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Why This is Important
Motion-activated interactions require precise control over movement. This is inaccessible to people with physical and motor disabilities.
Blind and visually impaired people use screen readers to interact with websites and apps. A screen reader is a type of assistive tech that converts things on screen to audio and/or braille. It's important that things are understandable and interactive to screen readers.
Keyboard accessibility is essential for people who do not use a computer mouse (which might be because they have unpredictable or very specific movement due to a motor disability). Many Blind and visually impaired people also use keyboard interactions in order to use their screen reader.
Error support is accessible to people with a diversity of disabilities. A cognitive disability might affect how a person perceives and understands things. A physical disability might lead to unpredictable movement. Other factors such as environment, stress, and multi-tasking may also lead to errors.
In order to be accessible, gestures and interactions must account for people with physical and motor disabilities, who might have unpredictable or very specific movement.
Sometimes, devices allow people to use physical gestures to perform functions, such as shaking your phone to undo or skip to the next song in your playlist. This is inaccessible to people with motor disabilities and people in a situation with a lot of movement, such as on a subway train or moving through a crowd.
Instead, provide conventional ways to perform functions - such as buttons, keyboard input, and voice input. This is more predictable and gives the user more control over what they’re doing.
This references WCAG criterion 2.5.4 Motion Actuation (Level A).
Level AAA compliance is considered more difficult to meet because it requires more resources to fulfill. It also might encompass conflicting access needs (meaning what is accessible to some might be inaccessible to others). Use your best judgment of your target audience and your team's capabilities to determine if this is a pragmatic goal to reach.
How to Implement This
This doesn’t necessarily mean that you should not use any motion-activated interactions. With interesting new ways of making art, such as 3D painting with Virtual Reality, motion-activated interactions can feel new and exciting to certain people.
This guideline simply means the motion-activated interaction should not be the default and there should be a way to turn it off. If you include motion-activated interactions, make sure there is a way to turn them off in Settings.
The exceptions to this rule are if a certain motion is essential to the experience (such as the 3D painting example) or if the motion is essential to operating a piece of assistive technology that the person is using.
How to Test This
It's unclear what the best way to test this is. Throw your device around and make note if anything happens? If you have any suggestions, please reach out in the form below.
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