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Re: guideline 7.1 about screen flickering (fwd)

From: Marja-Riitta Koivunen <marja@w3.org>
Date: Tue, 07 Aug 2001 18:29:08 -0400
Message-Id: <>
To: Anne Pemberton <apembert@erols.com>, "Jonathan Chetwynd" <j.chetwynd@btinternet.com>, "gregory j. rosmaita" <oedipus@hicom.net>, <w3c-wai-gl@w3.org>
I found one site with some Quicktime motion examples (if you worry about 
flickering don't try it)


The site is more explaining the effects than trying to demonstrate 
difficulties in reading text so there are still better examples. But try to 
make sense of the text explaining the phenomenon when the images are moving 
and then stop them or cover them and see if the reading becomes easier.

I don't have a suggestion for the actual guideline text right now. This is 
partly handled at UAAG by letting the users turn movement off and giving 
control of the frequency or selected steps.

Sometimes the use of these kinds of images is clearly necessary, as in the 
example site, but here the user could initiate them as in my opinion the 
movement is not needed for directing user's attention. The images are 
pretty visible anyway. The animation could also automatically stop after 
the first couple of rounds if it is not initiated by the user. In addition, 
as you said, they could be labeled with some metadata so that they could be 
filtered etc.


At 09:26 AM 8/6/2001 -0400, Anne Pemberton wrote:
>         Seems we are very close to agreement here. The concerns you 
> mention, such as monitoring the visual presentation of a web page as well 
> as the metadata and text tags, needs to be addressed in the techniques 
> for the guideline, not in the guideline itself. The guidelines say to 
> separate presentation and content, but don't provide advice on what you 
> need when you recombine them on a web site, as for a visual presentation, 
> audio presentation, etc.
>         Yes, you will always find badly designed sites, and some of the 
> worst are those that address web accessibility!  And some of the best are 
> found from the most surprising sources (see my comments this morning on 
> the gold mine on the AFB site for pictures of Helen Keller).  The 
> solution to badly designed sites, unless they are educational or 
> government, is to not use them .... if they are educational or 
> government, it's worth complaining about. The guidelines will never 
> prevent bad design, but if the guidelines prevent a badly designed site 
> from claiming to be accessible if it excludes too many people by its 
> design. Remember, if the graphic isn't there, no matter how badly 
> presented, the user can't choose to use it .... Period ...
>                                                 Anne
>At 08:29 AM 8/6/01 -0400, Marja-Riitta Koivunen wrote:
>>I very much enjoy graphics and multimedia myself and think it is 
>>extremely important. My goal is to make it easy for different users, not 
>>I myself have seen user interfaces that have been designed so that 
>>important text is right next to a moving image. This design made it 
>>really difficult to concentrate on reading the text as your eyes 
>>constantly wondered to the changing image. I don't have examples right 
>>now nor time to create them but if you are interested to you can program 
>>different variations yourself and see what the effect is. When the image 
>>is further away and the movement is less strong the text becomes easier 
>>to read.
>>Having difficulties in reading text does not prevent enjoying the 
>>movement or images especially if the user does not need or care to read 
>>the text and does not get epilepsy or other difficulties from the 
>>movements. However, if the designer thinks the text is important for 
>>users to read, he/she might want to select a different design.
>>I think it is important to gather as much knowledge as possible that is 
>>related to the guidelines. Another step is then to evaluate the effects 
>>on different disabilities and decide how much weight we need to put on 
>>different things. For instance, it might be important for users already 
>>having difficulties in reading or attention, not to add extra 
>>disturbances near an important text or at least let users turn these 
>>disturbances off when so wished. That users with good reading abilities 
>>or attention also have difficulties does not, in my opinion, make the 
>>problem disappear, it is only easier to discover.
>>At 07:18 AM 8/1/2001 -0400, Anne Pemberton wrote:
>>>         I didn't ask for "good references from the web" that defined 
>>> anything, I wanted an example of a movement on an actual site that kept 
>>> you, yourself, from understanding what was there. Over the past two 
>>> years, I've watched some 650 kids learn to use the computer and 
>>> thoroughly enjoyed all the movement included in their games and on the 
>>> web sites I gave them to use. So the definition is over-ridden by the 
>>> observation of actual people using computer and the web ...
>>>A further note: If your intent in this line of reasoning is hope that 
>>>you will be able to do away with banner ads on the web, you probably 
>>>need to think this through better. Advertisers aren't lining up waiting 
>>>to hear our words of wisdom.
>>>As for using Jakob Neilsen as a reference is like asking me to read the 
>>>wisdom on a sheet of toilet paper. As I told Kynn yesterday, Neilsen has 
>>>a disclaimer for not including graphics on his site which is so 
>>>overwhelmingly irritating and annoying that I am unable to read anything 
>>>else on his site.
>>>                                 Anne
>>>At 04:00 AM 8/1/01 -0400, Marja-Riitta Koivunen wrote:
>>>>I agree we learn to see but many things also develop normally in a 
>>>>certain way e.g. in our visual cortex there are cells specialized in 
>>>>detecting movement and it is hard keep the eye saccades out of the 
>>>>movement if it is strong enough. That is why advertisers want to use 
>>>>movement in the banners as it easily get's the user's attention.
>>>>I tried to find a good reference from the Web, but it was difficult 
>>>>without going too deep and I don't have more time now. The more 
>>>>understandable references are similar to this one:
>>>>In the visual periphery we can instantly detect even slight movement.
>>>>This is an important safety feature, developed long ago to recognize 
>>>>stalking predators. The eye's periphery reports a movement, the brain 
>>>>thinks it's important, and the vision is automatically centered on the 
>>>>threat. It is so imprinted on us that we can't do anything about it, 
>>>>and shouldn't.
>>>>Also Jacob Nielsen refers to it.
>>>>At 10:51 AM 7/30/2001 -0400, Anne Pemberton wrote:
>>>>>         While your point is well taken, your reason is not based on 
>>>>> fact. A cognitive system is not built and dropped in place, it is 
>>>>> *built* or developed over one's lifespan, and not all cognitive 
>>>>> systems are built to respond the same way to all stimuli whether 
>>>>> movement, sound, or images (including images of text, since for 
>>>>> perhaps most web user, text comes to them as an image).
>>>>>         Most of us trained our cognitive systems before the stimuli 
>>>>> under discussion was invented. Children growing up with this type of 
>>>>> stimuli will learn to respond to it more appropriately than us old geezers do.
>>>>>         Have you tried to read material close to a flickering source? 
>>>>> What site? so we can all test it. Or do you mean to say that you have 
>>>>> tried to read material close to a moving source, an animation, for 
>>>>> example (like that RADAR icon), and you were unable to read the text? 
>>>>> How close was the animation? Was text size appropriate to the icon or 
>>>>> did one overpower the other? What site did you test it on? Were there 
>>>>> any contributing factors preventing your understanding other than the 
>>>>> problem graphic? Does this happen whenever you encounter certain type 
>>>>> of graphics? Is there any reason that hitting the stop button (or the 
>>>>> equivalent in your browser) is insufficient? Does it help to enlarge 
>>>>> the text size near a competing graphic?
>>>>>         An remember, that being irritated or annoyed is not a disability.
>>>>>                                                         Anne
>>>>>At 09:52 AM 7/30/01 -0400, Marja-Riitta Koivunen wrote:
>>>>>>At 06:49 AM 7/27/2001 +0100, Jonathan Chetwynd wrote:
>>>>>>>given that placements are a more subtle way of advertising, perhaps 
>>>>>>>in the
>>>>>>>RADAR case and given the client group, it might make sense to advise 
>>>>>>>that an
>>>>>>>animated gif is liable to irritate, rather than rely on a medical 
>>>>>>And not only to irritate. Sometimes it makes it almost impossible to 
>>>>>>read a text that is near a flickering image as our cognitive system 
>>>>>>is built to pay attention to the movement.
>>>>Anne Pemberton
>>>Anne Pemberton
Received on Thursday, 9 August 2001 10:33:45 UTC

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