Animation

Side effects for certain users

Poorly designed animations may affect users with:

• Photosensitive epilepsy – seizures can be triggered by flashing and/or brightly coloured light, with red and/or high contrast animations carrying the most risk.
• Visual impairments– screen readers sometimes struggle to present content that changes unexpectedly.
• Vestibular disorders – symptoms like motion sickness, headaches, and nausea can occur when viewing large-scale animations and media.
• Migraine sensitivities or headaches – may have similar responses to people with vestibular disorders.
• Difficulties reading or concentration – on-screen movement can be distracting and this may prevent people from completing tasks or getting the information they need.

Length of animation

WCAG states an animation should be:

• less than 5 seconds, or
• any animation over 5 seconds should include an option for the user to pause, stop or hide it.

Animation and seizures

As we’ve seen, bright, strobing animations can cause seizures in people with photosensitive epilepsy. In addition to the general animation considerations outlined above, it’s also vital that:

• Animations don’t flash more than 3 times per second.
• Flashing elements are small in size.
• Tonally similar colours, or more gradual animations are used.
• Red is avoided, or applied very carefully if creating any sort of flashing or blinking.