On Input
Changing the setting of any user interface component does not automatically cause a change of context, unless the user has been advised of the behavior before using the component.
In plain language
Changing something in a form (like picking an option from a dropdown) shouldn't automatically trigger a big change — like submitting the form or opening a new page — unless the user was warned in advance that it would.
Why it matters
An unexpected jump to a new page or window is disorienting for anyone, but especially for people with cognitive disabilities or screen reader users, who may not immediately realize the context changed and lose track of what they were doing.
In practice
Fails this criterion
Selecting an option from a dropdown menu instantly opens a new browser window, with no warning that this would happen.
Meets this criterion
The same dropdown reveals more form fields on the same page when an option is selected — no navigation, no surprise. If a selection needs to navigate somewhere, the user is told about that behavior beforehand.
Test it yourself
Interact with the site's dropdowns, checkboxes, and other form controls. Does simply changing a setting trigger an unexpected navigation or major change? If so, and there was no advance warning, this criterion is failing.