Animation from Interactions
Motion animation triggered by interaction can be disabled, unless the animation is essential to the functionality or the information being conveyed.
In plain language
If an action (like scrolling or hovering) triggers a moving animation, there should be a way to turn that motion off — unless the animation is truly essential to what's being conveyed.
Why it matters
Motion effects like parallax scrolling can cause dizziness, nausea, or disorientation for people with vestibular (inner ear and balance) disorders. Letting people disable non-essential motion removes that physical harm without removing the feature for everyone else.
In practice
Fails this criterion
A site has decorative parallax scrolling where background images shift as you scroll, with no setting to turn it off.
Meets this criterion
The same site's scrolling animation automatically disables itself when the user's operating system has "reduce motion" turned on.
Test it yourself
Turn on your operating system's "reduce motion" setting, then scroll and interact with the site. Do animations triggered by your actions stop or reduce? If motion still plays with no way to disable it, this criterion is failing.