ABSTRACT
Exposure to flashing lights with certain visual patterns or at specific frequencies can trigger seizures in about 3% of individuals who have epilepsy. Use an appropriate flash rate to capture a user’s attention in an urgent situation. Things that flash are likely to draw attention better than equivalent things that are steadily displayed. This explains why police cars are equipped with flashing lights. One problem to avoid is flashing an indicator too slowly. Indicators that flash too rapidly can be annoying, as if the light is flickering due to a component failure rather than cycling rapidly to communicate a special meaning. Sometimes, flashing indicates that something is in progress or acts as a call-to-action. The condition is called “photosensitive epilepsy.” To protect against seizures in such individuals, the Epilepsy Foundation recommends keeping flashing rates below 2 Hz and including occasional pattern breaks.
