Increased color preference through the introduction of luminance noise in chromatic stimuli.

Humans exhibit consistent color preferences that are often described as a curvilinear pattern across hues. The recent literature posits that color preference is linked to the preference for objects or other entities associated with those colors. However, many studies examine this preference using isoluminant colors, which don't reflect the natural viewing experience typically influenced by different light intensities. The inclusion of random luminance levels (luminance noise) in chromatic stimuli may provide an initial step towards assessing color preference as it is presented in the real world. Employing mosaic stimuli, this study aimed to evaluate the influence of luminance noise on human color preference. Thirty normal trichromats engaged in a two-alternative forced-choice paradigm, indicating their color preferences between presented pairs. The chromatic stimuli included saturated versions of 8 standard hues, presented in mosaics with varying diameters under different luminance noise conditions. Results indicated that the inclusion of luminance noise increased color preference across all hues, specifically under the high luminance noise range, while the curvilinear pattern remained unchanged. Finally, women exhibit a greater sensitivity to the presence of luminance noise than men, potentially due to differences between men and women in aesthetic evaluation strategies.

Chromatic vision and structural assessment in primary congenital glaucoma.

Primary congenital glaucoma is a rare disease that occurs in early birth and can lead to low vision. Evaluating affected children is challenging and there is a lack of studies regarding color vision in pediatric glaucoma patients. This cross-sectional study included 21 eyes of 13 children with primary congenital glaucoma who were assessed using the Farnsworth D-15 test to evaluate color vision discrimination and by spectral domain optical coherence tomography to measure retinal fiber layer thickness. Age, visual acuity, cup-to-disc ratio and spherical equivalent data were also collected. Global and sectional circumpapillary and macular retinal fiber layer thicknesses were measured and compared based on color vision test performance. Four eyes (19%) failed the color vision test with diffuse dyschromatopsia patterns. Only age showed statistical significance in color vision test performance. Global and sectional circumpapillary and macular retinal fiber layer thicknesses were similar between the color test outcomes dyschromatopsia and normal. While the color vision test could play a role in assessing children with primary congenital glaucoma, further studies are needed to correlate it with damage to retinal fiber layer thickness.

Chromatic discrimination in fixed saturation levels from tufted capuchin monkeys with different color vision genotypes.

Recent research has proposed new approaches to investigate color vision in Old World Monkeys by measuring suprathreshold chromatic discrimination. In this study, we aimed to extend this approach to New World Monkeys with different color vision genotypes by examining their performance in chromatic discrimination tasks along different fixed chromatic saturation axes. Four tufted capuchin monkeys were included in the study, and their color vision genotypes were one classical protanope, one classical deuteranope, one non-classical protanope, and a normal trichromat. During the experiments, the monkeys were required to perform a chromatic discrimination task using pseudoisochromatic stimuli with varying target saturations of 0.06, 0.04, 0.03, and 0.02 u'v' units. The number of errors made by the monkeys along different chromatic axes was recorded, and their performance was quantified using the binomial probability of their hits during the tests. Our results showed that dichromatic monkeys made more errors near the color confusion lines associated with their specific color vision genotypes, while the trichromatic monkey did not demonstrate any systematic errors. At high chromatic saturation, the trichromatic monkey had significant hits in the chromatic axes around the 180° chromatic axis, whereas the dichromatic monkeys had errors in colors around the color confusion lines. At lower saturation, the performance of the dichromatic monkeys became more challenging to differentiate among the three types, but it was still distinct from that of the trichromatic monkey. In conclusion, our findings suggest that high saturation conditions can be used to identify the color vision dichromatic phenotype of capuchin monkeys, while low chromatic saturation conditions enable the distinction between trichromats and dichromats. These results extend the understanding of color vision in New World Monkeys and highlight the usefulness of suprathreshold chromatic discrimination measures in exploring color vision in non-human primates.

Aesthetic Dentistry - What You Decided and What I Want: Shade Selection

ABSTRACT Objective: To assess the relationship between patients' and dentists' perceptions of shade selection and its impact on satisfaction with the prosthesis. Material and Methods: A single group pre-post study was conducted at the Prosthodontics department of a teaching hospital in India. One hundred ten participants were selected through a systematic random sampling technique with inclusion and exclusion criteria. Patients' attitudes regarding the aesthetics of their maxillary anterior teeth were recorded using a validated questionnaire. Shades for the intended prosthetic crown selected by the dentist and chosen by the patient were recorded separately, and patient satisfaction with the appearance of the final prosthesis was recorded. We used descriptive statistics followed by Pearson's Chi-square test and a binomial logistic regression model for inferential statistics. Results: 109 participant's data were available for final analysis. Patients choose lighter shades than the dentist's selection, which is statistically significant (p=0.000). 73.4% were satisfied with the final prosthesis, and the binomial logistic regression model identified using patient-selected shade for the final prosthesis was significantly associated with patients' satisfaction with the final prosthesis (OR=3.3, p=0.001). Conclusion: The patient's preference should be considered with the dentist's option when selecting a shade to create good esthetics.

Data-Driven Models of Efficient Chromatic Coding in the Outer Retina.

Recent experimental work on zebrafish has shown the in vivo activity of photoreceptors and horizontal cells (HCs) as a function of the stimulus spectrum, highlighting the appearance of chromatic-opponent signals at their first synaptic connection. Altogether with the observed lack of excitatory intercone connections, these findings suggest that the mechanism yielding early color opponency in zebrafish is dominated by inhibitory feedback. We propose a neuronal population model based on zebrafish retinal circuitry to investigate whether networks with predominantly inhibitory feedback are more advantageous in encoding chromatic information than networks with mixed excitatory and inhibitory mechanisms. We show that networks with dominant inhibitory feedback exhibit a unique and reliable encoding of chromatic information. In contrast, this property is not guaranteed in networks with strong excitatory intercone connections, exhibiting bistability. These findings provide a theoretical explanation for the absence of excitatory intercone couplings in zebrafish color circuits. In addition, our study shows that these networks, with only one type of horizontal cell, are suitable to encode most of the variance from the zebrafish environment. However, at least two successive layers of inhibitory neurons are needed to reach the optimum. Finally, we contrast the encoding performance of networks with different opsin sensitivities, showing an improvement of only 13% compared with zebrafish, suggesting that the zebrafish retina is adapted to encode color information from its habitat efficiently.

Differences in chromatic noise suppression of luminance contrast discrimination in young and elderly people.

Aging causes impairment of contrast sensitivity and chromatic discrimination, leading to changes in the perceptual interactions between color and luminance information. We aimed to investigate the influence of chromatic noise on luminance contrast thresholds in young and older adults. Forty participants were divided equally into Young (29.6 ± 6.3-year-old) and Elderly Groups (57.8 ± 6.6-year-old). They performed a luminance contrast discrimination task in the presence of chromatic noise maskers using a mosaic stimulus in a mosaic background. Four chromatic noise masking protocols were applied (protan, deutan, tritan, and no-noise protocols). We found that luminance contrast thresholds were significantly elevated by the addition of chromatic noise in both age groups (P < 0.05). In the Elderly group, but not the younger group, thresholds obtained in the tritan protocol were lower than those obtained from protan and deutan protocols (P < 0.05). For all protocols, the luminance contrast thresholds of elderly participants were higher than in young people (P < 0.01). Tritan chromatic noise was less effective in inhibiting luminance discrimination in elderly participants.

Parámetros para la evaluación visual e instrumental del color dental en estudios in-vitro. Revisión de la literatura / Parameters for visual and instrumental assessment of tooth colour in in-vitro studies. Literature review

Objetivo: establecer los parámetros para la evaluación visual e instrumental del color dental en estudios in-vitro a partir de la literatura científca publicada entre 2015 y 2021. Métodos: se realizó la búsqueda en las bases de datos: PubMed, Web of Science, Science Direct, Scopus, Scielo y Lilacs; también en el motor de búsqueda Google Académico y las bibliotecas de las editoriales Wiley y Springer. Las palabras clave utilizadas fueron tooth, color, in-vitro, color perception, shade matching, thresholds, appearance, surrounding, "CIELAB" y "CIEDE2000". Teniendo en cuenta los criterios de elegibilidad, se seleccionaron los estudios de acuerdo al título, resumen y texto completo. Resultados: la búsqueda arrojó un total de 37 publicaciones que se agruparon en tres tópicos: 1. toma de color visual: condiciones ambientales, observadores y nivelación; 2. toma de color instrumental: instrumentos; y 3. procesamiento de datos: cálculo de la diferencia de color y umbrales de perceptibilidad (PT) y aceptabilidad (AT). Conclusiones: los aspectos más importantes en la evaluación visual son la iluminación, el ambiente para registro (sitio, entorno y fondo alrededor de la muestra), las condiciones geométricas de visualización, los observadores y el uso de guías. En la evaluación instrumental es relevante elegir el aparato apropiado de acuerdo con su precisión y reproducibilidad, como los espectroradiómetros y los espectrofotómetros de uso clínico. Se presenta el procesamiento de datos para establecer las variaciones de cada coordenada, las diferencias de color (ΔE): CIELAB y CIEDE2000, los umbrales y los lineamientos.

Objective: To establish the parameters for the visual and instrumental evaluation of tooth color in in-vitro studies based on the scientifc literature published between 2015 and 2021. Methods: The search was carried out in the databases of PubMed, Web of Science, Science Direct, Scopus, Scielo, Lilacs; search engine Google Scholar and publishers' library of Wiley and Scielo, using the keywords "tooth", "color", "in vitro", "color perception", "shade matching", "thresholds", "appearance", "surrounding", "CIELAB", and "CIEDE2000". The literature was selected according to the title, abstract and full text taking into the eligibility criteria. Results: It yielded a total of 37 publications, which were grouped into three topics: 1. visual color acquisition: environmental conditions for color acquisition, observers and levelling. 2. instrumental color sampling: instruments. 3. Data processing: Calculation of color diference and perception thresholds (PT) and acceptability thresholds (AT). Conclusions: The most important aspects in the visual assessment are lighting, the environment for color registration (site, environment and background around the sample), the geometric conditions of visualization, the observers and the use of guides. Regarding the instrumental assessment of color, the appropriate devices must be chosen according to its precision and reproducibility, being the spectrophotometers and spectroradiometers the most precise ones. It is presented how the data processing is carried out to establish the variations of each coordinate, the color diferences (ΔE): CIELAB and CIEDE2000, thresholds and guidelines.

What do male and female zebrafish prefer? Directional and colour preference in maze tasks.

Studies regarding the animals' innate preferences help elucidate and avoid probable sources of bias and serve as a reference to improve and develop new behavioural tasks. In zebrafish research, data obtained in behavioural assessments are often not replicated between research groups or even inside the same laboratory raising huge concerns about replicability and reproducibility. Among the potential causes that are not well considered, sexual differences can be a probable source of bias. Thus, this study aimed to investigate the male and female zebrafish directional and colour preferences in the plus-maze and T-maze behavioural tasks. Experiment 1 evaluated directional preference, and experiment 2 evaluated colour preference in a plus-maze task; experiment 3 evaluated preference between black or white in a T-maze task. Individual preferences were expressed as the percentage of time spent in each zone. Our results showed that male and female zebrafish demonstrated no difference in directional preference in the plus-maze task. Surprisingly, male and female zebrafish showed colour preference differences in the plus-maze task; males did not show any colour preference, while female zebrafish demonstrated a red preference compared to white, blue and yellow colours. Moreover, both male and female zebrafish demonstrated a strong black colour preference compared to the white colour in the T-maze task. Our findings characterized the spontaneous preference of male and female zebrafish for direction and colour, identifying possible biases and providing insights that contribute to the standardization of future protocols.

Chromatic discrimination in fixed saturation levels from trichromats and subjects with congenital color vision deficiency.

Color vision tests use estimative of threshold color discrimination or number of correct responses to evaluate performance in chromatic discrimination tasks. Both approaches have advantages and disadvantages. In the present investigation, we compared the number of errors during color discrimination task in normal trichromats and participants with color vision deficiency (CVD) using pseudoisochromatic stimuli at fixed saturation levels. We recruited 28 normal trichromats and eight participants with CVD. Cambridge Color Test was used to categorize their color vision phenotype, and those with a phenotype suggestive of color vision deficiency had their L- and M-opsin genes genotyped. Pseudoisochromatic stimuli were shown with target chromaticity in 20 vectors radiating from the background chromaticity and saturation of 0.06, 0.04, 0.03, 0.02, 0.01, and 0.005 u'v' units. Each stimulus condition appeared in four trials. The number of errors for each stimulus condition was considered an indicator of the participant's performance. At high chromatic saturation, there were fewer errors from both phenotypes. The errors of the normal trichromats had no systematic variation for high saturated stimuli, but below 0.02 u'v' units, there was a discrete prevalence of tritan errors. For participants with CVD, the errors happened mainly in red-green chromatic vectors. A three-way ANOVA showed that all factors (color vision phenotype, stimulus saturation, and chromatic vector) had statistically significant effects on the number of errors and that stimulus saturation was the most important main effect. ROC analysis indicated that the performance of the fixed saturation levels to identify CVD was better between 0.02 and 0.06 u'v' units reaching 100%, while saturation of 0.01 and 0.005 u'v' units decreased the accuracy of the screening of the test. We concluded that the color discrimination task using high saturated stimuli separated normal trichromats and participants with red-green color vision deficiencies with high performance, which can be considered a promising method for new color vision tests based in frequency of errors.

Comparison of visual shade matching and photographic shade analysis.

OBJECTIVE: To compare the performance of a standardized photographic shade analysis (PSA) and visual shade matching (VSM) using two color difference formulas. MATERIALS AND METHODS: Fifty observers (35 undergraduate and 15 graduate students) evaluated the color of two upper left central incisors (LT-light tooth, and DT-dark tooth). VSM was performed using the VITA 3D Master (3D) shade guide in a controlled clinical environment. For PSA, a cross-polarized filter and a gray card (Whibal) were used to standardize the photographs taken (target teeth and shade tabs from 3D). From the pictures obtained, the CIELAB coordinates, and color differences ( Δ E ab * and ΔE00 ) were obtained. The shade tabs selected by two experienced researchers were conducted as part of the pilot study, and finally used as a standard for the analysis. Data were analyzed using descriptive statistics and the chi-square test (p ≤ 0.05). RESULTS: Shade tabs selections of VSM and PSA agreed only for LT. The best "Match" selected by the researchers agreed with data from PSA using ΔE00 . PSA using ΔE00 showed higher total percentages of "Match" and higher percentage of agreement among observers. A relationship was found for LT performing the PSA (p < 0.05). CONCLUSIONS: The performance of the PSA was better than the VSM, but only when the CIEDE2000 color difference formula was used. Therefore, the color difference formulas influenced on the performance of PSA. Finally, the PSA improved the precision of the VSM. CLINICAL SIGNIFICANCE: To use a standardized PSA to improve the VSM and shade communication in clinical esthetic dentistry.

Heavy and light smokers have slight differences in chromatic discrimination.

Objectives: The effects of smoking on color vision have been scarcely studied. To bridge such gap, this study examined if there were differences in chromatic discrimination between heavy and light smokers. Methods: The psychophysical Trivector test was used to evaluate chromatic discrimination in healthy controls (n = 36), heavy smokers (n = 29), and light smokers (n = 32). The subject's task was to identify the orientation of the Landolt C ring gap - presented and randomized in one of the four positions (e.g., up, down, right, and left). Results: The thresholds for Protan (red), Deutan (green) and Tritan (blue) were higher in heavy smokers compared to nonsmokers but not to light smokers. Conclusions: The results confirm that heavy smoking and chronic exposure to its harmful compounds affect color discrimination when compared to light smoking; and this is more pronounced in heavy smokers than light smokers. This is particularly important to understand the differences among smokers on visual and multisensory processing.

Relation between smoking and visual processing in bipolar disorder.

Background: Although some studies have shown impairments in patients with bipolar disorder (BPD) and in smokers, it is unclear how these two factors work together. Our premise was that chronic smoking affects color discrimination and this is more pronounced in BPD. Objective: Our main purpose was to investigate the influence of smoking and BPD on color discrimination. Methods: Twenty-three smokers and 23 BPD smokers patients, aged 25-45 years old, participated in this study. Color vision testing was performed using the Trivector subtest of the Cambridge Colour Test. Participants' task was to indicate the pseudoisochromatic stimulus in four directions (up, down, right, and left). Results: It was shown that the smokers had better color vision than BPD smokers for the Protan (p < .001), Deutan (p < .001), and Tritan (p < .001) (red, green, and blue, respectively) axes. Thus, the BPD smokers' group had greater difficulty distinguishing the chromaticity variations (i.e., presented diffuse color vision impairments and not specific to any axis). Conclusions: The present study highlights a possible relationship between smoking and BPD in color discrimination. This highlights the importance of understanding the diffuse effects of this relationship.

Variaciones histórico-culturales de la estética dental / Historical and cultural variations of teeth aesthetics

Resumen La estética dentaria es un tema de amplia relevancia en la odontología actual, tanto en el ambiente universitario como en la práctica privada. Cuando las personas expresan que desean una sonrisa más hermosa, dentistas y pacientes piensan automáticamente en aclarar el color de los dientes como un componente importante de este proceso. ¿Cuál es la razón de esta concordancia tácita? Algunos podrían argüir que una sonrisa saludable es naturalmente más blanca, pero sabemos que la funcionalidad fisiológica no necesariamente está asociada a una estética socialmente determinada. Es más, muchas veces los procedimientos estéticos implican modificaciones corporales que no necesariamente son naturales, ni saludables. El objetivo de esta revisión, es brindar elementos de discusión acerca de aspectos históricos y culturales relacionados con el posicionamiento del color dentario como parte importante de un ideal estético. Se pretende argumentar, que el deseo de tener dientes más blancos reside eminentemente en influencias culturales. Asimismo, se invita a la reflexión de que, si los "dientes blancos" debiesen ser equiparados a "dientes saludables", con las consecuentes ramificaciones que implicaría esta suposición, en nuestro mundo profesional.

Abstract Dental aesthetics is a topic of wide relevance in current dentistry, both in dental education and in private practice. When people express that they want a beautiful smile, both dentists and patients think of whitening tooth color. What is the reason for this tacit agreement? Some might argue that a healthy smile is naturally whiter, but we know that physiological functionality is not always associated with socially determined aesthetics. Furthermore, some aesthetics procedures might involve body modifications that are not necessarily natural nor healthy. The aim of this review is to to provide elements of discussion about historical and cultural aspects related to the positioning of tooth color as an important part of an aesthetic ideal. To argue that the desire for whiter teeth resides in cultural influences. To invite reflection if "white teeth" should be equated with "healthy teeth", with the consequences this assumption would imply in our professional field.

Valoración del grado de pigmentación en dientes acrílicos sometidos a humo del cigarrillo / Assessment of the degree of pigmentation in acrylic teeth subjected to cigarette smoke

INTRODUCCIÓN. Los cambios de color en los dientes acrílicos dependen de varios factores, con el humo de cigarrillo como uno de los principales agentes de igmentación de las prótesis. OBJETIVO. Valorar el grado de pigmentación en dientes acrílicos sometidos al humo del cigarrillo, mediante espectrofotometría digital. MATERIALES Y MÉTODOS. Estudio observacional, analítico, de caso y control. Muestra de 60 dientes acrílicos divididos en dos grupos: A (resina acrílica de 3 capas) y B (resina acrílica de 4 capas). Se subdividió en: grupo 1: dientes sometidos a humo de cigarrillo estándar con filtro de carbón; grupo 2: dientes sometidos a humo de cigarrillo estándar sin filtro; y, grupo 3: grupo control. Cada uno de éstos se expuso a 150 cigarrillos, 5 diarios durante 30 días y el grupo control fue mantenido a 37ºC en saliva artificial durante 30 días sin aplicación de humo de cigarrillo. Para la toma de color se empleó espectrofotómetro Vita Easyshade®. Los análisis se realizaron en el programa estadístico International Business Machines Statistical Package for the Social Sciences mediante la prueba de Kruskal-Wallis y comparaciones de Dunn. RESULTADOS. Se determinó que la pigmentación del grupo B fue mayor a la del grupo A, con una diferencia significativa entre ellos (p< 0,05). No se encontró datos estadísticamente significativos entre cigarrillos (con filtro - sin filtro). CONCLUSIÓN. La exposición al humo de cigarrillo pigmentó los dientes acrílicos de ambas propiedades siendo mayor en los dientes de resina acrílica de 4 capas.

INTRODUCTION. Color changes in acrylic teeth depend on several factors, with cigarette smoke as one of the main agents of denture pigmentation. OBJECTIVE. To assess the degree of pigmentation in acrylic teeth subjected to cigarette smoke, using digital spectrophotometry. MATERIALS AND METHODS. Observational, analytical, case-control study. Sample of 60 acrylic teeth divided into two groups: A (3-layer acrylic resin) and B (4-layer acrylic resin). It was subdivided into: group 1: teeth subjected to standard cigarette smoke with charcoal filter; group 2: teeth subjected to standard cigarette smoke without filter; and, group 3: control group. Each of these was exposed to 150 cigarettes, 5 daily for 30 days and the control group was maintained at 37ºC in artificial saliva for 30 days without application of cigarette smoke. Vita Easyshade® spectrophotometer was used for color determination. The analyses were performed in the statistical program International Business Machines Statistical Package for the Social Sciences using the Kruskal-Wallis test and Dunn's comparisons. RESULTS. It was determined that the pigmentation of group B was greater than that of group A, with a significant difference between them (p< 0,05). No statistically significant data was found between cigarettes (filtered - unfiltered). CONCLUSION. Cigarette smoke exposure pigmented acrylic teeth of both properties being higher in 4-layer acrylic resin teeth.

Detection of conspicuous and cryptic food by common marmosets (Callithrix jacchus): An evaluation of the importance of color and shape cues.

In primates, the advantage of trichromacy (i.e., color vision expressed by most humans) over dichromacy (i.e., color vision expressed by many colorblind humans) has been linked to the detection of yellowish/reddish targets against a background of mature green leaves. Nevertheless, mostly because of studies conducted in humans, we know that achromatic cues might also play an important role in object identification, particularly when camouflage is involved. For instance, dichromacy favors the detection of camouflaged targets by exploitation of shape cues. The present study sought to evaluate the relative importance of color and shape cues on the detection of food targets by female and male marmosets (Callithrix jacchus). Animals were observed with respect to their foraging behavior and the number of food targets captured. We confirmed that females are advantageous in detecting conspicuous food against a green background and revealed that females and males rely on shape cues to segregate cryptic food. Unexpectedly, males outperformed females in cryptic food foraging, while camouflage improved males' (but not females') performance. Here we show that dichromats could potentially benefit from a better segregation of green natural targets (e.g., immature fruits, green insects, and gum trees) when viewed against a green dappled background.

Influence of background color on color perception in dentistry.

OBJECTIVE: To evaluate the influence of neutral color backgrounds on the perception of color differences in dentistry. METHODS: A software was developed for this study that calculated the perceptibility (PT) and acceptability (AT) thresholds of color differences between a pair of computer-simulated incisor samples (n = 60 pairs) over three neutral color (white, gray and black) backgrounds. CIELAB and CIEDE2000 color difference formulas were used. Five groups of volunteer observers (N = 100) participated in the psychophysical experiment (n = 20): Dentists; Dental students; Dental auxiliaries; Dental technicians; and Laypersons. The psychophysical experiment was performed in a dark environment on a calibrated high-resolution screen. To determine PT and AT values, the 60 pairs of samples were randomly presented to each observer over the different backgrounds. The data were adjusted (TSK Fuzzy) and analyzed statistically using Student t-test and ANOVA (α = 0.05). RESULTS: Regardless of the metric and the background used, the PT values showed no difference among different observers (p > 0.05). Dentists showed the lowest PT values. Dental technicians showed the lowest AT (p ≤ 0.05) and similar values for the three backgrounds (p > 0.05), regardless of the metric used. The other groups of observers showed the lowest and the highest AT values when using black and white backgrounds, respectively (p ≤ 0.05). CONCLUSIONS: The lowest AT values using a black background indicates that the use of this background allows for the evaluation of slight color differences, and should be used for challenging color differences in esthetic dentistry. This study showed the influence of the observer experience on color evaluation in dentistry. CLINICAL SIGNIFICANCE: There was no influence of the background color on the perceptibility threshold. However, dentists and dental technicians showed greater ability to perceive slight color differences compared to other groups of observers.

Comparison of visual analog shade matching, a digital visual method with a cross-polarized light filter, and a spectrophotometer for dental color matching.

STATEMENT OF PROBLEM: During the selection of tooth color, subjective communication with the laboratory and an incorrect color registration technique can lead to a poor color match of a restoration to adjacent teeth and oral structures. PURPOSE: The purpose of this cross-sectional study was to compare color registration and color matching in a young Chilean population with 3 different methods: visual with a shade guide, digital visual with a cross-polarized filter, and instrumental with a spectrophotometer. MATERIAL AND METHODS: A total of 60 young volunteers were selected for tooth color registration of the maxillary right central incisor by using 3 different methods. Tooth color registration was performed using the CIELab and ΔE coordinate system. RESULTS: Significant differences were detected between the coordinates recorded by the visual analog method in comparison with the other 2 methods. In contrast, no significant differences were found between the L∗ and b∗ coordinates of the spectrophotometer and the digital visual method with use of a cross-polarization filter. The ΔE obtained between the visual shade and spectrophotometer was 7.35, and the ΔE between the digital visual method with the use of a cross-polarization filter and the spectrophotometer was 6.12. CONCLUSIONS: No statistically significant differences were observed in the digital image with the cross-polarization filter and the spectrophotometer in the L∗ and b∗ coordinate of the CIELab system. In contrast, the visual analog method led to large differences with the other methods under study. The ΔE of the digital visual method with the use of cross-polarization filters and the spectrophotometer was 6.2, considered as an acceptable color mismatch (<ΔE 6.8).

Efficacy of color discrimination tests used in dentistry.

OBJECTIVE: To evaluate the efficacy of visual discrimination tests used for color research in dentistry. MATERIALS AND METHODS: Volunteers (N = 120) were divided in three groups of observers (n = 40; gender-balanced): S-dental students; D-dentists; and L-laypersons. Two general color discrimination tests (I-Ishihara and FM-Farnsworth-Munsell 100 Hue) and the test of color discrimination competency in dentistry using the VITA Classical shade guide (VC) were performed and data were recorded according to manufacturers' or literature recommendations. Data were statistically analyzed using Mann-Whitney U test for the gender influence and Kruskal-Wallis test for the observer influence, and Bonferroni as post-hoc test (α = 0.05). Pearson (α = 0.05) was used to examine the correlation among visual tests (I, FM, and VC). RESULTS: Observers and visual tests were not influenced by gender (P > .05). Different observer groups had no influence on I test (P > .05). S and D showed similar level of color perception using FM and VC (P > .05), but these observers showed greater color perception than L (P ≤ .05). FM and VC also showed significant correlation (P ≤ .05) for the overall D observers (r = -0.362), male D (r = -0.594) and female S (r = -0.457). CONCLUSION: Observer experience significantly influenced on color perception, irrespective of gender. FM test showed greater correlation to color correspondence in dentistry (VC) than I test. CLINICAL SIGNIFICANCE: Observer experience is more relevant than gender for the color selection process in dentistry. Considering the visual discrimination tests for color research in dentistry, the Farnsworth-Munsell 100 Hue test seems to be more efficacious than the Ishihara test.

Specificity of the chromatic noise influence on the luminance contrast discrimination to the color vision phenotype.

Many studies have examined how color and luminance information are processed in the visual system. It has been observed that chromatic noise masked luminance discrimination in trichromats and that luminance thresholds increased as a function of noise saturation. Here, we aimed to compare chromatic noise inhibition on the luminance thresholds of trichromats and subjects with severe deutan or protan losses. Twenty-two age-matched subjects were evaluated, 12 trichromats and 10 with congenital color vision impairment: 5 protanopes/protanomalous, and 5 deuteranopes/deuteranomalous. We used a mosaic of circles containing chromatic noise consisting of 8 chromaticities around protan, deutan, and tritan confusion lines. A subset of the circles differed in the remaining circles by the luminance arising from a C-shaped central target. All the participants were tested in 4 chromatic noise saturation conditions (0.04, 0.02, 0.01, 0.005 u'v' units) and 1 condition without chromatic noise. We observed that trichromats had an increasing luminance threshold as a function of chromatic noise saturation under all chromatic noise conditions. The subjects with color vision deficiencies displayed no changes in the luminance threshold across the different chromatic noise saturations when the noise was composed of chromaticities close to their color confusion lines (protan and deutan chromatic noise). However, for tritan chromatic noise, they were found to have similar results to the trichromats. The use of chromatic noise masking on luminance threshold estimates could help to simultaneously examine the processing of luminance and color information. A comparison between luminance contrast discrimination obtained from no chromatic and high-saturated chromatic noise conditions could be initially undertaken in this double-duty test.

Color Preference of Three Parasitoids Imported to the Americas for the Biological Control of the Coffee Berry Borer (Curculionidae: Scolytinae).

The African parasitoids Cephalonomia stephanoderis Waterston (Bethylidae: Hymenoptera), Prorops nasuta Betrem (Bethylidae: Hymenoptera), and Phymastichus coffea LaSalle (Eulophidae: Hymenoptera) are biological control agents of the coffee berry borer (Coleoptera: Curculionidae). In this study, we investigated in laboratory the female behavioral responses of these parasitoids to 14 different wavelengths (340-670 nm) against a control (570 nm, yellow). When nonchooser females were included in the analysis, none parasitoids species showed a preference between 340, 350, 370, 460, 490, 520, 540, 590, 640, and 650 nm with respect to the control wavelength. In contrast, the three species of parasitoids were more attracted to wavelengths of 380, 400, and 420 nm than the control wavelength. Phymastichus coffea and P. nasuta were more attracted to the wavelength of 400 and 420 nm compared to C. stephanoderis. At 380 nm, P. coffea and C. stephanoderis wasps showed the higher responses in comparison to P. nasuta females. When nonchooser wasps were excluded from the analysis, we observed other differences among the parasitoid species. For instance, P. coffea were more attracted to 490-540 nm than to 570 nm, whereas the bethylids did not discriminate between 490-540 nm or 570 nm. Our results are discussed in relation to possible implications associated with the vision of these parasitoid species.