Mobile accessibility is all about providing users with options. Unfortunately, designers sometimes make assumptions about their users' behavior, particularly when designing and implementing motion-based controls. Those assumptions can create serious accessibility barriers.
For instance, imagine you’re building an app that shows the latest news from a variety of sources. Users can shake their mobile devices to refresh their feed — but some people may not have the ability to shake their devices. If they don’t have an alternative, they cannot use the app.
The Web Content Accessibility Guidelines (WCAG) addresses motion-actuated functionality in WCAG 2.1 Success Criterion (SC) 2.5.4, “Motion Actuation.” Here’s the full text of this criterion:
Functionality that can be operated by device motion or user motion can also be operated by user interface components and responding to the motion can be disabled to prevent accidental actuation.
This requirement has exceptions for motions that are used to operate functionality through an accessibility-supported interface and “essential" motions. For example, if you’re building an app that counts the user’s steps by using the device’s gyroscope, you don’t need to provide an alternative.
In this article, we’ll discuss why this success criterion is important — and provide tips for avoiding common mistakes when designing your product.
Why is motion actuation important for digital accessibility?
Some users may have difficulty moving their devices to trigger certain features. That’s particularly true when the motion requires precision. Providing an alternative to motion actuation ensures a better experience for a wide range of users:
- People who are unable to perform certain motions due to physical disabilities.
- People who mount their mobile devices to their wheelchairs or desks.
- People who have tremors that might activate motion controls accidentally.
- People who disable their devices’ motion-detection features.
Accessibility improves experiences for all users, not just people with disabilities. If you’re creating a mobile app, some of your users may have phones with broken gyroscopes; others may use your app in crowded public environments.
Motion-activated controls can be useful, but they shouldn’t be required. WCAG SC 2.5.4 is a Level A success criterion, which means that your product cannot be considered reasonably accessible if it fails to meet this requirement (read more about the differences between WCAG levels).
Quick Tips for Using Motion in Mobile Websites and Apps
WCAG 2.5.4 is pretty straightforward: You need to offer an alternative to motion actuation wherever possible — and ensure that motion actuation can be disabled.
This second point is especially crucial. Remember, if users can’t turn off motion controls, some of them may activate those controls accidentally. That’s not great for the user experience (UX).
Here are some other tips to keep in mind:
- Keep your controls predictable. For example, if a shaking motion refreshes one screen, it should have the same functionality on other screens.
- Make sure that the alternative to the motion control is also accessible. Don’t require precise pointer gestures as an alternative to motion actuation. For more guidance, reference WCAG 2.1 SC 2.5.1 “Pointer Gestures.”
- Don’t expect your users to “figure out" the controls. Provide clear instructions that explain how gestures work within your website or app.
Finally, remember that WCAG doesn’t prevent you from using motion controls, colorful graphics, or other features. The guidelines simply help you make those features accessible for as many users as possible.
Following the best practices of inclusive design won’t limit your product. When you think about all of your users from the first stages of development, everyone wins — but for optimal results, you’ll need to make a firm commitment to accessibility.