method first suggested by L3, the particle flow method1, are yet inconclusive.

  13. The colour of fossil feathers.

    PubMed

    Vinther, Jakob; Briggs, Derek E G; Prum, Richard O; Saranathan, Vinodkumar

    2008-10-23

    Feathers are complex integumentary appendages of birds and some other theropod dinosaurs. They are frequently coloured and function in camouflage and display. Previous investigations have concluded that fossil feathers are preserved as carbonized traces composed of feather-degrading bacteria. Here, an investigation of a colour-banded feather from the Lower Cretaceous Crato Formation of Brazil revealed that the dark bands are preserved as elongate, oblate carbonaceous bodies 1-2 microm long, whereas the light bands retain only relief traces on the rock matrix. Energy dispersive X-ray analysis showed that the dark bands preserve a substantial amount of carbon, whereas the light bands show no carbon residue. Comparison of these oblate fossil bodies with the structure of black feathers from a living bird indicates that they are the eumelanin-containing melanosomes. We conclude that most fossil feathers are preserved as melanosomes, and that the distribution of these structures in fossil feathers can preserve the colour pattern in the original feather. The discovery of preserved melanosomes opens up the possibility of interpreting the colour of extinct birds and other dinosaurs.

  14. Filtering and polychromatic vision in mantis shrimps: themes in visible and ultraviolet vision.

    PubMed

    Cronin, Thomas W; Bok, Michael J; Marshall, N Justin; Caldwell, Roy L

    2014-01-01

    Stomatopod crustaceans have the most complex and diverse assortment of retinal photoreceptors of any animals, with 16 functional classes. The receptor classes are subdivided into sets responsible for ultraviolet vision, spatial vision, colour vision and polarization vision. Many of these receptor classes are spectrally tuned by filtering pigments located in photoreceptors or overlying optical elements. At visible wavelengths, carotenoproteins or similar substances are packed into vesicles used either as serial, intrarhabdomal filters or lateral filters. A single retina may contain a diversity of these filtering pigments paired with specific photoreceptors, and the pigments used vary between and within species both taxonomically and ecologically. Ultraviolet-filtering pigments in the crystalline cones serve to tune ultraviolet vision in these animals as well, and some ultraviolet receptors themselves act as birefringent filters to enable circular polarization vision. Stomatopods have reached an evolutionary extreme in their use of filter mechanisms to tune photoreception to habitat and behaviour, allowing them to extend the spectral range of their vision both deeper into the ultraviolet and further into the red.

  15. Filtering and polychromatic vision in mantis shrimps: themes in visible and ultraviolet vision

    PubMed Central

    Cronin, Thomas W.; Bok, Michael J.; Marshall, N. Justin; Caldwell, Roy L.

    2014-01-01

    Stomatopod crustaceans have the most complex and diverse assortment of retinal photoreceptors of any animals, with 16 functional classes. The receptor classes are subdivided into sets responsible for ultraviolet vision, spatial vision, colour vision and polarization vision. Many of these receptor classes are spectrally tuned by filtering pigments located in photoreceptors or overlying optical elements. At visible wavelengths, carotenoproteins or similar substances are packed into vesicles used either as serial, intrarhabdomal filters or lateral filters. A single retina may contain a diversity of these filtering pigments paired with specific photoreceptors, and the pigments used vary between and within species both taxonomically and ecologically. Ultraviolet-filtering pigments in the crystalline cones serve to tune ultraviolet vision in these animals as well, and some ultraviolet receptors themselves act as birefringent filters to enable circular polarization vision. Stomatopods have reached an evolutionary extreme in their use of filter mechanisms to tune photoreception to habitat and behaviour, allowing them to extend the spectral range of their vision both deeper into the ultraviolet and further into the red. PMID:24395960

  16. Healthy Living, Healthy Vision

    MedlinePlus

    ... Eye Emergencies How to Jump Start a Car Battery Safely Electronic Screens and Your Eyes Nutrition and ... External Resources The Cost of Vision Problems The Future of Vision Vision Problems in the U.S. Healthy ...

  17. Pregnancy and Your Vision

    MedlinePlus

    ... Eye Emergencies How to Jump Start a Car Battery Safely Electronic Screens and Your Eyes Nutrition and ... External Resources The Cost of Vision Problems The Future of Vision Vision Problems in the U.S. Healthy ...

  18. Colour as a signal for entraining the mammalian circadian clock.

    PubMed

    Walmsley, Lauren; Hanna, Lydia; Mouland, Josh; Martial, Franck; West, Alexander; Smedley, Andrew R; Bechtold, David A; Webb, Ann R; Lucas, Robert J; Brown, Timothy M

    2015-04-01

    Twilight is characterised by changes in both quantity ("irradiance") and quality ("colour") of light. Animals use the variation in irradiance to adjust their internal circadian clocks, aligning their behaviour and physiology with the solar cycle. However, it is currently unknown whether changes in colour also contribute to this entrainment process. Using environmental measurements, we show here that mammalian blue-yellow colour discrimination provides a more reliable method of tracking twilight progression than simply measuring irradiance. We next use electrophysiological recordings to demonstrate that neurons in the mouse suprachiasmatic circadian clock display the cone-dependent spectral opponency required to make use of this information. Thus, our data show that some clock neurons are highly sensitive to changes in spectral composition occurring over twilight and that this input dictates their response to changes in irradiance. Finally, using mice housed under photoperiods with simulated dawn/dusk transitions, we confirm that spectral changes occurring during twilight are required for appropriate circadian alignment under natural conditions. Together, these data reveal a new sensory mechanism for telling time of day that would be available to any mammalian species capable of chromatic vision.

  19. An RGB Approach to Prismatic Colours

    ERIC Educational Resources Information Center

    Theilmann, Florian; Grusche, Sascha

    2013-01-01

    Teaching prismatic colours usually boils down to establishing the take-home message that white light consists of "differently refrangible" coloured rays. This approach explains the classical spectrum of seven colours but has its limitations, e.g. in discussing spectra from setups with higher resolution or in understanding the well…

  20. Biological Components of Colour Preference in Infancy

    ERIC Educational Resources Information Center

    Franklin, Anna; Bevis, Laura; Ling, Yazhu; Hurlbert, Anya

    2010-01-01

    Adult colour preference has been summarized quantitatively in terms of weights on the two fundamental neural processes that underlie early colour encoding: the S-(L+M) ("blue-yellow") and L-M ("red-green") cone-opponent contrast channels ( Ling, Hurlbert & Robinson, 2006; Hurlbert & Ling, 2007). Here, we investigate whether colour preference in…

  1. Binocular Vision

    PubMed Central

    Blake, Randolph; Wilson, Hugh

    2010-01-01

    This essay reviews major developments –empirical and theoretical –in the field of binocular vision during the last 25 years. We limit our survey primarily to work on human stereopsis, binocular rivalry and binocular contrast summation, with discussion where relevant of single-unit neurophysiology and human brain imaging. We identify several key controversies that have stimulated important work on these problems. In the case of stereopsis those controversies include position versus phase encoding of disparity, dependence of disparity limits on spatial scale, role of occlusion in binocular depth and surface perception, and motion in 3D. In the case of binocular rivalry, controversies include eye versus stimulus rivalry, role of “top-down” influences on rivalry dynamics, and the interaction of binocular rivalry and stereopsis. Concerning binocular contrast summation, the essay focuses on two representative models that highlight the evolving complexity in this field of study. PMID:20951722

  2. Robot Vision

    NASA Technical Reports Server (NTRS)

    Sutro, L. L.; Lerman, J. B.

    1973-01-01

    The operation of a system is described that is built both to model the vision of primate animals, including man, and serve as a pre-prototype of possible object recognition system. It was employed in a series of experiments to determine the practicability of matching left and right images of a scene to determine the range and form of objects. The experiments started with computer generated random-dot stereograms as inputs and progressed through random square stereograms to a real scene. The major problems were the elimination of spurious matches, between the left and right views, and the interpretation of ambiguous regions, on the left side of an object that can be viewed only by the left camera, and on the right side of an object that can be viewed only by the right camera.

  3. Artificial vision.

    PubMed

    Humayun, M S; de Juan, E

    1998-01-01

    Outer retinal degenerations such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD) lead to blindness because of photoreceptor degeneration. To test whether controlled electrical stimulation of the remaining retinal neurons could provide form vision, we electrically stimulated the inner retinal surface with micro-electrodes inserted through the sclera/eye wall of 14 of these patients (12 RP and 2 AMD). This procedure was performed in the operating room under local anaesthesia and all responses were recorded via a video camera mounted on the surgical microscope. Electrical stimulation of the inner retinal surface elicited visual perception of a spot of light (phosphene) in all subjects. This perception was retinotopically correct in 13 of 14 patients. In a resolution test in a subject with no light perception, the patient could resolve phosphenes at 1.75 degrees centre-to-centre distance (i.e. visual acuity compatible with mobility; Snellen visual acuity of 4/200).

  4. Vision Screening

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Visi Screen OSS-C, marketed by Vision Research Corporation, incorporates image processing technology originally developed by Marshall Space Flight Center. Its advantage in eye screening is speed. Because it requires no response from a subject, it can be used to detect eye problems in very young children. An electronic flash from a 35 millimeter camera sends light into a child's eyes, which is reflected back to the camera lens. The photorefractor then analyzes the retinal reflexes generated and produces an image of the child's eyes, which enables a trained observer to identify any defects. The device is used by pediatricians, day care centers and civic organizations that concentrate on children with special needs.

  5. Colour annealing - a toy model of colour reconnections

    SciTech Connect

    Sandhoff, Marisa; Skands, Peter; /Fermilab

    2005-12-01

    We present a simple toy model for colour reconnections at the nonperturbative level. The model resembles an annealing-type algorithm and is applicable to any collider and process type, though we argue for a possible enhancement of the effect in hadron-hadron collisions. We present a simple application and study of the consequences for semileptonic t{bar t} events at the Tevatron.

  6. Characterisation of the n-colour printing process using the spot colour overprint model.

    PubMed

    Deshpande, Kiran; Green, Phil; Pointer, Michael R

    2014-12-29

    This paper is aimed at reproducing the solid spot colours using the n-colour separation. A simplified numerical method, called as the spot colour overprint (SCOP) model, was used for characterising the n-colour printing process. This model was originally developed for estimating the spot colour overprints. It was extended to be used as a generic forward characterisation model for the n-colour printing process. The inverse printer model based on the look-up table was implemented to obtain the colour separation for n-colour printing process. Finally the real-world spot colours were reproduced using 7-colour separation on lithographic offset printing process. The colours printed with 7 inks were compared against the original spot colours to evaluate the accuracy. The results show good accuracy with the mean CIEDE2000 value between the target colours and the printed colours of 2.06. The proposed method can be used successfully to reproduce the spot colours, which can potentially save significant time and cost in the printing and packaging industry.

  7. The neural correlate of colour distances revealed with competing synaesthetic and real colours.

    PubMed

    Laeng, Bruno; Hugdahl, Kenneth; Specht, Karsten

    2011-03-01

    Synaesthetes claim to perceive illusory colours when reading alphanumeric symbols so that two colours are said to be bound to the same letter or digit (i.e., the colour of the ink, e.g., black, and an additional, synaesthetic, colour). To explore the neural correlates of this phenomenon, we used a Stroop single-letter colour-naming task and found that distances in colour space between the illusory and real colours of a letter target (as computed from either the RGB or CIExyY coordinates of colours) systematically influenced the degree of neuronal activation in colour-processing brain regions. The synaesthetes also activated the same fronto-parietal network during the classic colour-word Stroop task and single-letter tasks. We conclude that the same neural substrate that supports the conscious experience of colour, as triggered by physical wavelength, supports the experience of synaesthetic colours. Thus, two colour attributes (one that is wavelength-dependent and one that is illusory) can be bound to the same stimulus position and simultaneously engage the colour areas in proportion to their similarity in colour space.

  8. Printing colour at the optical diffraction limit.

    PubMed

    Kumar, Karthik; Duan, Huigao; Hegde, Ravi S; Koh, Samuel C W; Wei, Jennifer N; Yang, Joel K W

    2012-09-01

    The highest possible resolution for printed colour images is determined by the diffraction limit of visible light. To achieve this limit, individual colour elements (or pixels) with a pitch of 250 nm are required, translating into printed images at a resolution of ∼100,000 dots per inch (d.p.i.). However, methods for dispensing multiple colourants or fabricating structural colour through plasmonic structures have insufficient resolution and limited scalability. Here, we present a non-colourant method that achieves bright-field colour prints with resolutions up to the optical diffraction limit. Colour information is encoded in the dimensional parameters of metal nanostructures, so that tuning their plasmon resonance determines the colours of the individual pixels. Our colour-mapping strategy produces images with both sharp colour changes and fine tonal variations, is amenable to large-volume colour printing via nanoimprint lithography, and could be useful in making microimages for security, steganography, nanoscale optical filters and high-density spectrally encoded optical data storage.

  9. Profile of a low vision clinic population.

    PubMed

    Mohidin, Norhani; Yusoff, Suzainah

    1998-01-01

    BACKGROUND: Causes of low vision and types of low vision devices (LVDs) prescribed in other low vision clinics have been studied extensively. Similar studies have not been conducted in Malaysia. This paper reports the results of a retrospective study of 573 patients seen at the Universiti Kebangsaan Malaysia-Malaysian Association for the Blind (UKM-MAB) low vision clinic in Kuala Lumpur. METHODS: The record cards of 573 patients seen at the UKM-MAB clinic over 10 years were examined and the following information extracted: date of first consultation, age, sex, cause of visual impairment as diagnosed by an ophthalmologist and types of low vision devices (LVDs) prescribed. RESULTS: The majority of patients were from the younger age groups with 423 (73.8 per cent) less than 50 years of age. Three hundred and ninety-five (68.9 per cent) of the subjects were males and 178 (31.1 per cent) female. The main causes of low vision were congenital structural defects including nystagmus among patients in the zero to 29 years age group, retinitis pigmentosa among the 30 to 59 years age group and age-related macular degeneration (ARM) among those over 60 years of age. CONCLUSIONS: Since the majority of the patients were from the younger age group the main causes of low vision were congenital and hereditary diseases. Three hundred and forty-one (59.5 per cent) patients seen at the low vision clinic accepted the use of LVDs.

  10. What colour is a shadow?

    NASA Astrophysics Data System (ADS)

    Hughes, S. W.

    2009-05-01

    What colour is a shadow? Black, grey, or some other colour? This article describes how to use a digital camera to test the hypothesis that a shadow under a clear blue sky has a blue tint. A white sheet of A4 paper was photographed in full sunlight and in shadow under a clear blue sky. The images were analysed using a shareware program called ImageJ. The average red, green and blue pixel values in a region of interest drawn on a photograph of the paper in sunlight and shadow were 0.3, 0.32, 0.38 and 0.2, 0.3, 0.5 respectively, demonstrating that a shadow under a blue sky has a blue tint. The experiment would be a useful exercise for a science class.

  11. Prentice Medal Lecture 2013: Visual Accessibility: A Challenge for Low-Vision Research

    PubMed Central

    Legge, Gordon E.

    2014-01-01

    Low vision may be defined as any chronic form of vision impairment, not correctable by glasses or contact lenses, that adversely affects everyday function. Visual accessibility refers to factors that make an environment, device or display usable by vision. In this article, I discuss the concept of visual accessibility with special reference to low vision. What role can vision science play in enhancing visual accessibility for people with low vision? I propose that greater efforts to embed low-vision research in real-world contexts and collaboration with other disciplines will accelerate progress. I describe examples from my current research projects on architectural accessibility and reading accessibility. PMID:24978657

  12. Visual impairment in the hearing impaired students

    PubMed Central

    Gogate, Parikshit; Rishikeshi, Nikhil; Mehata, Reshma; Ranade, Satish; Kharat, Jitesh; Deshpande, Madan

    2009-01-01

    Background: Ocular problems are more common in children with hearing problems than in normal children. Neglected visual impairment could aggravate educational and social disability. Aim: To detect and treat visual impairment, if any, in hearing-impaired children. Setting and Design: Observational, clinical case series of hearing-impaired children in schools providing special education. Materials and Methods: Hearing-impaired children in selected schools underwent detailed visual acuity testing, refraction, external ocular examination and fundoscopy. Ocular motility testing was also performed. Teachers were sensitized and trained to help in the assessment of visual acuity using Snellen's E charts. Refractive errors and squint were treated as per standard practice. Statistical Analysis: Excel software was used for data entry and SSPS for analysis. Results: The study involved 901 hearing-impaired students between four and 21 years of age, from 14 special education schools. A quarter of them (216/901, 24%) had ocular problems. Refractive errors were the most common morbidity 167(18.5%), but only 10 children were using appropriate spectacle correction at presentation. Fifty children had visual acuity less than 20/80 at presentation; after providing refractive correction, this number reduced to three children, all of whom were provided low-vision aids. Other common conditions included strabismus in 12 (1.3%) children, and retinal pigmentary dystrophy in five (0.6%) children. Conclusion: Ocular problems are common in hearing-impaired children. Screening for ocular problems should be made mandatory in hearing-impaired children, as they use their visual sense to compensate for the poor auditory sense. PMID:19861747

  13. Visual modelling suggests a weak relationship between the evolution of ultraviolet vision and plumage coloration in birds.

    PubMed

    Lind, O; Delhey, K

    2015-03-01

    Birds have sophisticated colour vision mediated by four cone types that cover a wide visual spectrum including ultraviolet (UV) wavelengths. Many birds have modest UV sensitivity provided by violet-sensitive (VS) cones with sensitivity maxima between 400 and 425 nm. However, some birds have evolved higher UV sensitivity and a larger visual spectrum given by UV-sensitive (UVS) cones maximally sensitive at 360-370 nm. The reasons for VS-UVS transitions and their relationship to visual ecology remain unclear. It has been hypothesized that the evolution of UVS-cone vision is linked to plumage colours so that visual sensitivity and feather coloration are 'matched'. This leads to the specific prediction that UVS-cone vision enhances the discrimination of plumage colours of UVS birds while such an advantage is absent or less pronounced for VS-bird coloration. We test this hypothesis using knowledge of the complex distribution of UVS cones among birds combined with mathematical modelling of colour discrimination during different viewing conditions. We find no support for the hypothesis, which, combined with previous studies, suggests only a weak relationship between UVS-cone vision and plumage colour evolution. Instead, we suggest that UVS-cone vision generally favours colour discrimination, which creates a nonspecific selection pressure for the evolution of UVS cones.

  14. Adolescents with Low Vision: Perceptions of Driving and Nondriving

    ERIC Educational Resources Information Center

    Sacks, Sharon Zell; Rosenblum, L. Penny

    2006-01-01

    Two studies examined how adolescents with low vision perceive their ability to drive. The results of both studies indicated similarities in the participants' responses with respect to knowledge of visual impairment, information about options for driving with low vision, frustrations and obstacles imposed by not being able to drive, and independent…

  15. 21 CFR 886.5870 - Low-vision telescope.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5870 Low-vision telescope. (a) Identification... use by a patient who has impaired vision to increase the apparent size of objects. This generic type of device includes handheld or spectacle telescopes. (b) Classification. Class I (general...

  16. 21 CFR 886.5870 - Low-vision telescope.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5870 Low-vision telescope. (a) Identification... use by a patient who has impaired vision to increase the apparent size of objects. This generic type of device includes handheld or spectacle telescopes. (b) Classification. Class I (general...

  17. Accommodating Extension Clients Who Face Language, Vision, or Hearing Challenges

    ERIC Educational Resources Information Center

    Angima, Sam; Etuk, Lena; Maddy, Deborah

    2016-01-01

    A survey-based study explored approaches used by one land-grant university to meet the needs of Extension clients who face language, vision, or hearing challenges. In attempts to serve such clients, the greatest gaps existed for clients whose main language was Spanish, followed by those who had vision impairments and then those who had hearing…

  18. Visual Memory for Objects Following Foveal Vision Loss

    ERIC Educational Resources Information Center

    Geringswald, Franziska; Herbik, Anne; Hofmüller, Wolfram; Hoffmann, Michael B.; Pollmann, Stefan

    2015-01-01

    Allocation of visual attention is crucial for encoding items into visual long-term memory. In free vision, attention is closely linked to the center of gaze, raising the question whether foveal vision loss entails suboptimal deployment of attention and subsequent impairment of object encoding. To investigate this question, we examined visual…

  19. Bullying in German Adolescents: Attending Special School for Students with Visual Impairment

    ERIC Educational Resources Information Center

    Pinquart, Martin; Pfeiffer, Jens P.

    2011-01-01

    The present study analysed bullying in German adolescents with and without visual impairment. Ninety-eight adolescents with vision loss from schools for students with visual impairment, of whom 31 were blind and 67 had low vision, were compared with 98 sighted peers using a matched-pair design. Students with low vision reported higher levels of…

  20. The visually impaired patient.

    PubMed

    Rosenberg, Eric A; Sperazza, Laura C

    2008-05-15

    Blindness or low vision affects more than 3 million Americans 40 years and older, and this number is projected to reach 5.5 million by 2020. In addition to treating a patient's vision loss and comorbid medical issues, physicians must be aware of the physical limitations and social issues associated with vision loss to optimize health and independent living for the visually impaired patient. In the United States, the four most prevalent etiologies of vision loss in persons 40 years and older are age-related macular degeneration, cataracts, glaucoma, and diabetic retinopathy. Exudative macular degeneration is treated with laser therapy, and progression of nonexudative macular degeneration in its advanced stages may be slowed with high-dose antioxidant and zinc regimens. The value of screening for glaucoma is uncertain; management of this condition relies on topical ocular medications. Cataract symptoms include decreased visual acuity, decreased color perception, decreased contrast sensitivity, and glare disability. Lifestyle and environmental interventions can improve function in patients with cataracts, but surgery is commonly performed if the condition worsens. Diabetic retinopathy responds to tight glucose control, and severe cases marked by macular edema are treated with laser photocoagulation. Vision-enhancing devices can help magnify objects, and nonoptical interventions include special filters and enhanced lighting.

  1. Put on that colour, it fits your emotion: Colour appropriateness as a function of expressed emotion.

    PubMed

    Dael, Nele; Perseguers, Marie-Noëlle; Marchand, Cynthia; Antonietti, Jean-Philippe; Mohr, Christine

    2016-01-01

    People associate affective meaning with colour, and this may influence decisions about colours. Hue is traditionally considered the most salient descriptor of colour and colour-affect associations, although colour brightness and saturation seem to have particularly strong affective connotations. To test whether colour choices can be driven by emotion, we investigated whether and how colour hue, brightness, and saturation are systematically associated with bodily expressions of positive (joy) and negative (fear) emotions. Twenty-five non-colour-blind participants viewed videos of these expressions and selected for each video the most appropriate colour using colour sliders providing values for hue, brightness, and saturation. The overall colour choices were congruent with the expressed emotion--that is, participants selected brighter and more saturated colours for joy expressions than for fear expressions. Also, colours along the red-yellow spectrum were deemed more appropriate for joy expressions and cyan-bluish hues for fear expressions. The current study adds further support to the role of emotion in colour choices by (a) showing that emotional information is spontaneously used in an unconstrained choice setting, (b) extending to ecologically valid stimuli occurring in everyday encounters (dressed bodies), and

  2. Colour and odour drive fruit selection and seed dispersal by mouse lemurs

    PubMed Central

    Valenta, Kim; Burke, Ryan J.; Styler, Sarah A.; Jackson, Derek A.; Melin, Amanda D.; Lehman, Shawn M.

    2013-01-01

    Animals and fruiting plants are involved in a complex set of interactions, with animals relying on fruiting trees as food resources, and fruiting trees relying on animals for seed dispersal. This interdependence shapes fruit signals such as colour and odour, to increase fruit detectability, and animal sensory systems, such as colour vision and olfaction to facilitate food identification and selection. Despite the ecological and evolutionary importance of plant-animal interactions for shaping animal sensory adaptations and plant characteristics, the details of the relationship are poorly understood. Here we examine the role of fruit chromaticity, luminance and odour on seed dispersal by mouse lemurs. We show that both fruit colour and odour significantly predict fruit consumption and seed dispersal by Microcebus ravelobensis and M. murinus. Our study is the first to quantify and examine the role of bimodal fruit signals on seed dispersal in light of the sensory abilities of the disperser. PMID:23939534

  3. Raven's Coloured Progressive Matrices as a Measure of Cognitive Functioning in Cerebral Palsy

    ERIC Educational Resources Information Center

    Pueyo, R.; Junque, C.; Vendrell, P.; Narberhaus, A.; Segarra, D.

    2008-01-01

    Background: Cognitive dysfunction is frequent in Cerebral Palsy (CP). CP motor impairment and associated speech deficits often hinder cognitive assessment, with the result being that not all CP studies consider cognitive dysfunction. Raven's Coloured Progressive Matrices is a simple, rapid test which can be used in persons with severe motor…

  4. The original colours of fossil beetles.

    PubMed

    McNamara, Maria E; Briggs, Derek E G; Orr, Patrick J; Noh, Heeso; Cao, Hui

    2012-03-22

    Structural colours, the most intense, reflective and pure colours in nature, are generated when light is scattered by complex nanostructures. Metallic structural colours are widespread among modern insects and can be preserved in their fossil counterparts, but it is unclear whether the colours have been altered during fossilization, and whether the absence of colours is always real. To resolve these issues, we investigated fossil beetles from five Cenozoic biotas. Metallic colours in these specimens are generated by an epicuticular multi-layer reflector; the fidelity of its preservation correlates with that of other key cuticular ultrastructures. Where these other ultrastructures are well preserved in non-metallic fossil specimens, we can infer that the original cuticle lacked a multi-layer reflector; its absence in the fossil is not a preservational artefact. Reconstructions of the original colours of the fossils based on the structure of the multi-layer reflector show that the preserved colours are offset systematically to longer wavelengths; this probably reflects alteration of the refractive index of the epicuticle during fossilization. These findings will allow the former presence, and original hue, of metallic structural colours to be identified in diverse fossil insects, thus providing critical evidence of the evolution of structural colour in this group.

  5. Measurement and prediction of pork colour.

    PubMed

    Van Oeckel, M J; Warnants, N; Boucqué, C V

    1999-08-01

    The extent to which instrumental colour determinations by FOPu (light scattering), Göfo (reflectance) and Labscan II (CIE L*, CIE a* and CIE b*, hue and chroma) are related to the Japanese colour grades was studied. Additionally, four on-line methods: pH1, FOP1, PQM1 (conductivity) and DDLT (Double Density Light Transmission, analogous to Capteur Gras/Maigre), were evaluated for their ability to predict subjectively and objectively colour. One hundred and twenty samples of m. longissimus thoracis et lumborum, from animals of different genotypes, were analysed. Of the instrumental colour determinations, CIE L* (r=-0.82), FOPu (r=-0.70) and Göfo (r=0.70) were best correlated with the Japanese colour scores. The Japanese colour grades could be predicted by the on-line instruments, pH1, FOP1, PQM1 and DDLT, with determination coefficients between 15 and 28%. Ultimate meat colour, determined by Japanese colour standards, FOPu, Göfo and CIE L*, was better predicted by DDLT than by the classic on-line instruments: FOP1, pH1 and PQM1, although the standard error of the estimate was similar for all instruments. This means that DDLT, although originally designed for estimating lean meat percentage, can additionally give information about meat quality, in particular colour. However, it must be stressed that the colour estimate by DDLT refers to a population of animals, rather than to individual pigs, because of the number of erroneously assigned samples.

  6. Ultraviolet Light: Some Considerations for Vision Stimulation.

    ERIC Educational Resources Information Center

    Knowlton, Marie

    1986-01-01

    The article examines evidence of visual impairment caused by excessive amounts of ultraviolet (UV) light. Among considerations when using a source of UV light for vision stimulation are the position of the child and teacher, use of window glass filters or protective glasses, and careful recordkeeping of all UV stimulation. (Author/JW)[

  7. Neurological Vision Rehabilitation: Description and Case Study

    ERIC Educational Resources Information Center

    Kingston, John; Katsaros, Jennifer; Vu, Yurika; Goodrich, Gregory L.

    2010-01-01

    The wars in Afghanistan and Iraq have been notable for the high rates of traumatic brain injury (TBI) that have been incurred by the troops. Visual impairments often occur following TBI and present new challenges for rehabilitation. We describe a neurological vision rehabilitation therapy that addresses the unique needs of patients with vision…

  8. How Bees Discriminate a Pattern of Two Colours from Its Mirror Image

    PubMed Central

    Horridge, Adrian

    2015-01-01

    A century ago, in his study of colour vision in the honeybee (Apis mellifera), Karl von Frisch showed that bees distinguish between a disc that is half yellow, half blue, and a mirror image of the same. Although his inference of colour vision in this example has been accepted, some discrepancies have prompted a new investigation of the detection of polarity in coloured patterns. In new experiments, bees restricted to their blue and green receptors by exclusion of ultraviolet could learn patterns of this type if they displayed a difference in green contrast between the two colours. Patterns with no green contrast required an additional vertical black line as a landmark. Tests of the trained bees revealed that they had learned two inputs; a measure and the retinotopic position of blue with large field tonic detectors, and the measure and position of a vertical edge or line with small-field phasic green detectors. The angle between these two was measured. This simple combination was detected wherever it occurred in many patterns, fitting the definition of an algorithm, which is defined as a method of processing data. As long as they excited blue receptors, colours could be any colour to human eyes, even white. The blue area cue could be separated from the green receptor modulation by as much as 50°. When some blue content was not available, the bees learned two measures of the modulation of the green receptors at widely separated vertical edges, and the angle between them. There was no evidence that the bees reconstructed the lay-out of the pattern or detected a tonic input to the green receptors. PMID:25617892

  9. How bees discriminate a pattern of two colours from its mirror image.

    PubMed

    Horridge, Adrian

    2015-01-01

    A century ago, in his study of colour vision in the honeybee (Apis mellifera), Karl von Frisch showed that bees distinguish between a disc that is half yellow, half blue, and a mirror image of the same. Although his inference of colour vision in this example has been accepted, some discrepancies have prompted a new investigation of the detection of polarity in coloured patterns. In new experiments, bees restricted to their blue and green receptors by exclusion of ultraviolet could learn patterns of this type if they displayed a difference in green contrast between the two colours. Patterns with no green contrast required an additional vertical black line as a landmark. Tests of the trained bees revealed that they had learned two inputs; a measure and the retinotopic position of blue with large field tonic detectors, and the measure and position of a vertical edge or line with small-field phasic green detectors. The angle between these two was measured. This simple combination was detected wherever it occurred in many patterns, fitting the definition of an algorithm, which is defined as a method of processing data. As long as they excited blue receptors, colours could be any colour to human eyes, even white. The blue area cue could be separated from the green receptor modulation by as much as 50°. When some blue content was not available, the bees learned two measures of the modulation of the green receptors at widely separated vertical edges, and the angle between them. There was no evidence that the bees reconstructed the lay-out of the pattern or detected a tonic input to the green receptors.

  10. Structural colour: Colour mixing in wing scales of a butterfly

    NASA Astrophysics Data System (ADS)

    Vukusic, P.; Sambles, J. R.; Lawrence, C. R.

    2000-03-01

    Green coloration in the animal kingdom, as seen in birds' feathers and reptile integument, is often an additive mixture of structurally effected blue and pigmentary yellow. Here we investigate the origin of the bright green coloration of the wing scales of the Indonesian male Papilio palinurus butterfly, the microstructure of which generates an extraordinary combination of both yellow and blue iridescence. The dual colour arises from a modulation imposed on the multilayer, producing the blue component as a result of a previously undiscovered retro-reflection process.

  11. Selection on quantitative colour variation in Centaurea cyanus: the role of the pollinator's visual system.

    PubMed

    Renoult, J P; Thomann, M; Schaefer, H M; Cheptou, P-O

    2013-11-01

    Even though the importance of selection for trait evolution is well established, we still lack a functional understanding of the mechanisms underlying phenotypic selection. Because animals necessarily use their sensory system to perceive phenotypic traits, the model of sensory bias assumes that sensory systems are the main determinant of signal evolution. Yet, it has remained poorly known how sensory systems contribute to shaping the fitness surface of selected individuals. In a greenhouse experiment, we quantified the strength and direction of selection on floral coloration in a population of cornflowers exposed to bumblebees as unique pollinators during 4 days. We detected significant selection on the chromatic and achromatic (brightness) components of floral coloration. We then studied whether these patterns of selection are explicable by accounting for the visual system of the pollinators. Using data on bumblebee colour vision, we first showed that bumblebees should discriminate among quantitative colour variants. The observed selection was then compared to the selection predicted by psychophysical models of bumblebee colour vision. The achromatic but not the chromatic channel of the bumblebee's visual system could explain the observed pattern of selection. These results highlight that (i) pollinators can select quantitative variation in floral coloration and could thus account for a gradual evolution of flower coloration, and (ii) stimulation of the visual system represents, at least partly, a functional mechanism potentially explaining pollinators' selection on floral colour variants.

  12. Colour and surface fluorescence development and their relationship with Maillard reaction markers as influenced by structural changes during cornflakes production.

    PubMed

    Farroni, Abel; Buera, María Del Pilar

    2012-12-01

    The aim of this work was to study colour and surface fluorescence development in relation to the chemical markers for the Maillard reaction at the cooking, flaking and toasting stages of cornflake production process. Colour was measured by a calibrated computer vision system. Surface fluorescence was measured on compressed samples. Aqueous extracted Maillard reaction markers (hydroxymethylfurfural, carboxymethyl-lysine, absorbance at 420nm and total fluorescence) were measured on protease hydrolyzed samples. Sample microstructure was observed by scanning electron microscopy. During cooking the colour coordinates L(∗) and b(∗) decreased and a(∗) increased. After flaking, the samples appeared lighter, while the pigment concentration, fluorescence and hydroxymethylfurfural did not change. Toasting generated bubbles in the matrix and L(∗) apparently increased, although brown pigment concentration increased. Pigment concentration did not correlate with surface colour due to the destruction or generation of interfaces. Surface and microstructure effects can be avoided by milling and compressing the samples.

  13. Digital enhancement of haematoxylin- and eosin-stained histological images for red-green colour-blind observers.

    PubMed

    Landini, G; Perryer, G

    2009-06-01

    Individuals with red-green colour-blindness (CB) commonly experience great difficulty differentiating between certain histological stain pairs, notably haematoxylin-eosin (H&E). The prevalence of red-green CB is high (6-10% of males), including among medical and laboratory personnel, and raises two major concerns: first, accessibility and equity issues during the education and training of individuals with this disability, and second, the likelihood of errors in critical tasks such as interpreting histological images. Here we show two methods to enhance images of H&E-stained samples so the differently stained tissues can be well discriminated by red-green CBs while remaining usable by people with normal vision. Method 1 involves rotating and stretching the range of H&E hues in the image to span the perceptual range of the CB observers. Method 2 digitally unmixes the original dyes using colour deconvolution into two separate images and repositions the information into hues that are more distinctly perceived. The benefits of these methods were tested in 36 volunteers with normal vision and 11 with red-green CB using a variety of H&E stained tissue sections paired with their enhanced versions. CB subjects reported they could better perceive the different stains using the enhanced images for 85% of preparations (method 1: 90%, method 2: 73%), compared to the H&E-stained original images. Many subjects with normal vision also preferred the enhanced images to the original H&E. The results suggest that these colour manipulations confer considerable advantage for those with red-green colour vision deficiency while not disadvantaging people with normal colour vision.

  14. Quantifying plant colour and colour difference as perceived by humans using digital images.

    PubMed

    Kendal, Dave; Hauser, Cindy E; Garrard, Georgia E; Jellinek, Sacha; Giljohann, Katherine M; Moore, Joslin L

    2013-01-01

    Human perception of plant leaf and flower colour can influence species management. Colour and colour contrast may influence the detectability of invasive or rare species during surveys. Quantitative, repeatable measures of plant colour are required for comparison across studies and generalisation across species. We present a standard method for measuring plant leaf and flower colour traits using images taken with digital cameras. We demonstrate the method by quantifying the colour of and colour difference between the flowers of eleven grassland species near Falls Creek, Australia, as part of an invasive species detection experiment. The reliability of the method was tested by measuring the leaf colour of five residential garden shrub species in Ballarat, Australia using five different types of digital camera. Flowers and leaves had overlapping but distinct colour distributions. Calculated colour differences corresponded well with qualitative comparisons. Estimates of proportional cover of yellow flowers identified using colour measurements correlated well with estimates obtained by measuring and counting individual flowers. Digital SLR and mirrorless cameras were superior to phone cameras and point-and-shoot cameras for producing reliable measurements, particularly under variable lighting conditions. The analysis of digital images taken with digital cameras is a practicable method for quantifying plant flower and leaf colour in the field or lab. Quantitative, repeatable measurements allow for comparisons between species and generalisations across species and studies. This allows plant colour to be related to human perception and preferences and, ultimately, species management.

  15. Quantifying Plant Colour and Colour Difference as Perceived by Humans Using Digital Images

    PubMed Central

    Kendal, Dave; Hauser, Cindy E.; Garrard, Georgia E.; Jellinek, Sacha; Giljohann, Katherine M.; Moore, Joslin L.

    2013-01-01

    Human perception of plant leaf and flower colour can influence species management. Colour and colour contrast may influence the detectability of invasive or rare species during surveys. Quantitative, repeatable measures of plant colour are required for comparison across studies and generalisation across species. We present a standard method for measuring plant leaf and flower colour traits using images taken with digital cameras. We demonstrate the method by quantifying the colour of and colour difference between the flowers of eleven grassland species near Falls Creek, Australia, as part of an invasive species detection experiment. The reliability of the method was tested by measuring the leaf colour of five residential garden shrub species in Ballarat, Australia using five different types of digital camera. Flowers and leaves had overlapping but distinct colour distributions. Calculated colour differences corresponded well with qualitative comparisons. Estimates of proportional cover of yellow flowers identified using colour measurements correlated well with estimates obtained by measuring and counting individual flowers. Digital SLR and mirrorless cameras were superior to phone cameras and point-and-shoot cameras for producing reliable measurements, particularly under variable lighting conditions. The analysis of digital images taken with digital cameras is a practicable method for quantifying plant flower and leaf colour in the field or lab. Quantitative, repeatable measurements allow for comparisons between species and generalisations across species and studies. This allows plant colour to be related to human perception and preferences and, ultimately, species management. PMID:23977275

  16. Fruit over sunbed: carotenoid skin colouration is found more attractive than melanin colouration.

    PubMed

    Lefevre, Carmen E; Perrett, David I

    2015-01-01

    Skin colouration appears to play a pivotal part in facial attractiveness. Skin yellowness contributes to an attractive appearance and is influenced both by dietary carotenoids and by melanin. While both increased carotenoid colouration and increased melanin colouration enhance apparent health in Caucasian faces by increasing skin yellowness, it remains unclear, firstly, whether both pigments contribute to attractiveness judgements, secondly, whether one pigment is clearly preferred over the other, and thirdly, whether these effects depend on the sex of the face. Here, in three studies, we examine these questions using controlled facial stimuli transformed to be either high or low in (a) carotenoid colouration, or (b) melanin colouration. We show, firstly, that both increased carotenoid colouration and increased melanin colouration are found attractive compared to lower levels of these pigments. Secondly, we show that carotenoid colouration is consistently preferred over melanin colouration when levels of colouration are matched. In addition, we find an effect of the sex of stimuli with stronger preferences for carotenoids over melanin in female compared to male faces, irrespective of the sex of the observer. These results are interpreted as reflecting preferences for sex-typical skin colouration: men have darker skin than women and high melanization in male faces may further enhance this masculine trait, thus carotenoid colouration is not less desirable, but melanin colouration is relatively more desirable in males compared to females. Taken together, our findings provide further support for a carotenoid-linked health-signalling system that is highly important in mate choice.

  17. Social perception in synaesthesia for colour.

    PubMed

    Janik McErlean, Agnieszka B; Susilo, Tirta; Rezlescu, Constantin; Bray, Amy; Banissy, Michael J

    2016-12-11

    Synaesthesia is a rare phenomenon in which stimulation in one modality (e.g., audition) evokes a secondary percept not associated with the first (e.g., colour). Prior work has suggested links between synaesthesia and other neurodevelopmental conditions that are linked to altered social perception abilities. With this in mind, here we sought to examine social perception abilities in grapheme-colour synaesthesia (where achromatic graphemes evoke colour experiences) by examining facial identity and facial emotion perception in synaesthetes and controls. Our results indicate that individuals who experience grapheme-colour synaesthesia outperformed controls on tasks involving fine visual discrimination of facial identity and emotion, but not on tasks involving holistic face processing. These findings are discussed in the context of broader perceptual and cognitive traits previously associated with synaesthesia for colour, with the suggestion that performance benefits shown by grapheme-colour synaesthetes may be related to domain-general visual discrimination biases observed in this group.

  18. Colour Consideration for Waiting areas in hospitals

    NASA Astrophysics Data System (ADS)

    Zraati, Parisa

    2012-08-01

    Colour is one the most important factors in the nature that can have some affects on human behaviour. Many years ago, it was proven that using colour in public place can have some affect on the users. Depend of the darkness and lightness; it can be vary from positive to negative. The research will mainly focus on the colour and psychological influences and physical factors. The statement of problem in this research is what is impact of colour usually applied to waiting area? The overall aim of the study is to explore the visual environment of hospitals and to manage the colour psychological effect of the hospital users in the waiting area by creating a comfortable, pleasant and cozy environment for users while spend their time in waiting areas. The analysisconcentrate on satisfaction and their interesting regarding applied colour in two private hospital waiting area in Malaysia.

  19. Resources for Adapting Low Vision Training Materials for the Adult with Low Literacy Skills. Practice Report

    ERIC Educational Resources Information Center

    Tucker, Laurel A.

    2004-01-01

    Adults with low vision who seek clinical low vision services need to be able to read (that is, to interpret or understand words, numbers, and symbols in print meaningfully). Reading difficulties that adults encounter during low vision therapy may be directly connected to a visual impairment or may be related to other reading problems, such as…

  20. Colour assortative pairing in a colour polymorphic lizard is independent of population morph diversity

    NASA Astrophysics Data System (ADS)

    Pérez i de Lanuza, Guillem; Font, Enrique; Carretero, Miguel Ángel

    2016-10-01

    Previous work with a colour polymorphic population of Podarcis muralis (Lacertidae) revealed that lizards pair by ventral colour, favouring the same colour (i.e. homomorphic) pairs. Such assortative pairing, which probably results in colour assortative mating, can have consequences for the genetic structure of the population and potentially promote speciation. The population previously studied, located in the Pyrenees, encompasses white, yellow and orange animals, as well as intermediate white-orange and yellow-orange morphs. However, other Pyrenean populations of P. muralis have less ventral colour morphs. Our aim in this study is to test the generality of the assortative colour pairing system, extending our previous analyses to populations with different morph compositions and frequencies. The results show that the assortative pattern of pairing is similar in all the populations analysed and, hence, independent of morph composition and not restricted to pentamorphic populations. This suggests that assortative pairing by colour is a general phenomenon for colour polymorphic populations of P. muralis.

  1. Colour assortative pairing in a colour polymorphic lizard is independent of population morph diversity.

    PubMed

    Pérez I de Lanuza, Guillem; Font, Enrique; Carretero, Miguel Ángel

    2016-10-01

    Previous work with a colour polymorphic population of Podarcis muralis (Lacertidae) revealed that lizards pair by ventral colour, favouring the same colour (i.e. homomorphic) pairs. Such assortative pairing, which probably results in colour assortative mating, can have consequences for the genetic structure of the population and potentially promote speciation. The population previously studied, located in the Pyrenees, encompasses white, yellow and orange animals, as well as intermediate white-orange and yellow-orange morphs. However, other Pyrenean populations of P. muralis have less ventral colour morphs. Our aim in this study is to test the generality of the assortative colour pairing system, extending our previous analyses to populations with different morph compositions and frequencies. The results show that the assortative pattern of pairing is similar in all the populations analysed and, hence, independent of morph composition and not restricted to pentamorphic populations. This suggests that assortative pairing by colour is a general phenomenon for colour polymorphic populations of P. muralis.

  2. The multiple disguises of spiders: web colour and decorations, body colour and movement.

    PubMed

    Théry, Marc; Casas, Jérôme

    2009-02-27

    Diverse functions have been assigned to the visual appearance of webs, spiders and web decorations, including prey attraction, predator deterrence and camouflage. Here, we review the pertinent literature, focusing on potential camouflage and mimicry. Webs are often difficult to detect in a heterogeneous visual environment. Static and dynamic web distortions are used to escape visual detection by prey, although particular silk may also attract prey. Recent work using physiological models of vision taking into account visual environments rarely supports the hypothesis of spider camouflage by decorations, but most often the prey attraction and predator confusion hypotheses. Similarly, visual modelling shows that spider coloration is effective in attracting prey but not in conveying camouflage. Camouflage through colour change might be used by particular crab spiders to hide from predator or prey on flowers of different coloration. However, results obtained on a non-cryptic crab spider suggest that an alternative function of pigmentation may be to avoid UV photodamage through the transparent cuticle. Numerous species are clearly efficient locomotory mimics of ants, particularly in the eyes of their predators. We close our paper by highlighting gaps in our knowledge.

  3. The multiple disguises of spiders: web colour and decorations, body colour and movement

    PubMed Central

    Théry, Marc; Casas, Jérôme

    2008-01-01

    Diverse functions have been assigned to the visual appearance of webs, spiders and web decorations, including prey attraction, predator deterrence and camouflage. Here, we review the pertinent literature, focusing on potential camouflage and mimicry. Webs are often difficult to detect in a heterogeneous visual environment. Static and dynamic web distortions are used to escape visual detection by prey, although particular silk may also attract prey. Recent work using physiological models of vision taking into account visual environments rarely supports the hypothesis of spider camouflage by decorations, but most often the prey attraction and predator confusion hypotheses. Similarly, visual modelling shows that spider coloration is effective in attracting prey but not in conveying camouflage. Camouflage through colour change might be used by particular crab spiders to hide from predator or prey on flowers of different coloration. However, results obtained on a non-cryptic crab spider suggest that an alternative function of pigmentation may be to avoid UV photodamage through the transparent cuticle. Numerous species are clearly efficient locomotory mimics of ants, particularly in the eyes of their predators. We close our paper by highlighting gaps in our knowledge. PMID:18990672

  4. A paradox of temporal perception revealed by a stimulus oscillating in colour and orientation.

    PubMed

    Clifford, Colin W G; Arnold, Derek H; Pearson, Joel

    2003-09-01

    Psychophysical experiments with stimuli oscillating concurrently in colour and orientation revealed an apparently paradoxical dissociation between the perceived simultaneity of stimulus changes and the perceptual pairing of the events demarked by those changes. When subjects were required to report whether changes in colour and orientation were simultaneous, judgements were generally accurate within +/-10 ms. When subjects were required to report which colour was paired predominantly with which orientation, judgements showed a systematic temporal bias of up to 50 ms in favour of colour. This dissociation between different temporal judgements concerning the same stimulus sequence is not predicted by any of the current models of binding in conscious vision. We propose an account of these data based on the temporal response properties of colour- and orientation-selective model neurons such that the perceived pairing of visual attributes is modelled as the cross-correlation of time-varying neural response profiles and thus reflects both neuronal latencies and the rate of rapid adaptation rather than simply the temporal pattern of responses to stimulus transitions.

  5. The Physical Environment and the Visually Impaired.

    ERIC Educational Resources Information Center

    Braf, Per-Gunnar

    Reported are results of a project carried out at the Swedish Institute for the Handicapped to determine needs of the visually impaired in the planning and adaptation of buildings and other forms of physical environment. Chapter 1 considers implications of impaired vision and includes definitions, statistics, and problems of the visually impaired…

  6. Local adaptation and divergence in colour signal conspicuousness between monomorphic and polymorphic lineages in a lizard.

    PubMed

    McLean, C A; Moussalli, A; Stuart-Fox, D

    2014-12-01

    Population differences in visual environment can lead to divergence in multiple components of animal coloration including signalling traits and colour patterns important for camouflage. Divergence may reflect selection imposed by different receivers (conspecifics, predators), which depends in turn on the location of the colour patch. We tested for local adaptation of two genetically and phenotypically divergent lineages of a rock-inhabiting lizard, Ctenophorus decresii, by comparing the visual contrast of colour patches to different receivers in native and non-native environments. The lineages differ most notably in male throat coloration, which is polymorphic in the northern lineage and monomorphic in the southern lineage, but also differ in dorsal and lateral coloration, which is visible to both conspecifics and potential predators. Using models of animal colour vision, we assessed whether lineage-specific throat, dorsal and lateral coloration enhanced conspicuousness to conspecifics, increased crypsis to birds or both, respectively, when viewed against the predominant backgrounds from each lineage. Throat colours were no more conspicuous against native than non-native rock but contrasted more strongly with native lichen, which occurs patchily on rocks inhabited by C. decresii. Conversely, neck coloration (lateral) more closely matched native lichen. Furthermore, although dorsal coloration of southern males was consistently more conspicuous to birds than that of northern males, both lineages had similar absolute conspicuousness against their native backgrounds. Combined, our results are consistent with local adaptation of multiple colour traits in relation to multiple receivers, suggesting that geographic variation in background colour has influenced the evolution of lineage-specific coloration in C. decresii.

  7. Ultraviolet vision and foraging in dip and plunge diving birds

    PubMed Central

    Håstad, Olle; Ernstdotter, Emma; Ödeen, Anders

    2005-01-01

    Many fishes are sensitive to ultraviolet (UV) light and display UV markings during courtship. As UV scatters more than longer wavelengths of light, these signals are only effective at short distances, reducing the risk of detection by swimming predators. Such underwater scattering will be insignificant for dip and plunge diving birds, which prey on fishes just below the water surface. One could therefore expect to find adaptations in the eyes of dip and plunge diving birds that tune colour reception to UV signals. We used a molecular method to survey the colour vision tuning of five families of dip or plunge divers and compared the results with those from sister taxa of other foraging methods. We found evidence of extended UV vision only in gulls (Laridae). Based on available evidence, it is more probable that this trait is associated with their terrestrial foraging habits rather than piscivory. PMID:17148194

  8. Ultraviolet vision and foraging in dip and plunge diving birds.

    PubMed

    Håstad, Olle; Ernstdotter, Emma; Odeen, Anders

    2005-09-22

    Many fishes are sensitive to ultraviolet (UV) light and display UV markings during courtship. As UV scatters more than longer wavelengths of light, these signals are only effective at short distances, reducing the risk of detection by swimming predators. Such underwater scattering will be insignificant for dip and plunge diving birds, which prey on fishes just below the water surface. One could therefore expect to find adaptations in the eyes of dip and plunge diving birds that tune colour reception to UV signals. We used a molecular method to survey the colour vision tuning of five families of dip or plunge divers and compared the results with those from sister taxa of other foraging methods. We found evidence of extended UV vision only in gulls (Laridae). Based on available evidence, it is more probable that this trait is associated with their terrestrial foraging habits rather than piscivory.

  9. Color vision test

    MedlinePlus

    ... from birth) color vision problems: Achromatopsia -- complete color blindness , seeing only shades of gray Deuteranopia -- difficulty telling ... test - color; Ishihara color vision test Images Color blindness tests References Adams AJ, Verdon WA, Spivey BE. ...

  10. Chemicals Industry Vision

    SciTech Connect

    none,

    1996-12-01

    Chemical industry leaders articulated a long-term vision for the industry, its markets, and its technology in the groundbreaking 1996 document Technology Vision 2020 - The U.S. Chemical Industry. (PDF 310 KB).

  11. A Robot Vision System.

    DTIC Science & Technology

    1985-12-01

    ix e ...... . . . . . . .. . - . 1 I. Introduction This project includes the design and implementation of a vision - based goal achievement system. The... vision system design base . Final Conclusions Stereo vision is useless beyond about 15 feet for the camera separation of .75 feet, a picture...model. Such monocular vision and modelling, duplicated for two cameras, would give a second source of model data for resolving ambiguities, and

  12. Quebec model for low vision rehabilitation.

    PubMed

    Robillard, Nicole; Overbury, Olga

    2006-06-01

    The increase in longevity (and secondary morbidity) in the Quebec population adds social and financial pressure to society, as it does elsewhere in Canada and in many western countries. This article gives a brief history of the evolution of vision rehabilitation services in Quebec and describes how services are provided for people with low vision throughout the province. Although numerous groups, associations, centres, and resources are available to assist people with vision impairments, such as the Canadian National Institute for the Blind-Québec, the majority of visual rehabilitation services are provided by government-sponsored rehabilitation centres, namely the Centres régionaux de réadaptation en déficience physique that are located strategically throughout the province. Low vision clinical evaluations in these centres are shared by 36 optometrists throughout the province. Between 5 and 7 ophthalmologists are involved in low vision care, half in university-affiliated hospitals, primarily in Montreal. There may be delays of up to 6 months to be seen in a funded low vision clinic. Statistics obtained from la Régie de l'assurance maladie du Québec show that there are approximately 8,000 requests for low vision aids every year, and that 80% of clients retain at least some level of visual function. Services are covered by Medicare and low vision aids are provided at no cost, although ophthalmologists cannot prescribe low vision aids through the Medicare-funded system. We must ensure that the capacity of our system continues to provide adequately for clientele in the future.

  13. Colour As a Signal for Entraining the Mammalian Circadian Clock

    PubMed Central

    Walmsley, Lauren; Hanna, Lydia; Mouland, Josh; Martial, Franck; West, Alexander; Smedley, Andrew R.; Bechtold, David A.; Webb, Ann R.; Lucas, Robert J.; Brown, Timothy M.

    2015-01-01

    Twilight is characterised by changes in both quantity (“irradiance”) and quality (“colour”) of light. Animals use the variation in irradiance to adjust their internal circadian clocks, aligning their behaviour and physiology with the solar cycle. However, it is currently unknown whether changes in colour also contribute to this entrainment process. Using environmental measurements, we show here that mammalian blue–yellow colour discrimination provides a more reliable method of tracking twilight progression than simply measuring irradiance. We next use electrophysiological recordings to demonstrate that neurons in the mouse suprachiasmatic circadian clock display the cone-dependent spectral opponency required to make use of this information. Thus, our data show that some clock neurons are highly sensitive to changes in spectral composition occurring over twilight and that this input dictates their response to changes in irradiance. Finally, using mice housed under photoperiods with simulated dawn/dusk transitions, we confirm that spectral changes occurring during twilight are required for appropriate circadian alignment under natural conditions. Together, these data reveal a new sensory mechanism for telling time of day that would be available to any mammalian species capable of chromatic vision. PMID:25884537

  14. The eyes and vision of butterflies.

    PubMed

    Arikawa, Kentaro

    2017-03-22

    Butterflies use colour vision when searching for flowers. Unlike the trichromatic retinas of humans (blue, green, and red cones; plus rods) and honeybees (ultraviolet, blue, and green photoreceptors), butterfly retinas typically have six or more photoreceptor classes with distinct spectral sensitivities. The eyes of the Japanese yellow swallowtail (Papilio xuthus) contain ultraviolet, violet, blue, green, red and broad-band receptors, with each ommatidium housing nine photoreceptor cells in one of three fixed combinations. The Papilio eye is thus a random patchwork of three types of spectrally heterogeneous ommatidia. To determine whether Papilio use all of their receptors to see colours, we measured their ability to discriminate monochromatic lights of slightly different wavelengths. We found that Papilio can detect differences as small as 1-2 nm in three wavelength regions, rivalling human performance. We then used mathematical modelling to infer which photoreceptors are involved in wavelength discrimination. Our simulation indicated that the Papilio vision is tetrachromatic, employing the ultraviolet, blue, green and red receptors. The random array of three ommatidial types is a common feature in butterflies. To address the question of how butterflies' spectrally complex eyes evolved, we studied their developmental process. We have found that the development of butterfly eyes shares its molecular logic with that of Drosophila: the three-way stochastic expression pattern of the transcription factor Spineless determines the fate of ommatidia, creating the random array in Papilio. This article is protected by copyright. All rights reserved.

  15. Brilliant Colours from a White Snow Cover

    ERIC Educational Resources Information Center

    Vollmer, Michael; Shaw, Joseph A

    2013-01-01

    Surprisingly colourful views are possible from sparkling white snow. It is well known that similarly colourful features can exist in the sky whenever appropriate ice crystals are around. However, the transition of light reflection and refraction from ice crystals in the air to reflection and refraction from those in snow on the ground is not…

  16. Robot Vision Library

    NASA Technical Reports Server (NTRS)

    Howard, Andrew B.; Ansar, Adnan I.; Litwin, Todd E.; Goldberg, Steven B.

    2009-01-01

    The JPL Robot Vision Library (JPLV) provides real-time robot vision algorithms for developers who are not vision specialists. The package includes algorithms for stereo ranging, visual odometry and unsurveyed camera calibration, and has unique support for very wideangle lenses

  17. Worldwide patterns of bird colouration on islands.

    PubMed

    Doutrelant, Claire; Paquet, Matthieu; Renoult, Julien P; Grégoire, Arnaud; Crochet, Pierre-André; Covas, Rita

    2016-05-01

    Island environments share distinctive characteristics that offer unique opportunities to investigate parallel evolution. Previous research has produced evidence of an island syndrome for morphological traits, life-history strategies and ecological niches, but little is known about the response to insularity of other important traits such as animal signals. Here, we tested whether birds' plumage colouration is part of the island syndrome. We analysed with spectrophotometry the colouration of 116 species endemic to islands and their 116 closest mainland relatives. We found a pattern of reduced brightness and colour intensity for both sexes on islands. In addition, we found a decrease in the number of colour patches on islands that, in males, was associated with a decrease in the number of same-family sympatric species. These results demonstrate a worldwide pattern of parallel colour changes on islands and suggest that a relaxation of selection on species recognition may be one of the mechanisms involved.

  18. Improved colour matching technique for fused nighttime imagery with daytime colours

    NASA Astrophysics Data System (ADS)

    Hogervorst, Maarten A.; Toet, Alexander

    2016-10-01

    Previously, we presented a method for applying daytime colours to fused nighttime (e.g., intensified and LWIR) imagery (Toet and Hogervorst, Opt.Eng. 51(1), 2012). Our colour mapping not only imparts a natural daylight appearance to multiband nighttime images but also enhances the contrast and visibility of otherwise obscured details. As a result, this colourizing method leads to increased ease of interpretation, better discrimination and identification of materials, faster reaction times and ultimately improved situational awareness (Toet e.a., Opt.Eng.53(4), 2014). A crucial step in this colouring process is the choice of a suitable colour mapping scheme. When daytime colour images and multiband sensor images of the same scene are available the colour mapping can be derived from matching image samples (i.e., by relating colour values to sensor signal intensities). When no exact matching reference images are available the colour transformation can be derived from the first-order statistical properties of the reference image and the multiband sensor image (Toet, Info. Fus. 4(3), 2003). In the current study we investigated new colour fusion schemes that combine the advantages of the both methods, using the correspondence between multiband sensor values and daytime colours (1st method) in a smooth transformation (2nd method). We designed and evaluated three new fusion schemes that focus on: i) a closer match with the daytime luminances, ii) improved saliency of hot targets and iii) improved discriminability of materials

  19. Both coloured overlays and coloured lenses can improve reading fluency, but their optimal chromaticities differ.

    PubMed

    Lightstone, A; Lightstone, T; Wilkins, A

    1999-07-01

    Some individuals read more fluently when the text is coloured: i.e., when coloured sheets of plastic (overlays) are placed upon the page, or when coloured lenses are worn. Overlays provide a surface colour whereas lenses mimic a change in the colour of a light source. The neural mechanisms that underlie colour constancy ensure that the chromaticity of overlays and lenses is processed differently by the visual system. We investigated (1) the relationship between the optimal colours of overlays and lenses, and (2) how reading rate is affected by a particular colour in overlays and lenses. In 100 patients we noted (1) the overlay(s) chosen from among the 29 combinations of the 10 IOO Intuitive Overlays which sample chromaticity systematically and (2) the chromaticity co-ordinates of the lenses subsequently chosen using the intuitive Colorimeter, a device providing a light source that can be adjusted in hue, saturation and luminance independently. The relationship between the chromaticities of the overlays and the lenses showed considerable variation. In a second study, patients attending the Specific Learning Difficulties clinic at the Institute of Optometry, London, were given overlays to use for two months. Seventeen who derived benefit were examined using the Intuitive Colorimeter. Patients were asked to read aloud randomly ordered common words (Wilkins Rate of Reading Test): (1) with no colour, (2) with the chosen overlay, (3) with lenses matching the chosen overlay and (4) with lenses matching the Colorimeter setting. The aids increased reading rate significantly only in conditions (2) and (4). There was no significant improvement when lenses matching the overlay colour were used, and under this condition the reading rate was significantly poorer than in conditions (2) and (4). The colour of a lens will improve reading only if it is selected under conditions that mimic a change in the colour of a light source: coloured overlays give no clinically reliable guide

  20. Computational approaches to vision

    NASA Technical Reports Server (NTRS)

    Barrow, H. G.; Tenenbaum, J. M.

    1986-01-01

    Vision is examined in terms of a computational process, and the competence, structure, and control of computer vision systems are analyzed. Theoretical and experimental data on the formation of a computer vision system are discussed. Consideration is given to early vision, the recovery of intrinsic surface characteristics, higher levels of interpretation, and system integration and control. A computational visual processing model is proposed and its architecture and operation are described. Examples of state-of-the-art vision systems, which include some of the levels of representation and processing mechanisms, are presented.

  1. Microwave vision for robots

    NASA Technical Reports Server (NTRS)

    Lewandowski, Leon; Struckman, Keith

    1994-01-01

    Microwave Vision (MV), a concept originally developed in 1985, could play a significant role in the solution to robotic vision problems. Originally our Microwave Vision concept was based on a pattern matching approach employing computer based stored replica correlation processing. Artificial Neural Network (ANN) processor technology offers an attractive alternative to the correlation processing approach, namely the ability to learn and to adapt to changing environments. This paper describes the Microwave Vision concept, some initial ANN-MV experiments, and the design of an ANN-MV system that has led to a second patent disclosure in the robotic vision field.

  2. A child's vision.

    PubMed

    Nye, Christina

    2014-06-01

    Implementing standard vision screening techniques in the primary care practice is the most effective means to detect children with potential vision problems at an age when the vision loss may be treatable. A critical period of vision development occurs in the first few weeks of life; thus, it is imperative that serious problems are detected at this time. Although it is not possible to quantitate an infant's vision, evaluating ocular health appropriately can mean the difference between sight and blindness and, in the case of retinoblastoma, life or death.

  3. Vision and multiple sclerosis.

    PubMed

    Hickman, Simon J; Raoof, Naz; McLean, Rebecca J; Gottlob, Irene

    2014-01-01

    Multiple sclerosis can affect vision in many ways, including optic neuritis, chronic optic neuropathy, retrochiasmal visual field defects, higher order cortical processing, double vision, nystagmus and also by related ocular conditions such as uveitis. There are also side effects from recently introduced multiple sclerosis treatments that can affect vision. This review will discuss all these aspects and how they come together to cause visual symptoms. It will then focus on practical aspects of how to recognise when there is a vision problem in a multiple sclerosis patient and on what treatments are available to improve vision.

  4. Acquired color vision deficiency.

    PubMed

    Simunovic, Matthew P

    2016-01-01

    Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.

  5. The Impact of Visual Impairment on Perceived School Climate

    ERIC Educational Resources Information Center

    Schade, Benjamin; Larwin, Karen H.

    2015-01-01

    The current investigation examines whether visual impairment has an impact on a student's perception of the school climate. Using a large national sample of high school students, perceptions were examined for students with vision impairment relative to students with no visual impairments. Three factors were examined: self-reported level of…

  6. Vision multiplexing: an optical engineering concept for low-vision aids

    NASA Astrophysics Data System (ADS)

    Peli, Eli

    2007-09-01

    The normal visual system provides a wide field of view apparently at high resolution. The wide field is continuously monitored at low resolution for navigation and detection of objects of interest. These objects are sampled using the high-resolution fovea, applying a temporal multiplexing scheme. Most vision impairments that cause low vision impact upon only one of the components; the peripheral low-resolution wide field or the central high-resolution fovea. The loss of one of these components prevents the interplay of central and peripheral vision needed for normal function and causes disability. Traditional low-vision aids improve the impacted component, but usually at a cost of a significant loss in the surviving component. For example, magnifying devices increase resolution but reduce the field of view, while minifying devices increase the field of view but reduce resolution. A general optical engineering approach - vision multiplexing - is presented. Vision multiplexing seeks to provide both the wide field of view and the high-resolution information in ways that could be accessed and interpreted by the visual system. The use of various optical and electro-optical methods in the development of a number of new visual aids, all of which apply vision multiplexing to restore the interplay of high-resolution and wide-angle vision using eye movements in a natural way, will be described. Vision-multiplexing devices at various stages of development and testing illustrate the successes and difficulties in applying this approach for patients with tunnel vision, hemianopia (half blindness), and visual acuity loss (usually due to central retinal disease).

  7. Kac's ring: The case of four colours

    NASA Astrophysics Data System (ADS)

    Jain, Manan

    2017-04-01

    We present an instance from nonequilibrium statistical mechanics which combines increase in entropy and finite Poincaré recurrence time. The model we consider is a variation of the well-known Kac's ring where we consider balls of four colours. As is known, Kac introduced this model where balls arranged between lattice sites, in each time step, move one step clockwise. The colour of the balls change as they cross marked sites. This very simple example rationalize the increase in entropy and recurrence. In our variation, the interesting quantity which counts the difference in the number of balls of different colours is shown to reduce to a set of linear equations if the probability of change of colour is symmetric among a pair of colours. The transfer matrix turns out to be non-Hermitian with real eigenvalues, leading to all colours being equally likely for long times, and a monotonically varying entropy. The new features appearing due to four colours is very instructive.

  8. Physicochemical and physiological basis of dichromatic colour

    NASA Astrophysics Data System (ADS)

    Kreft, Samo; Kreft, Marko

    2007-11-01

    Out of three perceptual characteristics of the colour of any substance, the hue depends mostly on the spectral properties of a substance, while the brightness and saturation depend also on the concentration of a substance and its thickness. Here, we report that evident change of the hue of the colour (i.e., from green to red) is due to a change in concentration or the thickness of a layer in some exceptional substances such as pumpkin seed oil or an aqueous solution of bromophenol blue. In some regions of Central Europe, salad dressing is made preferably with the pumpkin seed oil, which has a strong characteristic nut-like taste and remarkable properties of the colour: it appears red in a bottle, but green when served as a salad dressing. The colour of the pumpkin seed oil was previously described as brownish yellow, dark green, dark green to red ochre or dark reddish brown to light yellow green. We elucidated the physicochemical and physiological basis of such dichromatism by Beer-Lambert law and by the characteristics of human colour perception. Our concept was corroborated by the outcome of calculations of colour from spectral properties using colour matching functions. We found that dichromatism is observed if the absorption spectrum of any substance has at least two local minima: one wide but shallow and one narrow but deep local minimum.

  9. Biological components of colour preference in infancy.

    PubMed

    Franklin, Anna; Bevis, Laura; Ling, Yazhu; Hurlbert, Anya

    2010-03-01

    Adult colour preference has been summarized quantitatively in terms of weights on the two fundamental neural processes that underlie early colour encoding: the S-(L+M) ('blue-yellow') and L-M ('red-green') cone-opponent contrast channels (Ling, Hurlbert & Robinson, 2006; Hurlbert & Ling, 2007). Here, we investigate whether colour preference in 4-5-month-olds may be analysed in the same way. We recorded infants' eye-movements in response to pairwise presentations of eight colour stimuli varying only in hue. Infants looked longest at reddish and shortest at greenish hues. Analyses revealed that the L-M and S-(L+M) contrast between stimulus colour and background explained around half of the variation in infant preference across the hue spectrum. Unlike adult colour preference patterns, there was no evidence for sex differences in the weights on either of the cone-opponent contrast components. The findings provide a quantitative model of infant colour preference that summarizes variation in infant preference across hues.

  10. Artificial selection for food colour preferences.

    PubMed

    Cole, Gemma L; Endler, John A

    2015-04-07

    Colour is an important factor in food detection and acquisition by animals using visually based foraging. Colour can be used to identify the suitability of a food source or improve the efficiency of food detection, and can even be linked to mate choice. Food colour preferences are known to exist, but whether these preferences are heritable and how these preferences evolve is unknown. Using the freshwater fish Poecilia reticulata, we artificially selected for chase behaviour towards two different-coloured moving stimuli: red and blue spots. A response to selection was only seen for chase behaviours towards the red, with realized heritabilities ranging from 0.25 to 0.30. Despite intense selection, no significant chase response was recorded for the blue-selected lines. This lack of response may be due to the motion-detection mechanism in the guppy visual system and may have novel implications for the evolvability of responses to colour-related signals. The behavioural response to several colours after five generations of selection suggests that the colour opponency system of the fish may regulate the response to selection.

  11. Most and Least Preferred Colours Differ According to Object Context: New Insights from an Unrestricted Colour Range.

    PubMed

    Jonauskaite, Domicele; Mohr, Christine; Antonietti, Jean-Philippe; Spiers, Peter M; Althaus, Betty; Anil, Selin; Dael, Nele

    2016-01-01

    Humans like some colours and dislike others, but which particular colours and why remains to be understood. Empirical studies on colour preferences generally targeted most preferred colours, but rarely least preferred (disliked) colours. In addition, findings are often based on general colour preferences leaving open the question whether results generalise to specific objects. Here, 88 participants selected the colours they preferred most and least for three context conditions (general, interior walls, t-shirt) using a high-precision colour picker. Participants also indicated whether they associated their colour choice to a valenced object or concept. The chosen colours varied widely between individuals and contexts and so did the reasons for their choices. Consistent patterns also emerged, as most preferred colours in general were more chromatic, while for walls they were lighter and for t-shirts they were darker and less chromatic compared to least preferred colours. This meant that general colour preferences could not explain object specific colour preferences. Measures of the selection process further revealed that, compared to most preferred colours, least preferred colours were chosen more quickly and were less often linked to valenced objects or concepts. The high intra- and inter-individual variability in this and previous reports furthers our understanding that colour preferences are determined by subjective experiences and that most and least preferred colours are not processed equally.

  12. Most and Least Preferred Colours Differ According to Object Context: New Insights from an Unrestricted Colour Range

    PubMed Central

    Jonauskaite, Domicele; Mohr, Christine; Antonietti, Jean-Philippe; Spiers, Peter M.; Althaus, Betty; Anil, Selin; Dael, Nele

    2016-01-01

    Humans like some colours and dislike others, but which particular colours and why remains to be understood. Empirical studies on colour preferences generally targeted most preferred colours, but rarely least preferred (disliked) colours. In addition, findings are often based on general colour preferences leaving open the question whether results generalise to specific objects. Here, 88 participants selected the colours they preferred most and least for three context conditions (general, interior walls, t-shirt) using a high-precision colour picker. Participants also indicated whether they associated their colour choice to a valenced object or concept. The chosen colours varied widely between individuals and contexts and so did the reasons for their choices. Consistent patterns also emerged, as most preferred colours in general were more chromatic, while for walls they were lighter and for t-shirts they were darker and less chromatic compared to least preferred colours. This meant that general colour preferences could not explain object specific colour preferences. Measures of the selection process further revealed that, compared to most preferred colours, least preferred colours were chosen more quickly and were less often linked to valenced objects or concepts. The high intra- and inter-individual variability in this and previous reports furthers our understanding that colour preferences are determined by subjective experiences and that most and least preferred colours are not processed equally. PMID:27022909

  13. Bumblebees (Bombus terrestris) and honeybees (Apis mellifera) prefer similar colours of higher spectral purity over trained colours.

    PubMed

    Rohde, Katja; Papiorek, Sarah; Lunau, Klaus

    2013-03-01

    Differences in the concentration of pigments as well as their composition and spatial arrangement cause intraspecific variation in the spectral signature of flowers. Known colour preferences and requirements for flower-constant foraging bees predict different responses to colour variability. In experimental settings, we simulated small variations of unicoloured petals and variations in the spatial arrangement of colours within tricoloured petals using artificial flowers and studied their impact on the colour choices of bumblebees and honeybees. Workers were trained to artificial flowers of a given colour and then given the simultaneous choice between three test colours: either the training colour, one colour of lower and one of higher spectral purity, or the training colour, one colour of lower and one of higher dominant wavelength; in all cases the perceptual contrast between the training colour and the additional test colours was similarly small. Bees preferred artificial test flowers which resembled the training colour with the exception that they preferred test colours with higher spectral purity over trained colours. Testing the behaviour of bees at artificial flowers displaying a centripetal or centrifugal arrangement of three equally sized colours with small differences in spectral purity, bees did not prefer any type of artificial flowers, but preferentially choose the most spectrally pure area for the first antenna contact at both types of artificial flowers. Our results indicate that innate preferences for flower colours of high spectral purity in pollinators might exert selective pressure on the evolution of flower colours.

  14. Colouration and colour changes of the fiddler crab, Uca capricornis: a descriptive study.

    PubMed

    Detto, Tanya; Hemmi, Jan M; Backwell, Patricia R Y

    2008-02-20

    Colour changes in animals may be triggered by a variety of social and environmental factors and may occur over a matter of seconds or months. Crustaceans, like fiddler crabs (genus Uca), are particularly adept at changing their colour and have been the focus of numerous studies. However, few of these studies have attempted to quantitatively describe the individual variation in colour and pattern or their adaptive significance. This paper quantitatively describes the colour patterns of the fiddler crab Uca capricornis and their ability to change on a socially significant timescale. The most dramatic changes in colour pattern are associated with moulting. These ontogenetic changes result in a general reduction of the colour pattern with increasing size, although females are more colourful and variable than similarly-sized males. Uca capricornis are also capable of rapid colour changes in response to stress, but show no endogenous rhythms associated with the semilunar and tidal cycles commonly reported in other fiddler crabs. The extreme colour polymorphism and the relative stability of the colour patterns in Uca capricornis are consistent with their use in visually mediated mate recognition.

  15. Individual colour patches as multicomponent signals.

    PubMed

    Grether, Gregory F; Kolluru, Gita R; Nersissian, Karen

    2004-08-01

    Colour patches are complex traits, the components of which may evolve independently through a variety of mechanisms. Although usually treated as simple, two-dimensional characters and classified as either structural or pigmentary, in reality colour patches are complicated, three-dimensional structures that often contain multiple pigment types and structural features. The basic dermal chromatophore unit of fishes, reptiles and amphibians consists of three contiguous cell layers. Xanthophores and erythrophores in the outermost layer contain carotenoid and pteridine pigments that absorb short-wave light; iridophores in the middle layer contain crystalline platelets that reflect light back through the xanthophores; and melanophores in the basal layer contain melanins that absorb light across the spectrum. Changes in any one component of a chromatophore unit can drastically alter the reflectance spectrum produced, and for any given adaptive outcome (e.g. an increase in visibility), there may be multiple biochemical or cellular routes that evolution could take, allowing for divergent responses by different populations or species to similar selection regimes. All of the mechanisms of signal evolution that previously have been applied to single ornaments (including whole colour patches) could potentially be applied to the individual components of colour patches. To reach a complete understanding of colour patch evolution, however, it may be necessary to take an explicitly multi-trait approach. Here, we review multiple trait evolution theory and the basic mechanisms of colour production in fishes, reptiles and amphibians, and use a combination of computer simulations and empirical examples to show how multiple trait evolution theory can be applied to the components of single colour patches. This integrative perspective on animal colouration opens up a host of new questions and hypotheses. We offer specific, testable functional hypotheses for the most common pigmentary

  16. The colour wheels of art, perception, science and physiology

    NASA Astrophysics Data System (ADS)

    Harkness, Nick

    2006-06-01

    Colour is not the domain of any one discipline be it art, philosophy, psychology or science. Each discipline has its own colour wheel and this presentation examines the origins and philosophies behind the colour circles of Art, Perception, Science and Physiology (after image) with reference to Aristotle, Robert Boyle, Leonardo da Vinci, Goethe, Ewald Hering and Albert Munsell. The paper analyses and discusses the differences between the four colour wheels using the Natural Colour System® notation as the reference for hue (the position of colours within each of the colour wheels). Examination of the colour wheels shows the dominance of blue in the wheels of art, science and physiology particularly at the expense of green. This paper does not consider the three-dimensionality of colour space its goal was to review the hue of a colour with regard to its position on the respective colour wheels.

  17. How to assess vision.

    PubMed

    Marsden, Janet

    2016-09-21

    Rationale and key points An objective assessment of the patient's vision is important to assess variation from 'normal' vision in acute and community settings, to establish a baseline before examination and treatment in the emergency department, and to assess any changes during ophthalmic outpatient appointments. » Vision is one of the essential senses that permits people to make sense of the world. » Visual assessment does not only involve measuring central visual acuity, it also involves assessing the consequences of reduced vision. » Assessment of vision in children is crucial to identify issues that might affect vision and visual development, and to optimise lifelong vision. » Untreatable loss of vision is not an inevitable consequence of ageing. » Timely and repeated assessment of vision over life can reduce the incidence of falls, prevent injury and optimise independence. Reflective activity 'How to' articles can help update you practice and ensure it remains evidence based. Apply this article to your practice. Reflect on and write a short account of: 1. How this article might change your practice when assessing people holistically. 2. How you could use this article to educate your colleagues in the assessment of vision.

  18. Detection and discrimination of colour, a comparison of physiological and psychophysical data

    NASA Astrophysics Data System (ADS)

    Valberg, A.; Lee, B. B.

    1989-01-01

    Whereas the physiological basis of colorimetry (colour matches) is well understood in terms of the trireceptor theory of colour vision, colour discrimination and scaling still lack a comparable foundation. We present here experimental data that demonstrate how sensitivity and responsiveness of different types of cone-opponent and non-opponent cells of the macaque monkey correlate with human threshold sensitivity on the one hand, and how they in combination can be used to construct a suprathreshold equidistant colour space. Psychophysical thresholds correlate well with the threshold envelope of the most sensitive cells when stimuli are projected upon a steady white background. Detection thresholds for stimuli of differing wavelength and purity (saturation) generally indicate a transition from a phasic non-opponent system to a tonic opponent system of on-centre cells as purity increases. Detection and chromatic discrimination thresholds coincide only for long and short wavelengths of high purity, whereas they differ for mid-spectral lights. Different cell types may thus support detection and discrimination with different stimuli. With chromatic scaling of surface colours on the other hand, when stimuli are darker than an adaptation field still other cell types are needed. We demonstrate that it is possible, from a combination of on- and off-opponent cells, to reconstruct a uniform colour space, using summed outputs of cells with the same cone combination and vector addition for cells with different combinations. Different hues are represented by opponent cells with inputs from different cone types, the hue percept being related to the ratio of the activities of these cell systems.

  19. Coherent modulation of stimulus colour can affect visually induced self-motion perception.

    PubMed

    Nakamura, Shinji; Seno, Takeharu; Ito, Hiroyuki; Sunaga, Shoji

    2010-01-01

    The effects of dynamic colour modulation on vection were investigated to examine whether perceived variation of illumination affects self-motion perception. Participants observed expanding optic flow which simulated their forward self-motion. Onset latency, accumulated duration, and estimated magnitude of the self-motion were measured as indices of vection strength. Colour of the dots in the visual stimulus was modulated between white and red (experiment 1), white and grey (experiment 2), and grey and red (experiment 3). The results indicated that coherent colour oscillation in the visual stimulus significantly suppressed the strength of vection, whereas incoherent or static colour modulation did not affect vection. There was no effect of the types of the colour modulation; both achromatic and chromatic modulations turned out to be effective in inhibiting self-motion perception. Moreover, in a situation where the simulated direction of a spotlight was manipulated dynamically, vection strength was also suppressed (experiment 4). These results suggest that observer's perception of illumination is critical for self-motion perception, and rapid variation of perceived illumination would impair the reliabilities of visual information in determining self-motion.

  20. Why colour in subterranean vertebrates? Exploring the evolution of colour patterns in caecilian amphibians.

    PubMed

    Wollenberg, K C; Measey, C John

    2009-05-01

    The proximate functions of animal skin colour are difficult to assign as they can result from natural selection, sexual selection or neutral evolution under genetic drift. Most often colour patterns are thought to signal visual stimuli; so,their presence in subterranean taxa is perplexing. We evaluate the adaptive nature of colour patterns in nearly a third of all known species of caecilians, an order of amphibians most of which live in tropical soils and leaf litter. We found that certain colour pattern elements in caecilians can be explained based on characteristics concerning above-ground movement. Our study implies that certain caecilian colour patterns have convergently evolved under selection and we hypothesize their function most likely to be a synergy of aposematism and crypsis, related to periods when individuals move overground. In a wider context, our results suggest that very little exposure to daylight is required to evolve and maintain a varied array of colour patterns in animal skin.

  1. Edges, colour and awareness in blindsight.

    PubMed

    Alexander, Iona; Cowey, Alan

    2010-06-01

    It remains unclear what is being processed in blindsight in response to faces, colours, shapes, and patterns. This was investigated in two hemianopes with chromatic and achromatic stimuli with sharp or shallow luminance or chromatic contrast boundaries or temporal onsets. Performance was excellent only when stimuli had sharp spatial boundaries. When discrimination between isoluminant coloured Gaussians was good it declined to chance levels if stimulus onset was slow. The ability to discriminate between instantaneously presented colours in the hemianopic field depended on their luminance, indicating that wavelength discrimination totally independent of other stimulus qualities is absent. When presented with narrow-band colours the hemianopes detected a stimulus maximally effective for S-cones but invisible to M- and L-cones, indicating that blindsight is mediated not just by the mid-brain, which receives no S-cone input, or that the rods contribute to blindsight. The results show that only simple stimulus features are processed in blindsight.

  2. FPGA Vision Data Architecture

    NASA Technical Reports Server (NTRS)

    Morfopoulos, Arin C.; Pham, Thang D.

    2013-01-01

    JPL has produced a series of FPGA (field programmable gate array) vision algorithms that were written with custom interfaces to get data in and out of each vision module. Each module has unique requirements on the data interface, and further vision modules are continually being developed, each with their own custom interfaces. Each memory module had also been designed for direct access to memory or to another memory module.

  3. Motion cues improve the performance of harnessed bees in a colour learning task.

    PubMed

    Balamurali, G S; Somanathan, Hema; Hempel de Ibarra, N

    2015-05-01

    The proboscis extension conditioning (PER) is a successful behavioural paradigm for studying sensory and learning mechanisms in bees. Whilst mainly used with olfactory and tactile stimuli, more recently reliable PER conditioning has been achieved with visual stimuli such as colours and looming stripes. However, the results reported in different studies vary quite strongly, and it remains controversially discussed how to best condition visual PER. It is particularly striking that visual PER leads to more limited performance as compared to visual conditioning of free-flying bees. It could be that visual PER learning is affected by the lack of movement and that the presence of visual motion cues could compensate for it. We tested whether bees would show differences in learning performances when conditioned either with a colour and motion stimulus in combination or with colour alone. Colour acquisition was improved in the presence of the motion stimulus. The result is consistent with the idea that visual learning might be tightly linked to movement in bees, given that they use vision predominantly during flight. Our results further confirm recent findings that successful visual PER conditioning in bees is achievable without obligatorily removing the antennae.

  4. Salience of Primary and Secondary Colours in Infancy

    ERIC Educational Resources Information Center

    Franklin, Anna; Pitchford, Nicola; Hart, Lynsey; Davies, Ian R. L.; Clausse, Samantha; Jennings, Siobhan

    2008-01-01

    Primary colour terms ("black", "white", "red", "green", "yellow", and "blue") are more fundamental in colour language than secondary colour terms ("pink", "purple", "orange", "brown", and "grey"). Here, we assess whether this distinction exists in the absence of language, by investigating whether primary colours attract and sustain preverbal…

  5. Globular Clusters: Chemical Abundance - Integrated Colour calibration

    NASA Astrophysics Data System (ADS)

    Moyano Loyola, G.; Faifer, F. R.; Forte, J. C.

    In this work, we improve the chemical abundance - integrated colour cali- bration presented in Forte, Faifer & Geisler, 2007 (FFG07 hereafter) using a new (g-i) vs. (C-T1) colours calibration obtained from M87. Using this calibration and better values of the reddening for the galactic globulars, we found that a quadratic calibration is still enough to represent the observa- tional data, as in FFG07.

  6. Colour preferences of juvenile turbot (Scophthalmus maximus).

    PubMed

    Li, Xian; Chi, Liang; Tian, Huiqin; Meng, Lingjie; Zheng, Jimeng; Gao, Xiaolong; Liu, Ying

    2016-03-15

    The background colour of aquaculture tanks is normally chosen based on practical experience and/or observations of fish behaviour and the growth rates achieved. However, some farmed species, including turbot, are sentient and can show a preference for a particular environment. In the current study, a self-referent colour preference device was developed and the self-referent colour preference of farmed fish investigated. In experiment 1, the background colour preference of juvenile turbot cultured under a grey background for >3months post-incubation was evaluated. Based on these results, in experiment 2, juvenile turbot were adapted to blue, pink, white, or black backgrounds for 50days and their preferences established. Meanwhile, the growth rates, feed intake, and metabolic rates (including oxygen consumption rate, and ammonia excretion rate) of the turbot were evaluated. The results showed that turbot farmed under a grey background, or after long-term white, blue, pink and black colour adaptation, always displayed a preference for a white background and a dislike for black, red, or brown backgrounds, although their body colour was greyish. Long-term adaptation influenced the frequency of juveniles selecting white, black, pink or blue backgrounds. They showed the highest growth rate, feed intake, and metabolic rates under blue and white backgrounds, and the lowest under a black background in accordance with their preferences shown in experiment 1. Although it is unclear how turbot determine their self-referent colour preferences over such a short period of time, these results indicate that dark colours are unsuitable for the aquaculture of turbot culture in terms of the welfare of the fish.

  7. THE COLOUR GLASS CONDENSATE: AN INTRODUCTION

    SciTech Connect

    IANCU,E.; LEONIDOV,A.; MCLERRAN,L.

    2001-08-06

    In these lectures, the authors develop the theory of the Colour Glass Condensate. This is the matter made of gluons in the high density environment characteristic of deep inelastic scattering or hadron-hadron collisions at very high energy. The lectures are self contained and comprehensive. They start with a phenomenological introduction, develop the theory of classical gluon fields appropriate for the Colour Glass, and end with a derivation and discussion of the renormalization group equations which determine this effective theory.

  8. Plants and colour: Flowers and pollination

    NASA Astrophysics Data System (ADS)

    Miller, Renee; Owens, Simon J.; Rørslett, Bjørn

    2011-03-01

    While there is a range of colours found in plants the predominant colour is green. Pigments in plants have several roles e.g. photosynthesis and signalling. If colour is to be used as a signal then it must stand out from green. However, one should be aware that there are also coloured compounds where we have not yet fully investigated the role of colour in their functions—they may have roles in, for example, defence or heat exchange. In this paper, we will describe the basic chemistry of the major pigments found in plants and especially floral pigments. We will then discuss their locations in parts of the flower (such as sepals, petals, pollen and nectar), the cells in which they are found and their sub-cellular locations. Floral pigments have a large role to play in pollination of flowers by animals. They can and are modified in many ways during the development of flowers in nature, for example, at emergence and post-pollination. There are a range of biochemical mechanisms of colour change both within flowers and in isolated pigments. Some of the factors influencing colour are temperature, co-pigments, pH, metals, sugars, anthocyanin stacking and cell shape. There is a renewed interest in analysing floral pigments and how they are modified partly because of advances in recombinant DNA technologies, but also because of pollinators and their significance to biodiversity and for evolutionary studies. There is continued strong interest from the horticultural industry for the introduction of new colours e.g. the blue rose and for the exploitation of natural dyes. Funding in this area may impact future research in a potentially beneficial way but it must not deflect us from science-based conservation.

  9. Colour hard-copy from workstation screens

    NASA Astrophysics Data System (ADS)

    Clayton, C. A.

    It is possible to produce a colour print on the DEC LJ250 inkjet printer of either the entire screen or a portion of the screen from VAXstations, DECstations, SUN workstations and the IKON image display. This document describes how to achieve this with each of the above workstations. The IKONPAINT software which is used to produce colour hard-copy from the IKON screen on the inkjet printer is fully documented in SUN/71 and is not described here.

  10. Colour cyclic code for Brillouin distributed sensors

    NASA Astrophysics Data System (ADS)

    Le Floch, Sébastien; Sauser, Florian; Llera, Miguel; Rochat, Etienne

    2015-09-01

    For the first time, a colour cyclic coding (CCC) is theoretically and experimentally demonstrated for Brillouin optical time-domain analysis (BOTDA) distributed sensors. Compared to traditional intensity-modulated cyclic codes, the code presents an additional gain of √2 while keeping the same number of sequences as for a colour coding. A comparison with a standard BOTDA sensor is realized and validates the theoretical coding gain.

  11. Biomimetic machine vision system.

    PubMed

    Harman, William M; Barrett, Steven F; Wright, Cameron H G; Wilcox, Michael

    2005-01-01

    Real-time application of digital imaging for use in machine vision systems has proven to be prohibitive when used within control systems that employ low-power single processors without compromising the scope of vision or resolution of captured images. Development of a real-time machine analog vision system is the focus of research taking place at the University of Wyoming. This new vision system is based upon the biological vision system of the common house fly. Development of a single sensor is accomplished, representing a single facet of the fly's eye. This new sensor is then incorporated into an array of sensors capable of detecting objects and tracking motion in 2-D space. This system "preprocesses" incoming image data resulting in minimal data processing to determine the location of a target object. Due to the nature of the sensors in the array, hyperacuity is achieved thereby eliminating resolutions issues found in digital vision systems. In this paper, we will discuss the biological traits of the fly eye and the specific traits that led to the development of this machine vision system. We will also discuss the process of developing an analog based sensor that mimics the characteristics of interest in the biological vision system. This paper will conclude with a discussion of how an array of these sensors can be applied toward solving real-world machine vision issues.

  12. Artificial human vision camera

    NASA Astrophysics Data System (ADS)

    Goudou, J.-F.; Maggio, S.; Fagno, M.

    2014-10-01

    In this paper we present a real-time vision system modeling the human vision system. Our purpose is to inspire from human vision bio-mechanics to improve robotic capabilities for tasks such as objects detection and tracking. This work describes first the bio-mechanical discrepancies between human vision and classic cameras and the retinal processing stage that takes place in the eye, before the optic nerve. The second part describes our implementation of these principles on a 3-camera optical, mechanical and software model of the human eyes and associated bio-inspired attention model.

  13. Flower colour adaptation in a mimetic orchid.

    PubMed

    Newman, Ethan; Anderson, Bruce; Johnson, Steven D

    2012-06-22

    Although the tremendous variability in floral colour among angiosperms is often attributed to divergent selection by pollinators, it is usually difficult to preclude the possibility that floral colour shifts were driven by non-pollinator processes. Here, we examine the adaptive significance of flower colour in Disa ferruginea, a non-rewarding orchid that is thought to attract its butterfly pollinator by mimicking the flowers of sympatric nectar-producing species. Disa ferruginea has red flowers in the western part of its range and orange flowers in the eastern part--a colour shift that we hypothesized to be the outcome of selection for resemblance to different local nectar-producing plants. Using reciprocal translocations of red and orange phenotypes as well as arrays of artificial flowers, we found that the butterfly Aeropetes tulbaghia, the only pollinator of the orchid, preferred both the red phenotype and red artificial flowers in the west where its main nectar plant also has red flowers, and both the orange phenotype and orange artificial flowers in the east, where its main nectar plant has orange flowers. This phenotype by environment interaction demonstrates that the flower colour shift in D. ferruginea is adaptive and driven by local colour preference in its pollinator.

  14. Colourful parrot feathers resist bacterial degradation.

    PubMed

    Burtt, Edward H; Schroeder, Max R; Smith, Lauren A; Sroka, Jenna E; McGraw, Kevin J

    2011-04-23

    The brilliant red, orange and yellow colours of parrot feathers are the product of psittacofulvins, which are synthetic pigments known only from parrots. Recent evidence suggests that some pigments in bird feathers function not just as colour generators, but also preserve plumage integrity by increasing the resistance of feather keratin to bacterial degradation. We exposed a variety of colourful parrot feathers to feather-degrading Bacillus licheniformis and found that feathers with red psittacofulvins degraded at about the same rate as those with melanin and more slowly than white feathers, which lack pigments. Blue feathers, in which colour is based on the microstructural arrangement of keratin, air and melanin granules, and green feathers, which combine structural blue with yellow psittacofulvins, degraded at a rate similar to that of red and black feathers. These differences in resistance to bacterial degradation of differently coloured feathers suggest that colour patterns within the Psittaciformes may have evolved to resist bacterial degradation, in addition to their role in communication and camouflage.

  15. Some challenges in modern hair colour formulations.

    PubMed

    Wis-Surel, G M

    1999-10-01

    Formulation of hair coloring product involves two stages, first a development of product base followed by formulation of desired shade. During that process a special consideration needs to be given to a whole range of product characteristics such as dye stability in the product medium, colour wearability on hair, light fading and finally rheology of the product. This paper reviews improvement in permanent coloring products as it relates to dye and base composition. Examples are shown where a reduction or elimination of certain dyes, m-phenylenediamine or sodium picramate, improves long term stability and product performance on hair. In cases when only reduction of the dyes was carried out, improvement in stability was achieved through their use as secondary colour contributors and not as primary ones. There are also other composition aspects that impact colour performance of the final product. For example, pH of the coloring mixture has a pronounced effect on the final colour developed in hair. It is shown that a shift in tonality caused by pH change can be predicted for finished product using a simple system composed of the main coupler-intermediate pair employed in the product. The colour response to pH change of this simple system was found to mirror that of the product. This predictability can be used as a formulation tool to develop more efficient dye systems. Effects of some functional materials on colour result such as propylene glycol, ascorbic acid or silicone are also shown.

  16. Colourful parrot feathers resist bacterial degradation

    PubMed Central

    Burtt, Edward H.; Schroeder, Max R.; Smith, Lauren A.; Sroka, Jenna E.; McGraw, Kevin J.

    2011-01-01

    The brilliant red, orange and yellow colours of parrot feathers are the product of psittacofulvins, which are synthetic pigments known only from parrots. Recent evidence suggests that some pigments in bird feathers function not just as colour generators, but also preserve plumage integrity by increasing the resistance of feather keratin to bacterial degradation. We exposed a variety of colourful parrot feathers to feather-degrading Bacillus licheniformis and found that feathers with red psittacofulvins degraded at about the same rate as those with melanin and more slowly than white feathers, which lack pigments. Blue feathers, in which colour is based on the microstructural arrangement of keratin, air and melanin granules, and green feathers, which combine structural blue with yellow psittacofulvins, degraded at a rate similar to that of red and black feathers. These differences in resistance to bacterial degradation of differently coloured feathers suggest that colour patterns within the Psittaciformes may have evolved to resist bacterial degradation, in addition to their role in communication and camouflage. PMID:20926430

  17. Improving Access to Vision Care for People Who are Homeless through Eyeglasses Recycling.

    PubMed

    Lam, Janna; Robertson, Kirstin; Robertson, Wesley; Bernstein, Rebecca

    2015-11-01

    Visual impairment disproportionately affects the health and function of people who are homeless. A common and correctable cause of visual impairment is refractive error. However, eyeglasses remain an unmet need for the poor and underinsured. This report describes eyeglasses recycling and vision screening to reduce the burden of correctable visual impairment.

  18. Agnosic vision is like peripheral vision, which is limited by crowding.

    PubMed

    Strappini, Francesca; Pelli, Denis G; Di Pace, Enrico; Martelli, Marialuisa

    2017-04-01

    Visual agnosia is a neuropsychological impairment of visual object recognition despite near-normal acuity and visual fields. A century of research has provided only a rudimentary account of the functional damage underlying this deficit. We find that the object-recognition ability of agnosic patients viewing an object directly is like that of normally-sighted observers viewing it indirectly, with peripheral vision. Thus, agnosic vision is like peripheral vision. We obtained 14 visual-object-recognition tests that are commonly used for diagnosis of visual agnosia. Our "standard" normal observer took these tests at various eccentricities in his periphery. Analyzing the published data of 32 apperceptive agnosia patients and a group of 14 posterior cortical atrophy (PCA) patients on these tests, we find that each patient's pattern of object recognition deficits is well characterized by one number, the equivalent eccentricity at which our standard observer's peripheral vision is like the central vision of the agnosic patient. In other words, each agnosic patient's equivalent eccentricity is conserved across tests. Across patients, equivalent eccentricity ranges from 4 to 40 deg, which rates severity of the visual deficit. In normal peripheral vision, the required size to perceive a simple image (e.g., an isolated letter) is limited by acuity, and that for a complex image (e.g., a face or a word) is limited by crowding. In crowding, adjacent simple objects appear unrecognizably jumbled unless their spacing exceeds the crowding distance, which grows linearly with eccentricity. Besides conservation of equivalent eccentricity across object-recognition tests, we also find conservation, from eccentricity to agnosia, of the relative susceptibility of recognition of ten visual tests. These findings show that agnosic vision is like eccentric vision. Whence crowding? Peripheral vision, strabismic amblyopia, and possibly apperceptive agnosia are all limited by crowding, making it

  19. Is Reading Impairment Associated with Enhanced Holistic Processing in Comparative Visual Search?

    PubMed

    Wang, Jiahui; Schneps, Matthew H; Antonenko, Pavlo D; Chen, Chen; Pomplun, Marc

    2016-11-01

    This study explores a proposition that individuals with dyslexia develop enhanced peripheral vision to process visual-spatial information holistically. Participants included 18 individuals diagnosed with dyslexia and 18 who were not. The experiment used a comparative visual search design consisting of two blocks of 72 trials. Each trial presented two halves of the display each comprising three kinds of shapes in three colours to be compared side-by-side. Participants performed a conjunctive search to ascertain whether the two halves were identical. In the first block, participants were provided no instruction regarding the visual-spatial processing strategy they were to employ. In the second block, participants were instructed to use a holistic processing strategy-to defocus their attention and perform the comparison by examining the whole screen at once. The results did not support the hypothesis associating dyslexia with talents for holistic visual processing. Using holistic processing strategy, both groups scored lower in accuracy and reacted faster, compared to the first block. Impaired readers consistently reacted more slowly and did not exhibit enhanced accuracy. Given the extant evidence of strengths for holistic visual processing in impaired readers, these findings are important because they suggest such strengths may be task dependent. Copyright © 2016 John Wiley & Sons, Ltd.

  20. Restoration of cone vision in a mouse model of achromatopsia.

    PubMed

    Alexander, John J; Umino, Yumiko; Everhart, Drew; Chang, Bo; Min, Seok H; Li, Qiuhong; Timmers, Adrian M; Hawes, Norman L; Pang, Ji-Jing; Barlow, Robert B; Hauswirth, William W

    2007-06-01

    Loss of cone function in the central retina is a pivotal event in the development of severe vision impairment for many prevalent blinding diseases. Complete achromatopsia is a genetic defect resulting in cone vision loss in 1 in 30,000 individuals. Using adeno-associated virus (AAV) gene therapy, we show that it is possible to target cones and rescue both the cone-mediated electroretinogram response and visual acuity in the Gnat2 ( cpfl3 ) mouse model of achromatopsia.