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Requirement •  Explanation •  Example (do NOT click if susceptible to seizures)

Accessibility Initiative

Section 508 Requirement

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


Some individuals with photosensitive epilepsy can have a seizure triggered by displays that flicker, flash, or blink from 2 to 55 flashes per second. Scrolling or blinking text can also be very difficult to read for people with visual impairments and cognitive disabilities.

Usability studies show that all Web users are negatively affected by unnecessary screen movement and often attempt to remove the movement from their field of vision. Try to avoid animation, including scrolling text, unless it is essential to the context of the Web page.

Do NOT click the link below if you have a history of seizures:

View moving features (do NOT click if susceptible to seizures) that need to be avoided on your Web site(s).

If you would like a test run on your animated gif images, please email the graphic and Web address where it can be found to
If you would like to read more information about screen movement, visit the HiSoftware Web Site for a "Potential Screen Movement and Flickering Report."


For your convenience, you may also wish to download a printer-friendly Section 508 checklist (pdf).
For additional assistance with this requirement, send an email to

Web Services
200 Tillman Hall
Rock Hill, SC 29733
803/328-2855 (Fax)
Adobe ReaderWeb Work Request Form (pdf)