2.5.4 Motion Actuation (A)
Success Criterion 2.5.4 Motion Actuation (Level A):
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, except when:
- Supported Interface: The motion is used to operate functionality through an accessibility supported interface;
- Essential: The motion is essential for the function and doing so would invalidate the activity.
The motion actuation included in this success criterion includes both moving the device (shaking your phone) or gesturing toward a camera for it to interpret the movements. This criterion requires that functions activated through motion also be accessible through an accessible interface. It also requires that users be able to disable the motion-based controls to avoid accidental activation.
An example of when movement would be essential for an activity is a pedometer, which requires motion to register steps. Another exception is movement through space for GPS-based applications, such as applications that track runners, and Pokemon hunting in Pokemon Go. Finally, motion actuation that is part of a user’s assistive technology is acceptable.
Who it helps:
- Users with limited mobility who may have difficulty completing the movements.
- Users whose devices are mounted, such as some wheelchair users.
- Users who may accidentally activate gesture functions because of tremors.
“I have tremors, so I need to turn off motion activation — and then be able to do stuff without motion actuation."
- Comic with cerebral palsy who uses a wheelchair