Understanding WCAG SC 2.5.4: Motion Actuation
Version and Level: 2.1/2.2 (Level A)

WCAG SC 2.5.4 requires that functionality operated by device motion or user motion can also be operated by other mechanism such as user interface components and that motion-based operation can be disabled to prevent accidental activation. This ensures accessibility for users who may not be able to perform certain motions or who might accidentally trigger motion-based functionality due to a disability.

Benefits:

  1. Motor Impairments: Ensures users with limited motor abilities such as a fixed mountain devices on a wheelchair, can operate functions without relying on motion.
  2. Prevents Accidental Activation: Reduces the risk of unintended actions due to accidental device movement.

Main Objective:

To ensure that any motion-based functionality can also be operated through conventional user interface components, this refers to users who are unable to perform specific motions with their devices, such as tilting the device to the right or left to move between pages or slides. Providing an additional mechanism such as right and left arrow buttons, or 'next page' and 'previous page' buttons, will resolve the issue.

Success criterion 2.5.4 also ensures that users can disable motion detection to prevent accidental actuation. Users who may experience unintentional shakes or tremors can accidentally trigger some web functionality, such as the undo function, while typing text on an input form control. Providing the option to turn off motion triggers will resolve this issue.

There are some exceptions to this success criterion. For example, certain games require right or left motions, and navigation applications like Google Maps need the user to point the device to align directions on the application.

Best Practices:

  • Provide alternative controls for motion-based functions: Provide alternative controls for motion-based functions, such as buttons for actions that might be triggered by gestures.

  • Include a mechanism to disable motion actuation: Include a mechanism to disable motion actuation in system settings.

  • Implement confirmation or cancellation for motion-triggered actions: Implement a confirmation or cancellation mechanism for motion-triggered actions.

Examples & Explanation:

Example: Shaking Device to Issue an "Undo" Command

What Should Be Avoided

A website's form includes a feature where shaking the device triggers an "Undo" command to clear the last input, without providing an alternative method to perform this action. The "Undo" command can only be activated by shaking the device. Users are unable to disable the shake functionality to prevent accidental activation.

Explanation:In this scenario, users who cannot perform the shaking gesture or who might accidentally trigger the shake cannot effectively use the "Undo" command. This lack of alternative methods and settings does not meet accessibility standards.

What Should Be Done

In the corrected implementation, users have the option to use an "Undo" button and can disable the shake functionality if it is not suitable for them. This ensures that all users, regardless of their ability to perform shaking gestures, can interact with the website and customize their interaction with the form.

Explanation:Since single-pointer activation and an additional single-pointer activation are available to users, this success criterion passes.

Next Up

Expand your knowledge with SC 2.5.7 - Dragging Movements. Learn to make dragging movements accessible for all users.

Go to SC 2.5.7