Typography & Accessibility

Introduction
Making texts accessible to readers with disabilities is an important part of a technical communicator's job. Typography--the fonts, text size, text scaling, and associated factors in print or online documents--profoundly affects accessibility for visually impaired readers, as well as for those with other difficulties with reading, such as dyslexia. As an added bonus, accessible text is often easy and comfortable for readers without special needs, as well.

Keeping accessibility in mind when choosing fonts is not only important for including readers with disabilities, it can also be a safety issue. The text on medication labels and medical devices (such as syringes) must be as legible as possible to as many readers as possible, to prevent dangerous and costly accidents. Where possible, non-typographical methods of identification (such as color coded lids on eyedrop bottles) should also be used in these situations, but it is easy to underestimate the difference seemingly small details may make to end users.

Font Size
Larger fonts will almost invariably be easier and more comfortable for readers, with or without disabilities. Specific minimal size recommendations vary between organizations, and within available research, but it is better to err on the side of larger rather than smaller.

One study specifically recommends 18 points, based on web-based reading, but as discussed later, allowing the user to scale font size may be preferable to any set font size, when scaling is possible (Rello et al., 2013). The American Foundation for the Blind also recommends 18 point type in printed materials, or, at minimum, 16.

Font Spacing (kerning)
The spacing between letters differs from font to font, and can be manipulated to produce different visual effects as part of layout. Manipulating this spacing can change how difficult it is to differentiate letters or letter groups from one another, or to identify words by shape. In a poll taken by the BDA, for example, dyslexic readers expressed a desire to have enough space between "r" and "n" in words such as "modern," to ensure that "rn" was visually distinct from "m." (https://bdatech.org/what-technology/typefaces-for-dyslexia/).

However, it does not follow that more space between letters will always be beneficial, particularly if the amount of space between letters approaches the amount of space between words. One early theory of reading suggested that readers do not go letter by letter, but rather identify familiar words by their shape on the page, which would be altered by excessive space between letters. Psychologists no longer ascribe to that theory, but there is still evidence that visually identifying discrete words is an important part of reading English. (Note that this may not be the case in every language. Written Japanese, for example, does not alter the space between characters to indicate the groupings in which those characters should be read, except, occasionally, when those groupings constitute phonetically represented foreign words).

Since the average person probably will not comment on kerning unless it is exceedingly annoying (as when it causes one to confuse "modern" and "modem" in text), so empirical information on ideal kerning will have to come from ongoing formal research.

In the meantime, using an acceptable font and refraining from manually altering kerning should go a long way towards meeting users' needs in this area, as font preference already takes into account the kerning associated with that font.

Line Spacing
As with kerning, there is no hard and fast rule for accessibility. Conceptual distinctions provided by ensuring more space between paragraphs than between individual lines of body texts are not less valuable to a user simply because that user has difficulty with the physical act of reading. In addition, a recent study found that dyslexic users were more impacted by text size than by line spacing (Rello et al., 2013).

Serif or Sans Serif?
Various sources suggest that sans serif fonts (such as Arial) are easier and more comfortable for people with visual disabilities or dyslexia to read. However, widely-used serif fonts (such as Times New Roman) may also be comfortable. Anecdotal evidence suggests that familiarity with a font is as important for many readers as the actual characteristics of that font.

Compatibility with Adaptive Technologies
Many readers with disabilities already have their own preferred tools for reading online or other electronic content. These tools including screen-reading software, e-readers, tablets, and many others. These tools often cannot pull text from images or .pdf files, and do not always respond well to documents or sites that specify a particular font size. Whenever possible, it is best to allow users to tailor text to their own specifications.

Other
Other considerations include (but are not limited to): font weight and style (bold is generally good, italic has been demonstrated to be unhelpful), and capitalization (writing in all capital letters is considered less legible than a mixture of capital and lowercase letters).

Sources of Accessibility Guidelines and Standards
Many disciplines, individuals, and organizations provide recommendations for optimally accessible typography, with varying degrees of justification for those recommendations.

Graphic Design
Graphic designers have well-established guidelines for what constitutes comfortable, well-formatted text, often based more on aesthetic traditions than on any objective research. It doesn't follow that these recommendations are incorrect or useless; they can be helpful and accurate. However, graphic design resources should not be the first place a writer looks for recommendations on accessible text. The major pitfall to be aware of when following graphic design principles for a document is that making a design "original" or using any form of decorative font can decrease accessibility in ways that can be both significant and difficult to predict.

Research
Published research in many fields documents and describe how people read (with or without disabilities), which fonts best suit various groups of readers, which fonts can be read most quickly by a sampling of readers, and many other topics relevant to accessible type. Some of these studies present specific recommendations, and are a good source of ideas and information for a writer with the time to sift through and learn some of the relevant terminology.

Direct Feedback from Individuals with Disabilities
Although information gathered directly from individuals with specific accessibility needs tends to be anecdotal, and needs and preferences will vary according to specific concerns, it is unwise to attempt to benefit any group of people without asking what members of that group actually want. In specific cases (such as an online publication or webpage), direct polling of one's readers could be helpful. While this process will inevitably turn up some requests that have less to do with accessibility than with aesthetics, building a dialogue with readers has few downsides from the perspective of writers or publishers, and may provide useful insights on populations not covered in more formal research.

Organizations
Typographical recommendations form part of the style guides of many organizations, and organizations formed by or for individuals with various disabilities also give recommendations. Not every organization is transparent about where those recommendations come from, and in some cases, they have as much to do with branding as they do with accessibility. However, many do reflect concrete research, and most are a decent starting point for anyone working to a deadline.

American Foundation for the Blind (AFB)
Print recommendations: http://www.afb.org/info/reading-and-writing/making-print-more-readable/35

Web recommendations: http://www.afb.org/info/programs-and-services/technology-evaluation/creating-accessible-websites/tips-and-tricks/1235

British Broadcasting Corporation (BBC)
General accessibility guidelines: http://www.bbc.co.uk/gel/guidelines/how-to-design-for-accessibility.

British Dyslexia Association (BDA)
Recommended fonts based on member feedback: https://bdatech.org/what-technology/typefaces-for-dyslexia/

Carnegie Museums
Guidelines: http://web-accessibility.carnegiemuseums.org/design/font/.

Stanford Online Accessibility Program (SOAP)
Web-focused recommendations: https://soap.stanford.edu/tips-and-tools/tips/fonts-and-typography

Limitations of this Page
The research and design principles discussed here likely apply only to non-handwritten language using Latin characters, read left to right and top to bottom, and punctuated in a similar way to English. Without additional research, there is no way to be sure that the same principles apply to languages using different character sets, different syntax, or different reading direction. When considering how to format a page that will be translated into multiple different languages, style guides for each language should be consulted, whenever possible. Including typographical considerations as part of the process of localization will benefit end users.