Never Use White Text on a Black Background: Astygmatism and Conference Slides

TL;DR – never use white text on a black background in your slides.

This post has been a long time coming. Every conference I go to, there will be at least one (and more often ten or twenty) presentations that use white text on a black background. These slides range from hard-to-read to outright illegible and in particularly bad set-ups are so visually painful that I have to close my eyes or turn away from the projection screen. Even conferences that provide advice on designing accessible presentations nod at the “make slides high contrast” but are silent on the white text issue. So! Here it is.

The facts:

  • approximately half the population has some degree of astigmatism
  • white text on black backgrounds creates a visual fuzzing effect called “halation”
  • halation is known to reduce readability of text and is particularly bad for people with astygmatism

The visual aids:



So please, everyone, strike white text with black backgrounds from your color repetoire, the same way you’ve removed color combinations that are illegible to color-blind people. It’s not a question of preferences, it’s an accessibility issue.

Conferences and Invisible Disabilities

For two decades, if you suggested that I was disabled, I would have given you a strange look and a skeptical, “okaaaay?”

Sure, I have asthma and have to take meds twice a day (okay, six times a day during flare-ups) but that is as normal to me as brushing my teeth twice a day. And yes, I am intimately familiar with the emergency departments of six different hospitals, but that’s because I’ve moved a lot. And sure, there are a lot of things I haven’t been able to do because of my asthma, but I’m not the kind of person who wants to hang out in a bar or go clubbing on a regular basis or attend academic conferences-

Yeah, I hope I just made you do a double-take.

What do the History of Science Society; the North American Conference on British Studies; and the Society for the History of Authorship, Reading, and Publishing have in common? Besides being awesome professional societies (or I wouldn’t belong to them!), they have all held conferences that I attended where I suffered severe respiratory distress because of the asthma-unfriendly cities they chose for their conferences.

I’m not going to sugarcoat it. When my co-collaborators and I decided we wanted to present our work at SHARP and then I realized the conference was in Paris, I nearly burst into tears because dear God, I didn’t want to have to suffer through an asthma attack on purpose. It took me four weeks to recover from that conference in Paris last summer. I almost didn’t apply to present at the Alliance of Digital Humanities Organizations conference next summer because it’s going to be in Montreal, which isn’t quite as bad as Paris, by which I mean it’ll probably “only” take me a week or so before I can breathe normally again.

So this is a plea for conference organizers to add more items to a checklist that, I appreciate, is already pretty long! But if you want your conferences to be truly accessible, you need to take into account the invisible, as well as visible, disabilities.

  1. Do you know what the air quality is like in the city you’ve chosen for your conference? Hint: if it’s a city where cigarette, cigar, and/or marijuana smoking is socially acceptable, it’s not going to be good. Also, think about vehicle and manufacturing exhaust, and the likelihood of wildfires. No, you can’t work miracles – cities are cities – but you should be aware of the situation, know when you’re choosing a venue that will potentially hurt people attending your conference, and keep your attendees informed about potential air quality issues.
  2. Is the hotel you’ve chosen strictly non-smoking? Because, let’s face it, any hotel with smoking rooms is going to cross-contaminate the non-smoking rooms, even if it’s just via the laundry.
  3. Is your meeting venue attached to your hotel? Or will attendees have to go outside, running the “smoker’s gauntlet” that inevitably springs up right outside hotel doors? Because not everyone can hold their breath and run – and frankly, we shouldn’t have to.
  4. Does your hotel AND meeting venue have year-round climate control? Yes, that means air conditioning in the summer, even in northern climates. Because asthmatics can’t just “open a window” and the lack of climate control leads to issues with humidity and mold growth, air circulation, and other asthma-attack-inciting conditions.

That’s it. Four things to keep your conference attendees from having to choose between their careers and their health. Because we all like to breathe.