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Author Topic: Why Do Flashing Lights Set Off An Epileptic Fit ?  (Read 5810 times)

Offline neilep

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Dear All,

Hope you're all well !

Once again we value your contributions so much !


This thread does contain some flashing lights !

Here they are !



Nice eh ?


How and why does the occurrence of a flashing light set off in some people an epileptic fit ?

Thanks

NEIL
MWAH MWAH MWAH
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Offline Karen W.

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Why Do Flashing Lights Set Off An Epileptic Fit ?
« Reply #1 on: 27/11/2007 18:24:22 »
Happens to people who are effected by photo sensitive epilepsy!
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http://en.wikipedia.org/wiki/Photosensitive_epilepsy
"Photosensitive epilepsy is a form of epilepsy in which seizures are triggered by visual stimuli that form patterns in time or space, such as flashing lights, bold, regular patterns, or regular moving patterns."
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 http://en.wikipedia.org/wiki/Strobe_light   
Strobe lights and epilepsy

Strobe lighting can trigger seizures in photosensitive epilepsy. Thus, most strobe lights on sale to the public are factory-limited to about 10-12 flashes per second in their internal oscillators, although externally triggered strobe lights will often flash as frequently as possible. At a frequency of 10 Hz, 65% of affected people are still at risk. The British Health and Safety Executive recommend that a net flash rate for a bank of strobe lights does not exceed 5 flashes per second, at which only 5% of photosensitive epileptics are at risk. It also recommends that no strobing effect continue for more than 30 seconds due to the potential for discomfort and disorientation.

Dennō Senshi Polygon, a 1997 episode of the Japanese animated television program Pokémon was involved in an incident in which reportedly 685 young viewers were taken to hospitals by ambulances after experiencing epileptic seizures (most of the patients recovered on the way to hospitals, although over 150 children were admitted to hospital care). The seizures were provoked by a scene in the episode of an explosion during which solid red and blue patterns blinked at a rate of about 12 Hz for about 6 seconds. Currently, the episode is banned worldwide, including in Japan.

It has been reported that the launch video for the London 2012 logo induced epileptic seizures in some people. The section of the video responsible has been removed.[2]



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I cant seem to find out how it triggers the seizures though!
« Last Edit: 27/11/2007 18:26:10 by Karen W. »
 

Offline RD

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Why Do Flashing Lights Set Off An Epileptic Fit ?
« Reply #2 on: 28/11/2007 18:00:56 »
I cant seem to find out how it triggers the seizures though!

As it is frequency dependent it must be a resonance effect...

Quote
The frequency or speed of flashing light that is most likely to cause seizures varies from person to person. Generally, flashing lights most likely to trigger seizures are between the frequency of 5 to 30 flashes per second (Hertz).
http://www.epilepsyfoundation.org/answerplace/Medical/seizures/precipitants/photosensitivity/photosensitivity.cfm
 

Offline Karen W.

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Why Do Flashing Lights Set Off An Epileptic Fit ?
« Reply #3 on: 29/11/2007 00:31:46 »
Thanks! I read a lot of similar information. This was good!
 

Offline adwkiwi

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Why Do Flashing Lights Set Off An Epileptic Fit ?
« Reply #4 on: 09/12/2007 21:48:52 »
As it is frequency dependent it must be a resonance effect...
Well a seizure is coherent electrical activity, ie overly synschonised. Perhaps the frequency that sets a given person of is the frequency at which their neural activity entrains to the signal.

It's occurred to me, though, that just because the visual stimulus is flashing at, say, 10Hz, doesn't mean that there's anything in visual cortex 'flashing' at 10Hz. The neural representation doesn't need to be similar to the signal in order to represent it. So it may be that it's not the frequency, per se, that does the entraining.
 

paul.fr

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Why Do Flashing Lights Set Off An Epileptic Fit ?
« Reply #5 on: 09/12/2007 22:09:50 »
Ahhhhhhhhh

thanks Neil, no seizures for a number of years...then i read this post, and see that flashy light.........
 

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Why Do Flashing Lights Set Off An Epileptic Fit ?
« Reply #5 on: 09/12/2007 22:09:50 »

 

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