Saturday, March 14, 2015

Typefaces for Dyslexia

Example showing the letterforms of b, p, and d, and how they have a thicker stroke on the bottom.
Both typefaces claim that heavier strokes on the bottom prevent dyslexic readers from flipping the letters when viewing them. The original caption: A heavier bottom is used to show which way is supposed to be down.

I've been writing this post in fits, so it may be a bit disjointed. I started it on my flight home from CSUN, and continued to work on it on subsequent flights. Apologies if it's a bit chaotic.

TL;DR: Typefaces designed to help dyslexics have no effect.

I'll list information about the two typefaces that I am aware of (which are designed explicitly for readers with dyslexia), as well as notes from the talk at CSUN and a couple other examples.


I am aware of two typefaces that are designed with dyslexic readers in mind.


Open Dyslexic is an open source typeface for readers with dyslexia. The rationale behind the design:

OpenDyslexic is created to help with some of the symptoms of dyslexia. Letters have heavy weighted bottoms to indicate direction. You are able to quickly figure out which part of the letter is down which aids in recognizing the correct letter, and sometimes helps to keep your brain from rotating them around. Consistently weighted bottoms can also help reinforce the line of text. The unique shapes of each letter can help prevent confusion through flipping and swapping.


Dyslexie is a paid typeface (free for home use). The site references research that supports the following claim:

Representative research among many dyslectics has shown that the font Dyslexie actually helps them with reading texts faster and with fewer errors.

I would like to note that copying that text directly from the browser wasn't easy. The use of Cufon to embed the typeface drops each word into its own element that itself hides and replaces the raw text in a canvas element. I'm sure you can imagine how much that offends me.

The following video explains the idea behind the typeface:

Study: Can a font improve reading?

The latest study to suggest that typefaces designed to aid reading for dyslexics had little to no effect was presented at CSUN this past week. As I noted on Twitter, I already had an idea what the results would be, and I came away feeling validated.

The study hasn't been pubished yet and I saw its first general presentation. The study was conducted at Mount Allison University, a 2,500 student college with 215 full-time students with disabilities. 50% of those students are classified as having a learning disability.

The questions asked by the study:

  • Do the style of the letters on a page mean that you read faster and make fewer errors?
  • Do persons with LD [learning disabilities] using this font read faster and make fewer errors?
Anne Comfort, Matt Kalichuk, Harry Wenban and Dr. Louise Wasylkiw

The typefaces (Open Dyslexic and Dyslexie) make claims about their benefits, aggregated in the presentation as:

  • Students with surface dyslexia experience letters flipping and moving around; Letters needed to be bottom heavy to prevent them from moving around
  • New font would increase reading speed
  • Will also increase accuracy (fewer errors)
  • Will decrease reading stress
  • Widely promoted to on-line uses and in word processing (Instapaper, iPad, an app)
  • Strong anecdotal feedback
Anne Comfort, Matt Kalichuk, Harry Wenban and Dr. Louise Wasylkiw

The presenter outlined some literature references, the procedure the team followed to perform the study, the nature of the participants (and control group), and the overall results.

The first bullet in the summary wraps it up nicely:

  • The font does NOT improve reading speed or accuracy for students with LD.
Anne Comfort, Matt Kalichuk, Harry Wenban and Dr. Louise Wasylkiw

An interesting note from the study was that half of each group (50% of control, 57% of LD group) said they would consider using the font and were then shown how to access it (download and install it, which I assume was Open Dyslexic). In a follow-up, none of those participants were using the font.

Another interesting point was that 40% of the control group and 48% of the LD group thought they performed better when using Open Dyslexic, though that was not the case.

As anyone who's done user testing knows, it's not uncommon for users to report one thing while doing or thinking another, so I consider this to be anecdotal reinforcement that the typeface had no benefit for users.

Study: Good Fonts for Dyslexia: An Experimental Study

In late 2013 I found a write-up on a Spanish study that reviewed which fonts were easiest for readers with dyslexia. The post summarizes the study:

Based on the evaluation of 48 dyslexic subjects ages 11-50, reading 12 texts with 12 different fonts, they determined that reading performance was best with sans serif, monospaced, and roman fonts used in the study. They also found that reading was significantly impaired when italic fonts were used.


Use of the OpenDyslexic font did not enhance text readability or reading speed. The study participants strongly preferred Verdana or Helvetica over the OpenDyslexic alternative.

You can find the full text of the study in a PDF file on the site for the Natural Language Processing group of the Department of Information and Communication Technologies at Pompeu Fabra University.

General Tips

For those of us who build applications and sites with content of any length (whether instructions for shopping carts or rant-laden long-form articles), I have found a few techniques are generally agreed upon by the community (feedback is welcome!):

  • Avoid justified text.
  • Use generous line spacing / leading.
  • Use generous letter spacing.
  • Avoid italics.
  • Generally use sans serif faces.
  • Use larger text.
  • Use good contrast.
  • Use clear, concise writing.

This generally follows rules for good typography.

You may have heard that Comic Sans is easier for readers with dyslexia to understand, but so far that evidence appears to be anecdotal. Certainly not enough to warrant punishing all your other users.

If you read an article that suggests users with dyslexia see letters flip or rotate, then be wary. Not only was this assertion challenged by participants in the study reported at CSUN, but generally the participant reaction was anger. The flipping/rotating may be a myth perpetuated by those without dyslexia in an effort to make sense of its effects.

Update: March 26, 2015

In a post from 2011 (Dyslexia, Fonts & Open Source), Mike Gifford outlines some of the issues related to supporting readers with dyslexia, including typefaces.

Update: April 17, 2014

Neil Milliken notes that, as someone with dyslexia, he finds the custom dyslexic typefaces unhelpful and unattractive.

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