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Re: Revising 2.4, cont.

From: Anne Pemberton <apembert@erols.com>
Date: Wed, 23 May 2001 17:00:28 -0400
Message-Id: <>
To: Adam Victor Reed <areed2@calstatela.edu>, w3c-wai-gl@w3.org

	Something was wrong with your link to the dell site. It came up page not

	I did check the other site, linked to the British Epilepsy organization,
and found the following note on the first page: 

>Visual display units (VDUs) 
>Contrary to public belief, the use of professional VDUs rarely presents
any risk to the person with epilepsy. However, the use of domestic
televisions as computer displays is likely to present a greater risk.
People using televisions as computer or computer games displays should view
at a distance of 2.5 metres or more. 

Seems there may not be any relativity to these types of seizures with
computer monitors unless they are TV's ...

I'd like to suggest that the note about flicker and seizures be removed
from the guidelines until and unless any hard data on it can be found. 

And repeat again, that the term "eliminate" is excessively heavy and not
well supported in documentation anyway. 


At 10:31 AM 5/23/01 -0700, Adam Victor Reed wrote:
>The site with the timeout was http://www.dell.com/refurbished.
>I am not a neurologist, but I did witness a seizure from stroboscopic
>light in an undergraduate physics lab, and that strobe flickered at a
>rate not very different from what I have seen on many web pages. Note
>that my not having witnesed actual seizures from video displays may
>be a result of living in North America. According to
>"Photosensitivity seizures are a bigger concern in the United Kingdom
>than they are in the U.S., because UK electrical current cycles at a
>slower rate than ours. This slows the flicker of the television there
>slightly, making television viewing more likely to provoke a seizure."
>Your point, that the inclusion of animations may be unobjectionable if
>motion and flicker can be prevented in the user agent, is well taken.
>I think that the following revision takes care of this:
>2.4 Do not limit the time that a user may need to understand or
>interact with your content.  Eliminate:
>        * demands that the user respond within a preset period
>        * automatic refresh and delayed redirection
>        * motion and flicker that cannot be prevented by the user.
>Content must cooperate with user agent mechanisms for disabling
>movement, or for control of the rate at which it occurs. Note that
>flicker effects can cause seizures in people with photoepilepsy.
>				Adam Reed
>				areed2@calstatela.edu
>Context matters. Seldom does *anything* have only one cause.
Anne Pemberton

Received on Wednesday, 23 May 2001 16:51:21 UTC

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