Usability and accessibility are slightly different lenses to assess user experience. It is possible to be strong in one area and weak in the other. Using either approach alone could result in an inaccurate view of your site’s user experience. Evaluating your website with both usability and accessibility in mind gives all users the best possible user experience.
What is Usability?
Usability relates to the how easy things are to use. Generally, usability is measured against five criteria—memorability, efficiency, errors, learnability, and satisfaction (MEELS). In support of those criteria, ask yourself the following when evaluating a website’s usability:
- What tasks are users expected to complete using the website?
- How easily can someone complete those tasks?
- What test scenarios could assess the completion of those tasks?
- What data should you record to capture in assessing those tasks?
- How satisfied is the user with the steps needed to complete the tasks?
When you have answered those questions, ask what and how things should change to improve user experience. Typically, traditional usability testing does not consider the disabled user. We believe that keeping all users in mind is vital to your site’s success, though.
What is Accessibility?
Accessibility relates to how a disabled individual uses something. Section 508 requires that all government websites are accessible to disabled users. Section 504 expands these accessibility requirements to any group receiving federal funding.
Accessible sites present information through multiple sensory channels, such as sound and sight. That multisensory approach allows disabled users to access the same information as nondisabled users. For example, if you have a video on your site, you must provide visual access to the audio information through in-sync captioning.
However, remember that providing a secondary channel to meet the Section 508 requirements does not guarantee that disabled users will have an equal and positive experience on your site. You must design your secondary channel with both audience and context in mind.
For example, if an image is decorative, you should tag it with null alt text, which tells the screen reader to skip over it. However, when an image conveys information, like a chart, you must consider:
- What information does the alt text convey?
- What does the surrounding text say about the chart?
- What is the take-home message of the chart?
Poor attention to audience and context reduces the disabled person’s user experience. Accordingly, testing these secondary channels becomes as important as testing the primary channels.
Tying Things Together: Usability and Accessibility Best Practices
Although many usability books and articles provide the ideal number of users to test, they rarely address the importance of diversity in test subjects. When selecting test pools, testers often focus on “the average user.” This, however, is at the expense of smaller user groups—such as disabled individuals.
Leaving disabled individuals out of usability testing creates a gap in testing methodology. For example, a new navigation menu on a website may test well with nondisabled users and receive good scores in all the MEELS categories. However, if the color contrast is not sufficient, or the menu is not tagged to work with screen readers, or the keyboard-based navigation correctly, blind and low-vision users will not be able to use it.
By not testing with disabled individuals, it is possible to have a website with high satisfaction and strong usability for a nondisabled population. While this population may indeed be the desired “average site user,” your website may be completely unusable—and inaccessible—to the disabled population.
So the next time you evaluate your site, keep all of your users in mind and ensure that it is an equally successful experience for all.