How to Present More Readable Text for People with Dyslexia

Universal Access in the Information Society manuscript No. (will be inserted by the editor)

How to Present more Readable Text for People with Dyslexia

Luz Rello · Ricardo Baeza-Yates

Received: date / Accepted: date

Abstract The presentation of a text has a significant readability · text color · background color · font size · effect on the reading speed of people with dyslexia. This character, line and paragraph spacings · column width. paper presents a set of recommendations to customize texts on a computer screen in a more accessible way for this target group. This set is based in an eye track- 1 Introduction ing study with 92 people, 46 with dyslexia and 46 as control group, where the reading performance of the Dyslexia is a neurological reading disability which is participants was measured. The following parameters characterized by difficulties with accurate and/or flu- were studied: color combinations for the font and the ent word recognition and by poor spelling and decoding screen background, font size, column width as well as abilities. Secondary consequences may include problems character, line and paragraph spacing. It was found that in reading comprehension and reduced reading experi- larger text and larger character spacing lead the partic- ence that can impede growth of vocabulary and back- ipants with and without dyslexia to read significantly ground knowledge [43]. Since a great amount of infor- faster. The study is complemented with questionnaires mation is presented as text, this condition makes more to obtain the participants preferences for each of these difficult for people with dyslexia to access written in- parameters, finding other significant effects. These re- formation. At the same time, access to information and sults provide evidence that people with dyslexia may communication technologies is recognized as a basic hu- benefit from specific text presentation parameters that man right by United Nations [102]. make text on a screen more readable. So far, these rec- Related to its social relevance, there are two reasons ommendations based on eye tracking data are the most motivating the decision to approach textual accessibil- complete for people with dyslexia. ity for users with dyslexia: first, they are a relatively large group of users, since dyslexia is frequent and uni- Keywords Dyslexia · eye tracking · textual acces- versal, and second, this kind of accessibility practices sibility · text customization · recommendations · are not only good for people with dyslexia but also for other target groups.

Luz Rello Human-Computer Interaction Institute Frequent and universal. There is a universal neuro- Carnegie Mellon University, USA cognitive basis for dyslexia [65] but its manifestations E-mail: [email protected] are variable due to different orthographies [35]. Depend- (this research was conducted while the first author was doing ing on the language, the estimations of dyslexia varies. her PhD at the Web Research Group, Universitat Pompeu Fabra, Barcelona) The Interagency Commission on Learning Disabilities [42] states that 10-17.5% of the population in the U.S.A. Ricardo Baeza-Yates Yahoo Labs, Sunnyvale, CA, USA & has some level of dyslexia while Brunswick [16] esti- Web Research Group mates 10% for English and 3.5% for Italian. According Universitat Pompeu Fabra, Barcelona to different statistics, from 8.6 [45] to 11% [18] of the E-mail: [email protected] Spanish speaking population has dyslexia. The authors 2 made an estimation of the presence of dyslexic texts in that people with dyslexia encounter are explained. Sec- the Web and the results show that at least 0.67% of the tion 3 covers related work. Section 4 explains the ex- spelling errors found in the English Web [3] and 0.43 in perimental methodology, while Section 5 presents the the Spanish Web [78] are made by people with dyslexia. results. Section 6 presents a discussion and Section 7 the limitations of the study. Finally in Section 8 a set Good for others groups. The use of Web accessibil- of recommendations is proposed. Conclusions and fu- ity practices for people with dyslexia is beneficial for ture challenges are given in Section 9. all, since dyslexic-accessible practices alleviate difficulties faced by all Internet users, as well as other users with disabilities [26,31,55,69,111]. According to Zarach [111], the guidelines to enhance readability for people 2 Dyslexia with dyslexia, also benefit people without dyslexia. For example, Dixon [26] tested a piece of educational soft- Brain structure, brain function and genetics studies ware with dyslexic and non–dyslexic readers and the confirm the biological foundations of dyslexia [104]. results suggest that the symptoms of dyslexia are com- However, despite its universal neuro-cognitive basis, mon to varying degrees among most people. Pollak [69] dyslexia manifestations are variable and culture-specific showed how students with and without dyslexia bene- [35]. This variability is due to the different language or- fit from using multimodal documents. Also, Evett and thographies concerning their grade of consistency and Brown [31] found that the web style guidelines for blind regularity [16]. English has an opaque –or deep– or- or low vision readers are closely parallel to those for thography in which the relationships between letters dyslexic readers. Later, McCarthy and Swierenga re- and sounds are inconsistent and many exceptions are mark the overlap of dyslexic-accessible recommenda- permitted. English presents a significantly greater chal- tions with more general textual accessibility recommen- lenge to young readers than other languages, such as dations [55]. Hence, the present work is also extensi- Spanish or Italian, with a more regular alphabetic sys- ble to general usability problems and to other target tem that contains consistent mappings between letters groups. and sounds, that is, a transparent –or shallow– orthog- Previous research indicate that the text presenta- raphy. For instance, in [65], Italian participants with tion may have an impact on the reading performance dyslexia performed better on reading tasks than English of people with dyslexia [1,37,50]. To the best of the au- people with the same condition. Along an orthographic thors’ knowledge, this is the first time that eye tracking transparency scale for European languages, English ap- is applied with such an extensive group of people, 46 pears as the language with the deepest orthography and participants with dyslexia and 46 without dyslexia, to Spanish as the second most shallow after Finnish [93]. define dyslexic-accessible text presentation recommen- Since the challenge of mapping phoneme to grapheme dations. The present proposal would improve the ability depends on the orthographic transparency of the lan- of people with dyslexia to read and access a wider range guage, Spanish shall be not be as challenging as other of information content, empowering them by slightly languages according to this scale [93]. leveling the playing field. This paper presents the fol- Hence, for the reasons described above, dyslexia has lowing main contributions: been called a hidden disability, due to the difficulty of – Larger font size, ranging from 18 to 26 points, lead its diagnosis in languages with shallow orthographies people with and without dyslexia to read signifi- [104], where diagnoses depend more on reading speed cantly faster. that on the errors [24]. – Larger character spacing, ranging from +7% to People with dyslexia encounter problems, not only +14%, lead people with and without dyslexia to with some text presentation conditions, such as small read significantly faster compared to smaller char- font size [55,89], but also with language-related condi- acter spacing (-7%). tions. The following presents the dyslexia-related dif- – Black text on white background instead of using ficulties according to their language level. They were grey scales for the text is significantly preferred by collected from the cognitive neuroscience literature, people with and without dyslexia. with the exception of the discourse level, where there – White text on black background instead of using are recommendations from Web accessibility literature. grey scales for the background is significantly pre- The poorer reading comprehension which characterized ferred by people with and without dyslexia. dyslexia in this level has also been included because text The rest of the paper is organized as follows. In Sec- comprehension depends on longer segments of texts, not tion 2 dyslexia is defined and the common problems only words. These difficulties are: 3

(a) Orthography: cations of the visual display. The most studied in re- – Orthographically similar words, e.g. addition lationship with dyslexia is the visual stress syndrome and audition [28,95]; (Meares-Irlen syndrome) [49]. The Meares-Irlen syn- – alternation of different typographical cases, e.g. drome is characterized by symptoms of visual stress ElefANte (‘elefante’) [56]; and visual perceptual distortions that are alleviated by – letter recognition [7,10]; using individually prescribed colored filters. Also pa- – number recognition [20,51,84]; and tients susceptible to pattern glare, that is perceptual – poor spelling, such as letter reversals, e.g. trail distortions and discomfort from patterns, are prone to for trial [2,15,43,109]. Meares-Irlen syndrome and are also likely to find col- (b) Phonology: ored filters useful [30]. Kriss and Evans [49] compared – Irregular words, e.g. vase1 [22,28,95]; and colored overlays on a group of 32 children with dyslexia – homophonic words or pseudo homophonic with a control group of same size. The difference in words, like weather and whether [33,62]. prevalence of the two groups did not reach statistical (c) Morphology: significance. The authors conclude that Meares-Irlen – Derivational errors, e.g. discomfortable [64,95, syndrome is prevalent in the general population and 103]. possibly a little more common in dyslexia. Children (d) Lexicon: with dyslexia seemed to benefit more from colored over- – New words, e.g. fantabulous [6,24]; lays than non-dyslexic children. The authors stress that – pseudo–words and non–words,2 e.g. happisfac- Meares-Irlen syndrome and dyslexia are separate enti- tion [27,70,95,103]; ties and are detected and treated in different ways [49]. – less frequent words, e.g. pristine [34,82,88,92]; Moreover, Jeanes et al. [44] showed how color overlays – long words, e.g. prestidigitation [24,63,82,107]; helped the reading of children in school whithout tak- – word additions, omissions and word recognition ing into consideration dyslexia or other visual difficul- [13,14,43,54]; ties. Gregor and Newell [37] and later Dickinson et al. – substitutions of functional words,3 e.g. of by for [25] have shown that visual changes in the presenta- [64,95,107]; tion of text may alleviate some of the problems gener- – confusions of small words, e.g. in buy is, or buy ated by dyslexia and the visual comorbidities related to and but [24,105]; and dyslexia. – misspellings recognition [39,77]. (e) Discourse: – Short sentences and short paragraphs benefit ac- 3 Related Work cessibility for people with dyslexia according to Web accessibility literature [9,11,61]. According to a survey by McCarthy and Swierenga [55], – Poor reading comprehension [104]. In dyslexia studies about dyslexia and accessibility are scarce com- this is related to decoding and not to problems pared to other groups of users with special needs. How- in oral or listening comprehension [23], that is, in ever, Al-Wabil et al. [1] claim that there are consider- dyslexia, normally poor comprehension is caused able barriers for people with dyslexia. by a decoding mistake, such as word recognition. In the Web Content Accessibility Guidelines Oral and reading comprehension need to be dif- (WCAG) [17], dyslexia is only one more disability ferentiated, since decoding and listening com- within a diverse group of cognitive disabilities. Accord- prehension have been shown to have different ing to Santana et al. [89] this lack of explicit considera- implications in measuring comprehension [48]. tion of dyslexia specificities in the guidelines make the Dyslexia affects decoding, though not listening needs of users with dyslexia unfulfilled. comprehension [38,57]. Previous work has been divided in user studies about text customization and recommendations. Additionally, there are visual difficulties associated with dyslexia [29] that could be alleviated by modifi- 3.1 User Studies 1 Words with no consistent correspondence between grapheme and phoneme, e.g. vase pronounced as /v¯az/. Gregor and Newell [37] asked 12 students with dyslexia 2 A non-word is a word that has no meaning, is not known to test different colors, sizes, spacings, column widths, to exist, or is disapproved. and similar letter highlighting to improve the subjective 3 Functional words are words that have little lexical meaning, but instead serve to express grammatical relationships readability of MS Word documents. The best parame- with other words within a sentence. ters were tested by seven people with dyslexia, which 4 reported a subjective increase in readability. The results questionnaires and semi-structured interviews with 23 of this investigation were included in the SeeWord tool participants with dyslexia were used, testing grey scales for MS Word [36]. After, Dickinson et al. [25] carried and colors for the text and the background, character, out a pilot study with six participants using the See- line and paragraph spacing as well as column width. Word software showing that reading accuracy improved The results were integrated in two text customization as well as the subjectively rated reading comfort. tools: the web service Text4All [99]4 for websites and Kurniawan and Conroy [50] tested different color the Android IDEAL eBook reader5 [47] for ebooks. Its schemes for reading online with 27 users with dyslexia. functionalities and usability were tested with 14 partic- The participants had to read five online articles and ipants with dyslexia using the think aloud protocol [52]. undertook comprehension questionnaires. The compre- The participants reported a subjective improvement of hension of readers with dyslexia was poorer for the com- the reading comfort and functional improvements pro- plex articles however the reading speed was not slower posed by the participants (mainly to the interface) were using the color scheme the users selected. subsequently integrated in the application. Santana et al. [90] developed the Mozilla Firefox extension Firefixia, a tool that allows readers with dyslexia to customize websites to improve readability. 3.2 Recommendations They tested Firefixia with four users and found that readers with dyslexia appreciate customization. The There is a common agreement in specific studies customization settings included in Firefixia are based about dyslexia and accessibility that the application of in previous user studies and recommendations. They dyslexic-accessible practices benefits also the readabil- include font type, font size, color, character spacing, ity for users without dyslexia [26,50,55]. Consequently, line spacing and column width. the guidelines for developing Web sites accessible to users with dyslexia [11,71,111] usually overlap with O’Brien et al. [59] compared the reading speeds us- guidelines for low-literacy users [58] or other disabili- ing twelve different font sizes between two groups: chil- ties such as low vision [31]. For example, according to dren with (aged 7 to 10 years), and without dyslexia Zarach [111] guidelines for enhanced readability for peo- (aged 6 to 8 years). They showed how dyslexic read- ple with dyslexia, also benefit people without dyslexia. ing follows the same curve shape as skilled reading, However, there is no universal profile of a user with with constant reading rates across large font sizes and dyslexia and therefore some authors recommend using a sharp decline in reading rates below a critical font a customizable environment for such users [37,58]. size. Readers with dyslexia presented higher critical font sizes. In relationship with the variables studied in the experiments, the recommendations for text presentation Zorzi et al. [113] conducted an experiment with 74 for people with dyslexia have focused in the following children with dyslexia (34 Italian and 40 French, aged parameters: text and background grey scale [86,101], between 8 and 14). The children read on paper texts text and background colors [11,12,37,71,86], font size with regular character spacing and extra large charac- [1,12,25,71,86,111], paragraph spacing [11,86], char- ter spacing (an increase of 2.5 pt in the standard letter acter spacing [66,71], line spacing [71,86] and column spacing using 14 points Times font). The texts with width [11,12,86]. larger character spacing lead to a better reading accu- Except from preliminary work [86], this study differs racy (number of errors) and speed (number of syllables from the rest of the related approaches specifically in per second). the application of eye tracking to measure readability of Schneps et al. [91] performed an experiment with a text. The current study addresses the methodological 27 high school students with reading struggles. They weaknesses of the authors’ previous work improving it tested line length and extra large spacing. Regarding in the following points: line length, they compare two screen dimensions: iPod Touch in portrait mode (5 cm × 7.5 cm) and the Ap- – The results are based in a larger number of partici- ple iPad in landscape mode (19.7 cm × 14.8 cm). They pants with dyslexia (46 participants instead of 23). found that using a small device improved readability – The results are compared with a similar control (faster reading speeds, less number of fixations and less group without dyslexia (46 people). regressive saccades). With regards to extra large spac- – Text comprehension is included as a control vari- ing they conclude that it improves comprehension in able. those most impaired. 4 http://www.text4all.net/dyswebxia.html In the authors’ previous work, Rello et al. [86] tested 5 https://play.google.com/store/apps/details?id= the same parameters of the present study. Eye tracking, org.easyaccess.epubreader 5

– The presentation of the conditions are counter- Font size: This independent variable has four levels balanced, instead of randomized, to cancel out order corresponding to four font sizes: 14, 18, 22 and 26 points eﬀects. Each of the counter-balanced conditions was (See Figure 1, right). read by the same number of participants. Character spacing: This independent variable has four levels corresponding to four distances between charac- 4 Methodology ters: -7%, 0%, +7% and 14% (See Figure 1, right).7

Eight experiments were conducted to study the effect Line spacing: This independent variable has four levels of eight text presentation parameters on readability. In corresponding to four values for spacing: 0.8, 1, 1.2 and the experiments, 92 participants (46 with dyslexia) had 1.4 lines. Each of the texts tested were composed of to read a set of texts, which were altered to include the seven lines. different values of the parameters. Paragraph spacing: This independent variable has four levels corresponding to four values for the spacing be- 4.1 Design tween paragraphs: 0.5, 1, 2 and 3 lines. To test paragraph spacing each of the slides contained three para- For each experiment there were four or eight conditions. graphs. Each of the conditions correspond with the levels of the parameters taken as independent variables. The experiments followed a within-subjects design, so every par- Column width: This independent variable has four lev- ticipant contributed to each of the conditions in the els corresponding with four values for column width experiments. The order of the experimental conditions tested: 22, 44, 66 and 88 characters per line (as the was counter-balanced to cancel out sequence effects. No fonts have letters with variable width, this is the aver- combinations of conditions were studied. Table 1 shows age number of characters per line). a summary of the experiments. The levels of the variables were chosen taking into To measure objective readability, eye Fixations Du- account the difficulties that people with dyslexia find ration is considered as dependent variable. To control (see Section 2); previous user studies (see Section 3); text comprehension of the texts a Comprehension Score and literature about recommendations for readers with as a control variable is used and to collect the partic- dyslexia (see Section 3). More details of the parameters ipant subjective preferences the Preference Ratings of used in comparison with the literature are given in Sec- the participants were used. They are explained in detail tion 6. The following presents the independent variables in the following. and their levels. Fixation Duration (objective readability): When read- Grey Text (white background): This independent vari- ing a text, the eye does not move contiguously over able has four levels corresponding to four grey scale text, but alternates saccades and visual fixations, that values for the text with white background: 0% (black is, jumps in short steps and rests on parts of the text. font), 25%, 50% and 75% (See Figure 1, left).6 Fixation duration denotes how long the eye rests still on a single place of the text. The means of the fixation duration are used as a performance metric. This data Grey Background (white text): This independent vari- is obtained directly from the eye tracker software. able has four levels corresponding with to grey scale Fixation duration has been shown to be a valid in- values for the background with white text: 0% (black dicator of readability. Rayner [74] presents a review of background), 25%, 50% and 75% (See Figure 1, left).6 the studies using eye movements to investigate cognitive processes that have appeared since the mid-1970s Text and Background Color: Eight color pairs to the 1990s and argues that eye movement measures (text/background) were tried: black/white, off- can be used to infer moment-to-moment cognitive pro- black/off-white, black/yellow, blue/white, black/creme, cesses in reading. Shorter fixations are associated with dark brown/light mucky green, brown/mucky green better readability, while longer fixations can indicate and blue/yellow (See Figure 1, middle).6 that processing loads are greater. For instance, readers

6 The CYMK code for the colors and their contrast are 7 Although there are others units that can be used, the shown in Appendix A. simplest is to use a percentage of the current font size. 6

Design Within-subjects Independent Color black/white Variables (text and background) oﬀ-black/oﬀ-white (one per experiment) black/yellow blue/white black/creme blue/yellow dark brown/light mucky green brown/mucky green Grey Text (white background) 0% (black font) 25% 50% 75% Grey Background (white text) 0% (black background) 25% 50% 75% Font Size 14 points 18 points 22 points 26 points Character Spacing -7% character 0% character +7% character 14% character Line Spacing 0.8 lines 1 line 1.2 lines 1.4 lines Paragraph Spacing 0.5 lines 1 line 2 lines 3 lines Column Width 22 character per line 44 character per line 66 character per line 88 character per line Dependent Fixation Duration (objective readability) Variables Preference Rating (subjective preferences) Control Variable Comprehension Score (objective comprehensibility) Participants Group D (46 participants) 26 female, 20 male Age: range from 11 to 45 (¯x = 20.70, s = 7.87) Education: high school (22), university (21), no higher education (3) Group C (46 participants) 27 female, 19 male Age: range from 13 to 37 (¯x = 23.50, s = 8.16) Education: high school (16), university (28), no higher education (2) Materials Base Texts 36 text fragments Text Presentation Comprehension Questionnaire 8 inferential items (1 item/condition) Preferences Questionnaire 8 items (1 item/condition) Equipment Eye tracker Tobii 1750

Procedure Steps: Instructions, demographic questionnaire, reading task, comprehension questionnaire, preference questionnaires

Table 1 Experimental methodology summary for the experiments. 7

Fig. 1 Examples of the text and background grey scales and colors used, as well as character spacing and font size.

grey scale: black/ black/ char. spacing: size: dyslexia dyslexia dyslexia dyslexia dyslexia dyslexia 0% white creme +14% 14 points off-black/ dark brown/ dyslexia dyslexia 25% dyslexia dyslexia dyslexia +7% dyslexia 18 points off-white light mucky green ! ! ! black/ brown/ ! dyslexia dyslexia 50% dyslexia dyslexia dyslexia 0% dyslexia 22 points yellow mucky green ! ! ! ! dyslexia dyslexia 75% dyslexia blue/ dyslexia blue/ dyslexia white yellow –7% dyslexia 26 points present longer fixations at low-frequency words than at recording of a complete session did not have an overall high-frequency words [41,46,72,75,76]. 100% comprehension score, it was discarded from the There are three studies that show why fixation du- analysis. ration is also a valid indicator for people with dyslexia. First, Hyönaand Olson [40] found that dyslexic readers Preference Rating (subjective preferences): To measure show the typical word frequency effect in which low- the participants’ preferences, they were asked to select frequency words are fixated longer than high-frequency the texts that they found easiest to read. For each ex- words. periment, they wrote their answers in a paper question- Second, Pirozzolo and Rayner [68] and Olson et naire while they saw the options on the screen. The par- al. [60] found that when dyslexic readers were given a ticipant could see the options for as long and as many text appropriate for their reading level, their eye move- times as desired. Whenever the participant selected one, ments (fixations, saccades and regressions) were much two, three or four options as most readable, the weights like those of normal readers at that particular age level. 1, 0.5, 0.33 and 0.25 respectively, were given to those Third, Rayner [73] showed that normal children’s options. To calculate the average preference rating the eye movements (fixation durations, saccade lengths, weights are summed and then divided by the number and the size of the perceptual span) could be similar of participants. to the dyslexic readers’ eye movements when they were given a text that was too difficult for them. 4.2 Participants In sum, as Rayner [74] concludes “the most appropriate conclusion remains that eye movements reflect Overall, 92 participants undertook the experiment. the difficulties that dyslexic individuals have reading They included 46 Spanish speakers (26 female, 20 male) and are not the cause of the reading problem”. with a confirmed diagnosis of dyslexia (group D) and 46 Spanish speakers (27 female, 19 male) without dyslexia, Comprehension Score (objective comprehensibility): which served as a control group (group C). The ages of Moving the eyes over a text does not guarantee its group D ranged from 13 to 37, with a mean age of 23.50 comprehension, specially in people with dyslexia where years (s = 8.16), while the ages of group C ranged from comprehension was found to be independent from read- 13 to 43, with a mean age of 20.70 years (s = 7.87). ability [77]. To check that the text was not only read, Apart from 3 participants with dyslexia and 2 with- but also understood, text comprehension is measured out dyslexia who had no higher education, the rest were using a comprehension questionnaire with inferential attending school or high school (22 participants with items, that is, questions that require a deep understand- dyslexia and 16 participants without dyslexia) or were ing of the content of the text. They include multiple- studying or had already finished university degrees (21 choice questions with three possible choices, one correct participants with dyslexia and 28 participants without choice and two wrong choices. Each item referred to the dyslexia). understanding of the whole stories presented because Participants from group D were asked to bring their fragments presented were too short to ask comprehen- diagnoses to the experiment, to guarantee that dyslexia sion questions for each fragment. From these answers, a was diagnosed in an authorized centre or hospital. In comprehension score, the percentage of correct answers the Catalan protocol of dyslexia diagnosis [94], the dif- is computed, where the correct choice scored 100% and ferent kinds of dyslexia, extensively found in literature, the others 0%. To guarantee that recordings analyzed in are not considered. Therefore, one can only guarantee this study were valid and comparable, the comprehen- that the participant was diagnosed in a authorized cen- sion score was used as a control variable, such that if the ter or hospital but not the exact type of dyslexia. Three 8 of these participants were also diagnosed with attention and four to eight possible choices depending on the deficit disorder. None of the participants were screened number of levels of the variable. Each item was com- for visual stress (Meares-Irlen) syndrome. posed of one statement and the options. The statement was always the same. See an example of an item below.

4.3 Materials – Leo mejor el texto... ‘I read best the text...’ 1 2 3 4 The materials used in the experiment were: base texts, comprehension questionnaires, and preferences questionnaires. The test presentation was also controlled. 4.3.4 Text Presentation

4.3.1 Base Texts For the experiment it was decided to present the texts in Arial because of the following reasons. First, Arial is For the reading tests two stories were used. The first the most common font used on screen for the Web [19]. story8 was written in verse, while the second is a frag- Second, Arial has been highly recommended in previous ment in prose.9 work. For instance, Evett and Brown [31] put in com- The overall text was divided in 36 fragments and parison recommendations for readers with low vision each of them was presented to the participants with and dyslexia, and both groups agree in using Arial and a different condition. To maintain the independence of Comic Sans. In addition, the British Dyslexia Associa- the variables, there were no combinations among the tion also recommends using Arial. Third, in Lockley’s conditions levels. The texts fragments belonging to dif- [53] study, Arial was the preferred font. Also in a re- ferent levels of the same condition were comparable to cent study using eye tracking with 48 participants with each other. They had the same number of words and dyslexia [79], Arial was the font which lead to shorter the same number of syllables for the shorter passages reading times compared to other eleven fonts.10 Un- (texts containing less than 22 words). The shorter texts justified text was used, since justified text alignment were extracted from the story written in verse so they produces irregular spacing between words that make were very similar to each other having the same rhythm reading harder [11,66,71]. and meter. The default parameters of text presentation were black text and white background for colors (no text and 4.3.2 Comprehension Questionnaire background grey scales were taken into consideration), 20 points for font size, 0% for character spacing, 1 for Multiple-choice questions with three possible choices, line spacing, 1 for paragraph spacing, and 66 characters one correct choice and two wrong were used. The com- for column width. prehension questionnaire was composed of three items about the general content of the text. An example of an item is given below. 4.4 Equipment and Software – ¿Por quéquer´ıanmatar las hormigas a su compañera? ‘Why did the ants wanted to kill their comrade?’ – Porque era ego´ısta. ‘Because she was selfish’. The eye tracker used was the Tobii T50 [98] that has – Porque ve´ıalas estrellas. ‘Because she saw the stars’. a 17-inch TFT monitor with a resolution of 1024x768 – Porque no rezaba. ‘Because she did not pray’. pixels. The time measurements of the eye tracker have a precision of 0.02 seconds. The eye tracker was calibrated 4.3.3 Preferences Questionnaire for each participant and the light focus was always in the same position. The distance between the participant The slides that the participant read were replayed and and the eye tracker was constant (approximately 60 cm. through a paper questionnaire, the participant chose or 24 in.) and controlled by using a fixed chair. what s/he thought was the best reading alternative be- The software used for analyzing the eye tracking tween the options given for each of the parameters. The data was Tobii Studio 3.0 and the R 2.14.1 statistical questionnaire had eight items, one for each experiment, software for the statistical analysis. 8 Los Encuentros del Caracol Aventurero (The Encounters of the Adventurous Snail) by Federico Garc´ıaLorca. 10 The fonts tested were: Arial, Arial Italic, Computer 9 From the book Soy dix-leso? (I am dys-dumb?) of the Modern Unicode, Courier, Garamond, Helvetica, Myriad, Papelucho series by Marcela Paz. This text example is given OpenDyslexic, OpenDyslexic Italic, Times, Times Italic, and in Appendix B. Verdana [79]. Non_Dys Font Contrast Back Colors Size Chart Spa Line Spa Par Spacing Column Contrast Width 1 46 3 0 5 32 5 2 3 2 0 28 3 19 9 19 10 24 3 0 17 16 24 0 5 22 16 4 3 0 7 0 8 19 8 1 5 9 6 11 7 15 8 4 Scale-0 = 1 Scale-0 = 2 Color-blackoff-whiteoff = 5 Size-14 = 4 Spacing +14 = 2 Line Spacing 0.8 = 3 Spacing .4 = 4 Column width 1/4 = 4 Scale-25 = 4 Scale-25 = 3 Color-yellow-black = 6 Size-18= 3 Spacing +7 = 4 Line Spacing 1 = 4 Spacing 2 = 3 Column width 2/4 = 3 Scale-50 = 3 Scale-50 = 1 Color-blue-white = 8 Size-22= 2 Spacing 0 = 1 Line Spacing 1.4 = 1 Spacing 1 = 2 Column width 3/4 = 2 Scale-75 = 2 Scale-75 = 4 Color-brown-green = 1 Size-26= 1 Spacing -7 = 3 Line Spacing 1.2 = 2 Spacing 3 = 1 Column width 4/4 = 1 Color-black-creme = 3 Color-dark brown-green = 2 Non_Dys Font Contrast Back Colors Size Chart Spa Line Spa Par Spacing Column Color-yellow-blue = 4 Contrast Width Color-black-white = 7 1 46 3 0 5 32 5 2 3 2 0 28 3 19 9 19 Font Contrast10 Back24 Colors Size Chart Spa Line Spa Par Spacing Column 3 0 17 16 24 0 5 22 Contrast16 Width 4 3 0 7 0 8 1 19 8 2 1 12 5 0 5 2 23 4 5 9 2 15 0 2 3 15 15 30 14 6 11 3 27 9 15 15 17 18 43 14 7 15 4 1 26 5 26 9 10 35 12 8 4 5 3 Scale-0 = 1 Scale-0 = 2 Color-blackoff-whiteoff = 5 Size-14 = 4 Spacing +14 = 2 Line6 Spacing 0.8 = 3 Spacing .4 = 4 Column width 7 7 1/4 = 4 4 Scale-25 = 4 Scale-25 = 3 Color-yellow-black = 6 Size-18= 3 Spacing +7 = 4 Line8 Spacing 1 = 4 Spacing 2 = 3 Column width 5 2/4 = 3 Scale-0 = 3 Scale-0 = 4 Color-black-white = 1 Size-14 = 1 Spacing +14 = 4 Line Spacing 0.8 = 1 Spacing .4 = 1 Column width Scale-50 = 3 Scale-50 = 1 Color-blue-white = 8 Size-22= 2 Spacing 0 = 1 Line Spacing 1.4 = 1 Spacing 1 = 2 Column width 1/4 = 1 3/4 = 2 Scale-25 = 2 Scale-25 = 1 Color-blackoff-whiteoff = 2 Size-18= 2 Spacing +7 = 2 Line Spacing 1 = 2 Spacing 2 = 2 Column width Scale-75 = 2 Scale-75 = 4 Color-brown-green = 1 Size-26= 1 Spacing -7 = 3 Line Spacing 1.2 = 2 Spacing 3 = 1 Column width 2/4 = 2 4/4 = 1 Scale-50 = 1 Scale-50 = 3 Color-yellow-black = 3 Size-22= 3 Spacing 0 = 3 Line Spacing 1.4 = 4 Spacing 1 = 3 Column width Color-black-creme = 3 3/4 = 3 Color-dark brown-green = 2 Scale-75 = 4 Scale-75 = 2 Color-blue-white = 4 Size-26= 4 Spacing -7 = 1 Line Spacing 1.2 = 3 Spacing 3 = 4 Column width Color-yellow-blue = 4 4/4 = 4 Color-black-white = 7 Color-brown-green = 5 Color-black-creme = 6 Font Contrast Back Colors Size Chart Spa Line Spa Par Spacing Column Color-dark brown-green = 7 Contrast Width Color-yellow-blue = 8 1 2 12 5 0 5 2 23 4 2 15 0 2 3 15 15 30 14 Text Grey Scale Text Grey Scale 3 27 9 15 15 17 18 43 14 100 4 1 26 5 26 9 10 35 12 0.25 (%) 5 3 75 6 7 Font Contrast Group D Group N Font Contrast Group D Group N 0.213 7 4 0% 27 46 45 49 0% 8 5 75% 15 3 46 49 75% 0.175 50 Scale-0 = 3 Scale-0 = 4 Color-black-white = 1 Size-14 = 1 Spacing +14 = 4 Line Spacing 0.8 = 1 50%Spacing .4 = 1 Column width 2 0 46 49 50% 1/4 = 1 25% 1 0 46 49 25% 0.138 25 9 Scale-25 = 2 Scale-25 = 1 Color-blackoff-whiteoff = 2 Size-18= 2 Spacing +7 = 2 Line Spacing 1 = 2 Spacing 2 = 2 Column width Font Contrast Group D Group N Font Contrast Group D Group N

2/4 = 2 Rating Preference 0% 60 93.8775510204082 0% 0.24 0.194 0.1 0 Scale-50 = 1 Scale-50 = 3 Color-yellow-black = 3 Size-22= 3 Spacing 0 = 3 Line Spacing 1.4 = 4 Spacing 1 = 3 Column width (sec.) Fixation Duration 25% 3/432.6086956521739 = 3 6.12244897959184 25% 0.223 0.217 0% 25% 50% 75% grey 0% 25% 50% 75% grey Scale-75 = 4 Scale-75 = 2 Color-blue-white = 4 Size-26= 4 Spacing -7 = 1 Line Spacing 1.2 = 3 50%Spacing 3 = 4 Column4.34782608695652 width 0 50% 0.233 0.211 Correlation 75% 4/42.17391304347826 = 4 0 Fig. 2 Participants’75% reading performance0.24 (ﬁxation0.204 duration Fig. 3 Participants’Group D readingGroup C performanceGroup (ﬁxation D durationGroup C Color-brown-green = 5 -0.968445715719153 99.1304347826087 100 0.017 0.023 Color-black-creme = 6 -0.993869371230394 mean) and preference ratings in % for text0.01 grey0.017 scales (white mean) and preference ratings in % for background grey scales Color-dark brown-green = 7 Back Contrast Group D Group N background). 0.017 0.00999999999999998 (white text). Color-yellow-blue = 8 100% 26 28 47 48 7.6233183856502211.8556701030928 25% 12 17 47 Text 48Grey Scale 4.484304932735438.76288659793814Text Grey Scale Background Grey Scale Background Grey Scale 50% 9 3 47 48 7.623318385650225.15463917525772 75% 0 0 47 48 0.25 60

100 (%) 0.25 (%) Back Contrast Group D Group N Back Contrast Group D Group N 100% 55.3191489361702 58.3333333333333 0.213 0% 75 0.236 0.208 0.213 45 Font Contrast Group D Group N Font Contrast 25%Group D Group25.531914893617 N 35.4166666666667 25% 0.227 0.209 0% 27 46 45 49 0% Correlation 50% 19.1489361702128 6.25 0.175 50% 50 0.238 0.201 0.175 30 75% 15 3 46 49 75% -0.118995939068828 75% 0 0 75% 0.237 0.211 50% 2 0 46 49 50% 0.188839041314493 0.0089999999999999825 0.00699999999999998 0.138 15 25% 1 0 46 49 25% 0.138 0.011 0.00799999999999998 Font Contrast Group D Group N Font Contrast Group D Group N

0.009999999999999980.00999999999999998 Rating Preference Preference Rating Preference

0% 60 93.8775510204082 0% 0.24 0.194 0.1 0 (sec.) Fixation Duration 0.1 0 Fixation Duration (sec.) Fixation Duration 3.964757709251093.48258706467661 0% 25% 50% 75% grey 0% 25% 50% 75% grey 25% 32.6086956521739 6.12244897959184 25% Size0.223 Group0.217 D Group N 0% 25% 50% 75% grey 4.845814977973560% 3.9800995024875525% 50% 75% grey 50% 4.34782608695652 0 50% 14 0.233 0.211 0 0 46 44 4.405286343612334.97512437810944 Group D Group C Group D Group C Correlation 75% 2.17391304347826 0 75% 18 0.24 0.204 2 3 48 Group D44 Group C Group D Group C -0.968445715719153 99.1304347826087 100 22 0.017 0.023 10 15 48 44 -0.993869371230394 26 0.01 0.017 34 26 48 44 Back Contrast Group D Group N Size0.017 0.00999999999999998Group D Group N Size Group D Group N Font Size Font Size 100% 26 28 47 48 147.6233183856502211.85567010309280 0 14 0.259 0.223 25% 12 17 47 48 184.484304932735438.762886597938144.16666666666667 6.81818181818182 Background18 Grey Scale 0.233Background0.2 Grey Scale – 0.25Finally, a Pearson’s Chi-squared80 test to show eﬀects 4.5 Procedure (%) 50% 9 3 47 48 Correlation 227.623318385650225.1546391752577220.8333333333333 34.0909090909091 22 0.216 0.198 75% 0 0 47 48 0.25 60 -0.791535362594822 26 70.8333333333333 59.0909090909091 26 (%) 0.208 0.186 0.213on the participants’ choices.60 Back Contrast Group D Group N Back-0.852378048645091 Contrast Group D Group N 0.051 0.037 100% 55.3191489361702 58.3333333333333 0% 0.236 0.208 0.213 45 0.025 0.014 0.175 40 25% 25.531914893617 35.4166666666667 25% 0.227 0.209 The sessions were conducted at0.00800000000000001 Pompeu0.012 Fabra Univer- Correlation 50% 19.1489361702128 6.25 50% 0.238 0.201 Please refer to Table 2 for all the means and stan- 0.175 14 24.519230769230830 19.8924731182796 0.138 20 -0.118995939068828 75% 0 0 75% 0.237 0.211 sity and needed18 thirty to forty12.0192307692308 minutes7.52688172043011 to complete. In 0.188839041314493 0.008999999999999980.00699999999999998

0.138 22 3.8461538461538515 6.45161290322581 dard deviations. Rating Preference

0.011 0.00799999999999998 (sec.) Fixation Duration 0.1 0 each session the participant was alone with the inter- points

0.009999999999999980.00999999999999998 Rating Preference 14 18 22 26 points 14 18 22 26

Fixation Duration (sec.) Fixation Duration 0.1 0 3.964757709251093.48258706467661 viewer (first0% 25% author)50% in75% thegrey quiet room0% prepared25% 50% for75% thegrey Group D Group C Group D Group C Size Group D Group N 4.845814977973563.98009950248755 14 0 0 46 44 4.405286343612334.97512437810944 study, andGroup had D to carryGroup outC the stepsGroup presented D Group in theC 18 2 3 48 44 5.1 Grey Text (White Background) 22 10 15 48 44 Character Spacing Character Spacing 26 34 26 48 44 following. Size Group D Group N Size GroupChart D Spa GroupGroup N D Group N Font Size Font Size 0.25 70 14 0 0 14 0.259 0.223 First, each participant was interviewed. The first (%) -7 5 0 46 49 Main effects: With two-way ANOVA, significant main 18 4.16666666666667 6.81818181818182 18 0.233 0.2 0.25 80 0 17 32 46 49 (%) 0.213 52.5 Correlation 22 20.8333333333333 34.0909090909091 22 0.216 0.198 +7 15 8 interview46 began49 with a questionnaire designed to col- -0.791535362594822 26 70.8333333333333 59.0909090909091 26 0.208 0.186 effects were found for the groups (F (1, 366) = +14 9 9 460.213 49 60 0.175 35 -0.852378048645091 0.051 0.037 Chart Spa Group D Group N lect demographic information.Chart Spa Then,Group D Group each N participant 0.025 0.014 14.520, p < 0.001) on fixation duration. However, no -7 10.8695652173913 0 0.175 -7 40 0.234 0.198 0.00800000000000001 0.012 0.138 17.5 0 36.9565217391304 65.3061224489796 watched a video0 with instructions.0.208 Third,0.19 the passages 14 24.519230769230819.8924731182796 effects of text grey scale (F (3, 366) = 0.086, p = 0.968) Correlation +7 32.6086956521739 16.3265306122449 0.138 +7 20 0.202 0.185 Rating Preference 18 12.01923076923087.52688172043011 (sec.) Fixation Duration 0.1 0 -0.838022023794689 +14 19.5652173913043 18.3673469387755 were recorded using+14 eye tracking. The0.21 participant0.179 was

22 3.846153846153856.45161290322581 Rating Preference –7% 0% +7% +14% char. –7% 0% +7% +14% char. -0.123430442777081 0.032 0.019 on fixation duration were found. There were no interac- Fixation Duration (sec.) Fixation Duration 0.1 0 asked to14 read18 in silence22 26 twopoints stories0.00599999999999998 contained14 180.011 22 in the26 testpoints Group D Group C Group D Group C 5 0 0.007999999999999980.00600000000000001 tion effects of text grey scale and the group (F (3, 366) = 17 32 and answerGroup theD comprehensionGroup C 15.8415841584158 questionnaire.Group10.6145251396648 D Finally,Group C 15 8 2.970297029702966.14525139664805 1.400, p = 0.242) either. The results of the post-hoc 9 9 each participant filled in the user3.96039603960395 preferences3.35195530726257 question- Line Spacing Line Spacing Character Spacing Character Spacing tests show0.25 that: 40 naire. (%) Chart Spa Group D Group N 0.25 70 (%) 0.213 30 -7 5 0 46 49 - Participants with dyslexia had significantly longer 0 17 32 46 49 0.213 52.5 0.175 20 +7 15 8 46 49 Line Spa Group D Group N fixation times (¯x = 0.234, s = 0.08 seconds) than +14 9 9 46 49 0.8 2 5 450.175 48 35 0.138 10 Chart Spa Group D Group N Chart Spa Group D Group N 1 15 19 45 48 -7 10.8695652173913 0 -7 0.234 0.198 the participants without dyslexia (¯x = 0.206, s = 1.2 18 19 545 Results0.138 48 17.5 Rating Preference Fixation Duration (sec.) Fixation Duration 0.1 0 0 36.9565217391304 65.3061224489796 0 0.208 0.19 1.4 10 5 45 48 0.8 1 1.2 1.4 lines 0.8 1 1.2 1.4 lines Correlation +7 32.6086956521739 16.3265306122449 +7 0.202 0.185 Rating Preference 0.06 seconds, p < 0.001) (Table 2). lines

Line Spa Group D Group N (sec.) Fixation Duration 0.1 Line Spa 0Group D Group N -0.838022023794689 +14 19.5652173913043 18.3673469387755 +14 0.21 0.179 Group D Group C Group D Group C 0.8 4.44444444444444 10.4166666666667 –7% 0% 0.8 +7% +14% char. 0.233–7% 0%0.206 +7% +14% char. -0.123430442777081 0.032 0.019 1 33.3333333333333 39.5833333333333 This section presents1 the analyses0.236 of the0.207 data of both 0.00599999999999998 0.011 Correlation 1.2 40 39.5833333333333 Group D 1.2 Group C 0.237Group D 0.205 Group C 5 0 0.007999999999999980.00600000000000001 0.451017032441845 1.4 22.2222222222222 10.4166666666667 1.4 0.226 0.204 Within Groups: There was no significant effect of text 17 32 15.841584158415810.6145251396648 groups D and C. The comprehension score was used 0.447213595499958 0.00700000000000001 0.001 15 8 2.970297029702966.14525139664805 0.00999999999999998 -0.001 Paragraph Spacing Paragraph Spacing 9 9 3.960396039603953.35195530726257 to filter the readingLine Spacing recordings. Recall thatLine if theSpacing read- grey scale on fixation duration for group D (F (3, 183) = 0.011 -0.002 0.25 60 0.25 3.0973451327433740 0.485436893203884 (%) ing recording did not have an overall (%) 100% comprehen- 0.459, p = 0.711) nor for group C (F (3, 183) = 4.42477876106194-0.485436893203884 0.213 45 sion score,0.213 we discarded it. Only4.86725663716813 one30 recording-0.970873786407768 from the 1.305, p = 0.274). group0.175 D and two from group C were20 discarded. 0.175 30 Line Spa Group D Group N 0.138 15 0.8 2 5 45 48 0.138 10 Par Spacing Group D Group N A Shapiro-Wilk test showed that the datasets were Preferences: Participants with and without dyslexia 1 15 19 45 48 0.4 23 4 131 38 Rating Preference Fixation Duration (sec.) Fixation Duration 1.2 18 19 45 48 Rating Preference 0.1 0 1 43 10 131 (sec.) Fixation Duration 0.1 38 0 1.4 10 5 45 48 normally distributed. Also, a Barlett’s test showed that found black0.5 text1 significantly2 3 lines more0.5 readable1 2 than3 lines 2 30 22 131 0.8 38 1 1.2 1.4 lines 0.8 1 1.2 1.4 lines lines Line Spa Group D Group N Line Spa Group D Group N 3 35 2 131 38 Group D Group C Group D 2 Group C 0.8 4.44444444444444 10.4166666666667 0.8 0.233 0.206 they were homogeneous.Group D Group Hence, C for eachGroup experiment D theGroup C text presented with different grey scales (χ (3) = Par Spacing Group D Group N Par Spacing Group D Group N 1 33.3333333333333 39.5833333333333 1 0.236 0.207 0.4 17.5572519083969 10.5263157894737 0.4 0.233 0.198 2 Correlation 1.2 40 39.5833333333333 1.2 0.237 0.205 following were used: 1 32.824427480916 26.3157894736842 1 0.228 0.198 15.128, p = 0.002 for group D and χ (3) = 39.869, p < 0.451017032441845 1.4 22.2222222222222 10.4166666666667 1.4 0.226 0.204 Correlation 2 22.9007633587786 57.8947368421053 2 0.22 0.196 0.447213595499958 0.00700000000000001 0.001 -0.274103716415761 3 26.7175572519084 5.26315789473684 3 0.221 0.197 0.001 for group C). 0.00999999999999998 -0.001 Paragraph Spacing Paragraph Spacing Column Width Column Width -0.676968662049936 0.013 0.002 0.011 -0.002 – Two-way ANOVA test for repeated measures plus a 0.00800000000000001 0.002 See Figure 2 for the fixation duration60 means and 0.25 60 0.25 (%)

3.097345132743370.485436893203884 (%) 0.001 0.001 4.42477876106194-0.485436893203884 complete pairwise post-hoc comparison using paired 5.909090909090911.02040816326531 preferences.0.213 45 4.86725663716813-0.970873786407768 0.213 45 t-tests with a Bonferroni adjustment,3.636363636363641.02040816326531 to show effects 0.175 0.45454545454545530 0.510204081632654 0.175 30 of the conditions on fixation duration among groups 0.138 15 0.138 15 Par Spacing Group D Group N D and C. Rating Preference 0.4 23 4 131 38 Rating Preference 5.2 Grey0.1 Background (White Text) 0 Fixation Duration (sec.) Fixation Duration Fixation Duration (sec.) Fixation Duration 0.1 0 1 43 10 131 38 – A one-way0.5 ANOVA1 2 test3 lines for repeated0.5 1 measures2 3 lines 22 44 66 88 char. 22 44 66 88 char. 2 30 22 131 38 Group D Group C Group D Group C 3 35 2 131 38 Group D Group C Group D Group C Par Spacing Group D Group N Par Spacing Group D Group N plus a complete pairwise post-hoc comparison us- Main effects: With two-way ANOVA, significant main 0.4 17.5572519083969 10.5263157894737 0.4 0.233 0.198 Column Width Group D Group N 1 32.824427480916 26.3157894736842 1 0.228 0.198 ing paired t-tests with a Bonferroni adjustment, to effects were found for the groups (F (1, 376) = 22 12 1 44 44 Text and Background Colors Correlation 2 22.9007633587786 57.8947368421053 2 0.22 0.196 44 14 24 44 44 -0.274103716415761 3 26.7175572519084 5.26315789473684 3 0.221 0.197 66 14 16 44 show the44 effectsColumn ofWidth the conditions on fixationColumn Width dura- 14.630,0.25 p < 0.001) on fixation duration. However there -0.676968662049936 0.013 0.002 88 4 3 44 44 0.00800000000000001 0.002 60 0.25 (%) Column Width Group D Group N tion within groups.Column Width Group D Group N were no effects of background grey scale (F (3, 376) = 0.001 0.001 0.213 22 27.2727272727273 2.27272727272727 22 0.219 0.191 5.909090909090911.02040816326531 45 44 31.8181818181818 54.5454545454545 0.213 44 0.214 0.19 3.636363636363641.02040816326531 0.175 Correlation 66 31.8181818181818 36.3636363636364 66 0.221 0.187 0.4545454545454550.510204081632654 0.175 30 0.402618283010223 88 9.09090909090909 6.81818181818182 88 0.215 0.187 0.138 -0.0148014204124575 0.005 0.004 0.138 0.0070000000000000115 0.003 (sec.) Fixation Duration 1 0.001 0 0.1

Preference Rating Preference / 0.1 2 2.336448598130840 2.13903743315508 / Fixation Duration (sec.) Fixation Duration ff 3 22 44 66 88 char.3.271028037383181.6042780748663122 44 66 88 char. creme yellow green ff white white yellow 4 0.467289719626169 0 Group D Group C Group D Group C black o blue/ blue/ 5 black/ brown/ white o black/ dark brown black/ 6 light green 7 Group D Group C Column Width Group D Group N 8 22 12 1 44 44 Text and Background Colors 44 14 24 44 44 66 14 16 44 44 0.25 88 4 3 44 44 Text and Background Colors Column Width Group D Group N Column Width Group D Group N 0.213 22 27.2727272727273 2.27272727272727 22 0.219 0.191 40 44 31.8181818181818 54.5454545454545 44 0.214 0.19 0.175 (%) Correlation 66 31.8181818181818 36.3636363636364 66 0.221 0.187 30 Colors Group D Group N 0.402618283010223 88 9.09090909090909 6.81818181818182 88 0.215 0.187 black-white 5 15 46 0.13865 -0.0148014204124575 0.005 0.004 blackoff-whiteoff 2 9 46 65 20

0.00700000000000001 0.003 (sec.) Fixation Duration yellow-black 15 11 46 65 1 0.001 0 0.1 blue-white 5 4 46 65 / / 10 2 2.336448598130842.13903743315508 ff brown-green 3 0 46 65 3 3.271028037383181.60427807486631 creme yellow green ff white white yellow black-creme 7 16 46 65 Rating Preference 4 0.467289719626169 0 0 black o dark brown-green 4 3 46 65 blue/ / 5 black/ blue/ black/ dark brown / yellow-blue 5 7 46 65 brown/ white o black/ ff 6 light green ff Colors Group D Group N Colors Group D Group N 7 Group D Group C black-creme black-white 10.8695652173913 23.0769230769231 black-creme 0.208 0.187 black o 8 blue/yellow black/whiteblue/whitedark brown yellow-blue blackoff-whiteoff 4.34782608695652 13.8461538461538 yellow-blue 0.214 0.182 black/creme brown/green white o black/yellow light green brown-green yellow-black 32.6086956521739 16.9230769230769 brown-green 0.221 0.194 Group D Group C blackoff-whiteoff blue-white 10.8695652173913 6.15384615384615 blackoff-whiteoff 0.222 0.201 black-white brown-green 6.52173913043478 0 Textblack-white and Background0.223 Colors 0.195 blue-white black-creme 15.2173913043478 24.6153846153846 blue-white 0.228 0.18 dark brown-green dark brown-green 8.69565217391304 4.61538461538461 40 dark brown-green 0.228 0.203 yellow-black yellow-blue 10.8695652173913 10.7692307692308 (%) yellow-black 0.23 0.189 black-creme 15.2173913043478 24.6153846153846 30 0.006000000000000010.00700000000000001 Colors Group D Group N yellow-blue 10.8695652173913 10.7692307692308 0.013 0.002 black-white 5 15 46 65 brown-green 6.52173913043478 0 0.014 0.014 blackoff-whiteoff 2 9 46 65 20 blackoff-whiteoff 4.34782608695652 13.8461538461538 0.015 0.021 yellow-black 15 11 46 65 black-white 10.8695652173913 23.0769230769231 0.02 0.015 blue-white 5 4 46 65 10 blue-white 10.8695652173913 6.15384615384615 0.02 0 brown-green 3 0 46 65 Correlation dark brown-green 8.69565217391304 4.61538461538461 0.022 0.023 black-creme 7 16 46 65 Rating Preference yellow-black 32.6086956521739 16.9230769230769 0 0.00900000000000001 dark brown-green 4 3 46 65 / black-creme / yellow-blue 5 7 46 65 ff 0.0918053760955382 yellow-blue ff 2.884615384615393.88888888888889black-creme 3.88888888888889 Colors Group D Group N Colors Group D Group N -0.735791591345596 brown-green 6.250000000000011.11111111111111yellow-blue 1.11111111111111 black-creme black-white 10.8695652173913 23.0769230769231 black-creme 0.208 0.187 black o blue/yellow blackoff-whiteoff black/white6.73076923076924blue/whitedark7.77777777777778 brown brown-green 7.77777777777778 yellow-blue blackoff-whiteoff 4.34782608695652 13.8461538461538 yellow-blue 0.214 0.182 black/creme brown/green white o black/yellow black-white 7.2115384615384711.6666666666667light green blackoff- 11.6666666666667 brown-green yellow-black 32.6086956521739 16.9230769230769 brown-green 0.221 0.194 Group D Group C whiteoff blackoff-whiteoff blue-white 10.8695652173913 6.15384615384615 blackoff-whiteoff 0.222 0.201 blue-white 9.615384615384628.33333333333334black-white 8.33333333333334 black-white brown-green 6.52173913043478 0 black-white 0.223 0.195 dark brown-green 9.61538461538462 0 blue-white 0 blue-white black-creme 15.2173913043478 24.6153846153846 blue-white 0.228 0.18 yellow-black 10.576923076923112.7777777777778dark brown- 12.7777777777778 dark brown-green dark brown-green 8.69565217391304 4.61538461538461 dark brown-green 0.228 0.203 green yellow-black yellow-blue 10.8695652173913 10.7692307692308 yellow-black 0.23 0.189 5 yellow-black 5 black-creme 15.2173913043478 24.6153846153846 0.006000000000000010.00700000000000001 yellow-blue 10.8695652173913 10.7692307692308 0.013 0.002 brown-green 6.52173913043478 0 0.014 0.014 blackoff-whiteoff 4.34782608695652 13.8461538461538 0.015 0.021 black-white 10.8695652173913 23.0769230769231 0.02 0.015 blue-white 10.8695652173913 6.15384615384615 0.02 0 Correlation dark brown-green 8.69565217391304 4.61538461538461 0.022 0.023 yellow-black 32.6086956521739 16.9230769230769 0.00900000000000001 black-creme 0.0918053760955382 yellow-blue 2.884615384615393.88888888888889black-creme 3.88888888888889 -0.735791591345596 brown-green 6.250000000000011.11111111111111yellow-blue 1.11111111111111 blackoff-whiteoff 6.730769230769247.77777777777778brown-green 7.77777777777778 black-white 7.2115384615384711.6666666666667blackoff- 11.6666666666667 whiteoff blue-white 9.615384615384628.33333333333334black-white 8.33333333333334 dark brown-green 9.61538461538462 0 blue-white 0 yellow-black 10.576923076923112.7777777777778dark brown- 12.7777777777778 green 5 yellow-black 5

Chart 2 60

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Back Contrast Colors

Chart 2 60

0 Untitled 1 Untitled 2 Untitled 3 Untitled 4

Back Contrast Colors 10

Conditions Group D Group C Group D Group C x¯ ± s %x ¯ ± s % %% Grey Text (white background) Fixation Duration Preference Rating 0% (black) 0.24±0.07 7.62 0.19±0.05 – 60.00 93.88 25% 0.22±0.08 – 0.22±0.07 11.86 32.60 6.12 50% 0.23±0.09 4.48 0.21±0.06 8.76 4.35 – 75% 0.24±0.09 7.62 0.20±0.06 5.15 2.17 – Grey Background (white text) Fixation Duration Preference Rating 0% (black) 0.24±0.09 3.96 0.21±0.06 3.48 55.32 58.33 25% 0.23±0.07 – 0.21±0.06 3.98 25.53 35.42 50% 0.24±0.07 4.85 0.20±0.06 – 19.15 6.25 75% 0.24±0.09 4.41 0.21±0.07 4.98 –– Text/Background Colors Fixation Duration Preference Rating black/creme 0.21±0.07 – 0.19±0.05 3.89 15.22 24.62 blue/yellow 0.21±0.08 2.88 0.18±0.05 1.11 10.87 10.78 green/brown 0.22±0.07 6.25 0.19±0.06 7.78 6.52 – oﬀ-black/oﬀ-white 0.22±0.08 6.73 0.20±0.06 11.67 4.35 13.85 black/white 0.22±0.07 7.21 0.20±0.06 8.33 10.87 23.08 light green/dark brown 0.23±0.07 9.62 0.20±0.04 12.78 8.70 4.62 blue/white 0.23±0.07 9.62 0.18±0.05 – 10.87 6.15 black/yellow 0.23±0.09 10.58 0.19±0.05 5.00 32.61 16.92 Font Size Fixation Duration Preference Rating 14 points 0.26±0.09 24.52 0.22±0.07 19.89 –– 18 points 0.23±0.07 12.02 0.20±0.05 7.53 10.42 6.82 22 points 0.22±0.06 3.85 0.20±0.05 6.45 39.58 34.09 26 points 0.21±0.05 – 0.19±0.04 – 50.00 59.09 Character Spacing Fixation Duration Preference Rating -7% 0.23±0.09 15.84 0.20±0.06 10.61 10.87 – 0% 0.21±0.07 2.97 0.19±0.05 6.15 36.96 65.31 +7% 0.20±0.06 – 0.19±0.05 3.35 32.60 16.33 +14% 0.21 ±0.06 3.96 0.18±0.05 – 19.57 18.37 Line Spacing Fixation Duration Preference Rating 0.8 lines 0.23±0.07 3.10 0.21±0.05 0.98 4.44 10.42 1 line 0.24±0.07 4.42 0.21±0.05 1.47 33.33 39.58 1.2 lines 0.24±0.07 4.87 0.21±0.06 0.49 40.00 39.58 1.4 lines 0.23±0.06 – 0.20±0.06 – 22.22 10.42 Paragraph Spacing Fixation Duration Preference Rating 0.5 lines 0.23±0.06 5.90 0.20±0.05 1.02 17.56 10.53 1 line 0.23±0.06 3.64 0.20±0.05 1.02 32.82 26.32 2 lines 0.22±0.05 – 0.20±0.04 – 22.90 57.89 3 lines 0.22±0.05 0.45 0.20±0.05 0.51 26.72 5.26 Column Width Fixation Duration Preference Rating 22 char./line 0.22±0.06 2.34 0.19±0.04 2.14 27.27 2.27 44 char./line 0.21±0.06 – 0.19±0.05 1.60 31.81 54.55 66 char./line 0.22±0.06 3.27 0.19±0.04 – 31.81 36.36 88 char./line 0.22±0.05 0.47 0.19±0.04 – 9.09 6.82

Table 2 Fixation Duration and Preference Rating results for group D (N = 45) and group C (N = 44). The average ﬁxation time results and the standard deviation are presented in seconds and the percentage shows their ﬁxation extra time in comparison with the lowest value. Numbers in boldface indicate the best cases.

0.136, p = 0.938) on fixation duration. Moreover, there Within Groups: No significant effect of background were no interaction effects of background grey scale and grey scale was found on fixation duration in group groups (F (3, 376) = 0.252, p = 0.860). The results of D(F (3, 188) = 0.188, p = 0.904), or in group C the post-hoc tests show that: (F (3, 188) = 0.204, p = 0.893).

- Participants with dyslexia had significantly longer Preferences: Participants with and without dyslexia fixation durations (¯x = 0.235, s = 0.08 seconds) found pure black background significantly more read- than the participants without dyslexia (¯x = 0.207, able than text presented with different grey scales s = 0.06 seconds, p < 0.001) (Table 2). (χ2(3) = 11.101, p = 0.011 for group D and χ2(3) = Non_Dys Font Contrast Back Colors Size Chart Spa Line Spa Par Spacing Column Contrast Width 1 46 3 0 5 32 5 2 3 2 0 28 3 19 9 19 10 24 3 0 17 16 24 0 5 22 16 4 3 0 7 0 8 19 8 1 5 9 6 11 7 15 8 4 Scale-0 = 1 Scale-0 = 2 Color-blackoff-whiteoff = 5 Size-14 = 4 Spacing +14 = 2 Line Spacing 0.8 = 3 Spacing .4 = 4 Column width 1/4 = 4 Scale-25 = 4 Scale-25 = 3 Color-yellow-black = 6 Size-18= 3 Spacing +7 = 4 Line Spacing 1 = 4 Spacing 2 = 3 Column width 2/4 = 3 Scale-50 = 3 Scale-50 = 1 Color-blue-white = 8 Size-22= 2 Spacing 0 = 1 Line Spacing 1.4 = 1 Spacing 1 = 2 Column width 3/4 = 2 Scale-75 = 2 Scale-75 = 4 Color-brown-green = 1 Size-26= 1 Spacing -7 = 3 Line Spacing 1.2 = 2 Spacing 3 = 1 Column width 4/4 = 1 Color-black-creme = 3 Color-dark brown-green = 2 Color-yellow-blue = 4 Color-black-white = 7

Font Contrast Back Colors Size Chart Spa Line Spa Par Spacing Column Contrast Width 1 2 12 5 0 5 2 23 4 2 15 0 2 3 15 15 30 14 3 27 9 15 15 17 18 43 14 4 1 26 5 26 9 10 35 12 5 3 6 7 7 4 8 5 Scale-0 = 3 Scale-0 = 4 Color-black-white = 1 Size-14 = 1 Spacing +14 = 4 Line Spacing 0.8 = 1 Spacing .4 = 1 Column width 1/4 = 1 Scale-25 = 2 Scale-25 = 1 Color-blackoﬀ-whiteoﬀ = 2 Size-18= 2 Spacing +7 = 2 Line Spacing 1 = 2 Spacing 2 = 2 Column width 2/4 = 2 Scale-50 = 1 Scale-50 = 3 Color-yellow-black = 3 Size-22= 3 Spacing 0 = 3 Line Spacing 1.4 = 4 Spacing 1 = 3 Column width 3/4 = 3 Scale-75 = 4 Scale-75 = 2 Color-blue-white = 4 Size-26= 4 Spacing -7 = 1 Line Spacing 1.2 = 3 Spacing 3 = 4 Column width 4/4 = 4 Color-brown-green = 5 Color-black-creme = 6 Color-dark brown-green = 7 Color-yellow-blue = 8 Text Grey Scale Text Grey Scale 100 0.25 (%)

75 Font Contrast Group D Group N Font Contrast Group D Group N 0.213 0% 27 46 45 49 0% 75% 15 3 46 49 75% 0.175 50 50% 2 0 46 49 50% 25% 1 0 46 49 25% 0.138 25 Font Contrast Group D Group N Font Contrast Group D Group N Preference Rating Preference 0% 60 93.8775510204082 0% 0.24 0.194 0.1 0 Fixation Duration (sec.) Fixation Duration 25% 32.6086956521739 6.12244897959184 25% 0.223 0.217 0% 25% 50% 75% grey 0% 25% 50% 75% grey 50% 4.34782608695652 0 50% 0.233 0.211 Correlation 75% 2.17391304347826 0 75% 0.24 0.204 Group D Group C Group D Group C -0.968445715719153 99.1304347826087 100 0.017 0.023 -0.993869371230394 0.01 0.017 Back Contrast Group D Group N 0.017 0.00999999999999998 100% 26 28 47 48 7.6233183856502211.8556701030928 25% 12 17 47 48 4.484304932735438.76288659793814 Background Grey Scale Background Grey Scale 50% 9 3 47 48 7.623318385650225.15463917525772 75% 0 0 47 48 0.25 60 (%) Back Contrast Group D Group N Back Contrast Group D Group N 100% 55.3191489361702 58.3333333333333 0% 0.236 0.208 0.213 45 25% 25.531914893617 35.4166666666667 25% 0.227 0.209 Correlation 50% 19.1489361702128 6.25 50% 0.238 0.201 0.175 30 -0.118995939068828 75% 0 0 75% 0.237 0.211 0.188839041314493 0.008999999999999980.00699999999999998 0.138 15 0.011 0.00799999999999998

0.009999999999999980.00999999999999998 Rating Preference

Fixation Duration (sec.) Fixation Duration 0.1 0 3.964757709251093.48258706467661 0% 25% 50% 75% grey 0% 25% 50% 75% grey Size Group D Group N 4.845814977973563.98009950248755 14 0 0 46 44 4.405286343612334.97512437810944 Group D Group C Group D Group C 18 2 3 48 44 22 10 15 48 44 26 34 26 48 44 Size Group D Group N Size Group D Group N Font Size Font Size 14 0 0 14 0.259 0.223 18 4.16666666666667 6.81818181818182 18 0.233 0.2 0.25 80 (%) Correlation 22 20.8333333333333 34.0909090909091 22 0.216 0.198 -0.791535362594822 26 70.8333333333333 59.0909090909091 26 0.208 0.186 0.213 60 -0.852378048645091 0.051 0.037 0.025 0.014 0.175 40 0.00800000000000001 0.012 14 24.519230769230819.8924731182796 0.138 20 18 12.01923076923087.52688172043011

22 3.846153846153856.45161290322581 Rating Preference

Fixation Duration (sec.) Fixation Duration 0.1 0 14 18 22 26 points 14 18 22 26 points Group D Group C Group D Group C

Non_Dys Font Contrast Back Colors Size Chart Spa Line Spa Par Spacing Column Contrast Character Spacing WidthCharacter Spacing 1 46 3 0 5 32 5 2 3 Chart Spa Group D Group N 2 0 28 3 0.25 19 9 19 70 10 24 3 0 17 16 24 0 5 (%) 22 16 -7 5 0 46 49 4 3 0 7 0 8 19 8 1 0 17 32 46 49 5 9 0.213 52.5 +7 15 8 46 49 6 11 +14 9 9 46 49 7 15 0.175 35 Chart Spa Group D Group N Chart Spa 8 Group D Group N 4 -7 10.8695652173913 0 -7 0.234 Scale-00.198 = 1 Scale-0 = 2 Color-blackoﬀ-whiteoﬀ = 5 Size-14 = 4 Spacing +14 = 2 Line Spacing 0.8 = 3 Spacing .4 = 4 Column width 0.138 17.5 1/4 = 4 0 36.9565217391304 65.3061224489796 0 0.208 0.19 Scale-25 = 4 Scale-25 = 3 Color-yellow-black = 6 Size-18= 3 Spacing +7 = 4 Line Spacing 1 = 4 Spacing 2 = 3 Column width

Correlation +7 32.6086956521739 16.3265306122449 +7 0.202 0.185 Rating Preference 2/4 = 3 Fixation Duration (sec.) Fixation Duration 0.1 0 -0.838022023794689 +14 19.5652173913043 18.3673469387755 +14 0.21 Scale-500.179 = 3 Scale-50 = 1 Color-blue-white = 8 Size-22= 2 –7%Spacing 00% = 1 +7%Line Spacing+14% 1.4 char.= 1 Spacing 1 = 2–7%Column width0% +7% +14% char. -0.123430442777081 0.032 0.019 3/4 = 2 Scale-75 = 2 Scale-75 = 4 Color-brown-green = 1 Size-26= 1 Spacing -7 = 3 Line Spacing 1.2 = 2 Spacing 3 = 1 Column width 0.00599999999999998 0.011 Group D Group C Group4/4 = 1 D Group C 5 0 0.007999999999999980.00600000000000001 Color-black-creme = 3 17 32 15.841584158415810.6145251396648 Color-dark brown-green = 2 15 8 2.970297029702966.14525139664805 Color-yellow-blue = 4 9 9 3.960396039603953.35195530726257 Color-black-white = 7 Line Spacing Line Spacing

Font Contrast Back Colors Size 0.25 Chart Spa Line Spa Par Spacing 40Column Contrast (%) Width 1 2 12 5 0 5 2 23 4 2 15 0 2 0.2133 15 15 30 30 14 3 27 9 15 15 17 18 43 14 4 1 26 5 260.175 9 10 35 20 12 Line Spa Group D Group N 5 3 6 7 0.8 2 5 45 48 0.138 10 7 4 1 15 19 45 48 8 5 1.2 18 19 45 48 Rating Preference Scale-0 = 3 Scale-0 = 4 Color-black-white = 1 Size-14 = (sec.) Fixation Duration 1 0.1Spacing +14 = 4 Line Spacing 0.8 = 1 Spacing .4 = 1 Column0 width 1.4 10 5 45 48 0.8 1 1.2 1.4 lines 1/4 = 10.8 1 1.2 1.4 lines lines Line Spa Group D Group N Line Spa Group D Scale-25Group N = 2 Scale-25 = 1 Color-blackoﬀ-whiteoﬀ = 2 Size-18= 2 Spacing +7 = 2 Line Spacing 1 = 2 Spacing 2 = 2 Column width 2/4 = 2 0.8 4.44444444444444 10.4166666666667 0.8 0.233 0.206 Group D Group C Group D Group C Scale-50 = 1 Scale-50 = 3 Color-yellow-black = 3 Size-22= 3 Spacing 0 = 3 Line Spacing 1.4 = 4 Spacing 1 = 3 Column width 1 33.3333333333333 39.5833333333333 1 0.236 0.207 3/4 = 3 Correlation 1.2 40 39.5833333333333 1.2 0.237 Scale-750.205 = 4 Scale-75 = 2 Color-blue-white = 4 Size-26= 4 Spacing -7 = 1 Line Spacing 1.2 = 3 Spacing 3 = 4 Column width 4/4 = 4 0.451017032441845 1.4 22.2222222222222 10.4166666666667 1.4 0.226 0.204 Color-brown-green = 5 0.447213595499958 0.00700000000000001 0.001 Color-black-creme = 6 0.00999999999999998 -0.001 Color-dark brown-green = 7 Paragraph Spacing Paragraph Spacing 0.011 -0.002 Color-yellow-blue = 8 0.25 60 3.097345132743370.485436893203884 (%) Text Grey Scale Text Grey Scale 4.42477876106194-0.485436893203884 4.86725663716813-0.970873786407768 0.213 45 100 0.25 (%)

75 Font Contrast Group D Group N 0.175 Font Contrast Group D 30 Group N 0.213 0% 27 46 45 49 0% 50 75% 15 3 0.13846 49 75% 15 0.175 Par Spacing Group D Group N 50% 2 0 46 49 50% 25 0.4 23 4 131 38 25% 1 0 46 49 25% Rating Preference 0.138

Fixation Duration (sec.) Fixation Duration 0.1 0 Font Contrast Group D Group N Font Contrast Group D Group N

1 43 10 131 38 Rating Preference 0% 60 93.8775510204082 0.5 0%1 2 3 lines 0.24 0.1940.5 1 2 3 lines 0.1 0 2 30 22 131 38 (sec.) Fixation Duration 25% 32.6086956521739 6.12244897959184 Group25% D Group C 0.223 0.217Group D Group C 0% 25% 50% 75% grey 0% 25% 50% 75% grey 3 35 2 131 38 50% 4.34782608695652 0 50% 0.233 0.211 Par Spacing Group D Group N Par Spacing CorrelationGroup D 75%Group N 2.17391304347826 0 75% 0.24 0.204 Group D Group C Group D Group C 0.4 17.5572519083969 10.5263157894737 0.4 -0.9684457157191530.233 0.198 99.1304347826087 100 0.017 0.023 1 32.824427480916 26.3157894736842 1 -0.9938693712303940.228 0.198 0.01 0.017 Correlation 2 22.9007633587786 57.8947368421053 2 0.22 Back Contrast0.196 Group D Group N 0.017 0.00999999999999998 -0.274103716415761 3 26.7175572519084 5.26315789473684 3 0.221 100% 0.197 26 28 47 48 7.6233183856502211.8556701030928Column Width 25% 12 17 47 Column48 Width 4.484304932735438.76288659793814 -0.676968662049936 0.013 0.002 Background Grey Scale Background Grey Scale 50% 9 3 47 48 7.623318385650225.15463917525772 0.00800000000000001 0.002 60 75% 0 0 47 0.25 48 (%) 0.25 60 (%) 0.001 Back Contrast0.001 Group D Group N Back Contrast Group D Group N 5.90909090909091100%1.0204081632653155.3191489361702 58.3333333333333 0.213 0% 0.236 45 0.208 0.213 45 3.6363636363636425%1.0204081632653125.531914893617 35.4166666666667 25% 0.227 0.209 Correlation0.45454545454545550%0.51020408163265419.1489361702128 6.25 0.175 50% 0.238 30 0.201 0.175 30 -0.118995939068828 75% 0 0 75% 0.237 0.211 0.188839041314493 0.008999999999999980.00699999999999998 0.138 15 11 0.138 0.011 150.00799999999999998

0.009999999999999980.00999999999999998 Rating Preference Preference Rating Preference Fixation Duration (sec.) Fixation Duration 0.1 0 0.1 3.964757709251093.482587064676610 Fixation Duration (sec.) Fixation Duration 0% 25% 50% 75% grey 0% 25% 50% 75% grey Size Group D Group N 22 44 66 88 char.4.845814977973563.9800995024875522 44 66 88 char. 14 0 0 Fig.46 4 Participants’44 reading performance4.405286343612334.97512437810944 (ﬁxation duration Fig. 5 Participants’Group D readingGroup C performanceGroup (ﬁxation D durationGroup C 18 2 3 48 Group44 D Group C Group D Group C 22 10 15 mean)48 and preference44 ratings in % for text and background mean) and preference ratings in % for font size. 26 34 26 48 44 Size Group D Group N colors. Size Group D Group N Column Width Group D Group N Font Size Font Size 14 0 0 14 0.259 0.223 22 12 1 44 44 18 4.16666666666667 6.81818181818182 18 Text and Background0.233 Colors 0.2 0.25 80 (%) 44 14 24 44 44 Correlation 22 20.8333333333333 34.0909090909091 22 0.216 0.198 66 14 16 44 44 -0.791535362594822 26 70.8333333333333 59.0909090909091 0.25 26 0.208 0.186 0.213 60 88 4 3 44 44 -0.852378048645091 0.051 0.037 Column Width Group D Group N Column Width Group D Group N 0.213 0.025 0.014 0.175 40 22 27.2727272727273 2.27272727272727 22 0.219 0.191 0.00800000000000001 0.012 14 24.519230769230819.8924731182796 44 31.8181818181818 54.5454545454545 44 0.214 0.19 0.138 20 0.175 18 12.01923076923087.52688172043011 Correlation 66 31.8181818181818 36.3636363636364 66 0.221 0.187

22 3.846153846153856.45161290322581 Rating Preference

Fixation Duration (sec.) Fixation Duration 0.1 0 0.402618283010223 88 9.09090909090909 6.81818181818182 88 0.215 0.187 0.138 -0.0148014204124575 0.005 0.004 14 18 22 26 points 14 18 22 26 points

0.00700000000000001 0.003 (sec.) Fixation Duration Group D Group C Group D Group C 1 0.001 0 0.1 / / 2 2.336448598130842.13903743315508 ff 3 3.271028037383181.60427807486631 creme yellow green ff white white yellow 4 0.467289719626169 0 Character Spacing Character Spacing black o blue/ black/ blue/ 2 5 Chart Spa Group D Group N black/ brown/ white o dark brown black/ 0.25 70 nificantly more readable (χ (7) (%) = 11.821, p = 0.107 for 6 light green -7 5 0 46 49 2 7 0 17 32 46 Group49 D Group C group0.213 D and χ (7) = 10.290,52.5 p = 0.172 for group C). 8 +7 15 8 46 49 +14 9 9 46 49 0.175See Figure 4 for the fixation35 duration means and Chart Spa Group D Group N Chart Spa Group D Group N -7 10.8695652173913 0 -7 0.234 0.198 0.138 17.5 0 36.9565217391304 65.3061224489796 0 Text and Background0.208 Colors0.19 preferences.

Correlation +7 32.6086956521739 16.3265306122449 +7 0.202 0.185 Rating Preference

Fixation Duration (sec.) Fixation Duration 0.1 0 -0.838022023794689 +14 19.5652173913043 18.3673469387755 40 +14 0.21 0.179 –7% 0% +7% +14% char. –7% 0% +7% +14% char. -0.123430442777081 0.032 0.019 (%) 0.00599999999999998 0.011 Group D Group C Group D Group C 30 Colors Group D Group N 5 0 0.007999999999999980.00600000000000001 black-white 5 15 46 65 17 32 15.841584158415810.6145251396648 5.4 Font Size 15 8 2.970297029702966.14525139664805 blackoﬀ-whiteoﬀ 2 9 46 65 20 9 9 3.960396039603953.35195530726257 Line Spacing Line Spacing yellow-black 15 11 46 65 blue-white 5 4 46 65 0.25 40

10 (%) brown-green 3 0 46 65 Main eﬀects: With two-way ANOVA, signiﬁcant main

Preference Rating Preference 0.213 black-creme 7 16 46 65 0 effects were identified in the fixation30 duration for the dark brown-green 4 3 46 65 / / yellow-blue 5 7 46 65 ff 0.175 20 ff groups (F (1, 372) = 19.713, p < 0.001) and for font Colors Group D Group N Colors Group D GroupLine Spa N Group D Group N 0.8 2 5 45 48 0.138 10 black-creme black-white 10.8695652173913 23.0769230769231 black-creme 0.208 0.187 black o 1 15 19 45 48 blue/white size (F (3, 372) = 8.804, p < 0.001). There was no in- black/creme blue/yellowbrown/green white o black/white dark brown black/yellow yellow-blue blackoff-whiteoff 4.34782608695652 13.8461538461538 yellow-blue 0.214 1.2 0.182 18 19 45 48 Rating Preference light green (sec.) Fixation Duration 0.1 0 brown-green yellow-black 32.6086956521739 16.9230769230769 brown-green 0.221 0.194 1.4 10 5 45 Group48 D Group C teraction effect0.8 for1 font1.2 size1.4 lines and groups0.8 (F1(3, 372)1.2 1.4 = lines lines blackoff-whiteoff blue-white 10.8695652173913 6.15384615384615 blackoff-whiteoff 0.222 Line Spa0.201 Group D Group N Line Spa Group D Group N Group D Group C Group D Group C black-white brown-green 6.52173913043478 0 black-white 0.223 0.8 0.195 4.44444444444444 10.4166666666667 0.8 0.233 0.206 0.458, p = 0.712). The results of the post-hoc tests blue-white black-creme 15.2173913043478 24.6153846153846 blue-white 0.228 1 0.18 33.3333333333333 39.5833333333333 1 0.236 0.207 dark brown-green dark brown-green 8.69565217391304 4.61538461538461 dark brown-green Correlation 0.228 1.2 0.203 40 39.5833333333333 1.2 0.237 0.205 show that: 0.451017032441845 1.4 22.2222222222222 10.4166666666667 1.4 0.226 0.204 yellow-black yellow-blue 10.8695652173913 10.7692307692308 yellow-black 0.23 0.189 0.447213595499958 0.00700000000000001 0.001 black-creme 15.2173913043478 24.6153846153846 0.006000000000000010.00700000000000001 21.790, p < 0.001 for group C). See Figure 3 for the 0.00999999999999998 -0.001 Paragraph Spacing Paragraph Spacing yellow-blue 10.8695652173913 10.7692307692308 0.013 0.002 0.011 -0.002 - Group D had significantly longer fixation durations brown-green 6.52173913043478 0 0.014 0.014 fixation duration means and preferences. 0.25 60

3.097345132743370.485436893203884 (%) blackoff-whiteoff 4.34782608695652 13.8461538461538 0.015 0.021 4.42477876106194-0.485436893203884 (¯x = 0.229, s = 0.07 seconds) than group C (¯x = black-white 10.8695652173913 23.0769230769231 0.02 0.015 4.86725663716813-0.970873786407768 0.213 45 blue-white 10.8695652173913 6.15384615384615 0.02 0 0.202, s = 0.05 seconds, p < 0.001) (Table 2). Correlation dark brown-green 8.69565217391304 4.61538461538461 0.022 0.023 0.175 30 yellow-black 32.6086956521739 16.9230769230769 0.00900000000000001 5.3 Text and Background Colors - Participants0.138 present significant15 longer fixation du- black-creme Par Spacing Group D Group N

0.0918053760955382 yellow-blue 2.884615384615390.43.88888888888889black-creme23 3.88888888888889 4 131 38 rations with 14 points font size Rating Preference than with 18 points Fixation Duration (sec.) Fixation Duration 0.1 0 -0.735791591345596 brown-green 6.2500000000000111.11111111111111yellow-blue43 1.11111111111111 10 131 38 0.5 1 2 3 lines 0.5 1 2 3 lines blackoff-whiteoff 6.7307692307692427.77777777777778brown-green30 7.77777777777778 22 131 38 (p = 0.054), 22 points (p = 0.002) and 26 points Main effects: With two-way ANOVA, significant main Group D Group C Group D Group C black-white 7.21153846153847311.6666666666667blackoff- 35 11.6666666666667 2 131 38 Par Spacing whiteoGroup ffD Group N effects were foundPar Spacing for the groupsGroup D Group ( NF (1, 732) = (p < 0.001) (Table 2). blue-white 9.615384615384620.48.33333333333334black-white17.55725190839698.3333333333333410.5263157894737 0.4 0.233 0.198 dark brown-green 9.615384615384621 0 blue-white32.824427480916 26.31578947368420 1 0.228 0.198 Correlation 2 22.9007633587786 57.8947368421053 40.028, p < 02.001) on fixation0.22 duration.0.196 However, yellow-black 10.576923076923112.7777777777778dark brown- 12.7777777777778 -0.274103716415761 3 26.7175572519084 5.26315789473684 3 0.221 0.197 green Column Width Column Width -0.676968662049936 no effects of text and background0.013 colors0.002 (F (7, 732) = 5 yellow-black 5 Within Groups: A significant effect of font size on fixa- 0.00800000000000001 0.002 60 0.25 (%) 0.848, p = 0.548) were found on0.001 fixation0.001 duration. tion duration in group D (F (3, 186) = 4.965, p = 0.002) 5.909090909090911.02040816326531 0.213 45 Moreover, no interaction effects3.63636363636364 of text1.02040816326531 and background and in group C (F (3, 186) = 4.043, p = 0.008) was 0.4545454545454550.510204081632654 0.175 30 colors and groups (F (7, 732) = 0.528, p = 0.814) have found. The results of the post-hoc tests show that: 0.138 been found either. The results of the post-hoc tests 15 0.1 Rating Preference 0 Fixation Duration (sec.) Fixation Duration show that: - For group22 D font44 size66 of88 26char. points lead22 to44 significant66 88 char. shorter fixationGroup D durationsGroup C (¯x = 0.208,Groups D= 0.05 sec-Group C - Participants with dyslexia had significantly longer Column Width Group D Group N onds) than texts with 14 points (¯x = 0.259, s = 0.09 22 12 1 44 44 Text and Background Colors 44 14 24 44 fixation44 durations (¯x = 0.221, s = 0.08 seconds) seconds, p = 0.003); and font size of 22 points lead 66 14 16 44 44 0.25 88 4 3 44 than the44 participants without dyslexia (¯x = 0.193, to significant shorter fixation durations (¯x = 0.216, Column Width Group D Group N Column Width Group D Group N 0.213 22 27.2727272727273 2.27272727272727 s = 0.06 seconds,22 p < 0.001) (Table0.219 2).0.191 s = 0.06 seconds) than texts with 14 points (¯x = 44 31.8181818181818 54.5454545454545 44 0.214 0.19 0.175 Correlation 66 31.8181818181818 36.3636363636364 66 0.221 0.187 0.259, s = 0.09 seconds, p = 0.003) (Table 2). 0.402618283010223 88 9.09090909090909 6.81818181818182 88 0.215 0.187 0.138 -0.0148014204124575 0.005 0.004

Within Groups: There was no0.00700000000000001 significant0.003 effect of text - Participants (sec.) Fixation Duration in group C had significant shorter fix- 1 0.001 0 0.1 / / and background2 colors on fixation2.33644859813084 duration2.13903743315508 for group ation durations with 26ff points font size (¯x = 0.186, 3 3.271028037383181.60427807486631 creme yellow green ff white white yellow 4 0.467289719626169 0 D(F (7, 366) = 0.467, p = 0.858) nor for group C s = 0.04 seconds) thanblack o with 14 points (¯x = 0.223, s blue/ blue/ 5 black/ brown/ white o black/ dark brown black/ (F (7, 366)6 = 1.149, p = 0.332). = 0.07 seconds, p = 0.005) (Tablelight2). green 7 Group D Group C 8

Preferences: Participants with and without dyslexia Preferences: ParticipantsText and Background with and Colors without dyslexia did not find any of the text and background colors sig- found texts40 sizes of 26 points significantly easier to read (%) 30 Colors Group D Group N black-white 5 15 46 65 blackoff-whiteoff 2 9 46 65 20 yellow-black 15 11 46 65 blue-white 5 4 46 65 10 brown-green 3 0 46 65 black-creme 7 16 46 65 Rating Preference 0 dark brown-green 4 3 46 65 / / yellow-blue 5 7 46 65 ff ff Colors Group D Group N Colors Group D Group N black-creme black-white 10.8695652173913 23.0769230769231 black-creme 0.208 0.187 black o blue/yellow black/whiteblue/whitedark brown yellow-blue blackoff-whiteoff 4.34782608695652 13.8461538461538 yellow-blue 0.214 0.182 black/creme brown/green white o black/yellow light green brown-green yellow-black 32.6086956521739 16.9230769230769 brown-green 0.221 0.194 Group D Group C blackoff-whiteoff blue-white 10.8695652173913 6.15384615384615 blackoff-whiteoff 0.222 0.201 black-white brown-green 6.52173913043478 0 black-white 0.223 0.195 blue-white black-creme 15.2173913043478 24.6153846153846 blue-white 0.228 0.18 dark brown-green dark brown-green 8.69565217391304 4.61538461538461 dark brown-green 0.228 0.203 yellow-black yellow-blue 10.8695652173913 10.7692307692308 yellow-black 0.23 0.189 black-creme 15.2173913043478 24.6153846153846 0.006000000000000010.00700000000000001 yellow-blue 10.8695652173913 10.7692307692308 0.013 0.002 brown-green 6.52173913043478 0 0.014 0.014 blackoff-whiteoff 4.34782608695652 13.8461538461538 0.015 0.021 black-white 10.8695652173913 23.0769230769231 0.02 0.015 blue-white 10.8695652173913 6.15384615384615 0.02 0 Correlation dark brown-green 8.69565217391304 4.61538461538461 0.022 0.023 yellow-black 32.6086956521739 16.9230769230769 0.00900000000000001 black-creme 0.0918053760955382 yellow-blue 2.884615384615393.88888888888889black-creme 3.88888888888889 -0.735791591345596 brown-green 6.250000000000011.11111111111111yellow-blue 1.11111111111111 blackoff-whiteoff 6.730769230769247.77777777777778brown-green 7.77777777777778 black-white 7.2115384615384711.6666666666667blackoff- 11.6666666666667 whiteoff blue-white 9.615384615384628.33333333333334black-white 8.33333333333334 dark brown-green 9.61538461538462 0 blue-white 0 yellow-black 10.576923076923112.7777777777778dark brown- 12.7777777777778 green 5 yellow-black 5

Chart 2 60

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Back Contrast Colors

Chart 2 60

0 Untitled 1 Untitled 2 Untitled 3 Untitled 4

Back Contrast Colors Non_Dys Font Contrast Back Colors Size Chart Spa Line Spa Par Spacing Column Contrast Width 1 46 3 0 5 32 5 2 3 2 Non_Dys Font Contrast 0 Back 28 Colors 3 Size 19 Chart Spa 9 Line Spa 19 Par Spacing10 Column 24 3 0 Contrast 17 16 24 0 5 22 Width 16 1 4 46 3 30 07 50 328 195 28 31 2 5 0 28 39 19 9 19 10 24 3 6 0 17 1611 24 0 5 22 16 4 7 3 0 157 0 8 19 8 1 5 8 94 6 Scale-0 = 1 Scale-0 = 2 Color-blackoff-whiteoff =11 5 Size-14 = 4 Spacing +14 = 2 Line Spacing 0.8 = 3 Spacing .4 = 4 Column width 7 15 1/4 = 4 8 Scale-25 = 4 Scale-25 = 3 Color-yellow-black = 6 4 Size-18= 3 Spacing +7 = 4 Line Spacing 1 = 4 Spacing 2 = 3 Column width Scale-0 = 1 Scale-0 = 2 Color-blackoff-whiteoff = 5 Size-14 = 4 Spacing +14 = 2 Line Spacing 0.8 = 3 Spacing .4 = 4 Column2/4 = width 3 Scale-50 = 3 Scale-50 = 1 Color-blue-white = 8 Size-22= 2 Spacing 0 = 1 Line Spacing 1.4 = 1 Spacing 1 = 2 Column1/4 = width4 Scale-25 = 4 Scale-25 = 3 Color-yellow-black = 6 Size-18= 3 Spacing +7 = 4 Line Spacing 1 = 4 Spacing 2 = 3 Column3/4 = width 2 Scale-75 = 2 Scale-75 = 4 Color-brown-green = 1 Size-26= 1 Spacing -7 = 3 Line Spacing 1.2 = 2 Spacing 3 = 1 Column2/4 = width3 Scale-50 = 3 Scale-50 = 1 Color-blue-white = 8 Size-22= 2 Spacing 0 = 1 Line Spacing 1.4 = 1 Spacing 1 = 2 Column4/4 = width 1 Color-black-creme = 3 3/4 = 2 Non_Dys Font Contrast Back Colors Size Chart Spa Line Spa Scale-75Par = 2 SpacingScale-75Column = 4 Color-darkColor-brown-green brown-green = 1 = 2 Size-26= 1 Spacing -7 = 3 Line Spacing 1.2 = 2 Spacing 3 = 1 Column width Contrast Width Color-yellow-blue = 4 4/4 = 1 1 46 3 0 5 32 5 2 3 Color-black-cremeColor-black-white = = 3 7 2 0 28 3 19 9 19 10 24 Color-dark brown-green = 2 3 0 17 16 24 0 5 22 16 Font Contrast Back Color-yellow-blueColors = 4 Size Chart Spa Line Spa Par Spacing Column 4 3 0 7 0 8 19 8 1 Contrast Color-black-white = 7 Width 5 9 1 2 12 5 0 5 2 23 4 6 11 2 Font Contrast 15 Back 0 Colors2 Size 3 Chart Spa 15 Line Spa 15 Par Spacing30 Column 14 7 15 3 27 Contrast 9 15 15 17 18 43 Width 14 8 4 1 4 2 1 1226 55 260 59 102 2335 124 Scale-0 = 1 Scale-0 = 2 Color-blackoff-whiteoff = 5 Size-14 = 4 Spacing +14 = 2 2 5 Line Spacing 0.8 = 3 Spacing15 .4 = 4 Column0 width 23 3 15 15 30 14 1/4 = 4 3 6 27 9 157 15 17 18 43 14 Scale-25 = 4 Scale-25 = 3 Color-yellow-black = 6 Size-18= 3 Spacing +7 = 4 Line Spacing 1 = 4 Spacing 2 = 3 Column width 4 7 1 2/426 = 3 54 26 9 10 35 12 Scale-50 = 3 Scale-50 = 1 Color-blue-white = 8 Size-22= 2 Spacing 0 = 1 5 8 Line Spacing 1.4 = 1 Spacing 1 = 2 Column width 35 6 Scale-0 = 3 Scale-03/4 = 4= 2 Color-black-white7 = 1 Size-14 = 1 Spacing +14 = 4 Line Spacing 0.8 = 1 Spacing .4 = 1 Column width Scale-75 = 2 Scale-75 = 4 Color-brown-green = 1 Size-26= 1 Spacing -7 = 3 7 Line Spacing 1.2 = 2 Spacing 3 = 1 Column width 4 1/4 = 1 8 Scale-25 = 2 Scale-254/4 = =1 1 Color-blacko5ff-whiteoff = 2 Size-18= 2 Spacing +7 = 2 Line Spacing 1 = 2 Spacing 2 = 2 Column width 2/4 = 2 Color-black-creme = 3 Scale-0 = 3 Scale-0 = 4 Color-black-white = 1 Size-14 = 1 Spacing +14 = 4 Line Spacing 0.8 = 1 Spacing .4 = 1 Column width Color-dark brown-green = 2 Scale-50 = 1 Scale-50 = 3 Color-yellow-black = 3 Size-22= 3 Spacing 0 = 3 Line Spacing 1.4 = 4 Spacing 1 = 3 Column1/4 = width1 3/4 = 3 Color-yellow-blue = 4 Scale-25 = 2 Scale-25 = 1 Color-blackoff-whiteoff = 2 Size-18= 2 Spacing +7 = 2 Line Spacing 1 = 2 Spacing 2 = 2 Column width Color-black-white = 7 Scale-75 = 4 Scale-75 = 2 Color-blue-white = 4 Size-26= 4 Spacing -7 = 1 Line Spacing 1.2 = 3 Spacing 3 = 4 Column2/4 = width2 4/4 = 4 Scale-50 = 1 Scale-50 = 3 Color-yellow-black = 3 Size-22= 3 Spacing 0 = 3 Line Spacing 1.4 = 4 Spacing 1 = 3 Column width Color-brown-green = 5 Font Contrast Back Colors Size Chart Spa Line Spa Par Spacing Column 3/4 = 3 Color-black-creme = 6 Contrast Scale-75 = 4 Scale-75 Width= 2 Color-blue-white = 4 Size-26= 4 Spacing -7 = 1 Line Spacing 1.2 = 3 Spacing 3 = 4 Column width 1 2 12 5 0 5 2 23 Color-dark4 brown-green = 7 4/4 = 4 2 15 0 2 3 15 15 30 14Color-brown-greenColor-yellow-blue == 58 3 27 9 15 15 17 18 43 14Color-black-creme = 6 Text Grey Scale Text Grey Scale 4 1 26 5 26 9 10 35 Color-dark12 brown-green = 7 5 3 Color-yellow-blue = 8 100 0.25 (%) 6 7 Text Grey Scale Text Grey Scale 7 4 75 Font Contrast Group D Group N Font Contrast Group D Group N 0.213 8 5 100 0% 27 46 45 49 0% 0.25 (%) Scale-0 = 3 Scale-0 = 4 Color-black-white = 1 Size-14 = 1 Spacing +14 = 4 Line Spacing 0.8 = 1 Spacing .4 = 1 Column width 75% 15 3 46 49 75% 0.175 50 1/4 = 1 75 Scale-25 = 2 Scale-25 = 1 Color-blackoff-whiteoff = 2 Size-18= 2 Spacing +7 = 2 Line Spacing 1 = 2 50%Font ContrastSpacing 2 = Group2 Column D width2 Group N 0 46 49 50% Font Contrast Group D Group N 0.213 0%25% 2/427 = 12 460 4546 49490%25% 0.138 25 Scale-50 = 1 Scale-50 = 3 Color-yellow-black = 3 Size-22= 3 Spacing 0 = 3 Line Spacing 1.4 =75% 4 Font ContrastSpacing 1 = 3GroupColumn D15 width Group N 3 46 49 75% Font Contrast Group D Group N 0.175 50 Preference Rating Preference 0% 3/4 =60 3 93.8775510204082 0% 0.24 0.194 0.1 0 50% 2 0 46 49 50% (sec.) Fixation Duration Scale-75 = 4 Scale-75 = 2 Color-blue-white = 4 Size-26= 4 Spacing -7 = 1 Line Spacing 1.2 = 325% Spacing 3 =32.6086956521739 4 Column width 6.12244897959184 25% 0.223 0.217 0.138 grey 25 0% 25% 50% 75% grey 25% 4/4 =1 4 0 46 49 25% 0% 25% 50% 75% 50% 4.34782608695652 0 50% 0.233 0.211 Color-brown-green = 5 Font Contrast Group D Group N Font Contrast Group D Group N Preference Rating Preference Correlation 0%75% 2.1739130434782660 93.87755102040820 0%75% 0.240.24 0.1940.204 0.1 Group D Group C 0 Group D Group C Color-black-creme = 6 (sec.) Fixation Duration -0.968445715719153 99.1304347826087 100 0.017 0.023 Color-dark brown-green = 7 25% 32.6086956521739 6.12244897959184 25% 0.223 0.217 0% 25% 50% 75% grey 0% 25% 50% 75% grey -0.993869371230394 0.01 0.017 Color-yellow-blue = 8 50% 4.34782608695652 0 50% 0.233 0.211 Correlation 75%Back Contrast Group D Group N 75% 0.017 0.00999999999999998 Group D Group C Group D Group C 2.17391304347826 0 0.24 0.204Text Grey Scale -0.968445715719153 100% 99.130434782608726 10028 47 48Text Grey Scale 7.623318385650220.017 11.85567010309280.023 25% 12 17 47 48 4.484304932735438.76288659793814 -0.993869371230394 1000.01 0.017 Background Grey Scale Background Grey Scale 0.25 (%) 50%Back Contrast Group D 9 Group N 3 47 48 7.623318385650220.017 0.009999999999999985.15463917525772 75% 0 0 47 48 0.25 60 100% 26 28 47 0.213 48 7.6233183856502275 11.8556701030928 (%) Font Contrast Group D Group N Font Contrast 25%Back ContrastGroup D GroupGroup D12 N Group N 17 47 48 Back Contrast 4.48430493273543Group D 8.76288659793814Group N Background Grey Scale Background Grey Scale 0% 27 46 45 49 0% 50%100% 55.31914893617029 58.33333333333333 47 48 0% 7.623318385650220.236 5.154639175257720.208 0.213 45 0.175 50 75% 15 3 46 49 75% 75%25% 25.5319148936170 35.41666666666670 47 48 25% 0.227 0.209 0.25 60 (%) 50% 2 0 46 49 50%Correlation 50%Back Contrast 19.1489361702128Group D Group N 6.25 50% Back Contrast Group 0.238D Group 0.201N 0.175 30 -0.118995939068828 75% 0 0 0.138 75% 250.237 0.211 25% 1 0 46 49 25% 100% 55.3191489361702 58.3333333333333 0% 0.236 0.208 0.213 45 Font Contrast Group D Group N 0.188839041314493Font Contrast 25% Group 25.531914893617D Group N 35.4166666666667 25% 0.008999999999999980.227 0.006999999999999980.209

Preference Rating Preference 0.138 15 0% 60 93.8775510204082 0% 0.24 0.194 0.1 0.0110 0.00799999999999998 Correlation 50% 19.1489361702128 6.25 (sec.) Fixation Duration 50% 0.238 0.201 0.175 30 25% 32.6086956521739 6.12244897959184 25%-0.118995939068828 75% 0.223 00.217 0 0% 75%25% 50% 75% grey 0.009999999999999980.237 0.009999999999999980% 0.21125% 50% 75% grey Rating Preference

Fixation Duration (sec.) Fixation Duration 0.1 0 50% 4.34782608695652 0 50% 0.233 0.211 3.964757709251093.48258706467661 0.188839041314493 0.008999999999999980.00699999999999998 0.138 0% 25% 50% 75% grey 15 0% 25% 50% 75% grey Correlation 75% 2.17391304347826 0 75% Size 0.24Group D 0.204 Group N Group D Group C 4.845814977973560.011 0.007999999999999983.98009950248755Group D Group C -0.968445715719153 99.1304347826087 100 14 0.017 0.0230 0 46 44 4.405286343612334.97512437810944 Group D Group C 0.009999999999999980.00999999999999998 Rating Preference Group D Group C

18 2 3 48 44 (sec.) Fixation Duration 0.1 0 -0.993869371230394 0.01 0.017 3.964757709251093.48258706467661 Back Contrast Group D Group N 22 0.017 0.0099999999999999810 15 48 44 0% 25% 50% 75% grey 0% 25% 50% 75% grey Size Group D Group N 4.845814977973563.98009950248755 100% 26 28 47 48 26 7.6233183856502211.855670103092834 26 48 44 14 0 0 46 44 4.405286343612334.97512437810944 Group D Group C Group D Group C 25% 12 17 47 48 Size4.48430493273543Group8.76288659793814 D Group N Size Group D Group N 18 2 3 48 Background44 Grey Scale Background Grey Scale Font Size Font Size 50% 9 3 47 48 14 7.623318385650225.154639175257720 0 14 0.259 0.223 22 10 15 48 44 75% 0 0 47 48 18 4.16666666666667 6.81818181818182 0.25 18 600.233 0.2 0.25 80 (%) 26 34 26 48 44 (%) Back Contrast Group D Group N CorrelationBack Contrast 22 Group D20.8333333333333Group N 34.0909090909091 22 0.216 0.198 Size Group D Group N Size Group D Group N Font Size 100% 55.3191489361702 58.3333333333333 0%-0.791535362594822 26 0.23670.83333333333330.208 59.0909090909091 26 0.208 0.186 Font Size 14 0 0 0.213 14 0.25945 0.223 0.213 60 25% 25.531914893617 35.4166666666667 25%-0.852378048645091 0.227 0.209 0.051 0.037 18 4.16666666666667 6.81818181818182 18 0.233 0.2 0.25 80 Correlation 50% 19.1489361702128 6.25 50% 0.238 0.201 0.025 0.014 (%) Correlation 22 20.8333333333333 34.0909090909091 0.175 22 0.21630 0.198 0.175 40 -0.118995939068828 75% 0 0 75% 0.237 0.211 0.00800000000000001 0.012 -0.791535362594822 26 70.8333333333333 59.0909090909091 26 0.208 0.186 0.213 0.188839041314493 0.008999999999999980.00699999999999998 14 24.519230769230819.8924731182796 60 -0.852378048645091 0.138 0.05115 0.037 0.138 20 0.011 0.00799999999999998 18 12.01923076923087.52688172043011 0.025 0.014 0.175 0.009999999999999980.00999999999999998 Rating Preference 40

22 3.846153846153856.45161290322581 Rating Preference

Fixation Duration (sec.) Fixation Duration 0.1 0 0.00800000000000001 0.012 (sec.) Fixation Duration 3.964757709251093.48258706467661 0.1 0 0% 1425% 50% 75% grey24.519230769230819.89247311827960% 25% 50% 75% grey points Size Group D Group N 4.845814977973563.98009950248755 0.138 14 18 22 26 points 20 14 18 22 26 18 12.01923076923087.52688172043011 14 0 0 46 44 4.405286343612334.97512437810944 Group D Group C Group D Group C Group D Group C Group D Group C 18 2 3 48 44 22 3.846153846153856.45161290322581 Rating Preference Fixation Duration (sec.) Fixation Duration 0.1 0 22 10 15 48 44 14 18 22 26 points 14 18 22 26 points 26 34 26 48 44 Size Group D Group N Size Group D Group N Font Size Font Size GroupCharacter D SpacingGroup C GroupCharacter D SpacingGroup C 14 0 0 14 0.259 0.223 18 4.16666666666667 6.81818181818182 18 0.233 0.2 0.25 80 Chart Spa Group D Group N (%) 0.25 70 (%) Correlation 22 20.8333333333333 34.0909090909091 22 -7 0.216 0.1985 0 46 49 -0.791535362594822 26 70.8333333333333 59.0909090909091 26 0 0.208 170.186 32 46 0.213 49 60 0.213 Character Spacing 52.5 Character Spacing -0.852378048645091 +7 0.051 150.037 8 46 49 Chart Spa 0.025Group D 0.014 Group N 0.25 70 +14 9 9 46 0.175 49 40 (%) -7 5 0 46 49 0.175 35 Chart0.00800000000000001 Spa Group D 0.012 Group N Chart Spa Group D Group N 0 17 32 46 49 14 -7 24.519230769230810.869565217391319.8924731182796 0 12 0.138 -7 200.234 0.198 0.213 52.5 18 +7 12.01923076923087.5268817204301115 8 46 49 0.138 17.5 0 36.9565217391304 65.3061224489796 0 0.208 0.19 +14 9 9 46 49 22 3.846153846153856.45161290322581 Rating Preference

Correlation +7 32.6086956521739 16.3265306122449 +7 0.202 0.185 0.175 Rating Preference 35 Fixation Duration (sec.) Fixation Duration 0.1 0 Chart Spa Group D Group N Chart Spa Group D Group N (sec.) Fixation Duration 0.1 0 -0.838022023794689 +14 19.5652173913043 18.3673469387755 +14 points 0.21 0.179 points -7 10.8695652173913 0 14 -7 18 22 26 0.234 14 0.198 18 22 26 –7% 0% +7% +14% char. –7% 0% +7% +14% char. -0.123430442777081 0.032 0.019 0.138 17.5 0 36.9565217391304 65.3061224489796 0 0.208 0.19 Fig. 6 Participants’Group D readingGroup C performance0.00599999999999998Group0.011 (ﬁxationD durationGroup C Fig.Group 7 Participants’ D Group reading C performanceGroup D (ﬁxationGroup duration C

Correlation +7 32.6086956521739 16.3265306122449 +7 0.202 0.185 Rating Preference 5 0 0.007999999999999980.00600000000000001 Fixation Duration (sec.) Fixation Duration 0.1 0 -0.838022023794689 +14 19.5652173913043 18.3673469387755 +14 0.21 0.179 17 32 mean) and preference ratings in15.8415841584158 % for10.6145251396648 character spacing. mean)–7% and0% preference+7% +14% ratingschar. in %–7% for line0% spacing.+7% +14% char. -0.123430442777081 0.032 0.019 15 8 2.970297029702966.14525139664805 9 9 Character Spacing 0.005999999999999983.960396039603953.35195530726257Character0.011 Spacing Group D Line SpacingGroup C Group D Line SpacingGroup C 5 0 0.007999999999999980.00600000000000001 Chart Spa Group D Group N 0.25 70 17 32 15.8415841584158 (%) 10.6145251396648 0.25 40 (%) -7 5 0 46 49 15 8 2.970297029702966.14525139664805 0 17 32 46 49 9 9 0.213 3.9603960396039552.5 3.35195530726257 0.213 Line Spacing 30 Line Spacing +7 15 8 46 49 +14 9 9 46 49 0.25 40 0.175 35 0.175 (%) 20 Chart Spa Group D Group N Chart Spa Group D Group N Line Spa Group D Group N -7 10.8695652173913 0 -7 0.234 0.198 0.213 30 0.8 2 5 45 0.138 48 17.5 0.138 0 36.9565217391304 65.3061224489796 0 0.208 0.19 10 1 15 19 45 48

Correlation +7 32.6086956521739 16.3265306122449 +7 0.202 0.185 Rating Preference 0.175 Rating Preference 20 1.2 18 19 45 (sec.) Fixation Duration 0.1 48 0 -0.838022023794689 +14 19.5652173913043 18.3673469387755 +14 0.21 0.179 (sec.) Fixation Duration 0.1 0 1.4 Line Spa Group D 10 Group N 5 45 –7% 48 0% +7% +14% char. –7% 0% +7% +14% char. -0.123430442777081 0.032 0.019 0.8 1 1.2 1.4 lines 0.8 1 1.2 1.4 lines lines 0.8 Line Spa Group D 2 Group N 5 45 48 Line Spa Group D Group N 0.138 10 0.00599999999999998 0.011 Group D Group C Group D Group C 1 0.8 4.4444444444444415 10.416666666666719 45 48 0.8 0.233 0.206 Group D Group C Group D Group C 5 0 0.007999999999999980.00600000000000001 1.2 18 19 45 48 Rating Preference 1 33.3333333333333 39.5833333333333 1 0.236 0.207 (sec.) Fixation Duration 0.1 0 17 32 15.841584158415810.6145251396648 Correlation 1.41.2 1040 39.58333333333335 45 48 1.2 0.237 0.205 15 8 2.970297029702966.14525139664805 0.8 1 1.2 1.4 lines 0.8 1 1.2 1.4 lines lines 0.451017032441845 1.4 Line Spa 22.2222222222222Group D Group10.4166666666667 N 1.4 Line Spa Group 0.226D Group 0.204N 9 9 3.960396039603953.35195530726257 Line Spacing Line Spacing 0.8 4.44444444444444 10.4166666666667 0.8 0.233 0.206 Group D Group C Group D Group C 0.447213595499958 0.007000000000000012 0.001 1 33.3333333333333 39.5833333333333 0.25 1 0.009999999999999980.236 40 -0.0010.207 Fig. 8 Participants’Paragraph Spacing reading performanceParagraph (ﬁxation Spacing duration than the rest of the sizes (χ (3) = (%) 9.051, p = 0.03 for Correlation 1.2 40 39.5833333333333 1.2 0.2370.011 -0.0020.205 0.451017032441845 1.4 22.2222222222222 10.4166666666667 1.4 2 0.226 0.204 mean)0.25 and preference ratings in %60 for paragraph spacing. group0.213 D and χ (3) = 20.7893.09734513274337, p <0.485436893203884030.01 for group C). (%) 0.447213595499958 0.007000000000000014.42477876106194-0.4854368932038840.001 0.175 0.009999999999999984.86725663716813-0.97087378640776820 -0.001 0.213 Paragraph Spacing 45 Paragraph Spacing See Figure 5 for the ﬁxation0.011 duration-0.002 means and Line Spa Group D Group N 0.25 60

3.097345132743370.485436893203884 (%) 0.8 2 5 45 48 0.138 10 0.175 30 4.42477876106194-0.485436893203884 1 15 19 45 48 preferences.

4.86725663716813-0.970873786407768 Rating Preference 0.213 45 1.2 18 19 45 48 0.138 15 Fixation Duration (sec.) Fixation Duration 0.1 0 1.4 10 5 45 48 Par Spacing Group D Group N 0.8 1 1.2 1.4 lines 0.8 1 1.2 1.4 lines 0.4 23 4 131 38 0.175 lines Rating Preference 30 Line Spa Group D Group N Line Spa Group D Group N (sec.) Fixation Duration 0.1 0 Group D Group C Group D Group C 0.8 4.44444444444444 10.4166666666667 0.8 1 0.233 430.206 10 131 38 0.5 1 2 3 lines 0.5 1 2 3 lines 2 30 22 131 38 0.138 15 1 33.3333333333333 39.5833333333333 1 0.236 0.207 Group D Group C Group D Group C Correlation 1.2 40 39.5833333333333 1.2 3 Par Spacing 0.237Group D 350.205 Group N 2 131 5.5 Character38 Spacing

0.4 Par Spacing Group D23 Group N 4 131 38 Par Spacing Group D Group N Rating Preference 0.451017032441845 1.4 22.2222222222222 10.4166666666667 1.4 0.226 0.204 (sec.) Fixation Duration 0.1 0 0.447213595499958 1 0.4 0.0070000000000000117.5572519083969430.001 10.526315789473710 131 38 0.4 0.233 0.198 0.5 1 2 3 lines 0.5 1 2 3 lines 2 1 0.0099999999999999832.82442748091630-0.001 26.315789473684222 131 38 1 Paragraph Spacing 0.228 0.198 Paragraph Spacing Group D Group C Group D Group C Correlation 3 2 0.01122.900763358778635-0.002 57.89473684210532 131 Main effects:38 2 With two-way ANOVA,0.22 0.196 significant main -0.274103716415761 3 Par Spacing 26.7175572519084Group D Group5.26315789473684 N 0.25 3 Par Spacing Group 0.221D 60Group 0.197N 3.097345132743370.485436893203884 (%) Column Width Column Width -0.676968662049936 0.4 4.4247787610619417.5572519083969-0.48543689320388410.5263157894737 effects were0.4 found for the0.2330.013 groups0.1980.002 (F (1, 368) = 1 32.824427480916 26.3157894736842 1 0.008000000000000010.228 0.1980.002 60 4.86725663716813-0.970873786407768 0.213 45 0.25 (%) Correlation 2 22.9007633587786 57.8947368421053 16.35, p2 < 0.001) and0.0010.22 for character0.1960.001 spacing -0.274103716415761 3 26.7175572519084 5.26315789473684 0.175 3 5.909090909090910.221 1.0204081632653130 0.197 line0.213 spacingColumn (F (3 Width, 372) = 0.238,45 p = 0.Column870) onWidth fixation -0.676968662049936 (F (3, 368) = 2.86, p = 0.037)3.636363636363640.013 of1.02040816326531 fixation0.002 duration. A 0.008000000000000010.4545454545454550.5102040816326540.002 60 0.138 15 0.1750.25 (%) 30 Par Spacing Group D Group N 0.001 0.001 duration were identified. However, there were no inter-

0.4 23 4 131 38 significant interaction of character5.90909090909091 Rating 1.02040816326531Preference spacing and groups Fixation Duration (sec.) Fixation Duration 0.1 0 0.1380.213 1545 1 43 10 131 38 0.5 1 2 3 3.63636363636364lines 1.020408163265310.5 1 2 3 lines action effects of line spacing and groups (F (3, 372) = 2 30 22 131 38 (F (3, 368) = 0.52, p = 0.665)0.454545454545455 has0.510204081632654 also been identified. 0.1750.1 Rating Preference 300 Group D Group C Group D Group C (sec.) Fixation Duration 3 35 2 131 38 0.109, p22= 044.955).66 The88 char. results of22 the44 post-hoc66 88 testschar. Par Spacing Group D Group N Par Spacing Group D Group N The results of the post-hoc tests show that: 0.138 15 0.4 17.5572519083969 10.5263157894737 0.4 0.233 0.198 show that:Group D Group C Group D Group C 1 32.824427480916 26.3157894736842 1 0.228 0.198 0.1 Rating Preference 0 Correlation 2 22.9007633587786 57.8947368421053 2 0.22 0.196 (sec.) Fixation Duration - There is a significant difference of fixation duration 22 44 66 88 char. 22 44 66 88 char. -0.274103716415761 3 26.7175572519084 5.26315789473684 3 Column Width 0.221Group D 0.197 Group N Column Width Column Width -0.676968662049936 22 0.013 120.002 1 44 44 - GroupGroup D hadD Text significantly andGroup Background C longer Colors Group fixation D durationsGroup C 0.00800000000000001 0.002 between group D (¯x = 0.212, s 60= 0.07 seconds) and 44 14 24 44 440.25 (%) 66 0.001 140.001 16 44 44 (¯0.25x = 0.233, s = 0.07 seconds) than group C (¯x = 88Column Width5.90909090909091Group1.02040816326531 D 4 Group N 3 44 group440.213 C (¯x = 0.188, s = 0.0545 seconds, p < 0.001) 22 Column3.63636363636364 Width Group1.02040816326531 D12 Group N 1 44 44 Column Width Group D Group N 0.2130.206, s = 0.06Text seconds, and Backgroundp < Colors0.001) (Table 2). 4422 0.45454545454545527.27272727272730.51020408163265414 2.2727272727272724 44 (Table440.175 2).22 0.219 30 0.191 6644 31.818181818181814 54.545454545454516 44 44 44 0.214 0.19 0.1750.25 Correlation 8866 31.81818181818184 36.36363636363643 44 - Participants440.138 66 present significant0.221 15 longer0.187 fixation dura- 0.402618283010223 88Column Width 9.09090909090909Group D Group6.81818181818182 N 88 Column Width Group 0.215D Group 0.187N 0.1380.213 Preference Rating Preference Within Groups: No significant effect of line spacing on -0.0148014204124575 22 27.2727272727273 2.27272727272727 tions0.1 with22 character spacing0.2190.005 -7%0 than0.1910.004 with spacing Fixation Duration (sec.) Fixation Duration 44 31.8181818181818 54.5454545454545 4422 44 66 880.007000000000000010.214 0.0030.19 (sec.) Fixation Duration char. 22 44 66 88 char. 0.1750.1 Correlation 66 31.8181818181818 36.3636363636364 1 66 0.2210.001 0.1870 fixation duration for group D (F (3, 186) = 0.267, p = +7% (p = 0.035) and spacing +14% (p = 0.013), / / 2 Group D Group2.33644859813084 C 2.13903743315508Group D Group C ff 0.402618283010223 88 9.09090909090909 6.81818181818182 88 0.215 0.187 0.138 -0.0148014204124575 3 3.271028037383180.005 1.604278074866310.004 0.849) orcreme foryellow groupgreen C (ffF (3white, 186)white = 0.032yellow, p = 0.993) but4 not with 1% (p = 0.0.467289719626169140) (Table0 2). 0.00700000000000001 0.003 (sec.) Fixation Duration black o Column Width Group D Group N blue/ blue/ 15 0.001 0 has been0.1black/ identified.brown/ white o black/ dark brown black/ 22 12 1 44 44 Text and Background Colors / 26 2.336448598130842.13903743315508 / light green 44 14 24 44 44 Group D Groupff C 37 3.271028037383181.60427807486631 green ff white 66 14 16 44 44 0.25 creme yellow white yellow Within48 Groups: No significant0.467289719626169 effect of0 character spac- 88 4 3 44 44 black o 5 blue/ black/ blue/ dark brown Column Width Group D Group N Column Width Group D Group N 0.213 black/ brown/ white o black/ ing on6 fixation duration for group D (F (3, 184) = Preferences: Participants did notlight findgreen any of the op- 22 27.2727272727273 2.27272727272727 22 0.219 0.191 7 Group D Group C 44 31.8181818181818 54.5454545454545 44 0.214 0.19 Text and Background Colors 2 8 0.175 tions of line spacing significantly easier to read (χ (3) = Correlation 66 31.8181818181818 36.3636363636364 66 0.221 0.187 1.896, p = 0.132) or for group C (F (3, 184) = 0.402618283010223 88 9.09090909090909 6.81818181818182 88 0.215 0.187 40 2

0.138 (%) -0.0148014204124575 0.005 0.004 1.283, p = 0.282) were identiﬁed. 2.164, p = 0.539 for group D and χ (3) = 3.179, p =

0.00700000000000001 0.003 (sec.) Fixation Duration 30 Colors Group D Group N Text and Background Colors 1 0.001 0 0.1 0.365 for group C). black-white 5 15 46 65 / 2 2.336448598130842.13903743315508 / blackoff-whiteoff 2 9 46 65 ff 2040

3 3.271028037383181.60427807486631 green ff white (%) yellow-black 15 11 46 Preferences:65 cremeParticipantsyellow with dyslexiawhite didyellow not find See Figure 7 for the fixation duration means and 4 0.467289719626169 0 blue-white 5 4 46 65 black o 1030 5 Colors Group D Group N blue/ black/ blue/ dark brown 2 brown-green 3 0 46 65 black/ brown/ white o black/ preference ratings. 6 black-white 5 15 46 any of65 the options significantly easierlight togreen read (χ (3) = black-creme 7 16 46 65 Rating Preference 7 blackoff-whiteoff 2 9 46 65 Group D Group C 200 dark brown-green 4 3 46 65 / 8 yellow-black 15 11 46 2.025,65 p = 0.567), while participants without dyslexia / yellow-blue 5 7 46 65 ff blue-white 5 4 46 65 10 ff Colors Group D Group N Colors Group D Group N brown-green 3 0 46 65 black-creme black-white 10.8695652173913 23.0769230769231 found text with 0%black-creme character spacing0.208 0.187 significantly more black o black-creme 7 16 46 65 Rating Preference blue/yellow black/whiteblue/whitedark brown yellow-blue blackoff-whiteoff 4.34782608695652 13.8461538461538 2 yellow-blueText and Background0.214 Colors0.182 black/creme0 brown/green white o black/yellow dark brown-green 4 3 46 65 5.7 Paragraph Spacing light green/ brown-green yellow-black 32.6086956521739 16.9230769230769 readable (χ (3) =brown-green 21.542, p < 0.2210.001).0.194 / yellow-blue 5 7 46 65 Group D Groupff C blackoff-whiteoff blue-white 10.8695652173913 6.15384615384615 40 blackoff-whiteoff 0.222 0.201 ff Colors Group D Group N Colors Group D Group N black-white brown-green 6.52173913043478 0 See (%) Figure 6black-white for the fixation0.223 duration0.195 means and black-creme black-white 10.8695652173913 23.0769230769231 black-creme 0.208 0.187 black o blue-white black-creme 15.2173913043478 24.6153846153846 30 blue-white 0.228 0.18 blue/yellow black/whiteblue/whitedark brown Colors Group D Group N yellow-blue blackoff-whiteoff 4.34782608695652 13.8461538461538 yellow-blue 0.214 0.182 Mainblack/creme effects: Withbrown/green two-waywhite o ANOVA,black/yellow significant main dark brown-green dark brown-green 8.69565217391304 4.61538461538461 dark brown-green 0.228 0.203 light green black-white 5 15 46 65 brown-green yellow-black 32.6086956521739 16.9230769230769 preference ratings.brown-green 0.221 0.194 yellow-black yellow-blue 10.8695652173913 10.7692307692308 yellow-black 0.23 0.189 Group D Group C blackoff-whiteoff 2 9 46 65 blackoff-whiteoff blue-white 10.8695652173913 6.15384615384615 20 blackoff-whiteoff 0.222 0.201 black-creme 15.2173913043478 24.6153846153846 0.006000000000000010.00700000000000001 effects were found for the groups (F (1, 374) = yellow-black 15 11 46 65 black-white brown-green 6.52173913043478 0 black-white 0.223 0.195 yellow-blue 10.8695652173913 10.7692307692308 0.013 0.002 blue-white 5 4 46 65 blue-white black-creme 15.2173913043478 24.6153846153846 10 blue-white 0.228 0.18 brown-green 6.52173913043478 0 0.014 0.014 28.545, p < 0.001) on fixation duration. However, no brown-green 3 0 46 65 dark brown-green dark brown-green 8.69565217391304 4.61538461538461 dark brown-green 0.228 0.203 blackoff-whiteoff 4.34782608695652 13.8461538461538 0.015 0.021 black-creme 7 16 46 65 yellow-black yellow-blue 10.8695652173913 10.7692307692308 Rating Preference yellow-black 0.23 0.189 black-white 10.8695652173913 23.0769230769231 0 0.02 0.015 dark brown-green 4 3 46 65 5.6 Line Spacing effects were found of paragraph spacing (F (3, 374) = black-creme 15.2173913043478 24.6153846153846 / 0.006000000000000010.00700000000000001/ blue-white 10.8695652173913 6.15384615384615 ff 0.02 0 yellow-blue 5 7 46 65 yellow-blue 10.8695652173913 10.7692307692308 0.013 0.002 Correlation dark brown-green 8.69565217391304 4.61538461538461 ff 0.022 0.023 0.453, p = 0.715) on fixation duration. Also, interaction Colors Group D Group N Colors brown-green Group 6.52173913043478D Group N 0 0.014 0.014 black-creme black-white 10.8695652173913 23.0769230769231 black-creme yellow-black 0.20832.60869565217390.187 16.9230769230769 black o 0.00900000000000001 blackoff-whiteoff 4.34782608695652 13.8461538461538 0.015blue/white 0.021 black/creme blue/yellowblack-cremebrown/green white o black/white dark brown black/yellow yellow-blue blackoff-whiteoff 4.34782608695652 13.8461538461538 yellow-blue black-white 0.21410.86956521739130.182 23.0769230769231 Main effects: With two-way ANOVA,0.02 0.015 significant main effects of paragraph spacing and groups (F (3, 374) = 0.0918053760955382 yellow-blue 2.884615384615393.88888888888889light greenblack-creme 3.88888888888889 brown-green yellow-black 32.6086956521739 16.9230769230769 brown-green blue-white 0.22110.86956521739130.194 6.15384615384615 0.02 0 -0.735791591345596 Groupbrown-green D Group6.25000000000001 C 1.11111111111111yellow-blue 1.11111111111111 blackoff-whiteoff blue-white 10.8695652173913 6.15384615384615 Correlationblackoff-whiteoffdark brown-green 0.2228.695652173913040.201 4.61538461538461 effects were identified for the0.022 groups0.023 (F (1, 372) = 0.234, p = 0.873) could not be found. black-white brown-green 6.52173913043478 0 black-white 0.223 0.195 blackoff-whiteoff 6.730769230769247.77777777777778brown-green 7.77777777777778 yellow-black 32.6086956521739 16.9230769230769 0.00900000000000001 blue-white black-creme 15.2173913043478 24.6153846153846 blue-white 0.228 0.18 black-white 7.2115384615384711.6666666666667blackoff- 11.6666666666667 17.793, p < 0.001)black-creme on fixation duration.whiteo Noff effects of The results of the post-hoc tests show that: dark brown-green dark brown-green 8.69565217391304 4.61538461538461 dark brown-green 0.228 0.203 0.0918053760955382 yellow-blueblue-white 2.884615384615399.615384615384623.888888888888898.33333333333334black-cremeblack-white 3.888888888888898.33333333333334 yellow-black yellow-blue 10.8695652173913 10.7692307692308 yellow-black 0.23 0.189 -0.735791591345596 darkbrown-green brown-green 6.250000000000019.615384615384621.111111111111110 yellow-blueblue-white 1.111111111111110 black-creme 15.2173913043478 24.6153846153846 0.006000000000000010.00700000000000001 blackoyellow-blackff-whiteoff 6.7307692307692410.57692307692317.7777777777777812.7777777777778brown-greendark brown- 7.7777777777777812.7777777777778 yellow-blue 10.8695652173913 10.7692307692308 0.013 0.002 black-white 7.2115384615384711.6666666666667blackogreenff- 11.6666666666667 brown-green 6.52173913043478 0 0.014 0.014 5 yellow-blackwhiteoff 5 blackoff-whiteoff 4.34782608695652 13.8461538461538 0.015 0.021 blue-white 9.615384615384628.33333333333334black-white 8.33333333333334 black-white 10.8695652173913 23.0769230769231 0.02 0.015 dark brown-green 9.61538461538462 0 blue-white 0 blue-white 10.8695652173913 6.15384615384615 0.02 0 yellow-black 10.576923076923112.7777777777778dark brown- 12.7777777777778 Correlation dark brown-green 8.69565217391304 4.61538461538461 0.022 0.023 green yellow-black 32.6086956521739 16.9230769230769 0.00900000000000001 5 yellow-black 5 black-creme 0.0918053760955382 yellow-blue 2.884615384615393.88888888888889black-creme 3.88888888888889 -0.735791591345596 brown-green 6.250000000000011.11111111111111yellow-blue 1.11111111111111 blackoff-whiteoff 6.730769230769247.77777777777778brown-green 7.77777777777778 black-white 7.2115384615384711.6666666666667blackoff- 11.6666666666667 whiteoff blue-white 9.615384615384628.33333333333334black-white 8.33333333333334 dark brown-green 9.61538461538462 0 blue-white 0 yellow-black 10.576923076923112.7777777777778dark brown- 12.7777777777778 green 5 yellow-black 5

Chart 2 60

45 Chart 2 6030

4515

300 Chart 2 Untitled 1 Untitled 2 Untitled 3 Untitled 4 60 15 Back Contrast Colors

45 0 Untitled 1 Untitled 2 Untitled 3 Untitled 4

30 Back Contrast Colors

0 Untitled 1 Untitled 2 Untitled 3 Untitled 4

Back Contrast Colors Non_Dys Font Contrast Back Colors Size Chart Spa Line Spa Par Spacing Column Contrast Width 1 46 3 0 5 32 5 2 3 2 0 28 3 19 9 19 10 24 3 0 17 16 24 0 5 22 16 4 3 0 7 0 8 19 8 1 5 9 6 11 7 15 8 4 Scale-0 = 1 Scale-0 = 2 Color-blackoﬀ-whiteoﬀ = 5 Size-14 = 4 Spacing +14 = 2 Line Spacing 0.8 = 3 Spacing .4 = 4 Column width 1/4 = 4 Scale-25 = 4 Scale-25 = 3 Color-yellow-black = 6 Size-18= 3 Spacing +7 = 4 Line Spacing 1 = 4 Spacing 2 = 3 Column width 2/4 = 3 Scale-50 = 3 Scale-50 = 1 Color-blue-white = 8 Size-22= 2 Spacing 0 = 1 Line Spacing 1.4 = 1 Spacing 1 = 2 Column width 3/4 = 2 Scale-75 = 2 Scale-75 = 4 Color-brown-green = 1 Size-26= 1 Spacing -7 = 3 Line Spacing 1.2 = 2 Spacing 3 = 1 Column width 4/4 = 1 Color-black-creme = 3 Color-dark brown-green = 2 Color-yellow-blue = 4 Color-black-white = 7

0.009999999999999980.00999999999999998 Rating Preference

22 3.846153846153856.45161290322581 Rating Preference

Fixation Duration (sec.) Fixation Duration 0.1 0 14 18 22 26 points 14 18 22 26 points Group D Group C Group D Group C

Character Spacing Character Spacing

Chart Spa Group D Group N 0.25 70 (%) -7 5 0 46 49 0 17 32 46 49 0.213 52.5 +7 15 8 46 49 +14 9 9 46 49 0.175 35 Chart Spa Group D Group N Chart Spa Group D Group N -7 10.8695652173913 0 -7 0.234 0.198 0.138 17.5 0 36.9565217391304 65.3061224489796 0 0.208 0.19

Correlation +7 32.6086956521739 16.3265306122449 +7 0.202 0.185 Rating Preference

Fixation Duration (sec.) Fixation Duration 0.1 0 -0.838022023794689 +14 19.5652173913043 18.3673469387755 +14 0.21 0.179 –7% 0% +7% +14% char. –7% 0% +7% +14% char. -0.123430442777081 0.032 0.019 0.00599999999999998 0.011 Group D Group C Group D Group C 5 0 0.007999999999999980.00600000000000001 17 32 15.841584158415810.6145251396648 15 8 2.970297029702966.14525139664805 9 9 3.960396039603953.35195530726257 Line Spacing Line Spacing 0.25 40 (%)

0.213 30

0.175 20 Line Spa Group D Group N 0.8 2 5 45 48 0.138 10 1 15 19 45 48

1.2 18 19 45 48 Rating Preference Fixation Duration (sec.) Fixation Duration 0.1 0 1.4 10 5 45 48 0.8 1 1.2 1.4 lines 0.8 1 1.2 1.4 lines lines Line Spa Group D Group N Line Spa Group D Group N 0.8 4.44444444444444 10.4166666666667 0.8 0.233 0.206 Group D Group C Group D Group C 1 33.3333333333333 39.5833333333333 1 0.236 0.207 Correlation 1.2 40 39.5833333333333 1.2 0.237 0.205 0.451017032441845 1.4 22.2222222222222 10.4166666666667 1.4 0.226 0.204 0.447213595499958 0.00700000000000001 0.001 0.00999999999999998 -0.001 Paragraph Spacing Paragraph Spacing 0.011 -0.002 0.25 60

3.097345132743370.485436893203884 (%) 4.42477876106194-0.485436893203884 4.86725663716813-0.970873786407768 0.213 45

0.175 30

0.138 15 Par Spacing Group D Group N 13 0.4 23 4 131 38 Rating Preference

Fixation Duration (sec.) Fixation Duration 0.1 0 1 43 10 131 38 0.5 1 2 3 lines 0.5 1 2 3 lines 2 30 22 131 38 3 35 2 131 38 Group D Group C Group D Group C Par Spacing Group D Group N - Group C hadPar significantly Spacing Group shorter D Group N fixation durations Fig. 9 Participants’ reading performance (fixation duration 0.4 17.5572519083969 10.5263157894737 0.4 0.233 0.198 1 32.824427480916 26.3157894736842 (¯x = 0.197,1 s = 0.05 seconds)0.228 than0.198 group D (¯x = mean) and preference ratings in % for column width. Correlation 2 22.9007633587786 57.8947368421053 2 0.22 0.196 -0.274103716415761 3 26.7175572519084 5.26315789473684 0.225, s 3= 0.06 seconds, p <0.2210.001)0.197 (Table 2). Column Width Column Width -0.676968662049936 0.013 0.002 0.00800000000000001 0.002 60 0.25 (%) 0.001 0.001 Within Groups: No significant5.90909090909091 effect1.02040816326531 of paragraph spac- 0.213 45 3.636363636363641.02040816326531 ing on fixation duration0.454545454545455 for group0.510204081632654 D (F (3, 187) = 0.175 30 0.544, p = 0.652) or for group C (F (3, 187) = 0.138 15

0.1 Rating Preference 0 0.024, p = 0.995) has been identified. (sec.) Fixation Duration 22 44 66 88 char. 22 44 66 88 char. Group D Group C Group D Group C Preferences: Participants did not find any of the op- Column Width Group D Group N 22 12 1 44 tions44 of line paragraph significantly easier to read Text and Background Colors 44 14 24 44 2 44 2 66 14 16 44 (χ (3)44 = 2.357, p = 0.502 for group D and χ (3) = Although0.25 no more significant effects were found, 88 4 3 44 44 Column Width Group D Group N Column Width Group D Group N people0.213 with dyslexia were in general more sensitive to 22 27.2727272727273 2.27272727272727 2.813, p = 022.421 for group C).0.219 0.191 44 31.8181818181818 54.5454545454545 44 0.214 0.19 0.175 Correlation 66 31.8181818181818 36.3636363636364 See Figure66 8 for the fixation0.221 duration0.187 means and text-presentation changes, since they presented larger 0.402618283010223 88 9.09090909090909 6.81818181818182 88 0.215 0.187 0.138 -0.0148014204124575 preferences. 0.005 0.004 differences in fixation duration among the different con-

0.00700000000000001 0.003 (sec.) Fixation Duration 1 0.001 0 ditions.0.1 / / 2 2.336448598130842.13903743315508 ff 3 3.271028037383181.60427807486631 Regardingcreme yellow thegreen differencesff white betweenwhite theyellow groups, the 4 0.467289719626169 0 black o 5.8 Column Width blue/ blue/ 5 resultsblack/ are consistentbrown/ white witho black/ otherdark brown eyeblack/ tracking studies 6 light green 7 that foundGroup significant D Group differences C among the two popu- Main8 effects: With two-way ANOVA, significant main lations [41,46,72,75,76]. effects for the groups (F (1, 372) = 30.776, p < 0.001) Regarding theText sensitivity and Background of Colors fixation duration with on fixation duration were found. However, there was no 40

respect (%) to the parameters, there are clearly two differ- effects of column width (F (3, 372) = 0.155, p = 0.927) 30 Colors Group D Group N ent groups for people with dyslexia, even when normal- black-white 5 15 46 on fixation65 duration. Moreover, there were no interac- blackoff-whiteoff 2 9 46 65 izing20 with respect to the range of values used in each yellow-black 15 11 46 65 blue-white 5 4 46 tion effects65 of column width and groups (F (3, 372) = 10 brown-green 3 0 46 65 parameter. The first group is the set of parameters that

0.216, p = 0.886). Rating Preference black-creme 7 16 46 65 0 dark brown-green 4 3 46 65 affect reading performance in a large percentage (10% / / yellow-blue 5 7 46 The65 results of the post-hoc tests show that: ff ff Colors Group D Group N Colors Group D Group N or above), which are in order of importance: font size, black-creme black-white 10.8695652173913 23.0769230769231 black-creme 0.208 0.187 black o blue/yellow black/whiteblue/whitedark brown yellow-blue blackoff-whiteoff 4.34782608695652 13.8461538461538 - Group C hadyellow-blue significantly shorter0.214 0.182 fixation durations black/creme brown/green white o black/yellow character spacing, text and backgroundlight green color, and text brown-green yellow-black 32.6086956521739 16.9230769230769 brown-green 0.221 0.194 Group D Group C blackoff-whiteoff blue-white 10.8695652173913 6.15384615384615 (¯x = 0.189,blackos ff=-whiteo 0.05ff seconds)0.222 than0.201 group D (¯x = grey scale. This group seems to suggest that the most black-white brown-green 6.52173913043478 0 black-white 0.223 0.195 blue-white black-creme 15.2173913043478 24.6153846153846 0.217, s = 0.05blue-white seconds, p <0.2280.001)0.18 (Table 2). important high-level characteristic that the text needs, dark brown-green dark brown-green 8.69565217391304 4.61538461538461 dark brown-green 0.228 0.203 yellow-black yellow-blue 10.8695652173913 10.7692307692308 yellow-black 0.23 0.189 black-creme 15.2173913043478 24.6153846153846 0.006000000000000010.00700000000000001 is to let people to distinguish letters well. The second yellow-blue 10.8695652173913 10.7692307692308 0.013 0.002 brown-green 6.52173913043478 0 Within Groups: There was0.014 no significant0.014 effect of group, where impact is 5% or less, is formed by para- blackoff-whiteoff 4.34782608695652 13.8461538461538 0.015 0.021 black-white 10.8695652173913 23.0769230769231 column width on fixation duration0.02 0.015 for group D graph spacing, background gray scale, line spacing and blue-white 10.8695652173913 6.15384615384615 0.02 0 Correlation dark brown-green 8.69565217391304 4.61538461538461 (F (3, 186) = 0.176, p = 00.022.913)0.023 nor for group C column width. This suggests that distinguishing words yellow-black 32.6086956521739 16.9230769230769 0.00900000000000001 (F (3, 186) = 0.201black-creme, p = 0.895). and lines is less important, and that most probably, 0.0918053760955382 yellow-blue 2.884615384615393.88888888888889black-creme 3.88888888888889 -0.735791591345596 brown-green 6.250000000000011.11111111111111yellow-blue 1.11111111111111 word spacing also does not have a large impact in read- blackoff-whiteoff 6.730769230769247.77777777777778brown-green 7.77777777777778 Preferences: Participantsblack-white 7.21153846153847 with dyslexia11.6666666666667blacko didff- 11.6666666666667 not find whiteoff ability (unless it gets really small). blue-white 9.615384615384628.33333333333334black-white 8.33333333333334 any of the optionsdark brown-green of column9.61538461538462 width significantly0 blue-white easier0 For group C the order above changes a bit, though 2 yellow-black 10.576923076923112.7777777777778dark brown- 12.7777777777778 to read (χ (3) = 0.845, p = 0.839), whilegreen participants groups remain the same. In the first group, character 5 yellow-black 5 without dyslexia found the option of 44 characters per spacing moves to the last position (fourth). In the sec- line significantly more readable (χ2(3) = 14.750, p = ond group paragraph spacing moves to the last position 0.002). and column width and line spacing are swapped. How- See Figure 9 for the fixation duration means and ever, as the readability impact of these three parameters preferences. mentioned is 2% or less, the order is not really relevant. Each parameter is discussed in detail in the following. 6 Discussion Text Grey scale. Using a pure black text on a pure General Comments. In general, participants with- white background is not recommended for people with out dyslexia read significantly faster and had shorter dyslexia due to its high contrast, as many of them are fixation durations than participants with dyslexia. For sensitive to the brightness and this can cause the words the font size variable, participants with dyslexia had to swirl or blur together [11]. No effects on objetive significantly shorter fixation durations when using big- readability could be found. Most of participants with- ger fonts compared to smaller fonts. out dyslexia (93,88%) chose black over white as the

Chart 2 60

0 Untitled 1 Untitled 2 Untitled 3 Untitled 4

Back Contrast Colors 14 most readable option, maybe because it is the most blue/white and blue/yellow where the best pairs of col- frequent color combination used in computer screens. ors, suggesting than in future experiments blue/creme However, only 60% of the participants with dyslexia should also be tried. chose this option. Font Size. Another key problem experienced by peo- Background Grey scale. No recommendations ple with dyslexia is finding the text too small [55]. Al- about grey scale background for people with dyslexia though the recommended font size for this target group could be found, apart from the suggestion of using light is 12 or 14 points [1,12,11], some readers with dyslexia grey as background [101], such as the color with the fol- may prefer a larger font [25,12]. lowing hexadecimal code: FFFFE5 [89]. No differences For both groups, texts presented with 18, 22, and on the objective readability of the participants could be 26 point size led to significant shorter fixation durations identified. However, most of the study participants said compared to texts with 14 points. For participants with that grey actually did not help them. Further experi- dyslexia, texts with 22 and 26 points also led to sig- ments shall be carried out about the role of the back- nificant shorter fixation durations than texts with 14 ground, because light on dark has different readability points. Hence, larger font sizes are more readable for requirements than dark on light [21]. people with and without dyslexia. Unexpectedly, more than half of the participants with and without dyslexia, 24 and 26 respectively, Text and Background Color. Poor color selections selected the biggest option (26 points). None chose are one of the key problems encountered by people the smaller option, 14 points, which is already a rec- with dyslexia when reading [55]. Although the pair off- ommended and relatively big font size. Since all the black/off-white is the one recommended for Web acces- columns had the same width (a mean of 50 characters sibility for dyslexics [11], it was the least often selected for 12 points), column width could not influence these by the participants with dyslexia (only two selected decisions. Further investigations shall be carried out to it). The most preferred color pair chosen by the par- find the font size preferred by people with and with- ticipants with dyslexia was black over yellow, which is out dyslexia, as clearly there must be a turning point not consistent with [11], who recommends to avoid high where a very large size starts making the reading more contrast (black/white is the highest contrast combina- difficult. tion). According to [67], high contrasts creates so much In a later study, Rello et al [87] tested the effect of vibration that it diminishes readability. Also, mucky font size and line spacing on Wikipedia web pages us- green/brown and blue/yellow pairs were chosen by peo- ing eye tracking. They found significant improvements ple with dyslexia, as in the experiments carried out by (in objective readability and comprehensibility) within Gregor and Newell [36,37]. groups starting from 18 points font size instead of 22 Surprisingly, the most often selected pair points. This can be due to the fact that this study mea- (black/yellow) has the highest mean for the fixa- sured the impact of font size in the context of the Web tion durations (0.23 seconds). As comparison, the and not in raw text. average of the color combinations is 0.22 seconds. On the other hand, the color pair which was the fastest to read was black/creme (mean of 0.21 for the fixation Character Spacing. Pedley recommends creating a duration). This pair of colors is used by the British slightly larger distance between individual words and Dyslexia Association for their website.11 reduce letter-spacing slightly [66], so that the letters According to the W3C algorithm [110], brightness within a word lie closer together while Rainger sug- differences of less than 125 and color differences of less gests to have large spacing between letter combinations than 500 are not supposed to be good. All the pair col- [71]. Zorzi et al. [113] conducted studies on paper – ors selected by the participants match this guideline, ex- not on screen– obtaining that larger character spac- cept dark brown/light mucky green pair (brightness dif- ings improved the reading performance of children with ference: 107, color difference: 240). However, the read- dyslexia (reading speed and reading errors). ability of colored text/background pairs is influenced Consistently, the results of the present study show by the size of the text [21] and the size used in this that participants (groups D and C) present significant study was 20 points. shorter fixation durations with character spacing of For group C, higher preferences ratings were +7% and +14%, while -7% lead to significant longer fix- strongly correlated with shorter fixations. In this case ation durations. However, no differences within groups could be found. Also, the results show that most of 11 http://www.bdadyslexia.org.uk/ the participants without dyslexia significantly prefer 15 the standard spacing among characters (32 users) and discriminate if the comprehension was due to compre- that participants with dyslexia prefer either the stan- hending a single fragment or the whole story. Further dard separation or more separated characters (17 users studies shall overcome this limitation and measure ob- for 0% and 15 for +7%). jective readability using more dependent measures. Moreover, the texts tested were small so the results Line Spacing. Even though it is recommended to use are not extensible to longer reading tasks such as emails a line spacing of 1.5 to 2 [71], the results show that or heavy-text web pages. For instance, the effect of font line spacing does not have a significant effect on the size and line spacing was tested on Wikipedia pages us- participants’ readability and preferences. Similarly, in ing eye tracking and a significant effect for only people [87] line spacing was tested using eye tracking finding with dyslexia started at 18 points font size instead of no effects on objective readability. 22 points as in the present study [87]. Another limitation is that this study does not take Paragraph Spacing. According to Bradford [11], into consideration the interaction effects between vari- paragraphs –even when they have a single line– should ables. All the conditions were tested independently. always be spaced out with an empty line between each While Tinker found multiple interactions between var- paragraph. However, the effect of paragraph spacing on ious typographical parameters [97] others did not [8, objective readability and on the user preferences has 87]. One example of interactions found by Tinker [96] been found in the results of the present study. was between font size and line width, showing that long lines, very short lines, and small type size, and the combinations of these lead to significantly slower readings. Column Width. Accordingly to [11,12], which rec- Using eye tracking, Beymer et al. [8] compared font size ommend to avoid long lines –60 to 70 characters– and and font type and found no significant effects. Also, no to avoid narrow columns [12], most of the participants interaction effects between font size and line width were preferred the intermediate values: paragraphs with lines found in Rello et al. [87] when reading Wikipedia texts. of 44 (14 users in group D and 24 in group C) or 66 A recent study [112] has shown that brain process- characters (14 users in group D and 16 in group C). ing differs from prose to poetry. The authors are not These results are not comparable with Schneps et al. aware the are no studies that compare the interaction [91] since they used a 34 points font and other devices of dyslexia and prose versus poetry. The fact that both in their experiment. Some of the participants said that genres have been used in the experiment could have they preferred the text with the widest column because added a hidden variable. However, all levels of each of they believed it was shorter than the others. Since the the conditions were always shown with the same kind texts had the same number of words a side effect of of text. Only line spacing and paragraph spacing used having a wider column width was that the text had texts in prose. less lines and seemed to be shorter. One of the reasons that could explain why the comprehension was so high in the study is that the different 7 Limitations of the Study use of text customization could have enhanced the comprehension. For instance, Frase and Schwartz used line Even if in shallow languages, as Spanish [93], one of the breaking to increase the speed of comprehension [32]. main characteristic of reading with dyslexia is that their reading process is slower [24], shorter fixation durations can be used as indicator of text readability, not as a 8 Text Customization Recommendations possible alleviation of the issues related to dyslexia and reading. Table 3 presents a set of recommendations for format- One limitation of the study is that it only uses fix- ting screen text in a more accessible way for people ation duration as a measure of reading performance. with dyslexia. Both quantitative data for the readabil- Other measures such as reading errors were not used ity (objective readability) of the text given by the eye because the reading was done in silence trying to emu- tracker and the user preferences (subjective readability) late natural online reading. Reading time was also not have been considered. Since the user preferences might used because the texts lengths were not the same. Com- change with time [5] priority was given to the objective prehension could also have been used as a measure, readability data in the recommendations. The authors’ however it was only used as a control variable because own results regarding font type are included, because the text presentation was modified for different frag- the experimental setting was very similar: same de- ments among the two stories and it was not possible to fault text presentation, same equipment (eye tracker), 16

Values with positive effects Condition Measures with Dyslexia without Dyslexia Font Size Obj. Readability 18, 22 and 26 points 22 and 26 points 26 points Subj. Preferences 26 points 26 points Recommendation: ranging from 18 to 26 points Character Spacing Obj. Readability +7% and +14% no effects no effects Subj. Preferences no effects 0% Recommendation: ranging from 0%, +7% to +14% Line Spacing Obj. Readability no effects no effects Subj. Preferences no effects no effects No recommendations Paragraph Spacing Obj. Readability no effects no effects Subj. Preferences no effects no effects No recommendations Grey Text (white background) Obj. Readability no effects no effects Subj. Preferences 0% 0% Grey Background (white text) Obj. Readability no effects no effects Subj. Preferences 0% 0% Recommendation: black font on white background, or white font on black background Colors (text/background) Obj. Readability no effects no effects Subj. Preferences no effects no effects No recommendations Column Width Obj. Readability no effects no effects Subj. Preferences no effects 44 char./line No recommendations Font Type Obj. Readability Arial Arial Courier Courier CMU CMU Helvetica Verdana Subj. Preferences Verdana Verdana Helvetica Helvetica Arial Arial Recommendation: Arial, Courier, CMU, Helvetica, and Verdana Obj. Readability roman roman sans serif sans serif monospaced monospaced Subj. Preferences roman roman sans serif no effects no effects proportional Recommendation: roman and sans serif

Table 3 Text customization results and recommendations for more readable screen text. Each of the parameters are independent from each other and no interactions between them were tested in the experiments. Font Size and Character Spacing distinguish between effects taking into account both groups and within groups because different effects were found in both cases. same independent and dependent variables and similar (WAI) [110] recommend text customization. Further- methodology [79]. more, depending on the individual, dyslexia could po- Notice that the results for each of the parameters tentially show reading performance issues in many pos- are independent from each other and no interactions sible ways. Also, the degree of severity differs from indi- between them were tested in the experiment. These are vidual to individual [108]. This suggests that text cus- only text customization recommendations, the combi- tomizability is more likely to better support the overall nation of the parameters and the final customization population than a single option. Therefore the recom- of the text are left to the user. Certain studies have mendations addressed in this work shall be taken as shown the benefits of self text customization [37,25]. a starting setting for text customization. Nonetheless, Furthermore, WebAIM [106], British Dyslexia Associ- note that only half of the participants with dyslexia – ation [12], as well as the Web Accessibility Initiative and without dyslexia– are able to guess correctly which 17 text parameters lead them to an objective faster read- Fig. 10 Text example using the dyslexic-accessible recom- ing. mendations for font size and character spacing. There is no According to the results of this study, the parame- evidence that the effects would be cumulatively positive. ters that enhance readability are very similar for both, people with and without dyslexia. Even if reading times for group C will be still smaller than for group D, these recommendations can be used for all the population without problems as the difficulty of reading is being balanced.

9 Conclusions and Future Work

The effect of eight text presentation parameters on objective readability and subjective preferences for people with and without dyslexia was tested. For readability, the main conclusions are that: – Larger font sizes significantly improve readability, Configuration especially for people with dyslexia (ranging from 18 to 24 points); Font Helvetica – Larger character spacings (up to +7% - +14%) sig- Color Ideal nificantly improve readability for people with and Synonyms without dyslexia; – Regarding preferences, both groups found texts with ‘Simpler’ no grey scales and with larger font sizes significantly more readable; – Participants without dyslexia also found texts with standard character spacing and 44 characters per However, there are still problems found by individ- line column width significantly more readable. uals with dyslexia which remain unsolved. Given that These findings can have impact on screen text pre- dyslexia is a learning disability that affects language, sentation recommendations and on the text options it can be assumed that accessibility can be approached chosen by developers, designers, or content produc- not only in terms of text presentation, but also in terms ers when they target people with dyslexia. For in- of text content [4]. The use of complicated language has stance, these recommendations have been adapted and been extensively pointed out as one of the key prob- included in two eBook readers for people with dyslexia, lems for this target group. For instance, more frequent one for Android (IDEAL eBook Reader [47]) and one and shorter words may improve readability for people for iOS (DysWebxia Reader [83]), in a game for chil- with dyslexia [24,82], so they may benefit from tools dren with dyslexia Piruletras or Dyseggxia [85], and in that modify the text content by performing lexical sim- the Text4All [99,100] web service.12 Below the recom- plification [80,81]. The authors are currently exploring mendations are summarized and Figure 10 shows an which other text-modification strategies apart from lex- example that uses the text recommendations for font ical simplification might be beneficial for users with size and character spacing, where the rest of the cus- dyslexia. tomization parameters were left to the user [80]: – Font Size: 18, 22 and 26 points (17-Inch screen). Acknowledgements The authors would like to thank Mari- Carmen Marcos for her assistance with the eye tracking hard- – Character Spacing: ranging from 0%, +7% to ware. Special thanks to the participants with dyslexia and +14%. their families. – Font/Background Colors: black font on white background, or white font on black background. References – Typeface: Arial, Courier, CMU, Helvetica, or Ver- dana. 1. Al-Wabil, A., Zaphiris, P., Wilson, S.: Web navigation – Font Style: roman and sans serif. for individuals with dyslexia: an exploratory study. Uni- versal Access in Human Computer Interaction. Coping 12 http://www.text4all.net/. with Diversity 4554, 593–602 (2007) 18

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Appendix A: Color and Brightness Appendix B: Text Example

The CYMK/RGB codes for the contrast and colors ¿Soy dix-leso? used are: by Marcela Paz (Papelucho series)

Text contrast: Por la tarde fuimos al doctor. Era un señorbastante – 0% (pure black font, 000000/0,0,0): Brightness text: 255; preguntón,que se hac´ıa el simpáticopor fuera, pero Brightness background: 0; Brightness difference: -255; se notaba que era malo por dentro. Me martillólas Color difference: 765. – 25% (404040/64,64,64): Brightness text: 255; Brightness costras y otras cuestiones con un martillito lindo. Y background: 63; Brightness difference: 192; Colour mientras hablaba y hablaba con la mamáse martillaba difference: 573. su otra mano gorda. – 50% (7E7E7E/126,126,126): Brightness text: 255; Brightness background: 126; Brightness difference: 129; Colour difference: 387. Yo pensaba quépasar´ıasi en vez de su mano gorda – 75% (BFBFBF/191,191,191): Brightness text: 255; se martillara el tremendo grano que ten´ıaen la nariz? Brightness background: 191; Brightness difference: 64; Pero apenas se lo rascóy siguiódale que dale hablando Colour difference: 191. de “este niño”.Y “este niño”por aqu´ıy “este niño” Background contrast: por allá. – 100% (pure black background, 000000/0,0,0): Brightness text: 0; Brightness background: 255; Brightness Tratéde entender lo que dec´ıan. difference: -255; Color difference: 765. – 25% (404040/64,64,64): Brightness text: 63; Brightness background: 255; Brightness difference: -192; Colour Casi lo entend´ı.No estoy seguro si la cosa es que difference: 573. soy superdotado o viceversa. Menos mal que además – 50% (7E7E7E/126,126,126): Brightness text: 126; parece que soy dixleso, que es algo muy guay y como Brightness background: 255; Brightness difference: -129; Colour difference: 387. distinto. Y tampoco me importa mucho ser as´ı. – 75% (BFBFBF/191,191,191): Brightness text: 191; Brightness background: 255; Brightness difference: -64; Mis padres fueron al colegio a hablar con mi profe Colour difference: 191. y volvieron furiosos. Colors: – black (000000/0,0,0) / white (FFFFFF/255,255,255): De todos modos yo tengo mi enfermedad propia y Color difference: 765, Brightness difference: 255; nadie me la quita. – off-black (0A0A0A/10,10,10) / off-white(FFFFE5/255,255,259): Color difference: 735, Brightness difference: 245; Pero en la noche, me desvelé.Porque claro, en el – black (000000/10,10,10) / yellow (FFFF00/255,255,0): d´ıaa uno le gusta ser enfermo y en la noche no. As´ı Color difference: 510, Brightness difference: 226; que despertéa mi padre apretetándolela nariz porque – blue (00007D/0,0,125) / white (FFFFFF/255,255,255): es el únicomodo de despertarlo. Color difference: 640, Brightness difference: 241; – dark brown (1E1E00/30,30,0) / light mucky green (B9B900/185,185,0): Color difference: 310, Brightness difference: 137 – brown (282800/40,40,0) / mucky green (A0A000/160,160,0): Color difference: 240, Brightness difference: 107 – black (000000/0,0,0) / creme (FAFAC8/250,250,200): Color difference: 700, Brightness difference: 244; – blue (00007D/0,0,125) / yellow (FFFF00/255,255,0): Color difference: 635, Brightness difference: 212