Univ Access Inf Soc (2017) 16:29–49 DOI 10.1007/s10209-015-0438-8 LONG PAPER How to present more readable text for people with dyslexia 1 2,3 Luz Rello • Ricardo Baeza-Yates Published online: 20 November 2015 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract The presentation of a text has a significant Keywords Dyslexia Á Eye tracking Á Textual effect on the reading speed of people with dyslexia. This accessibility Á Text customization Á Recommendations Á paper presents a set of recommendations to customize texts Readability Á Text color Á Background color Á Font size Á on a computer screen in a more accessible way for this Character, line and paragraph spacings Á Column width target group. This set is based on an eye tracking study with 92 people, 46 with dyslexia and 46 as control group, where the reading performance of the participants was 1 Introduction measured. The following parameters were studied: color combinations for the font and the screen background, font Dyslexia is a neurological reading disability which is size, column width as well as character, line and paragraph characterized by difficulties with accurate and/or fluent spacings. It was found that larger text and larger character word recognition and by poor spelling and decoding abili- spacings lead the participants with and without dyslexia to ties. Secondary consequences may include problems in read significantly faster. The study is complemented with reading comprehension and reduced reading experience that questionnaires to obtain the participants’ preferences for can impede growth of vocabulary and background knowl- each of these parameters, finding other significant effects. edge [43]. Since a great amount of information is presented These results provide evidence that people with dyslexia as text, this condition makes more difficult for people with may benefit from specific text presentation parameters that dyslexia to access written information. At the same time, make text on a screen more readable. So far, these rec- access to information and communication technologies is ommendations based on eye tracking data are the most recognized as a basic human right by United Nations [102]. complete for people with dyslexia. Related to its social relevance, there are two reasons motivating the decision to approach textual accessibility for users with dyslexia: First, they are a relatively large group of users, since dyslexia is frequent and universal, and sec- This research was conducted while Luz Rello was doing her PhD at ond, this kind of accessibility practices are good not only for Web Research Group, Universitat Pompeu Fabra, Barcelona. people with dyslexia but also for other target groups. & Luz Rello 1.1 Frequent and universal [email protected] Ricardo Baeza-Yates There is a universal neuro-cognitive basis for dyslexia [65], [email protected] but its manifestations are variable due to different 1 Human-Computer Interaction Institute, Carnegie Mellon orthographies [35]. Depending on the language, the esti- University, Pittsburgh, PA, USA mations of dyslexia vary. The Interagency Commission on 2 Yahoo Labs, Sunnyvale, CA, USA Learning Disabilities [42] states that 10–17.5 % of the 3 Web Research Group, Universitat Pompeu Fabra, Barcelona, population in the USA has some level of dyslexia while Spain Brunswick [16] estimates 10 % for English and 3.5 % for 123 30 Univ Access Inf Soc (2017) 16:29–49 Italian. According to different statistics, from 8.6 [45]to The rest of the paper is organized as follows. In Sect. 2, 11 % [18] of the Spanish speaking population has dyslexia. dyslexia is defined and the common problems that people The authors made an estimation of the presence of dyslexic with dyslexia encounter are explained. Section 3 covers texts in the Web, and the results show that at least 0.67 % related work. Section 4 explains the experimental of the spelling errors found in the English Web [3] and 0.43 methodology, while Sect. 5 presents the results. Section 6 in the Spanish Web [78] are made by people with dyslexia. presents a discussion, and Sect. 7 the limitations of the study. Finally in Sect. 8, a set of recommendations is 1.2 Good for others groups proposed. Conclusions and future challenges are given in Sect. 9. The use of Web accessibility practices for people with dyslexia is beneficial for all, since dyslexic-accessible practices alleviate difficulties faced by all Internet users, as 2 Dyslexia well as other users with disabilities [26, 31, 55, 69, 111]. According to Zarach [111], the guidelines to enhance Brain structure, brain function and genetics studies confirm readability for people with dyslexia also benefit people the biological foundations of dyslexia [104]. However, without dyslexia. For example, Dixon [26] tested a piece of despite its universal neuro-cognitive basis, dyslexia mani- educational software with dyslexic and nondyslexic readers festations are variable and culture-specific [35]. This and the results suggest that the symptoms of dyslexia are variability is due to the different language orthographies common to varying degrees among most people. Pollak concerning their grade of consistency and regularity [16]. [69] showed how students with and without dyslexia ben- English has an opaque—or deep—orthography in which efit from using multimodal documents. Also, Evett and the relationships between letters and sounds are inconsis- Brown [31] found that the Web style guidelines for blind or tent and many exceptions are permitted. English presents a low vision readers are closely parallel to those for dyslexic significantly greater challenge to young readers than other readers. Later, McCarthy and Swierenga [55] remark the languages, such as Spanish or Italian, with a more regular overlap of dyslexic-accessible recommendations with more alphabetic system that contains consistent mappings general textual accessibility recommendations. Hence, the between letters and sounds, that is, a transparent—or present work is also extensible to general usability prob- shallow—orthography. For instance, in [65], Italian par- lems and to other target groups. ticipants with dyslexia performed better on reading tasks Previous research indicates that the text presentation than English people with the same condition. Along an may have an impact on the reading performance of people orthographic transparency scale for European languages, with dyslexia [1, 37, 50]. To the best of the authors’ English appears as the language with the deepest orthog- knowledge, this is the first time that eye tracking is applied raphy and Spanish as the second most shallow after Finnish with such an extensive group of people, 46 participants [93]. Since the challenge of mapping phoneme to grapheme with dyslexia and 46 without dyslexia, to define dyslexic- depends on the orthographic transparency of the language, accessible text presentation recommendations. The present Spanish shall not be as challenging as other languages proposal would improve the ability of people with dyslexia according to this scale [93]. to read and access a wider range of information content, Hence, for the reasons described above, dyslexia has empowering them by slightly leveling the playing field. been called a hidden disability, due to the difficulty of its This paper presents the following main contributions: diagnosis in languages with shallow orthographies [104], where diagnoses depend more on reading speed than on the • Larger font size, ranging from 18 to 26 points, leads errors [24]. people with and without dyslexia to read significantly People with dyslexia encounter problems, not only with faster. some text presentation conditions, such as small font size • Larger character spacing, ranging from ?7to?14 %, [55, 89], but also with language-related conditions. The leads people with and without dyslexia to read signif- following presents the dyslexia-related difficulties accord- icantly faster compared to smaller character spacing ing to their language level. They were collected from the (À7 %). cognitive neuroscience literature, with the exception of the • Black text on white background instead of using gray discourse level, where there are recommendations from scales for the text is significantly preferred by people Web accessibility literature. The poorer reading compre- with and without dyslexia. hension which characterized dyslexia in this level has also • White text on black background instead of using gray been included because text comprehension depends on scales for the background is significantly preferred by longer segments of texts, not only words. These difficulties people with and without dyslexia. are: 123 Univ Access Inf Soc (2017) 16:29–49 31 (a) Orthography: Oral and reading comprehension need to be differentiated, since decoding and listening com- • Orthographically similar words, e.g., addition prehension have been shown to have different and audition [28, 95]; implications in measuring comprehension [48]. • alternation of different typographical cases, e.g., Dyslexia affects decoding, though not listening ElefANte (‘‘elefante’’) [56]; comprehension [38, 57]. • letter recognition [7, 10]; • number recognition [20, 51, 84]; and Additionally, there are visual difficulties associated with • poor spelling, such as letter reversals, e.g., trail dyslexia [29] that could be alleviated by modifications of for trial [2, 15, 43, 109]. the visual display. The most studied in relationship with (b) Phonology: dyslexia is the visual stress syndrome (Meares–Irlen syndrome) [49]. The Meares–Irlen syndrome