Why Accessibility Is at the Heart of Data Visualization
To make data viz more accessible, we first need to understand assistive technology
When I tell people I make data visualizations for blind people, the response is almost inevitably a quick pause while the gears of their mind start spinning wildly, then “How does that work?”
I’m not going to tell you how I do it. (At least, not in this article.) But I will tell you how I think about it, and suggest how you can too. Many people love data visualization because it makes data and other complex information accessible. But there are many people for whom data viz doesn’t make things accessible, and it’s not because they don’t understand data.
For example, data viz has played a critical role in educating people about COVID-19. But have you wondered how blind people are getting detailed information about the pandemic, given that so much of it is in chart or infographic form? The answer, for the most part, is that people with visual impairments are simply not afforded access to that critical data. To understand how we can—and must—change that, we first need to understand assistive technology.
Assistive Technology, or AT, is pretty much what it sounds like: technology that helps people overcome a constraint in how they interact with the world. In the case of people with a visual disability, that often means using a screen reader. A screen reader is software that literally reads text from the screen, a bit like an interactive audio book where the user can change the pace, skip passages, find text, or jump to sections or links they’re interested in. It also describes the structure of the text, like headings or tables or lists. But the caveat is that it only reads text, so if there’s something on the screen that’s not text, it’s hidden from them. Some non-text things have built-in descriptions, like form fields or buttons or links, which are announced along with their text labels. So images need text descriptions, called alt text, and complex images like charts need effective text descriptions to be useful to a screen reader.
Or course, visual disabilities aren’t the only ones to consider, but for a primarily visual medium like…