- From: Steven Livingstone <stv_es@hotmail.com>
- Date: Wed, 1 Aug 2001 16:18:01 -0700
- To: <w3c-wai-gl@w3.org>, "'Marja-Riitta Koivunen'" <marja@w3.org>
- Message-ID: <000001c11ae0$35ea2b60$0157a8c0@dev.citix.com>
Just on this note. I recently demonstrated a simple but nevertheless effective example of this kind of flickering. Using DHTML (which is becoming more standardized) as client script, you can accomplish various kinds of “filters”. I have encountered gradually more sights which do this as… a. An introductory or splash screen to their sight. Quite often (unlike MOST flash sites) there is no stop. You also cannot stop it by clicking on the browser stop button. My example used a document click to stop it and provided the non-animated version. My fear is that as this gets easier to do many more sites will have stuff like this. b. For some reason best known to god knows who, some creators feel that the site should have a slide show look to it. So as you move from page-to-page, simple DHTML is used to checker in the next page, or slide in the next one. c. Although not really commonplace yet, I guess these filters will be used more and more to provide ads and other multi-media features. Now, I should say that relative to most of you I am very new to the Accessibility scene and my best skills lie elsewhere, so these may not be particularly valid points. But nevertheless, hopefully these other skills will help me bring something to the table :) Thanks, Steven Steven Livingstone, Author Pro XML 2e and others. http://www.deltabis.com -----Original Message----- From: w3c-wai-gl-request@w3.org [mailto:w3c-wai-gl-request@w3.org] On Behalf Of Marja-Riitta Koivunen Sent: Wednesday, August 01, 2001 1:00 AM To: Anne Pemberton; Jonathan Chetwynd; gregory j. rosmaita; w3c-wai-gl@w3.org Subject: Re: guideline 7.1 about screen flickering (fwd) 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. http://www.useit.com/alertbox/9512. <http://www.useit.com/alertbox/9512.html> html <http://www.useit.com/alertbox/9512.html> Marja At 10:51 AM 7/30/2001 -0400, Anne Pemberton wrote: Marja, 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 condition. 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. Marja jonathan chetwynd IT teacher (LDD) j.chetwynd@btinternet.com http://www.peepo.com <http://www.peepo.com /> "The first and still the best picture directory on the web" Anne Pemberton apembert@erols.com http://www.erols.com/stevepem http://www.geocities.com/apembert45
Received on Wednesday, 1 August 2001 16:18:52 UTC