These standards apply to websites and mobile apps supported by departments, units, colleges and other communications teams, with the exception of accessibility standards, which are required for all ASU websites (including lab, faculty and classroom sites).
It is often tempting to add animation to a webpage to “make it look more innovative” or add an element of excitement. But seasoned web animators know that animation is powerful, and must be used correctly. Here are a few good reasons to incorporate animation:
Reduce cognitive load
Animations can cut the amount of effort needed for a user to understand an interaction. They can quickly give a user feedback, such as when a “daisy wheel” spins to indicate that the system is processing.
Animations can also bring the user’s attention to something new, or tell the user that an action needs to be taken (think of a “ringing bell” icon when a new social media message arrives).
They can also help prevent “change blindness” by calling attention to an element that has changed subtly.
Communicate content more effectively
Animation can be used in place of long paragraphs of text to demonstrate a concept or tell a story. It can be a better alternative to video for users with limited data access.
Some users with reading disabilities can engage with animated content more easily than with written words.
Web and mobile animations must follow WCAG 2.0 guidelines; they should be accessible and supportive to all users.
- Animations that convey meaning or content must include a text-based alternative. A transcription below the animation is acceptable.
- Any animation with audio must allow the user to control the audio. Any animation with more than three seconds of audio must provide play/pause/stop controls. Sound should not autoplay.
- Animations with audio that uses spoken words must be captioned, or a transcript must be provided below the animated element.
- Any animation that lasts more than five seconds, regardless of sound, must provide play/pause/stop controls. Animations that run on a continuous loop are considered to last more than five seconds.
- Animation controls must be placed in consistent locations and the click target must be at least 48x48 pixels.
- Color should not be used as a sole sensory indicator (e.g., “Place the green star on the red circle”).
- Be sensitive to users with vestibular disorders. Certain animations, especially in certain color combinations, can cause a feeling of illness.
- Parallax must be confined to small areas of the screen, as it can trigger illness.
- Do not use animations that can trigger epilepsy. Animations, including animated gifs, should not blink or flash more than three times per second. Avoid flashing fully saturated reds.
Animations used in element transitions (such as a dropdown or carousel slide) should be subtle and not call excessive attention to themselves. Avoid triggering several different animated elements on a page at the same time, as this might confuse the user.
Respect the user
When animating an element, ask:
- Does this support — or interrupt — a user’s task?
- Does it slow the user down or speed things up?
- Does it feel natural or obtrusive?
- Does it provide important information or is it a novelty?
Animations should only distract from the natural focus of the page’s content when necessary, such as to provide a notification or warn against a destructive possibility (such as the system logging the user out after too much inactivity).
Finally, animations should be consistent across the ASU ecosystem, and should seem familiar to what users encounter around the internet. Remember that most of our web visitors are visiting other ASU sites, and many are using more than one ASU mobile app. An “opening barn door” effect in your carousel might be fun, but it’s too different from other ASU sites and can cause confusion.
It takes as little as 13 milliseconds (ms) for our brains to "see" an image, which equates to about 80 frames per second; 90 frames per second is advised for virtual reality development.
Animations viewed from the center of a user’s cone of vision only need shorter durations (closer to the 70-200 ms spectrum) to complete due to the eye having less distance to travel.
Animations that are on the edge of the cone of vision, or peripheral vision, benefit from additional time for the user to move their eyes (300-700 ms). This allows users more time to recognize and identify objects moving into view.
Users’ eyes are very sensitive to changes in color when viewed directly. Therefore it is recommended that color and opacity changes take less than 100 ms.
CSS transition-duration: accepts both seconds and milliseconds. The default timing is 0 seconds.
The average person takes approximately 215-230 ms to react to a visual change.
200-500 ms is the recommended starting point to complete an animation. From there the animation can be fine-tuned so that it feels right.