- From: Marshall Jansen <marshall@hwg.org>
- Date: Tue, 19 Sep 2000 14:08:53 -0500
- To: Web Content Accessibility Guidelines <w3c-wai-gl@w3.org>
Action Marshall: write up something about visual presentation. Look at principle 4 for requirements that are not included. Ok, I've let this sit long enough. First disclaimer: I'm not a visual media expert, but I have had some experience. Second disclaimer: this probably needs some work to turn it into a useable document. The sighted user, when presented with a web page, follows an ingrained set of 'rules' as to what draws the eye first. The eye is drawn to several different things, but motion, size, and contrast are the primary attention-getters. The most attention-grabing item tends to be a combination of all three... a large, high contrast, 'moving' image will immedaitely draw the eye. In this case, motion is a misnomer, it might not be motion, but simply a color change. Strobe effects tend to have the greatest effect at grabbing attention. The BLINK tag is an example, and images that flash two high contrast colors are another. While the initial blink draws attention, the eye can eventually tune it out. You can cause the viewer to repeatedly be drawn to this item by implementing a delay. For example, a short (1 second) strobe effect will immediately draw the eye. If the author continuously strobes, the brain will eventually tune it out, but if a 5-10 second delay is in place, then every time the strobe effect happens for that 1 second, the eye will be drawn to it again. After gross motion and strobe effects, the eye will tend to be drawn to images rather than text. Brightly colored images tend to have a greater capability at attracting attention than black and white, and high-contrast simple images are more attracting than low contrast and complex images... the eye will be drawn to a 2-color high contrast icon than it will be drawn to a black and white photo. That said about images, some types of text are more visually attention-grabbing than images. First off is size... large text is read first. Secondly is a contrasting color, if your document is full of plain balck text, then red or blue text will 'jump out'. Obviously text that is both large and a contrasting color will be more visible on a first glance that text that is just big or just a different color. After those issues, the next is a font modificatioin, be it bold, italic, or a new font altogether. Bold text tends to be more noticeable, just as if it were a different size. In contrast, italic text tends to be LESS noticeable than standard text. Font changes are hard to judge in general... it would have to be seen on a case-by-case basis as to how significantly a font change draws the eye. Finally, after all of the above is said and done, the sighted user will 'default' to an initial point on the page, if there are no visual cues to draw them in. This tends to be cultural/language based. English readers will track to the top-right corner of the page even if there are multiple 'articles' visible. (i.e, if you have three separate columns of text, each one a separate 'article', English speaking readers will read the leftmost one first.) The next logical step would be to create a chart of all of the possible elements (strobing images/text; large, high contrast text; bold text, etc) and 'rate' them by how much they draw the eye. However, I don't feel particularly qualified for that task, as once you get into nuances, my understanding breaks down (i.e. which draws the eye more? Bold text that is a contrasting color to the rest of the document, or a small icon of high contrast colors? I personally have no idea, and would have to say 'it's about the same') Marshall. -- Marshall Jansen // marshall@hwg.org Senior Web Developer VP of Marketing and Outreach HTML Writers Guild, Inc. // <http://www.hwg.org/>www.hwg.org
Received on Tuesday, 19 September 2000 15:17:20 UTC