Color Discrimination Research Articles

Art in Endoscopy: "Pretty Pink".

In this image, we clearly see a vertical demarcation line of a neoplastic lesion in a Barrett’s esophagus, visualized in linked color imaging in magnification mode. This optical chromoscopy technique is integrated into the Fujifilm ELUXEO 7000 endoscopy system and has been developed to enhance color differences in the mucosa, focusing on increased discrimination of red colors.

Hiding Data in the Blue Channel

Cataract surgery replaces the aged human lens with a transparent silicone implant. The new lens removes optical distortions and light scattering media, as well as a yellow filter. This talk describes the appearances of natural scenes before and after cataract surgery. While Color Constancy experiments showed small changes, color discrimination experiments had large changes. These results provide a mechanistic signature of Color Constancy and Discrimination.

Colors before and after cataract surgery: A study of color constancy and discrimination

Virtual reality has experienced a strong advance in recent years, its use in industries such as video games, automotive and medicine is now a reality. Previous work has determined that color is one of the most important characteristics when it comes to creating a sense of realism in the user. Therefore, through the use of spectral techniques we have found that it is possible to improve the fidelity in the reproduction of a real scene inside a virtual reality scene. In order to do this, we have developed a workflow that allows the user to compare real scenes with virtual scenes. The results of this test show that there exists an improvement of the visual fidelity in the reproduction of real scenes inside a virtual reality system compared with previous works.

How skin color, class status, and gender intersect in the labor market: Evidence from a field experiment

This article examines skin color discrimination in two Brazilian labor markets using a field experimental approach. Fictitious resumes including photographs of job candidates were randomly assigned one skin color category via photo manipulation and submitted to entry-level job openings. In addition to assessing the extent of skin color discrimination, this article adopts an intersectional framework to examine how the effect of skin color in employment is moderated by class status and varies by gender. I found mixed results about the role of skin color in predicting the employment outcomes at the initial stages of the hiring process. Results from logistic regression and Linear Probability Models show that skin color is a weak predictor of hiring outcomes (e.g. receiving a callback from employers) among male applicants and for female applicants with brown skin. However, I find strong evidence that having dark skin is causally associated with hiring outcomes among female applicants. I also found that having a higher-class status erases skin color differences, thus identifying a potential mechanism that mitigates the effects of skin color in hiring.

Color discrimination and color preferences in Chimpanzees (Pan troglodytes).

Chimpanzees (Pan troglodytes) have been known for a long time to have color vision identical to humans (Grether in J Comp Psychol 29(2):167-177, 1940b; Jacobs et al. in Vis Res 36(16):2587-2594, 1996). With this study, we wonder if chimpanzees, as humans, show preferences for some colors rather than others. During a first range of experiments, we test their ability to discriminate all the colors from our set, through easy matching-to-sample tasks. The seven chimpanzees that participate in this first test show the results we can expect from chimpanzees with normal color vision. Then, six of them are tested for preferences. This range of experiments results in the existence of consistent tendencies across all the trials and situations, as chimpanzees would mostly first choose some particular colors, and conversely choose last different colors. Although the results for color discrimination are identical for all the seven chimpanzees, preference tests demonstrate four different tendencies. This study is the first step toward broader experiments, including more chimpanzee subjects, but also different species, with the only requirement of being trained to the basic use of a touch panel interface.

Colour discrimination among patients with schizophrenia in Lebanon

Background: Abnormalities and contrast sensitivity have already been studied in schizophrenia. However, the relationship between symptom severity in schizophrenia and colour vision sensitivity has not been studied systematically.Aim: Our objective was to evaluate colour discrimination in patients with schizophrenia compared to controls and examine if this colour discrimination is correlated with schizophrenia symptoms’ severity.Methods: This case–control study, performed between January and April 2017, included 50 schizophrenic patients and 50 healthy controls matched for age and sex. The Positive and Negative Symptoms Scale (PANSS) was used to determine the schizophrenia symptoms’ severity. Colour discrimination was evaluated using the total error score (TES) generated using the Farnsworth D-15 test. The higher the TES, the more severe colourblindness.Results: A significantly higher mean TES was found in schizophrenics (30.32) compared to healthy patients (13.07) (p < 0.001). Colour blindness was correlated to the severity of schizophrenic symptoms only in the subgroup of patients with severe schizophrenia.Conclusion: Colour vision defect is a common feature in schizophrenia, and may be more significant when related to psychotic symptoms.KEY POINTSA significantly higher mean TES was found in schizophrenics compared to healthy patients.Colour blindness was correlated to the severity of schizophrenic symptoms only in the subgroup of patients with severe schizophrenia.Colour vision defect is a common feature in schizophrenia, and may be more significant when related to psychotic symptoms.

Rapid picture naming in Parkinson's disease using the Mobile Universal Lexicon Evaluation System (MULES)

ObjectiveThe Mobile Universal Lexicon Evaluation System (MULES) is a test of rapid picture naming that captures extensive brain networks, including cognitive, language and afferent/efferent visual pathways. MULES performance is slower in concussion and multiple sclerosis, conditions in which vision dysfunction is common. Visual aspects captured by the MULES may be impaired in Parkinson's disease (PD) including color discrimination, object recognition, visual processing speed, and convergence. The purpose of this study was to compare MULES time scores for a cohort of PD patients with those for a control group of participants of similar age. We also sought to examine learning effects for the MULES by comparing scores for two consecutive trials within the patient and control groups. MethodsMULES consists of 54 colored pictures (fruits, animals, random objects). The test was administered in a cohort of PD patients and in a group of similar aged controls. Wilcoxon rank-sum tests were used to determine statistical significance for differences in MULES time scores between PD patients and controls. Spearman rank-correlation coefficients were calculated to examine the relation between MULES time scores and PD motor symptom severity (UPDRS). Learning effects were assessed using Wilcoxon rank-sum tests. ResultsAmong 51 patients with PD (median age 70 years, range 52–82) and 20 disease-free control participants (median age 67 years, range 51–90), MULES scores were significantly slower (worse performance) in PD patients (median 63.2 s, range 37.3–296.3) vs. controls (median 53.9 s, range 37.5–128.6, P = .03, Wilcoxon rank-sum test). Slower MULES times were associated with increased motor symptom severity as measured by the Unified Parkinson's Disease Rating Scale, Section III (rs = 0.37, P = .02). Learning effects were greater among patients with PD (median improvement of 14.8 s between two MULES trials) compared to controls (median 7.4 s, P = .004). ConclusionThe MULES is a complex test of rapid picture naming that captures numerous brain pathways including an extensive visual network. MULES performance is slower in patients with PD and our study suggests an association with the degree of motor impairment. Future studies will determine the relation of MULES time scores to other modalities that test visual function and structure in PD.

No evidence that footedness in pheasants influences cognitive performance in tasks assessing colour discrimination and spatial ability

ABSTRACTThe differential specialization of each side of the brain facilitates the parallel processing of information and has been documented in a wide range of animals. Animals that are more lateralized as indicated by consistent preferential limb use are commonly reported to exhibit superior cognitive ability as well as other behavioural advantages. We assayed the lateralization of 135 young pheasants (Phasianus colchicus), indicated by their footedness in a spontaneous stepping task, and related this measure to individual performance in either 3 assays of visual or spatial learning and memory. We found no evidence that pronounced footedness enhances cognitive ability in any of the tasks. We also found no evidence that an intermediate footedness relates to better cognitive performance. This lack of relationship is surprising because previous work revealed that pheasants have a slight population bias towards right footedness, and when released into the wild, individuals with higher degrees of footedness were more likely to die. One explanation for why extreme lateralization is constrained was that it led to poorer cognitive performance, or that optimal cognitive performance was associated with some intermediate level of lateralization. This stabilizing selection could explain the pattern of moderate lateralization that is seen in most non-human species that have been studied. However, we found no evidence in this study to support this explanation.

Color discrimination and gas chromatography-mass spectrometry fingerprint based on chemometrics analysis for the quality evaluation of Schizonepetae Spica.

Schizonepetae Spica (SS), the dried spike of Schizonepeta tenuifolia Briq., is a traditional Chinese medicinal herb. According to the color of persistent calyx, SS is categorized into two classes: the yellowish-green-type and the brownish-type. Based on the chemometrics analysis of gas chromatography-mass spectrometry (GC-MS), a novel model of identifying and evaluating the quality of SS in different colors was constructed for the first time in this work. 20 batches SS samples of different colors were collected and used to extract essential oils. The average essential oils yield of SS in yellowish-green color was significantly higher than that of SS in brownish color from the same origin (p<0.05). The GC-MS fingerprints of 20 batches SS samples whose correlation coefficients were over 0.964 demonstrated SS samples were consistent to some extent in spite of slightly different chemical indexes. A total of 39 common volatiles compounds were identified. Hierarchical clustering analysis (HCA), principal component analysis (PCA) and partial least-squares discriminate analysis (PLS-DA) were developed to distinguish SS samples characterized by different colors. Consistent results were obtained to show that SS samples could be successfully grouped according to their color. Finally, 4,5,6,7-tetrahydro-3,6-dimethyl-benzofuran and pulegone were detected as the key variables for discriminating SS samples of different colors and for quality control. The obtained results proved that SS of good quality were often yellowish-green and those of poor quality were often brownish.

Color discrimination, occupational prestige, and skin color in Brazil

ABSTRACTExisting literature pertaining to discrimination in Brazil often uses education and income as measures of class, but seldom includes occupational prestige. However, occupation, an aspect of daily life and a socioeconomic indicator, may explain a large amount of variation in acknowledgement of skin color discrimination among blacks and browns in Brazil. In this study, we examine whether those in different occupations acknowledge skin color discrimination differently. Based on existing literature, the expectation was that individuals in high status occupations would be more likely to acknowledge skin color discrimination. However, to the contrary, our analysis of the 2010 Latin American Political Opinion Project survey, in which we utilize an ordered logistic regression model with controls for education, expected labor market experience, gender, household income, skin color, location, and province, reveals blacks and browns in less prestigious occupations are more likely to report experiencing color discrimination, particularly among men. This study offers new insights about perceptions of color discrimination in Brazil by challenging the traditional idea that high status blacks and browns are more aware of color discrimination than those of lower status. Also, these findings are important to research on race and ethnicity generally, bridging studies in sociology, Latin American studies, and African diaspora studies.

Visual cells and visual pigments of the river lamprey revisited.

Retinas of the river lamprey Lampetra fluviatilis were studied by microspectrophotometry, electroretinography and single-photoreceptor electrophysiology to reconcile the apparently contradictory conclusions on the nature of lamprey photoreceptor cells drawn in the early work by Govardovskii and Lychakov (J Comp Physiology A 154:279-286, 1984) and in recent studies. In agreement with recent works, we confirmed former identification of short photoreceptors as rods and of long photoreceptors as cones. In line with the results of 1984, we show that within a certain range of light intensities the lamprey retina exhibits "color discrimination". We found that the overlap of working intensity ranges of rods and cones is not a unique feature of lamprey short receptors, and suggest that rod-cone (possibly color) vision may be common among vertebrates. We show that the decay of meta-intermediates in lamprey cones occurs almost 100 times faster than in typical rod metarhodopsins. Rate of decay of metarhodopsins of lamprey rods take an intermediate position between typical rods and cones. This makes lamprey rhodopsin similar to transmuted cone visual pigment in "rods" of nocturnal geckos. We argue that defining various types of photoreceptors as simply "rods" and "cones" may be functionally correct, but neglects their genetic, biochemical and morphological features and evolutionary history.

The Impact of Concurrent Antiretroviral Therapy and MDR-TB Treatment on Adverse Events.

South Africa has among the highest incidence of multidrug-resistant tuberculosis (MDR-TB) and more than 70% of patients are HIV co-infected. MDR-TB treatment is associated with frequent adverse events (AEs). Although guidelines recommend concurrent treatment of MDR-TB and HIV, safety data on concurrent therapy are limited. We conducted a prospective observational study of MDR-TB patients with and without HIV-coinfection in South Africa between 2011 and 2015. Participants received standardized MDR-TB and HIV regimens. Participants were followed monthly for the duration of MDR-TB therapy and screened for clinical and laboratory AEs. Audiometry was performed monthly during the intensive phase; color discrimination testing was performed every 2 months. We enrolled 150 HIV-infected and 56 HIV-uninfected participants. Nearly all experienced at least one clinical (93%) or laboratory (96%) AE. The most common clinical AEs were peripheral neuropathy (50%) and difficulty sleeping (48%); the most common laboratory AEs were hypokalemia (47%) and decreased creatinine clearance (46%). Among 19 clinical and lab AEs examined, there were no differences by HIV status, except for diarrhea (27% HIV-infected vs. 13% HIV-uninfected, P = 0.03). Hearing loss was experienced by 72% of participants (8% severe loss). Fourteen percent experienced color discrimination loss (4% severe loss). There were no differences in frequency or severity of hearing or vision loss by HIV status. AEs were common, but not more frequent or severe among MDR-TB/HIV co-infected participants receiving concurrent antiretroviral therapy. Given the favorable treatment outcomes associated with concurrent treatment, antiretroviral therapy initiation should not be delayed in MDR-TB patients with HIV-coinfection.

The visual ecology of Holocentridae, a nocturnal coral reef fish family with a deep-sea-like multibank retina.

The visual systems of teleost fishes usually match their habitats and lifestyles. Since coral reefs are bright and colourful environments, the visual systems of their diurnal inhabitants have been more extensively studied than those of nocturnal species. In order to fill this knowledge gap, we conducted a detailed investigation of the visual system of the nocturnal reef fish family Holocentridae. Results showed that the visual system of holocentrids is well adapted to their nocturnal lifestyle with a rod-dominated retina. Surprisingly, rods in all species were arranged into 6-17 well-defined banks, a feature most commonly found in deep-sea fishes, that may increase the light sensitivity of the eye and/or allow colour discrimination in dim light. Holocentrids also have the potential for dichromatic colour vision during the day with the presence of at least two spectrally different cone types: single cones expressing the blue-sensitive SWS2A gene, and double cones expressing one or two green-sensitive RH2 genes. Some differences were observed between the two subfamilies, with Holocentrinae (squirrelfish) having a slightly more developed photopic visual system than Myripristinae (soldierfish). Moreover, retinal topography of both ganglion cells and cone photoreceptors showed specific patterns for each cell type, likely highlighting different visual demands at different times of the day, such as feeding. Overall, their well-developed scotopic visual systems and the ease of catching and maintaining holocentrids in aquaria, make them ideal models to investigate teleost dim-light vision and more particularly shed light on the function of the multibank retina and its potential for dim-light colour vision.

Monolayer hydrophilic MoS2 with strong charge trapping for atomically thin neuromorphic vision systems

Through covalently introducing hydroxyl groups, monolayer hydrophilic MoS2 is synthesized with strong charge trapping and can be applied to an atomically thin neuromorphic visual system with image sensing, image memorization, and color discrimination.

Ганглиозные клетки с фоновой активностью сетчатки рыб и их возможная функция в оценке зрительной сцены

Extracellular spike activities were recorded from the axon terminals of single ganglion cells (GCs) in tectum opticum (TO) of living immobilized fish. The layer of units with sustained responses (USR) is located 190-200 µm under the surface of TO (deeper than every type of feature detectors). The sizes of the receptive fields (RFs) of both ON and OFF USRs make up to 4-5° which is comparable to the RF sizes of the feature detectors. We've shown that at least some minimal contrast between center and surround is crucial (obligatory) to induce spike discharge in USRs; the intensity of discharge depends on the contrast gradually; spike activity does not emerge in the absence of contrast. We've also shown that USRs of both ON- and OFF-types receive inputs from all three types of cones (L, M and S). We have found that USRs demonstrate color opponency both in the center and on the surround and moreover there is color opponency between center and surround. This makes USRs double opponent cells and thus they might participate in color discrimination. TO – the main visual centre appears to get plenty of information from feature detectors and USRs splitted in ON- and OFF-channels. Proper comprehension of the visual scene allows TO to perform its primary role – the external visual attention control.

Color Difference and Thermal Stability of Flexible Transparent InGaN/GaN Multiple Quantum Wells Mini-LED Arrays

We present studies of the color uniformity and thermal stability of a flexible and transparent ${32}\times {32}$ mini-LED array on polyethylene terephthalate (PET) substrate up to a brightness rating of 5000 nits at room temperature, whose brightness is required for outdoor display applications. Surprisingly, even at 5000 nits, the temperature variation on the surface of the LED array is less than 9 °C, despite the relatively low thermal diffusivity of the polymer substrates. The average surface temperature was 33 °C. This indicates that the heat dissipation of the fabricated LED array is superior with even a polymer substrate. Further, the narrow electroluminescent (EL) emissions from the mini-LED array help to realize wider color gamut than Rec. 2020 color gamut in display applications. The color differences from the EL spectra were calculated at three different brightness. The calculated values are far less than the color discrimination threshold of the human eye corresponding to 0.005 at all testing brightness and meet the display industry requirement for color difference.

Imaging stressed organelles via sugar-conjugated color-switchable pH sensors.

Stressed organelles are often challenging to image with canonical organelle probes owing to their propensity to dissipate from stressed organelles. We herein report the imaging of stressed lysosomes with color-switchable glyco-probes that contain an entity of mannose-6-carboxylate or sialic acid for targeting to and long-term retention in stressed lysosomes, and a diad of fluorescein/rhodamine-X-lactam exhibiting dramatic red-to-green fluorescence shift upon pH elevation. Relative to acidotropic dyes prone to dissipate from pH-elevated lysosomes, both glyco-probes are stably trapped in lysosomes without resorting to lysosomal acidity. Importantly, these probes are red emissive in acidic lysosomes (pH 4.5-5.8), but switched to green fluorescence in lysosomes of pH 6.0-7.4, allowing dual color discrimination of lysosomal pH alterations in cell starvation. These results support the use of sugar-armed sensors to investigate stressed lysosomes in biology and disease.

Chicken colour discrimination depends on background colour.

How well can a bird discriminate between two red berries on a green background? The absolute threshold of colour discrimination is set by photoreceptor noise, but animals do not perform at this threshold; their performance can depend on additional factors. In humans and zebra finches, discrimination thresholds for colour stimuli depend on background colour, and thus the adaptive state of the visual system. We have tested how well chickens can discriminate shades of orange or green presented on orange or green backgrounds. Chickens discriminated slightly smaller colour differences between two stimuli presented on a similarly coloured background, compared with a background of very different colour. The slope of the psychometric function was steeper when stimulus and background colours were similar but shallower when they differed markedly, indicating that background colour affects the certainty with which the animals discriminate the colours. The effect we find for chickens is smaller than that shown for zebra finches. We modelled the response to stimuli using Bayesian and maximum likelihood estimation and implemented the psychometric function to estimate the effect size. We found that the result is independent of the psychophysical method used to evaluate the effect of experimental conditions on choice performance.

The Navigation of Afrocentricism in Countee Cullen’s “Heritage” and Incident”: The Poetics of Identity

This paper brings forward the course and determination of Afro-American people toward their origin as experienced by African Americans. It remarkably remaps the poetics of identity amid the racial segregation as projected in Countee Cullen’s “Heritage” and “Incident.” Further, it deals with the color line discrimination over enslaved community and fabricated knowledge about their history as problematic of research. Because the slavery system has belittled Afro-Americans and alienated them from their atavistic culture so that they fail to enjoy human dignity and identity. My purpose, here, is to delve into the issue of color discrimination that not only hems the Afro- American community but also dislocates them from their heritage. Largely, this paper navigates their alienated position amid the vast opportunities of material progress in America. Moreover, this paper intends to go through the genealogical studies of the race as envisioned by Paul Gilroy and W.E.B. Du Bois who advocate for enslaved community’s dignity and identity. Admittedly, genealogical history of the race takes the Afro-American people back to the time before ‘the slave trade’ era when they were happy and free enjoying their culture and language with human dignity in their atavistic land, Africa.

Research progress on color determination methods of reagent strips in routine urinalysis

Clinically, routine urinalysis includes more than 10 items, such as urine protein, urinary pH, urinary bilirubin and so on. The above items are usually analyzed by dry chemical methods. The principle is that after the urine infiltrates the reagent strips, the color changes can be observed in each strip. The color depth is related to the component concentration, and the darker the color, the greater the measured component concentration, and vice versa. In this paper, four color discrimination methods in urinary dry chemical analysis were introduced, i.e. the method based on integrating sphere photoelectric conversion, the method based on charge-coupled device (CCD) image sensor, the method based on color sensor, and the method based on the combination of color sensor and fiber bundle. Besides, the four methods were compared and analyzed. Finally, the recent research progress in urinalysis was reviewed. Key words: Urine; Dry chemical method; Color; Urine reagent strip