This translation has not been editorially reviewed yet. The German version is authoritative. Deutsche Fassung

Accessibility

Why do shake and tilt functions need an alternative?

Functions triggered by shaking, tilting, or leaning the device need an alternative through ordinary control elements — and a way to turn them off. People with tremors shake their phone unintentionally and trigger the function without meaning to; people with a device mounted in a fixed position, for example on a wheelchair, can't move it at all. WCAG criterion 2.5.4 "Motion Actuation" covers both cases.

Shake to undo, and other motion functions

Motion control sounds modern and is common in apps: shaking undoes the last input, tilting scrolls forward, leaning steers a game. Websites too can offer such functions via a phone's motion sensors. The criterion requires two things. First, equivalent operation through visible elements: alongside "shake to undo" there must also be an undo button. Second, a way to turn off motion triggering — for anyone whose hands tremble and who would otherwise keep undoing things unintentionally. The only exception is anything that measures the motion itself, such as a step counter. The most honest question to ask beforehand is: does the website need motion control at all.

How the audit service reports this criterion

Whether a website responds to device motion could only be established by having the check trigger motion events and observe the consequences — an intervention our passive measurement engine deliberately avoids: it triggers no functions on your website. An automatic judgment would therefore not be backed by any measurement. The audit report instead openly marks the criterion as a point for manual review. Since motion-controlled functions are rare on ordinary business websites, this human review is usually quick — but it still belongs in the report, so the seal's claim remains fully supported.

Examples

Reversible only by shaking

Not met

window.addEventListener("devicemotion", (e) => {
  if (istSchuetteln(e)) rueckgaengig();
});

Passes

window.addEventListener("devicemotion", (e) => {
  if (istSchuetteln(e) && einstellungen.schuetteln) rueckgaengig();
});
// dazu: <button type="button">Rückgängig</button> und ein Schalter, der Schütteln abstellt

Those who cannot move the device or it tremble need the same command as a button and turn off the movement.

Ask your agency whether your website or app responds to shaking, tilting, or leaning.
Give every motion function a visible control element with the same effect alongside it.
Offer a setting that lets motion triggering be turned off completely.
When in doubt, skip motion control — a button serves the same purpose for everyone.

Deutsche Fassung dieser Seite

FAQ

What is motion actuation on websites and apps?

Motion actuation means a function is triggered by moving the device — shaking undoes, tilting scrolls, leaning steers. Phones report such movements to websites too, via built-in sensors. WCAG requires a visible control element with the same effect for every such function, plus a way to turn off motion triggering.

For whom is motion control an obstacle?

For two groups at once: people with tremors or spasms move their device unintentionally and trigger the function without meaning to — right in the middle of typing, an undo suddenly happens. People with a device mounted in a fixed position, for example on a wheelchair, can't perform the required motion at all. Without an alternative, the function stays completely out of reach for them.

Does the criterion also apply to ordinary business websites?

Mostly only marginally: motion-controlled functions are rare on classic business websites and tend to be found in apps and games instead. It's still worth checking, however, especially with embedded third-party components. Our audit report therefore lists the criterion as a manual check point — on a website with no motion functions it's answered quickly, but it's never silently skipped.