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Action Item from 24 August

From: Marshall Jansen <marshall@hwg.org>
Date: Tue, 19 Sep 2000 14:08:53 -0500
Message-Id: <200009191917.PAA21040@mail0.lig.bellsouth.net>
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

Second disclaimer: this probably needs some work to turn it into a useable

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

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 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

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