The Web Content Accessibility Guidelines (WCAG) is an initiative run by World Wide Web Consortium (W3C) to ensure web content is universally accessible. For more details on WCAG see this document. 

WCAG is organised around four main principles, often referred to by the acronym POUR: Perceivable, Operable, Understandable, and Robust. These principles allow web designers and web content providers to consider/design websites that are accessible to users regardless of their abilities or the assistive technologies they use.    

This article delves deeper into the third of the POUR Principles: ‘Understandable’ and how it applies to online surveys: 

Accessibility has, in the last few years, extended to cover cognitive disabilities such as Asperger’s syndrome, obsessive compulsive disorder and dyslexia. This has resulted in new guidance around reading age and complexity of language. With an expectation that web content should operate predictably and should avoid complex language unless necessary:

• Plain language instructions, appropriate labels
• Content appears & operates predictably
• Clear affordances, error prevention/recovery 

Survey information and instructions should be clear and navigation methods should be easy to understand and use. Use an introduction section to give your survey a clear structure and to provide helpful information at the start of the survey. Use page headings to continue the flow of helpful information throughout the survey.

WCAG suggests that content should not require a reading ability more advanced than ‘lower secondary education’ level, which is equivalent to Years 7 to 9 years of school (12 to 14 years old). If your survey content is within this threshold, then you are writing for accessibility. If not, look for opportunities to use more simple, common words. 

You may be tempted to format text in italic or bold for emphasis – only use this for individual words and not for whole sentences as it makes text harder to read. 

Avoid using BLOCK CAPITALS - the use of All Caps can reduce the readability of your text and reduces reading speed.  

Unlike the image shown, avoid changing the font, font colour and font size of your question text. If you must do this it should be used sparingly, as deviating from the default may cause problems for users with visual impairments. A recommended minimum font size is 12 pt. The font style is Arial and should be black on a white background. 

If you need to present a large amount of text in a question, break it up into a bulleted list.

In summary: 

Survey content must make sense, regardless of how it is accessed.