Page Design: Visual Elements No Flickering, Blinking or Moving
Content WAI Definition (Checkpoints 7.1, 7.2 and 7.3) Until user
agents allow users to control flickering, avoid causing the
screen to flicker. Until user agents allow users to control
blinking, avoid causing content to blink (i.e., change
presentation at a regular rate, such as turning on and off).
Until user agents allow users to freeze moving content, avoid
moving elements in pages. Avoid visual elements which can cause
the screen to flicker, move or blink. Screen flickering and
blinking can trigger epileptic seizures in people suffering from
photosensitive epilepsy. Older screen readers also have problems
with blinking or moving content and may crash or be unable to
render the content at all. Furthermore, it is difficult to read
some text that is flashing or moving, or to read the content of
a page when something else is flashing or moving on that page.
Users read at different speeds and moving text does not
accommodate those differences. Blin