In making web content accessible to people with varying levels of vision impairment, attention is often focused on providing alternatives for conveying the meaning of images and ensuring that text can be properly conveyed by screen readers.
It is also necessary to pay attention to how reliant the communication of the content is on other visual cues, including size and shape. This is addressed in Success Criterion 1.3.3: Sensory characteristics:
Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, size, visual location, orientation, or sound. (Level A)
People with some kinds of disabilities have limitations on their ability to distinguish or apply meaning to the characteristics of elements that rely on sensory perception.
However, Success Criterion 1.3.3 does not deal with colour. The use of colour in conveying meaning is covered in Guideline 1.4. You can find more information in the topic on colour for content authors.
Consider the following instruction: "Press the round button to submit the form, or the square button to cancel and clear the form."
This presents a real problem for a person who cannot distinguish round from square, including people with a range of specific types of visual impairment. Even a screen reader may have trouble conveying the distinction unless properly informed.
Yet this type of instruction is not uncommon in some of the most critical processes that a user can face on a webpage: the submission of user information to complete a procedure that may have great implications, including financial.
It's also important to be aware that the use of different shapes, changes in sizes, location on the webpage, which way round things are and auditory signals like beeps are known to be useful in conveying web content to people with some kinds of cognitive, learning and intellectual disabilities.
There is no need to refrain from using sensory characteristics of objects and elements to convey meaning. The key lies in the use of the word "solely".
The focus of Success Criterion 1.3.3: Sensory characteristics is on ensuring that "all users can access instructions for using the content, even when they cannot perceive shape or size or use information about spatial location or orientation".
What this means is that if your instruction relies on the user being able to distinguish differences in shape, then you must make sure you provide those instructions in some other way as well.
"Press the round button on the left to submit the form, or the square button on the right to cancel and clear the form."
That in itself is sufficient to conform to the requirements of Success Criterion 1.3.3.
Use textual identification
One of the most useful, and easy to apply, ways to provide instructions to users of content is to apply textual identification.
"Press the round button on the left labelled SUBMIT to submit the form, or the square button on the right labelled CANCEL to cancel and clear the form."
Note: The use of text generally makes it easier for screen readers to inform blind users. We sometimes have trouble getting our heads around concepts like this — that using a visual medium like text enhances accessibility for blind people — but it makes sense when you take the role of assistive technology into account.
If you find yourself giving users instructions like, "Look at the menu furthest to your left and select the option indicated by a triangle", you should consider whether it's feasible to just give them the link direct.
Text links, in particular, are very useful for providing context to users with disabilities as well as empowering them to act on the information provided.
Find a better way
You may find you have content that uses Unicode font glyphs for graphical symbols like arrows, ticks (or check marks) or crosses. These add visual appeal but are unlikely to be correctly described by a screen reader.
In that situation, you should consider whether using an image with an alt tag might be a better option as it can described by a screen reader, while still providing the visual flair for the sighted user.
Note: Success Criterion 1.3.3 includes sound in its list of sensory characteristics of webpage components that may impede accessibility to people with impaired hearing.
It is surprising how often the use of auditory signals on a website is implemented in an inaccessible way.
"Wait until you hear a 'beep', then click on the submit button."
Once again, the key to addressing this is to provide signals in alternative formats.
"Wait until you hear a 'beep' and see the word 'Complete' appear, then click on the submit button."
Successfully addressing the requirements of Success Criterion 1.3.3 comes down to paying attention to detail. Nothing complicated or onerous is required other than to understand the needs of all users of your web content.
WCAG 2.0 references
Related Techniques for WCAG 2.0
- G96: Providing textual identification of items that otherwise rely only on sensory information to be understood
- F14: Failure of Success Criterion 1.3.3 due to identifying content only by its shape or location
- F26: Failure of Success Criterion 1.3.3 due to using a graphical symbol alone to convey information