The basics
Some ways to improve accessibility are fairly well known:- Watch out for small fonts and low colour contrast. And when you provide documents on the web, make sure they still work if readers magnify the text size or change the background colour.
- Don’t rely on colour as the only way to convey important information.
- Add captions or transcripts to videos. Transcripts have the added benefit of making the video content indexable by search engines.
Storm danger levels by region. The image on the right simulates what someone with reduced red-green colour perception sees: it is difficult to distinguish between the highest and lowest danger levels.
Reducing cognitive load
Cognitive load refers to the amount of effort it takes to understand something. For some readers, small changes in cognitive load can have a big effect. In her amazing article “The Spoon Theory,” Christine Miserandino explains that people with chronic illness have to budget their energy very carefully. If a document is hard to access and understand, it may be too expensive in time and energy for some readers. You can reduce cognitive load by keeping documents short and well organized, and by using plain language. Plain language, which is too big a topic cover here, is a well-defined set of guidelines for clear writing, based on knowledge of how people process language.Screen readers
People who are visually impaired or who have reading disabilities often use screen readers. Consider the following points to make sure a screen reader will read your text correctly:- Use the correct symbol in your text. A minus sign looks like an en dash, but the screen reader will read them differently.
- Consider using words instead of symbols. “Approximately 5 grams” will be read correctly, while “~5 g” may not.
- Check that the reader reads the document elements in the correct order. In a PDF file with multiple columns, a screen reader may read straight across.
The web
HTML provides reflowable text so that users can adjust font size and colour, it uses tags to indicate the relative importance of headings, there is “alt” text to describe the images for those who can’t see them. The web has the potential to be a haven of accessibility. But only if you use it right.- Keyword stuffing in your alt attribute is like parking in the accessible spot. You can use a “title” attribute instead (part of the global attributes supported by the img tag).
- Use meaningful alt text, but don’t repeat the caption.
- Only write alt text for images that are important to understanding the document, but don’t leave any alt attributes empty, because in that case a screen reader will read the file name. Insert an empty string (“”).
- Try to keep the text in the HTML flowing in logical order, regardless of your layout. This way a screen reader will read it in the right order.
- Indicate headings with h tags instead of using font size, colour, or weight (this is also good for your search engine optimization, which helps people find your document, improving accessibility).
- Try the Web Disability Simulator Google Chrome extension to try navigating your web page with filters like reduced colour vision or hand tremor applied.
