Characterizing the flashing television images that precipitate seizures

Television is by nature a flickering medium. It is also designed to convey images that flash or flicker. This paper seeks to characterize the stimulus parameters of broadcast materials that have been responsible for triggering epileptic seizures. Three sources of evidence are considered: the characteristics of flicker and pattern predicted to induce seizures on the basis of clinical studies; the statistics of broadcast images; and the characteristics of video sequences that have been associated with anecdotal reports of seizures. The results of these studies have contributed to a revision, in mid-2001, of a Guidance Note issued by the Independent Television Commission (ITC) in the U.K. seeking to protect, so far as is reasonably practicable, the section of the population that is liable to photosensitive epilepsy.