Sex-related differences in chromatic sensitivity

Generally women are believed to be more discriminating than men in the use of colour names and this is often taken to imply superior colour vision. However, if both X-chromosome linked colour deficient males (~8%) and females (<1%) as well as heterozygote female carriers (~15%) are excluded from comparisons, then differences between men and women in red-green colour discrimination have been reported as not being significant (e.g., Pickford, 1944; Hood et al., 2006). We re-examined this question by assessing the performance of 150 males and 150 females on the Colour Assessment and Diagnosis (CAD) test (Rodriguez-Carmona, 2005). This is a sensitive test that yields small colour detection thresholds. The test employs direction-specific, moving, chromatic stimuli embedded in a background of random, dynamic, luminance contrast noise. A four-alternative, forced-choice procedure is employed to measure the subject’s thresholds for detection of colour signals in 16 directions in colour space, while ensuring that the subject cannot make use of any residual luminance contrast signals. In addition, we measured the Rayleigh anomaloscope matches in a subgroup of 111 males and 114 females. All the age-matched males (30.8 ± 9.7) and females (26.7 ± 8.8) had normal colour vision as diagnosed by a battery of conventional colour vision tests. Females with known colour deficient relatives were excluded from the study. Comparisons between the male and female groups revealed no significant differences in anomaloscope midpoints (p=0.709), but a significant difference in matching ranges (p=0.040); females on average tended to have a larger mean range (4.11) than males (3.75). Females also had significantly higher CAD thresholds than males along the red-green (p=0.0004), but not along the yellow-blue discrimination axis. The differences between males and females in red-green discrimination may be related to the heterozygosity in X-linked cone photopigment expression common among females

Functional evidence for cone-specific connectivity in the human retina

NoPhysiological studies of colour vision have not yet resolved the controversial issue of how chromatic opponency is constructed at a neuronal level. Two competing theories, the cone-selective hypothesis and the random-wiring hypothesis, are currently equivocal to the architecture of the primate retina. In central vision, both schemes are capable of producing colour opponency due to the fact that receptive field centres receive input from a single bipolar cell ¿ the so called `private line arrangement¿. However, in peripheral vision this single-cone input to the receptive field centre is lost, so that any random cone connectivity would result in a predictable reduction in the quality of colour vision. Behavioural studies thus far have indeed suggested a selective loss of chromatic sensitivity in peripheral vision. We investigated chromatic sensitivity as a function of eccentricity for the cardinal chromatic (L/M and S/(L + M)) and achromatic (L + M) pathways, adopting stimulus size as the critical variable. Results show that performance can be equated across the visual field simply by a change of scale (size). In other words, there exists no qualitative loss of chromatic sensitivity across the visual field. Critically, however, the quantitative nature of size dependency for each of the cardinal chromatic and achromatic mechanisms is very specific, reinforcing their independence in terms of anatomy and genetics. Our data provide clear evidence for a physiological model of primate colour vision that retains chromatic quality in peripheral vision, thus supporting the cone-selective hypothesis

Object knowledge modulates colour appearance

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

The reading of tajweed in surah Yaasin for red-green colour vision deficiencies / Siti Sarah Adam Wan … [et al.]

Colour Blindness or colour vision deficiency are difficulty to see certain colour and shade depending on their type of colour blindness. Generally, there are 3 types of vision deficiencies - protanopia (red-green), deuteranopia (green-red) and tritanopia (blue-yellow) (NEI, 2015). There are close to 300 million people around the world who are suffering from colour blindness. From that figure, 8% men and 0.5% women are suffering this vision deficiencies (Ng, 2017). Many people think people who are suffering from colorblindness are enable to see any colours. Their perception on those people can only view black and white in daily life. However, their judgment is wrong and science has proven colour vision deficiencies can see colours (Flück, 2006). Most common forms of colour vision problems are inherited (genetic) and are present at birth.However,in some cases, a person can have an acquired colour vision problem. Thus,it is caused by aging, eye problem, injury on eye, alcohol misuse, or a hard injury on head (Flück, 2006)

Defective Colour Vision

Zadatak je autora da na jednome mjestu sistematiziraju sve kolorne poremećaje – diskromatopsije te dijagnostičke metode i testove. Vrlo često smo svjedoci neadekvatnom i neispravnom dijagnosticiranju kolornih poremećaja u kliničkom radu. Smatramo da neadekvatno i nesistematski prikazana problematika kolornog vida u literaturi, neinformiranost o odabiru metoda i testova, načinu rada i interpretaciji dobivenih rezultata samog testiranja za svaki pojedini kolorni poremećaj doprinosi krivoj dijagnozi diskromatopsija. S obzirom na to da se osim u oftalmologiji i neurologiji vrlo često ispituje kolorni vid i u ordinacijama medicine rada, nađene diskromatopsije treba staviti pod nadzor oftalmologa kako pojedinac ili grupa ne bi bili oštećeni u odabiru zanimanja ili sličnoga krivom interpretacijom rezultata testiranja. Shvaćanje ozbiljnosti problema i informiranost unaprijedit će strategiju ispitivanja kolornog vida i dati važnost što ranijoj detekciji s ciljem ublažavanja posljedica za pojedinca i za društvo. Budući svakodnevnost ispitivanja kolornog vida nije najbolje definirana ni po načinu ni po uvjetima rada, potrebno je stvoriti jedinstvene kriterije kod dijagnosticiranja svakoga pojedinog kolornog poremećaja u čemu bi trebao pomoći ovaj članak.This review gives a summary of all colour vision disorders (dyschromatopsias) and diagnostic methods and tests. Colour vision is inadequately treated in current literature with regard to the choice of diagnostic methods and the interpretation of results for a single disorder, which contributes to wrong dyschromatopsia diagnosing seen every day in specialist practice. Examination for colour disorders is usually outpatient and is carried out by ophthalmology or neurology departments or occupational health services under the supervision of an ophthalmologist to prevent misinterpretation of results and wrong occupational choices. The problem is very serious, and proper education should be able to provide guidelines for correct and early diagnosis of dyschromatopsia. As the examination is not well defined, it is very important to set unique criteria in diagnosing any single colour vision disorder

Improved data association and occlusion handling for vision-based people tracking by mobile robots

This paper presents an approach for tracking multiple persons using a combination of colour and thermal vision sensors on a mobile robot. First, an adaptive colour model is incorporated into the measurement model of the tracker. Second, a new approach for detecting occlusions is introduced, using a machine learning classifier for pairwise comparison of persons (classifying which one is in front of the other). Third, explicit occlusion handling is then incorporated into the tracker

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

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 to be a general means of generating an increased diversity of developmental outcomes

DISCOV: A Neural Model of Colour Vision, with Applications to Image Processing and Classification

The DISCOV (Dimensionless Shunting Colour Vision) system models a cascade of primate colour vision cells: retinal ganglion, thalamic single opponent, and two classes of cortical double opponents. A unified model fotmalism derived from psychophysical axioms produces transparent network dynamics and principled parameter settings. DISCOV fits an array of physiological data for each cell type, and makes testable experimental predictions. Properties of DISCOV model cells are compared with properties of conesponding components in the alternative Neural Fusion model. A benchmark testbed demonstrates the marginal computational utility of each model cell type on a recognition task derived from orthophoto imagery.Air Force Office of Scientific Research (F49620-01-1-0423); National Geospatial-Intelligence Agency (NMA 201-01-1-2016); National Science Foundation (SBE-035437, DGE-0221680); Office of Naval Research (N00014-01-1-0624

Colour assessment outcomes – a new approach to grading the severity of color vision loss

INTRODUCTION: Recent studies have shown that a significant percentage of subjects with anomalous, congenital trichromacy can perform the suprathreshold, colour-related tasks encountered in many occupations with the same accuracy as normal trichromats. In the absence of detailed, occupation-specific studies, an alternative approach is to make use of new findings and the statistical outcomes of past practices that have been considered safe to produce graded, justifiable categories of colour vision that can be enforced. METHODS: We analyzed traditional color assessment outcomes and measured severity of colour vision loss using the CAD test in 1363 subjects (336 normals, 705 deutan, 319 protan and 3 tritan). The severity of colour vision 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. RESULTS: The correlation between the number of Ishihara (IH) test plates subjects fail and the severity of RG colour vision loss was very poor. The 38 plates IH test has high sensitivity when no errors are allowed (i.e., only 0.71% deutans and 0.63% protans pass). Protocols based on zero errors are uncommon since 18.15% of normal trichromats fail. The most common protocols employ either the 24 or the 14 plates editions with two or less errors. These protocols pass almost all normal trichromats, but the deutans and some protans that also pass (when two or less errors are allowed) can be severely deficient. This is simply because the most challenging plates have not been included in the 24 and 14 plates editions. As a result, normals no longer fail, but the deutans and protans that pass have more severe loss of colour vision since they fail less challenging plates. The severity of colour vision 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. DISCUSSION: Historical 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 Colour Vision category which can range from ‘supernormal’ (CV0), for the most stringent, colour-demanding tasks, to ‘severe colour deficiency’, when red / green colour vision is either absent or extremely weak (CV5)

Sheep and goats:manipulating visual perception through colour relationships

Sheep and Goats hides visual messages in plain sight. It is a print diptych which investigates the idea that artwork can be intentionally created to be experienced differently dependent on one’s visual abilities. Each silk-screened/ink-jet print is 84 cm x 112 cm. It is accompanied by a smart device fitted with augmented reality colour vision deficiency simulation and recolouring software. The collaboration of artist David Lyons with computer scientist David Flatla resulted in prints which communicate unique details exclusively to those colour blindness, while simultaneously containing imagery that those with typical colour vision experience. This was done through the use and understanding of colour theory, artistic principles and computer science applications. All the artwork is revealed to both audiences through the use of tablets whose software allows the translation of the imagery between the two audiences. The tablets with CVD simulation and recolouring software allow those with typical colour sight to view what those with colour blindness see, and those with colour blindness to gain an appreciation of what individuals with typical sight see.To indicate engagement of audiences of varied colour vision abilities, Triple Blind reference the circles of the Ishihara Colour Blind Test. The dualistic words ‘heaven’ and ‘HELL’ are used to suggest conflicting perceptions as are the clear varnish over-printed lyrics from the song “Sheep go to Heaven’ by the rock band Cake. This paper documents the development of the work, its theoretical underpinnings and artistic and social and philosophical implications