Tutorials from WAC. Click or press ALT+T to return to the Tutorials main page.

Understanding and Applying
Section 508 Standards

divider

Flashing or Flickering Elements:

(j) Pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz.

Causing a page or elements on a page to flash or flicker can have serious effects on users with epilepsy and light sensitivity. Flashing and moving graphics can also be extremely distracting and just plain annoying to other users.

Here is an example of a page with too many flickering elements: North Royalton Police Department (archive) . [Note: this page is an archive from February 2003. Visit the updated and much improved site and note the difference: North Royalton Police Department (current)].

Flashing or flickering elements are usually added through technologies such as animated gif's, Java applets, or third-party plug-ins or applications. Java applets and third party plug-ins can be identified by the presence of <APPLET> or <OBJECT> tags. Animated gif's are images that download in a single file (like ordinary image files), but have content that changes over short periods of time. Like other images, however, they are usually incorporated through the use of the <IMG> tag.

Next  Link and graphic of hand pointing to the next page.

divider

(a) Alternate Descriptions for Non-Text Elements | (b) Synchronization with Multimedia | (c) Use Color for Design, not Context | (d) Using Style Sheets | (e) Server-Side Image Maps | (f) Client-side Image Maps | (g & h) Data Table Headers | (i) Using Frames | (j) Flashing or Flickering Elements | (k) Updating Text-Only Versions | (l) Using Scripts to Create Dynamic Pages | (m) Using Applets and Plug-Ins | (n) Using Online Forms | (o) Skip Navigation Link | (p) Using Time Out Scripts | 508 Checklist | Testing for 508 Compliance |

Return to Start of Section 508 Tutorial

Information in this tutorial adapted from the Section 508 web site: http://www.section508.gov and the Access Board's Guide to the Section 508 Standards for Electronic and Information Technology.