Georgia Tech Research Institute
 
Accessibility Assistant

Accessibility Assistant

Issues

Indicator Lights (3 of 4)

Issue: Flashing lights can trigger seizures in some users.

Lights that flash at certain frequencies may induce seizures in users with photosensitive epilepsy. Seizures are typically induced by flash rates between 2 Hz and 55 Hz, and flashing that occupies a large portion of the visual field is more likely to induce seizures.

Populations Impacted: Users with photosensitive epilepsy.

Potential Solutions:
  • Avoid flashing lights with flash rates between 2 Hz and 55 Hz. If flashing indicator lights are used, ensure that the flash rate does not fall within these bounds.

  • Avoid flashing lights that occupy large areas. Flashing lights that occupy only part of the user's visual field are less likely to induce seizures than lights that fill the user's visual field. Therefore, flashing lights that cover large areas of the machine should be avoided.

Additional Comments: Although the solutions presented above will improve accessibility for those who are color blind (and for some with low vision), they in no way solve the problem for users who are blind and are therefore dependent on tactile or auditory differentiation of status information.

Applicable Guidelines:
Section 508 - 1194.25(i)
Section 255 - 1193.43(f)
HFDS - 5.2.1.2
EITAAC - 5.2.1.12.1