Typography and dyslexia
There are many typographical factors that can affect the ability of people with dyslexia to read text. These include text and background colours, font face and size, leading (line height), and line and paragraph length.
Here we consider one further factor, namely text justification and the evenness of text spacing. Below we provide a quick tutorial for InDesign users on how to eliminate any potential problems, together with a note on the relevant standards.
Low-tech methods of evaluating the problem
There are various ways of checking that text is evenly spaced, some perhaps more ‘scientific’ than others. For example, one way is to squint at a page in order to gauge the blotchiness or otherwise of each line. Another is to hold the page upside down so that words and their shapes become less recognizable, making the spacing easier to judge. Fortunately, InDesign provides a better way.
The InDesign method
In order to get a visual representation of any problems with justified text in InDesign:
- Select Edit (Windows) or InDesign (Mac), Preferences, Composition
- In the Highlight section, select H&J Violations (H&J = hyphenation and justification)
- Click OK
A visual representation of the problem
The following shows a document with two identical frames of justified text, side by side. With H&J violations enabled, yellow highlighting will indicate any problems areas—the darker the yellow, the greater the problem.
We will now fix the right-hand text frame, comparing it as we go along with the left-hand frame which will remain unmodified.
Adjusting spacing and scaling
- Open the Paragraph Styles panel and select the paragraph style for the text in question
- In the left panel of the paragraph styles dialogue box select Justification
- Apply the following settings
- Min word spacing: 90%
- Max word spacing: 150%
- Min letter spacing: -5%
- Max letter spacing: 3%
- Min glyph scaling: 97%
- Max glyph scaling: 103%
The (interim) result
The effect applying these settings can be seen in Figure 4 below.
With the above settings applied, almost all of the yellow has now gone. But the one remaining highlighted line is still quite stretched out. Adjusting the spacing and scaling further may get rid of the remaining yellow, but in this case, quite large increases will be necessary. The danger then will be that some spacing might become too narrow and words may run together, thereby decreasing readability. An alternative approach may be needed.
An editorial quick-fix
A third option would be to turn on (auto) hyphenation, to automatically add (soft or discretionary) hyphens at line ends. To do so:
- Open the relevant paragraph style again
- Select Hyphenation and check the Hyphenate check box
The final result
The end result can be seen below. All of the yellow highlighting has now gone (even though no hyphen has been added to the target problem line). Also gone, of course, are the excessively wide gaps between words.
Making use of this very powerful InDesign tool will minimise or eliminate altogether any text justification problems and hence improve the readability of the text for everyone. However, it likely to be particularly beneficial to people with dyslexia.
Note on the relevant standards
PDF/UA, being a technical rather than a content-orientated standard, does not address this kind of accessibility issue. Instead, it defers to WCAG 2.0.
The relevant WCAG 2.0 Success Criterion, 1.4.8, states:
For the visual presentation of blocks of text, a mechanism is available to achieve the following: (Level AAA) … (3) Text is not justified (aligned to both the left and the right margins).
The specific benefit of Success Criterion 1.4.8, in the present context, is given as:
People with some cognitive disabilities can read text more easily when the spacing between words is regular.
However, WCAG only addresses this issue in the context of justified text in HTML documents, which remains quite crude. It takes no account of the sophisticated text justification engine available to InDesign users. When a page requires text to be both left and right justified, this is clearly one area in which PDF has an advantage over HTML.
When PDF is a more accessible format than HTML
On which note, it is often assumed that HTML is a more accessible format than PDF across the board. As we will show in a forthcoming blog post, for some readers and some types of content, this is absolutely not so, and in some cases, the opposite is the case. The above is just one such example.
Want to know more?
This article is based on a single module from our accessible PDFs from InDesign training course manual. The course includes dozens of other such modules, providing all you need to know to make PDFs accessible to the widest possible range of readers.