Analysis of European colour vision certification requirements for air traffic control officers

The advantages of using colour in large-field, visual displays have been investigated with emphasis on ATC applications. This study examined and quantified the relationship between severity of colour vision loss in congenital deficiency and the corresponding changes in visual performance. Analysis of current colour assessment protocols and the current findings provide the basis for a new system of colour categories that can be enforced. The report also describes how a colour category can be selected for a given occupational task by examining the colour-related requirements and the applicant’s class of colour deficiency

Colour Vision Test for Railway Dispatchers

Introduction Colour codes are used extensively in railways to convey specific information governing movement of trains and equipment on the track. One such task is the railway traffic control display that uses colour coded video display terminals (VDTs) to convey information of the signal status, train movements and track status to the railway dispatcher. Because individuals with colour vision deficiencies (colour-defectives) may have problems with these colour-related tasks, questions were raised about the suitability of colour vision defectives to work as railway dispatchers. In order to answer that, a VDT based Dispatch Colour Vision Test based on the actual railway traffic display was developed previously. Purpose The main purpose of this thesis is to establish the pass/fail scores and repeatability of the VDT based Dispatch Colour Vision Test that resulted from the previous work. Secondly, the study will also examine whether clinical colour vision tests can predict the performance on the practical task. Methods The Dispatch colour vision test was divided into three parts based on the colour sets that the dispatcher had to recognize. The testing computer system used the the same RGB colour settings, graphics card and monitor as in railway dispatch centres. Subjects viewed the display colours and entered their responses by using a mouse. One hundred colour-normals and fifty two colour-defectives participated in the initial session. The test was repeated approximately after 10 days. Ninety three colour-normals (93%) and 44 (85%) colour-defectives participated in the second session. The total number of errors and time to complete the test was recorded. Results Pass/Fail on the VDT Dispatch colour vision test was based on colour-normal errors. Ignoring orange-red errors, two errors were allowed in the first session and one error was allowed in the second session. Based on this criterion, 42% of colour vision defectives could perform as well as colour normal subjects. The kappa coefficient of agreement between the sessions for the colour-defectives was 0.85. Detailed analysis between the colour differences and the errors showed only a weak correlation between the two. However, the general trend was that colour-defectives made more errors on colours that were near or along the same lines of confusions and the colours were nearly equal in luminance. Nevertheless, the interaction between luminance and location with respect to the lines of confusion was not easy to interpret. The time to complete the task for the colour-defectives who passed the test took 14% longer than colour-normals and colour-defectives who failed took 30% longer than colour-normals. All groups showed a similar learning effect with an 18% reduction in mean times to complete the task at the second session. There was no significant correlation between the number of errors and time to complete or the clinical tests and completion times for any of the groups. Clinical colour vision tests have limited value in predicting performance of colour-defectives on the Dispatch test. Logistic analysis results showed that the Farnsworth D-15 along with the Nagel was the best predictor of the VDT Dispatch colour test pass/fail results. However, these results were similar to using the Farnsworth D-15 test alone. Ninety-five percent of the individuals who failed the Farnsworth D-15 also failed the Dispatch test. However, approximately 25% of the individuals who passed the Farnsworth D-15 failed the VDT Dispatch colour test which is an unacceptable false negative rate. These results indicate the Farnsworth D-15 can only be used to predict who is likely to fail the dispatch test. Conclusions Forty two percent of colour vision defectives could perform as well as colour-normals in identifying VDT railway display colours and time to complete the task. Clinical colour vision tests were inadequate predictors of performance in practical task, overall. However, the Farnsworth D-15 was a very good predictor of who would fail the VDT Dispatch test. Hence a practical VDT Dispatch test may be needed to test individuals who would want to work as railway dispatchers

Color vision assessment-1: Visual signals that affect the results of the Farnsworth D-15 test

The Farnsworth D‐15 test (D‐15) is commonly used to screen for moderate to severe congenital color vision deficiency. The aim of this study was to establish reliable D‐15 statistics for normal, deutan and protan subjects, and to investigate the different visual signals one can use to carry out the test, even in dichromats and rod monochromats. Six hundred and seventy‐four subjects were examined using the D‐15, the Colour Assessment and Diagnosis test and the Nagel anomaloscope. A rod monochromat and five dichromats were tested using the standard D‐15 protocol before the caps were separated into two groups and subjects were asked to repeat the task. D‐15 spectral radiance data, measured under D65 illumination, were used to estimate differences in photoreceptor excitations for each of the caps. When no crossings and up to two adjacent transpositions on the D‐15 results diagram are accepted as a pass, 100% of normal trichromats, 54% of deutans and 43% of protans pass the D‐15. A rod monochromat and two protanopes and deuteranopes were able to complete the D‐15 when the caps were separated into two groups, despite severe loss or even complete absence of color vision. When up to two adjacent transpositions are accepted 50% of color deficient subjects, some with severe red/green loss, pass the D‐15. While the D‐15 is normally used to screen for moderate to severe color deficiency, subjects with severe loss can still use combined, residual red/green, yellow/blue and luminance signals to pass

Impact of congenital color vision defect on color‑related tasks among Secondary School Students in Ibadan, Southwest Nigeria

Aim: To assess the difficulties encountered by students with congenital color vision defects in daily living and school activities.Methods: A cross‑sectional descriptive study conducted among students of public secondary schools in Ibadan, Nigeria. Structured questionnaires were administered to all consenting students to determine difficulties encountered in aspects of color matching and color recognition.Results: A total of 1635 students (male:female 1:1.1) were screened of whom 37 (2.3%) had congenital color vision defect. A statistically significant proportion (P < 0.0001) of them reported difficulties with color‑related school work and day‑to‑day activities.Conclusion: Congenital color vision deficient students encounter some difficulty with school work and daily living activities, hence a need to identify them early and give appropriate career guidance.Keywords: Color vision, color vision defect, congenita

Basic and Applied Studies of Human Visual Function: Implications for Visually Demanding Occupations

Color vision is a complex process providing important information about objects within our environment. Color vision deficiency either congenital or acquired can impact real world performance. Current working environments either require normal color vision or utilize color as a tool to highlight critical information. The use of color in the workplace provides several advantages. Hence, color vision screening is required for entry into professions and occupational certifications. Acquired color vision deficiency may also impact job performance requiring clinical screening. The present dissertation focused on the considerations outlined by the Commission on Behavior and Social Sciences when choosing a clinical test for occupational purposes. In order to address these considerations, I conducted a series of four studies. The first study compared and contrasted three different computerized color vision tests for contrast sensitivity and analyzed how the minimum cutoff score differed between the tests. The results indicated that while log CS values were similar, there were enough differences between the values that caution should be applied when using the tests interchangeably for occupational screening. The second study assessed the Color Vision Field Test and found that it has excellent sensitivity and specificity for occupational screening when appropriate protocols are followed. The third study determined if the Cone Contrast Test could predict performance on the FM-100 Hue thereby providing a potential alternative test to the FM-100. Results indicated the CCT may be an effective substitute for the FM-100 to provide certification of jewelry appraisers, but the small sample size warrants additional comparative validation to support sole utilization of the CCT. This study also revealed exceptional hue discrimination in jewelry appraisers, a possible effect of perceptual learning. The last study expanded previous research on cell phone distraction to auditory distraction with a navigational system. Delayed response time was found which poses a threat to safety

Studies of normal and deficient colour vision with relevance to occupational environments

The studies described in this thesis aim to assess the importance of normal colour vision in visually demanding, colour-related tasks that are often safety-critical and aim to improve our understanding of how congenital deficiencies can affect the processing of colour signals and the corresponding changes in visual performance. The first study compares the colour vision requirements within different professional environments. 519 subjects were tested: 141 normal trichromats, 268 deutans and 110 protans. All subjects carried out the Ishihara 38-plate test, the CAD test and the Nagel anomaloscope, and sub-populations were examined with the AO-HRR plates, the Farnsworth D15, the City University test (2nd Ed.), the Holmes-Wright type A and B lanterns. Inconsistencies of outcome amongst the various tests and potential alternative practices are discussed. The second study focuses on understanding the discrepancies in performance observed on lantern tests when the subject’s task is to report the colour of small signal lights presented against a dark background field. These conditions were simulated using a psychophysical luminance pedestal technique. Variations in the measurement of chromatic sensitivity over the visual field, as well as the detection of targets where colours are combined with luminance contrasts, are discussed and explanations considered with regard to underlying retinal physiology. The last study investigates the use of colour signals in ATC (air traffic control) applications. The work carried out addresses current failings in acceptance criteria for applicants, and provides alternative methods of assessing suitability. The chromatic discrimination thresholds of normal trichromats and colour deficient subjects were related to performance on a set of visual search tasks selected to be more representative of typical colour usage in large field visual displays. Display parameters under which the performance of colour deficient observers could be comparable to that of normal trichromats are examined with regard to updating occupational acceptance criteria

DRIVER PREFERENCE CONCERNING IN-CAR ROUTE GUIDANCE AND NAVIGATION SYSTEM MAPS FOR DRIVERS WITH COLOR VISION DEFICIENCY

In-car Route Guidance and Navigation Systems (RGNS) are used to help drivers navigate. These maps have mainly been designed to accommodate drivers with normal color vision. However, the color perception of people with normal color vision differs from that of people with color vision deficiency. When navigating, understanding certain kinds of information presented by RGNS maps can be a more complex task for colorblind drivers and traffic safety may be impacted negatively. An important aspect related to the graphic design of RGNS maps is the use of a good combination of colors to improve map legibility. Cartographic representations with good legibility aid drivers in comprehending information and making appropriate decisions during driving tasks. This paper evaluates driver preference for RGNS maps designed for drivers with color vision deficiency. A total of 14 subjects participated in an experiment performed in a parked car. Maps were designed to accommodate red-blinds and green-blinds by using a color simulator and principles of perceptual grouping and figure-ground segregation. Based on the results, we conclude that the map grouping symbols representing car and direction arrows in blue segregated from the route in black was more acceptable to drivers compared to other combinations. It is recommended that RGNS should offer a specific graphic design to support drivers with color vision deficiency in navigating

El color en el material escolar

Este trabajo pretende estudiar el uso del color como recurso para la resolución de ejercicios en los libros de P5 (ciclo infantil), de primero y de segundo curso de primaria, ya que aproximadamente un 8% de la población masculina presenta anomalías en la percepción cromática y un uso inadecuado del color puede representar un impedimento para su aprendizaje. Los objetivos principales son: - Contactar con centros educativos catalanes para conocer qué libros utilizan. - Examinar diversos libros para calcular el porcentaje de páginas con ejercicios que precisan una buena discriminación cromática para ser resueltos. - Analizar colorimétricamente los colores presentes en los libros. - Comprobar si una muestra de ejercicios clasificados como dificultosos para una persona discromatópsica resultan, efectivamente, difíciles de resolver. - Contactar con algunas editoriales para dar a conocer propuestas de mejora del material escolar. Las conclusiones principales son: - Que el porcentaje medio de páginas erróneas hallado en los libros de matemáticas analizados es del 8%. - Que el binomio rojo-verde es frecuentemente encontrado en diversos ejercicios y desaconsejable por la confusión que ocasiona a un niño con problemas de percepción cromática. - Que diversas editoriales han mostrado una buena predisposición a solucionar este problema

Individualized Models of Colour Differentiation through Situation-Specific Modelling

In digital environments, colour is used for many purposes: for example, to encode information in charts, signify missing field information on websites, and identify active windows and menus. However, many people have inherited, acquired, or situationally-induced Colour Vision Deficiency (CVD), and therefore have difficulties differentiating many colours. Recolouring tools have been developed that modify interface colours to make them more differentiable for people with CVD, but these tools rely on models of colour differentiation that do not represent the majority of people with CVD. As a result, existing recolouring tools do not help most people with CVD. To solve this problem, I developed Situation-Specific Modelling (SSM), and applied it to colour differentiation to develop the Individualized model of Colour Differentiation (ICD). SSM utilizes an in-situ calibration procedure to measure a particular user’s abilities within a particular situation, and a modelling component to extend the calibration measurements into a full representation of the user’s abilities. ICD applies in-situ calibration to measuring a user’s unique colour differentiation abilities, and contains a modelling component that is capable of representing the colour differentiation abilities of almost any individual with CVD. This dissertation presents four versions of the ICD and one application of the ICD to recolouring. First, I describe the development and evaluation of a feasibility implementation of the ICD that tests the viability of the SSM approach. Second, I present revised calibration and modelling components of the ICD that reduce the calibration time from 32 minutes to two minutes. Next, I describe the third and fourth ICD versions that improve the applicability of the ICD to recolouring tools by reducing the colour differentiation prediction time and increasing the power of each prediction. Finally, I present a new recolouring tool (ICDRecolour) that uses the ICD model to steer the recolouring process. In a comparative evaluation, ICDRecolour achieved 90% colour matching accuracy for participants – 20% better than existing recolouring tools – for a wide range of CVDs. By modelling the colour differentiation abilities of a particular user in a particular environment, the ICD enables the extension of recolouring tools to helping most people with CVD, thereby reducing the difficulties that people with CVD experience when using colour in digital environments

Anàlisi de la pèrdua d'habilitats i reflexes durant la conducció associades a l'envelliment

La conducció és una tasca altament visual que requereix concentració i habilitats visuals per proporcionar una conducció segura. El Butlletí Oficial de l’Estat (BOE) intenta regular les aptituds psicofísiques requerides per obtenir o renovar el permís de conduir, concretament les capacitats visuals. L’envelliment provoca pèrdues d’habilitats, reflexes i un envelliment general. Per conseqüència, les estructures oculars com còrnia, cristal·lí, retina i nervi òptic, també es van envellint i es veuen sotmeses a canvis involutius morfològics i fisiològics, la qual cosa fa que es vagin perdent les funcions principals. Com per exemple: pèrdua de la transparència, sensibilitat corneal, canvi en la tonalitat, alteracions vasculars, disminució dels axons, etc. Aquestes pèrdues de les funcions de les estructures oculars afecten a que es produeixin canvis involutius de les funcions visuals i com a conseqüència a la conducció, fent que augmentin els riscos de provocar distraccions al volant. En el camp de la investigació, els estudis cercats es van realitzar mitjançant entrevistes, qüestionaris o simuladors de conducció interactius, on relacionen les habilitats visuals amb l’índex de riscos de provocar accidents en els diferents grups d’edats. En tots aquests estudis, els autors observen diferents variacions de les funcions visuals depenent de les edats que estan investigant