Motion Actuation, Done Properly
Features triggered by moving the device, such as shaking to undo or tilting to scroll, and the need to offer another way to do the same thing.
Marcus Adeyemi
Why does it matter?
People with devices mounted to a wheelchair or with limited movement cannot shake or tilt, and others trigger motion accidentally, so WCAG requires alternatives at level A.
What are the numbers?
- WCAG 2.5.4 Motion Actuation, A functions triggered by device or user motion can also be operated through interface controls
- Disabling users must be able to turn off motion actuation to prevent accidental activation
- Exceptions motion that is essential, such as a pedometer
- Examples shake to undo, tilt to pan, raise to wake
What should I do?
- Provide a button for every motion-triggered action
- Offer a setting to turn motion triggers off
- Avoid motion as the only way to reach a feature
- Test the app with the device fixed in place
- Document motion features in help content
What should I avoid?
Avoid:
- Shake-only undo or feedback
- Tilt-only navigation in games or maps
- Motion triggers that cannot be disabled
- Hiding the alternative in a submenu
When should I get help?
Short answer Bring in help when designing apps that use device sensors, or when users report accidental actions.
Where this comes from
- W3C Web Accessibility Initiative — Understanding SC 2.5.4 Motion Actuation
- Apple Human Interface Guidelines — Gestures
The figures and practices above come from the sources listed.
Working on something like this?
We take on Performance & Accessibility work for teams who want it done once, properly. Tell us what you are building and we will tell you honestly whether we are the right studio for it. Start a project.
Where to go next
Spotted something wrong? Report an error on this page. We correct on the page and say what changed.
