Avoid animated images
If images are a powerful force in commanding the attention of the user, moving images are many times more commanding. It is nearly impossible to ignore a page element that is moving, particularly one that is blinking rapidly on and off.
Animations are generally seen as an annoyance on Web sites. They make it difficult to focus on the primary content of a page. For some people, animations are more than an annoyance. They cause discomfort or even medical consequences, such as migraines or seizures. Even static images that only appear to be animated can be a trigger—for example, images with closely spaced stripes that seem to vibrate (Figure 4.5).
Figure 4.5: About.com uses a patterned background that appears to vibrate, which can cause discomfort and impair readability. www.about.com
Do not place an animation alongside primary content. An animation should appear on a page of its own so the decision to view it is an explicit user choice. Do not begin playing the animation right when the page loads. Instead, provide controls for starting and stopping the animation. Avoid images that include patterns that seem to animate, such as striped or patterned backgrounds.