7.14 London 2012 and Pokémon

(One of the official London 2012 Olympic Games logos)

After almost a decade of absence, photosensitive epilepsy re-surfaces in England. BBC News reports 1.5 alleged cases of seizure from watching a short animated segment of the Games promotion on TV (5 June, 2007). It involves a "diver diving into a pool which had a multi-colour ripple effect" according to a spokesperson. The segment was promptly removed from broadcasting and the london2012.org website.

It may not be a bad idea to give it a quick review, for video game designers/players and TV viewers alike.

Photosensitive epilepsy is a subset of epilepsy, involving 3-5% of all cases of epilepsy. Many cases, however, have no history of epilepsy at all. The most common trigger is the flickering light.

It has been established at the beginning of the TV age, that TV monitors with a refresh rate of 50Hz could provoke seizures. It was no longer a problem after the rate improved to 100Hz. During the the Disco era in the 1960s, the flashing strobe lights posed the same issue. Then in the late 1990s, with the immense popularity of TV-based video games, the occurrence of photosensitive seizures became alarmingly frequent. The trigger is still flickering light which is now software/game-specific. The London 2012 episode is, in fact, similar to that of the 700-1,000 children in Japan who suffered seizures after watching a Pokémon explosion cartoon 10 years ago. So it is really up to the video designers to carefully craft their products, e.g., 2 - 50Hz flickering is of course prohibited.

Nintendo Pokémon, i.e., Pocket Monster - ポケットモンスター

Photosensitive epilepsy is not a modern phenomenon. The Roman novelist and orator Apuleius (ca 125-170AD) noted that the spinning potter’s wheel could send onlookers into seizures. Others have reported that sunlight filtered through the leaves of a tree had the the same flickering effect when one passed under the tree. Even the whirling helicopter rotors, at low speed, has been reported to cause seizure. It is the periodicity heightened by contrast and brightness that can initiate aura which leads eventually to seizure.

If you are an avid video gamer (or a watcher for that matter), the following info maybe useful:

1. While playing TV-based video games, the viewing distance should be at least four times the monitor size (conventionally measured diagonally across the screen) - use a tape measure if necessary.
2. Eat and drink on a regular basis when playing.
3. No excessive play time - certainly not to continue when under stress (e.g., lack of sleep, running a fever, etc).
4. Do not play in a dark room, this to avoid high contrasts.
5. If episodes of photosensitivity, seek neurological consult, know how to manage the seizure, and dispose of the triggering games.

It is really a matter of common sense.