Interactive Method of Detecting Color Vision Disorders in Candidates for Drivers

INTERACTIVE METHOD OF DETECTING COLOR VISION DISORDERS IN CANDIDATES FOR DRIVERS

DARIUSZ BOBER, MACIEJ LASKOWSKI, JACEK KASIK

Summary The problems with detecting color vision disorders in candidates for drivers are discussed in this paper. Authors analyze the methods currently used to detect various types of color vision disorders in driving schools and their effectiveness. This problem is especially important in many countries, where colorblind people are prevented from having a driving license, thus the detection process should be most accurate, objective and faultless. A new interactive method of detecting people with potential color vision disorders is proposed in this article. The analysis of results ob- tained in driving school with the proposed method is also conducted and discussed.

Keywords: colorblindness, color vision disorders, visual impairment

1. Introduction Being colorblind may prevent a person from engaging in certain occupations, especially when color recognition is either important for safety (e.g. driver, pilot) or essential for the work itself (e.g. painter, designer). Some of those limitations are caused by legal regulations [1]. For example, in a number of countries colorblind people are not permitted to apply for driver or pilot licenses [1]. These limitations originate from Swedish railroad accident in 19th century, where investiga- tion showed that the fatal crash was caused by a colorblind engineer [2]. The usual justification for such restrictions is that drivers must be able to recognize color-coded signals, such as traffic lights or warning lights. In most cases, person affected with this vision impairment can live a normal life, as only color vision, not vision itself, is distorted. Many people are not even aware of being colorblind, as this disorder can usually be detected on only few occasions: during pre-school medial tests or while applying for a driver or pilot license [1]. But even then colorblindness can be not detected e.g. due to the carelessness of the medical examiner. Moreover, colorblindness cannot be treated (although there are certain types of tinted filters and contact lenses which may help a person to better distinguish different colors, but they have little practical use [1]). Because of this fact, medical units in many countries do not keep any medical records of the colorblind people [3]. Although in Poland the law permits colorblind people to apply for driver license [4], this color vision disorder may prevent the individual from performing certain actions or may affect negatively the understanding of visual messages if they are color based 6 Dariusz Bober, Maciej Laskowski, Jacek KBsik Interactive method of detecting color vision disorders in candidates for drivers

2. What are color vision disorders? For the color vision is responsible the system of receptors in the eye retina (see Fig. 1). The human eye has three types of cone cells located in the retina. Each type of cone cells are receptive for different wavelength of light, this way one cone cell is sensitive mainly to red, another to green and another to blue. By combination of this cone cells stimulation we see full palette of colors (see Fig. 2). Color vision disorders (colorblindness) are the situation where the function of one of these cone cells are lost, or perturbed.

Figure 1. The colors’ receptors in the retina [5] The majority of color vision disorder is the so called "red-green colorblind," with problems either in the red or green types of cone cell. The palette of colors seen by these people is reduced; an example is presented at Fig. 2. People with mutant red receptors has color vision disorder called protanope, and people with mutant green receptors has color vision disorder called deuteranope. People with the problem in blue receptors has color vision disorder called tritanope. This is relatively rare, with only 0.001% of occurrence [5].

Figure 2. The colors’ palettes viewed by people with different color vision disorders, and people with no disorder [5] The frequency of colorblindness is fairly high. One in twelve Caucasian (8%), one in 20 Asian (5%), and one in 25 African (4%) males are so-called "red-green" colorblind [5]. Red-green color vision defects are the most common form of color vision deficiency. Among populations with Northern European ancestry, this condition affects males more often than females, occurring in about 8 percent of males and 0.5 percent of females. Red-green color vision defects have a lower incidence in almost all other populations studied. Blue-yellow color vision defects affect males and females equally. This condition occurs in less than 1 in 10,000 people worldwide. Complete achromatopsia affects an estimated 1 in 30,000 people. This condition is much more common 7 Studies & Proceedings of Polish Association for Knowledge Management No. 42, 2011 among Pingelapese islanders, who live on one of the Eastern Caroline Islands of Micronesia. Five percent to 10 percent of this population has a total absence of color vision [6]. The beginner of color vision disorder research was John Dalton, in 1973 he wrote the first sci- entific paper entitled “Extraordinary facts relating to the vision of colors”. Thanks to his name, “red-green” type of color vision disorder is common named “daltonism”. Dalton himself was red- green colorblind and as a scientist he took interest in this topic [7]. The described above mecha- nism of color vision disorder is genetic, although in certain situations some chemical agents could also affect or increase the effect of natural disorder. As it was published in [8] a variety toxic substances including: central serous retinopathy, drug and toxic poisoning from lead, tobacco and alcohol, would produce defects of eye retinal diseases, brain injuries and in consequence the color vision disorder could appear in the group of people whose already have driver license. From the point of view of our research, the main issue is reduced to protanope and deuteranope disorder, because the traffic lights and road signs are mostly designed in red or green colors. “Red-green” colorblind candidates for driver may prevent the individual from performing certain actions or may affect negatively the understanding of visual messages. They are hard to distinguish colors between red and green with similar intensity (same brightness), for them green and red color is seen ad brown, and differences of brightness are especially small (see Fig. 3, blue rectangle).

Figure 3. The colors’ palettes viewed by people with different color vision disorders, and people with no disorder [5] To compensate the lack of red or green cone cells, people with color vision disorder rely more on the information from the blue cone cells. Thus, they are more sensitive to distinguish bluish of color than the people which haven’t got this disorder. For example, deuteranope people think "red and green" are almost the same color, in opposite they recognize "green and bluish green" as completely different colors (compare this colors at Fig. 3). To compensate the low resolution in the recognition of hues, colorblind people tend to be more sensitive to the differences in brightness and saturation. 8 Dariusz Bober, Maciej Laskowski, Jacek KBsik Interactive method of detecting color vision disorders in candidates for drivers

In addition, in situation where traffic lights are old or dirty and in consequence the light brightness is low, the protanope drivers could not notice that "red" light signalize the stop order. They feel “dark red” much darker almost as "black"(Fig. 3), since the cone cells that cover the longest range of wavelengths are defect, thus, they could think “the lights are off”. In some situations it could be dangerous.

3. A conception of testing method Authors considered the problem of detecting colorblindness in candidates for drivers. Alt- hough, as it was mentioned earlier, in Poland the colorblind people may apply for driver license, each candidate has to pass the medical examination, which includes a simple test for color vision disorder based on Ishihara plates. These plates contain a circle of dots appearing randomized in color and size. Typically, this is a test performed using printed albums, but there are web-based variations of this test, e.g. [9, 10]. There are dots within the pattern which form a number visible to people with normal color vision and invisible or difficult to see, for those with a color vision defect [11]. Ishihara plates are usually used for testing especially red-green color deficiencies, but some of the plates can also be used for testing blue-yellow color deficiencies. In many driving schools, this examination is performed on the same day to the whole training group. In some situations the medical examiner may inadvertently miss or ignore the results of colorblind test. Moreover, the Ishihara plates are often criticized, as some of the plates imply two (or sometimes more) correct answers (e.g. reading a number of 23 or 73 are accepted) [12]. Some people may also perceive this test as unintelligible or outdated [13]. It has to be noticed, that there are different types of color vision disorders – varying from monochromacy (total colorblindness), through dichromacy (when the affected person see no perceptible difference between two specific colors) to an impairment (but not loss) of normal, three-dimensional color vision. The dichromacy is especially interesting in case of candidates for drivers, as two of three forms of dichromacy (protanopia and deutanopia) affect green-yellow-red section of the visible spectrum. For protanopes, the brightness of reds, oranges and yellows is much reduced compared to normal vision. Moreover, reds may be confused with black or dark grays and red traffic lights may appear to be extinguished. [14]. The deuteranope suffers the same hue discrimination problems as the protanope, but without the abnormal dimming [14]. Tritanopia is a form of blue-yellow colorblindness, caused by the complete absence of blue retinal photoreceptors [14]. It is the rarest form of dichromacy [4]. Authors focused on developing the method for testing for dichromats, especially protanopes or deutanopes, as an alternative for the standard test, based on Ishihara plates. The proposed method consisted of two elements – a survey (used mainly for statistical purposes) and simple interactive driving simulator. The survey was designed in order to characterize the testing group in age, sex and place of residence (urban or rural areas) structure. Basing on the experiences from previous surveys [15], authors decided to record date and time of each test. The first version of the test is published on a beta-project website [16]. The interactive driving simulator is the most important part of the testing procedure. The driver has to drive through 20 (in total) changes of streetlights, responding properly to the signaled 9 Studies & Proceedings of Polish Association for Knowledge Management No. 42, 2011 color. Both the light color (red, yellow or green) and its position are chosen randomly. Changing the light color is used to avoid the situation when the driver reacts to the position of the light (e.g. stops when the signal light on the top is on). An example of a random light sequence for the simulation is presented in Fig. 4

Figure 4. An example set of 20 random streetlight positions Driver has to decide whether he drives or stops each time a signal light is lit. Individual deci- sions are counted and at the end of the test, the participant is shown his result – how many times he crossed the intersection on a red or yellow light and the number of unnecessary stops on the green light. The results for each simulation are stored in a database for further analysis. The research conception is shown in Fig. 5.

Figure 5. Research conception for testing candidates for drivers Although it is not possible to fully simulate any kind of dichromacy [4], the authors decided to transform some of the screens from the game using the Vischeck software (www.vischeck.com) in order to at least partially recreate the perception of the dichromate. The simulation results are presented in Fig 6 a-d. 10 Dariusz Bober, Maciej Laskowski, Jacek KBsik Interactive method of detecting color vision disorders in candidates for drivers

By comparing the degree of distortion of the transformation of discussed color vision dysfunction (Fig. 6 a–d) it should be noted that in case of changed position of the signal light it is almost impossible for the protanope or deutanope to distinguish which signal light is turned on. Therefore, the authors assumed that people with color vision disorders (especially protanopia and deutanopia) would make more mistakes in choosing the next action on the intersections then those, who have full color vision.

Figure 6. Game screens a) normal color vision, b) simulated protanopia c)simulated deutanopia d)simulated tritanopia 11 Studies & Proceedings of Polish Association for Knowledge Management No. 42, 2011

4. Test results analysis The testing group consisted of both candidates for drivers in one of local driving schools and students of Lublin Technical University, 80 persons in total, 16 women and 64 men. The results of the four respondents were removed from the analysis due to their uselessness (the respondents gave false information during the survey, e.g. incorrect age). One of the question is about zip code, so 55% of the respondents lived in urban areas, while 45% in rural. The age distribution of the testing group is presented in Fig. 7.

Figure 7. The age distribution for the testing group

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Figure 8. The results of the interactive driving simulation tests 12 Dariusz Bober, Maciej Laskowski, Jacek KBsik Interactive method of detecting color vision disorders in candidates for drivers

The students were also asked if they have driver license – 4 of them have no driving license, 33 have B-type driver license (for private car), while the rest have C-type driver license (for trucks).

Figure 9. The distribution of weight for the results of the driving simulator, for the first 38 respondents [17] Information on the number of incorrect and correct behavior of individual respondents is collected in the application database. Based on the data collected are determined, the following indicators:

(1) and

(2) where: wa – the sum of the counters abnormal events, wb – the sum of the counters of risky events, wc – the sum of the normal event counters, which are used for the classification of respondents to groups of people at risk of - color vision dysfunction. The distribution of weight for the results of the driving simulator, for the first 38 respondents, is presented at Fig. 9. For the purposes of a preliminary analysis of the sample acquired in the testing phase of the prototype system [17], the following thresholds: − for - C 1, r1 Ǩ <0.1, 0.4> or r2 Ǩ <0.2, 0.7>, which is classified as suspicion of color vision dysfunction; 13 Studies & Proceedings of Polish Association for Knowledge Management No. 42, 2011

− for - C 0, r1 Ǩ <0, 0.1) / (0.4, 1> and r2 Ǩ <0, 0.4) / (0.7, 1>, which is classified as there is no indication of color vision dysfunction. The lower ranges of values of r1 Ǩ <0, 0.1) and r2 Ǩ <0, 0.4) include chance of committing a one- mistake in deciding while driving by a participant in the study (e.g. crossing the intersection on yellow light). Over 94,7% (72) of the respondents made none or one type of mistake, thus proving normal color vision. Four respondents were diagnosed with possible dichromacy, as the number of their mistakes was relatively high. The percentage of potential dichromates is consistent with estima- tions [4], as about 5% of the whole human population is estimated to have some kind of color vision disorder. The results for this group are presented in Table 1. Table 1. Test results for group of potential colorblind users sex woman 1 man 3 place of residence village 2 city 2 driving license none 1 B-type 3 C-type - As dichromacy is usually sex-linked and affects mainly males [14], the test results are especially interesting. Moreover, two of the possible colorblind respondents were not aware of their colorblindness, which may prove an inaccurate medical examination while applying for the driver license. The authors would like to notice, that the results of the test should be confirmed by further medical examination.

5. Summary Advantages of the proposed solutions are mainly: • an interactive form of testing is much more attractive to potential customers (candidates for drivers) compared to Ishihara tests • by introducing the elements of the quasi-real world – driving simulator – the tested person behaves naturally, duplicating real-world behavior. The survey is conducted using a web browser (driving simulator is a Flash-based game itself), which enables easy access to a large sample of respondents. Survey answers are processed and stored automatically in a relational database, which greatly facilitate their subsequent treatment. The simulator is sensitive to the driver responsive only to the location of a signal light and not the color. Currently, the described test only allows testing the selected color vision disorder (dichromacy). Moreover, the testing process is not secured from users providing wrong survey answers – the results have to be analyzed by experts. Despite the mentioned drawbacks, the proposed system for interactive color vision dysfunction testing in drivers and candidates for drivers provides opportunities for anonymous testing for 14 Dariusz Bober, Maciej Laskowski, Jacek KBsik Interactive method of detecting color vision disorders in candidates for drivers

numerical group of respondents. The test results show that it can serve as an interesting solution for standard Ishihara test.

6. References [1] Shevell S. K. (2003) The Science of Color (2nd ed.). Optical Society of America, Oxford. [2] Vingrys, A.J., Cole, B.L. (1986) Origins of Colour Vision Standards within the Transportation Industry, Ophthalmic and Physiological Optics, 6(4) p. 369–375. [3] McIntyre D. (2002) Colour Blindness: Causes and Effects. Dalton Publishing, Chester. [4] Laskowski M., Szymczyk T. (2010) Economic and legal aspects of adjusting online advertisements for the visually impaired. Actual Problem of Economics 6 (108) 2010, p. 301–308. [5] Masataka O., Kei I. (2008) Color Universal Design (CUD) – How to make figures and presentations that are friendly to Colorblind people, Jikei Medial School, Japan. [6] Encyclopedic knowledge (2010): Colour Vision Deficiency (Colour Blindness), http://www.medic8.com/genetics/colour-vision-deficiency.htm. Accessed 2010-04-10. [7] Flück D. (2010) What is Color Blindness? Colblindor. http://www.colblindor.com/2010/03/02/what-is-color-blindness/. Accessed 2010-03-20 [8] Yates J.T., Diamantopoulos I., Daumann F-J. (1992) Acquired (Transient and Permanent) Colour Vision Disorders. http://ftp.rta.nato.int/public/ /PubFulltext/RTO/TR/RTO-TR- 016///TR-016-05.pdf, Accessed 2010-03-02. [9] Griggs P. B. (2009), MedlinePlus Encyclopedia: Color blindness tests, Virginia Mason Medical Center, Seattle, http://www.nlm.nih.gov/medlineplus/ency/imagepages/9962.htm, Accessed 2010-02-20. [10] Richmond Eye Associates Eye Health and Disorders (2010), Color Vision Test. http://www.richmondeye.com/colortest.asp, Accessed 2010-02-20. [11] Ishihara S. (1917) Tests for colour-blindness. Handaya, Tokyo, Hongo Harukicho. [12] Gegenfurtner K.R., Sharpe L.T. (1999) Color Vision: From Genes to Perception. Cambridge University Press, Cambridge. [13] Hoffman P.S. (2009) Accommodating Color Blindness. http://www.digitalspaceart.com/articles/ColorBlindness.pdf. Accessed 2010-02-23. [14] Kaiser, P.K., Boynton, R.M. (1996) Human Color Vision, Optical Society of America, Washington DC. [15] Bober D.: Internet jako narzBdzie badania potrzeb konsumentów energii elektrycznej. W: Miłosz M., Muryjas P. (red): Informatyka Stosowana – Eksploatacja, PTI, Katowice 2007, p. 117–126. (in Polish). [16] Tkaczyk P. i in.: System gromadzenia wyników ankiety „Badanie kierowcy z zakresie postrzegania kolorów sygnalizacji Vwietlnej”, adres: http://knip.pol.lublin.pl/ ~projekt16/ankieta.php?id=3, data 20.03.2010. (in Polish). [17] Bober D., Laskowski M., Kesik J. (2010) A prototype of a system for interactive detection of dichromats among the candidates for drivers. Prace Instytutu Elektrotechniki, Nr 247'10, Warszawa 2010, p. 141–157 (in Polish). 15 Studies & Proceedings of Polish Association for Knowledge Management No. 42, 2011

INTERAKTYWNA METODA WYKRYWANIA ZABURZEK WIDZENIA W KOLORZE WURÓD KANDYDATÓW NA KIEROWCÓW

Streszczenie W pracy tej adresowane s= problemy zwi=zane z detekcj= dysfunkcji w rozpoznawaniu kolorów wVród kandydatów na kierowców. Przeanalizowano metody rozpoznawania róbnych typów zaburzeL widzenia kolorów (wraz z ich efektywno- Vci=), wykorzystywane obecnie w oVrodkach szkolenia kierowców. Adresowany problem jest szczególnie istotny w przypadku krajów w których legislacja zabrania wydawania praw jazdy osobom z zaburzeniami w rozpoznawaniu kolorów, gdzie wy- krywanie takich zaburzeL powinno by4 szczególnie dokładne i obiektywne. Nowa interaktywna metoda wykrywania osób z potencjalnym zaburzeniem widzenia kolo- rów została zaprezentowana w tym artykule wraz z analiz= rezultatów badania przykładowej grupy potencjalnych kierowców.

Słowa kluczowe: brak wizji koloru, zaburzenia widzenia barw, zaburzenia widzenia

Dariusz Bober Katedra Informatyki Wydzał Matematyczno-Przyrodniczy Uniwersytet Rzeszowski ul. Dekerta 2, 35-030 Rzeszów e-mail: [email protected]

Maciej Laskowski Jacek KBsik Instytut Informatyki Wydział Elektrotechniki i Informatyki Politechnika Lubelska ul. Nadbystrzycka 36 b, 20-618 Lublin e-mail: [email protected] [email protected]