Fonts and dyslexia

Dyslexia and fonts

The Anatomy of Text. Based on a drawing of the PhD thesis of Eric Michael Weisenmill (A study of the readability of on-screen text, 1999)

I am not an expert in accessibility or cognitive challenges in communication/education, but I am concerned to give my students all (best) available options so they can make the most of my presentations. I have had a few students with dyslexia, and I spent quite a while researching the best font for dyslexia.

I was looking for a ‘simple’ answer. After all, I can almost safely think “for colorblind audience, choose/generate a palette using color brewer (python/maps)”. Why not expect “for dyslexic audience, use X font”.

I found that the answer is not straightforward, and basically, no font is more ‘dyslexia-friendly’ than any other per se. At least that claim is not supported by evidence, and there is no consensus on it.

Whenever possible I try to use the Atkinson Hyperlegible® font from the Braille Institute, which is “designed to improve legibility and readability for individuals with low vision”, and “feature clear, highly distinctive letters and numbers that make reading easier and more accessible.” However, I admit that I also have no scientific evidence at hand that it outperforms other fonts (I don’t say it doesn’t exist). But they show some of the details and it makes sense. But it doesn’t claim to be best or even different regarding dyslexic readers.

Some features of Atkinson Hyperlegible font (Braille Institute)

I am aware that the ‘dyslexia friendly’ font is offered in numerous places across the internet. Even Claude has a ‘dyslexia friendly’ font, but it is more related to marketing¹ than to an evidence-based feature (after some back-and-forth, it ended up admitting it).

To sum up, the consensus is closer to “let the person choose fonts and spacing” than “the font X is best for dyslexia”. In the end, the most effective approach is to empower users with choices. This is what specialists and organizations recommend (see below).

For my Quarto@revealjs presentations, I will be using the a11y extension by Mickaël Canouil (an incredibly helpful and prolific Quarto contributor!). This extension lets the user chose almost all aspects of the visible content (and even sound!). The most important for dyslexic readers are probably font type and the different spacing options and color combinations. As far as I understand, letting each person chose the visual style and aspect is the best one can do to effectively communicate to a broad audience.

---

Some resources

International Dyslexia Association (USA)

• Do Special Fonts Help People with Dyslexia?
• 3 Things to Know About “Dyslexic Fonts”

Dyslexia Canada

• Myths and misconceptions about dyslexia

DyslexiaHelp (Univ. of Michigan, USA)

• Good Fonts for Dyslexia (‘The fonts designed specifically for dyslexia, OpenDyslexic, did not lead to a better or worse readability’)
• Dyslexia Fonts
• Which Fonts are Best for Dyslexics?
• Non-evidence-based interventions for learning disabilities can be hard to pick out

Readability tutor

What is the Easiest Font to Read for Dyslexia?

Understood

• Do dyslexia fonts help?

Scientific research

• Letter spacing improves reading
• Dyslexie font does not benefit reading in children with or without dyslexia

---

Footnotes

1. I’m not aware that anyone makes money with this, but I didn’t find a better word