WCAG 2.1 – What is Motion Actuation?

As part of an ongoing series, we’re looking into the latest criteria that have been added in WCAG 2.1. In this blog post, we’ll be looking into Motion Actuation.

We’ve mentioned in a few posts that one of the reasons why the World Wide Web Consortium (W3C) created WCAG 2.1 was because of the introduction of mobile devices and smart phones that include features that were not present ten years ago. Two additions to devices that have become ordinary on mobile devices include a front facing camera and accelerometers.

A racing games controls menu

Some games, for example racing games, allow for steering by tilting the device.

An accelerometer measures a device’s movement throughout a 3d space and then feeds this information to another part of a computer. Using this information, a device knows whether it has changed orientation, and includes specific information such as the exact degree the device is titled.

2.5.4 – Motion Actuation (Level A)

The success criterion on motion actuation states in full:

Functionality that can be operated by device motion or user motion can also be operated by user interface components and responding to the motion can be disabled to prevent accidental actuation, except when:

Supported Interface
The motion is used to operate functionality through an accessibility supported interface;
Essential
The motion is essential for the function and doing so would invalidate the activity.

Front facing cameras and accelerometers enable users to interact with content in new ways. For example, by shaking the device it might initiate an ‘undo’ option. By waving your hand in front of the camera it could make a web browser go backward or forward. However, not all these types of features are useful for all users.

Users with a motor disability may have difficulty using an accelerometer in a precise ‘shaking’ manner, or be unable to make a clear hand gesture to the front facing camera. Furthermore, if the device is mounted to a wheel chair or work surface, tilting the device will not be possible. It is therefore important that a provision is made for such cases.

There needs to be a method included that will prevent motion actuation on web pages. This will not just help users with a disability, but all users who may inadvertently activate features or unintended actions, such as deleting text  or changing the volume of a video.

Exclusions

The success criterion mentions that there will be cases where motion actuation is essential. An example of this could be a pedometer that measures the number of steps a person takes using the accelerometer.

Conclusions

On most mobile devices today there are front facing cameras and accelerometers. These provide a number of useful features, and provide an additional method of interacting with content.

For some users and circumstances having an interaction using a front facing camera or accelerometer will not be appropriate and could lead to inaccurate interaction or because of where the device is situated, interaction will not be possible. A provision needs to be included to ensure that this type of interaction can be switched off.

Does your website have Motion Actuation active?

It’s possible that your website has been created to include features that may be useful for a number of visitors, but it’s important that provision is given to all users. Even if your website doesn’t include Motion Actuation, a website audit against WCAG 2.1 will ensure that your website can be used by all your visitors.

Feel free to contact Dig Inclusion for information on how we can help you.