Paka paka is the
anime technique that is used to create strong flashes of
colour. It is more generally known as
Transmitted Light Photographing.
In the early evening on December 16th,
1997, nearly 700 children were taken to area hospitals in
Japan with complaints of sudden
illness, akin to
epileptic seizures. Over 1700 children were absent from
elementary schools the very next day.
These children became ill at approximately 6:50 pm, while watching episode #38 of the original
Pokemon cartoon. The
Pikachu character successfully detonated incoming
rockets, and the resulting explosions appeared as blue and red
blasts of colour. It was also discovered in the later research that similar symptoms had occurred, although smaller in
scale, during the airing of "
YAT Anshin! Space Travel" story #25 on Saturday, March 29, 1997.
Formal experiments later confirmed that the
rapid,
rhythmic flashing of blues and reds triggered the seizures. The
symptoms varied, and all affected children recovered soon after.
Paka paka was used in this particular scene. Illuminating the
animation cell from behind during production
photography creates a more radiant flash or light effect.
This is commonly used in the
genre. In fact, paka paka was used in many previous episodes without (reported) incident. There were certainly other key factors at work, including the child's
proximity to the television, light levels in the room, and the size of the
screen.
Nor is this an
isolated incident.
Music videos,
cinema, and
advertisements have been known to cause seizures for a small percentage of the viewing
population. Early
videogames came with
health warnings for those who may be at risk.
Photosensitive epilepsy (PSE) is not a new
phenomenon.
Seizures (and/or extreme
discomfort) can be created experimentally using existing
biofeedback technology. Through an
electroencephalograph, a
stroboscopic flash can be synchronized with the brain waves of the subject, generating what is equivalent to a neurological
feedback loop. In this case the subtle rhythms of the mind are fed directly back through the visual cortex. Consciousness loss begins to
happen.
Source:
http://www.yusei.go.jp/policyreports/english/group/broadcasting/final_report_1.html