Give motion-activated features conventional controls
Where a feature responds to shaking, tilting or moving the device, G213 asks for two things. W3C joins them with an and. A conventional control that does the same job with no sensor input, and a setting that lets the reader turn the sensor response off. Both are required, and the test checks both. This is a sufficient technique for 2.5.4 Motion Actuation at Level A, and it is the only one W3C documents for that rule. The exclusions are where owners misjudge scope. It does not apply where the motion is essential to what the application does. It does not cover a person moving through space as registered by geolocation or beacons, or anything the device observes that is not deliberate gesturing. And it does not cover the incidental motion of using a keyboard, a pointer, or assistive technology.
How we find it in an audit
Our reviewers find every motion-triggered feature and ask two questions. Is there another way to do it, and can the motion trigger be switched off? Mobile apps and progressive web apps are where these live. Shake to undo, tilt to scroll, raise to activate. We check the setting is discoverable rather than buried three levels into a preferences screen.
How affected users experience it
Motion input assumes a device somebody can move. A phone clamped to a wheelchair mount cannot be shaken, so the feature is simply unavailable. At the other end, a person with a tremor triggers it constantly and cannot stop, so shake-to-undo destroys work at random. One group needs the button and the other needs the off switch, which is why W3C requires both rather than either.
Passes vs. fails
Passes
Undo and Redo buttons in the toolbar, plus a setting for shake-to-undo, so the gesture becomes a convenience instead of a requirement.
Fails
A notes app where shake-to-undo cannot be disabled and has no button equivalent, so one user loses text to accidental undos and another can never undo at all.
How this gets tested
The W3C publishes test rules that define what a checker looks for here.
- Device motion based changes to the content can also be created from the user interfaceA tool finds candidates, you decide
- Device motion based changes to the content can be disabledA tool finds candidates, you decide
Other ways to satisfy this rule
2 guides on this site are filed under 2.5.4 Motion Actuation. W3C lists this one as sufficient for that rule on its own. Implement it correctly, in a way your readers' software actually supports, and the rule is met.
This guide is our interpretation of W3C technique G213: Provide conventional controls and an application setting for motion activated input. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.