Am I the only one who often gets obsessed with stuff they discovered in really weird ways? I watch a film and some character listens to some music on their car stereo; I look it up and have a new favourite band for the next few months. That kind of thing.
Along those lines, quite a while ago I made an unfunny remark on Mastodon about the tendency of some widely-respected computer scientists to use a certain font in their presentations; just recently, prompted by referring to that post for the nth time – so much for jokes getting funnier by repetition – I decided to look into why they do this, even though that particular font is widely disliked. The answer turned out to be pretty much that they don’t care, and they wish people would focus on the content instead of the font. Fair enough.
Except someone also mentioned that that particular font might be good to use because it’s allegedly easier to read for dyslexic people.
Ah. Hmm. Hrrmph. Well, maybe I need to do something about this in future as well, then!
Cue a whole morning spent overthinking this!
The first thing to do was to find out whether that claim was really true of that font in particular. Answer: unsurprisingly, initial research pointed to ‘no’; some people say it helps, but just as for non-dyslexic people, opinions vary and you can’t generalize over ‘dyslexic people’ as a class here. For one thing, there are very different types of dyslexia. The chap who wrote that Reddit post says it only reminded him of the patronizing treatment he got as a dyslexic kid at school; again, that’s fair enough.
There are a couple of fonts – Dyslexie and OpenDyslexic – which claim to be designed to be helpful for dyslexic people. The idea of both seems to be the same: somehow making the stroke weight heavier at the bottom of the font maybe gives the letters more ‘gravity’, as if that would help them stay in place better?
Type designer David Jones happened upon my posts fretting about this on Mastodon and was able to point me to a handy introduction to the topic of legibility for dyslexic folk by big-shot typographer Chuck Bigelow. Bigelow looks at the actual scientific research: on this kind of bottom-heavy font in particular, it’s a wash.
Sidebar! Personal hypothesis about why these fonts might feel like they work for some dyslexic people
Readers recognize words by their whole shape, not a letter at a time. The more common the shape, the easier it is to recognize the word. This applies for dyslexic people just as much as non-dyslexic people. For (some) dyslexic people, it’s just harder to pick apart the differences between words that have similar shapes.
This is why place names on road signs are in mixed case, not upper case. In the UK, for example, they used to be in upper case, with the idea that because upper case is bigger it would be easier to read from further away. But people are more used to seeing place names written in running text in mixed case, so the shape is easier to recognize in mixed case. So in 1963 it was fixed to require ordinary mixed case on road signs.
My guess as to why the dyslexic fonts might work for some people is just that they have such unusual letterforms compared to normal fonts that they make the shapes of words unfamiliar enough as to force word recognition to fall back to a lower level. In the same way that non-dyslexic readers have to fall back on letter-at-a-time (or morpheme-at-a-time) recognition to deal with unfamiliar words like quixolotl (a quixotic axolotl) or all-caps words like ASTROLABE, these fonts make everyone fall back to engaging more with the shapes of individual letters, reducing confusions between similar-looking words.
The real problem with this is that it also implies that as dyslexic readers get more used to OpenDyslexia/Dyslexie, the more they’ll get used to identifying words by shape in them, and the more they’ll go back to struggling to tell similarly-shaped words apart.
This is just an educated guess. It would be interesting to come up with an experiment to see if it could be tested.
To me, promoting these fonts now feels like a kind of inclusionist techno-solutionism all too common on the hackerly left, like the able-bodied Mastodon HOA insisting on alt texts that actually make life worse for those who depend on assistive technologies. With this one weird trick, you too can help people overcome their disability! Unfortunately, inclusion and accessibility are hard (though that certainly doesn’t mean they’re not worthwhile!) and there isn’t one weird trick to include everyone without accidentally disadvantaging some. If there is something you can do to try to include more people, it needs careful thought and consideration about the best way to make that affordance available, and about how to avoid accidentally hindering more people than you help – or worse, hindering the people you’re actually trying to help. In this case, for individual dyslexic people who feel like these fonts actually do help them read, and know where to find the setting to make websites display in those fonts, sure; but for a general audience, maybe not – we need a different solution here.
Bigelow does point to some clear results saying there’s a change you can make that makes readability measurably better for dyslexic people: make the font bigger!
That study has some limitations: the sample size was small and included only children, but it seems it was prompted by a previous study which included adults and gave initial positive results for increased font size across age ranges, prompting further investigation by the authors, so the indications are good that this isn’t a fluke or limited to children. The other major limitation is that both studies concern passively lit running text at close distance, not bullet points projected on a wall on the opposite side of the room; intuitively that doesn’t feel like a relevant factor. Also, increasing the font size only works to a certain point, at which point the benefits stop increasing (but, crucially, things don’t actually get worse), which also makes intuitive sense: as a non-dyslexic person, very fine print is harder to read than normal-size print, but after a certain point it makes no difference – 6 pt type is pretty hard going, but I can read 10 pt type just as well as 72 pt type. The result of the study is specifically that this threshold seems to be about a third higher for dyslexic children.
Of course, bigger text on a slide means you can fit less on, but I’m of the view that less text per slide is better anyway. I’m still not very good at practicing what I preach on that topic, so encouragement from a larger font size probably ends up being good for me as presenter as well! And, of course, a bigger font size is probably going to be better for audience members with vision impairments too. Wins all around.
So I boosted the font size of the slides I was working on by about 50% where I could; slightly less in some cases. The change also prompted me to redesign or split up some otherwise overcrowded slides.
Bigelow points to two other positive results. One is for a shorter line length: with a fixed width projector screen, a bigger font means shorter line length anyway, so that’s an easy win as well. But also that seems more relevant for running text than for short points on a slide: if you have text that spans more than one line on a slide, that’s already suspect; three or more lines is barely even a slide any more – it’s stopped being a visual aid for speaking and turned into a copy and paste of the paper for reading.
The other vaguely positive result is for slightly increased letter spacing (which David Jones suggested might be the reason the font discussed at the start of this post works for some dyslexic people). The results here are less clear than for font size or line length, but choosing a familiar font with slightly looser spacing would also be a change that would be unlikely to make anything worse for some people. I can kind of see the problem here: at the moment I use Helvetica, and the letters ‘tt’ in the word ‘pattern’ sometimes join together at the crossbars, making them look like a single letter.
I looked at the fonts Andika and Atkinson Hyperlegible as potential alternatives that are specifically designed to avoid situations that make words difficult to read or tell apart, but I haven’t yet made up my mind about switching. Atkinson in particular seems to be aimed at helping people with vision impairment more than dyslexia – not that that would be a bad thing, but it also can’t be denied that some of its letterforms deviate from the principle of familiarity of form which seems significant in helping dyslexic people. From my anecdotal experience with my own short-sightedness (only −1.25 dioptres in both eyes, admittedly), it also feels like I probably did much, much more to help by increasing the font size than I could do by switching to a different font; from my experience, probably like an order of magnitude more. For my personal stuff in general, I’ve mostly standardized on Adrian Frutiger’s Univers (in the case of this website, through the noncommercial-licensed GhostScript digitization); perhaps I should look at using that on my slides as well. It feels like it has a little more character than Helvetica, perhaps simply through being less overexposed, and it does also have slightly looser tracking.
Anyway, make the font bigger – for real! I think there are only wins to be had in that direction. You’ll make better, simpler slides; your vision-impaired and dyslexic audience members may thank you.