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Re: Revising 2.4, cont.

From: Adam Victor Reed <areed2@calstatela.edu>
Date: Wed, 23 May 2001 10:31:24 -0700
To: w3c-wai-gl@w3.org
Message-ID: <20010523103124.A1103@uranus.calstatela.edu>
Anne,

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
http://www.scils.rutgers.edu/~beam/mm/photosensitivity/links.htm
"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.
Received on Wednesday, 23 May 2001 13:34:35 GMT

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