Flicker Rate
Any and all flickering text and objects should have a user controlled and accessible on/off switch. People with photosensitive epilepsy can have seizures triggered by flickering or flashing in the 4 to 59 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second as well as quick changes from dark to light (like strobe lights).
Example
Warning! This example consists of a flickering object. Click the On/Off switch to stop the flickering.
Links
Graphics That
Can Cause Seizures
http://www.webaim.org/techniques/images/4)
