Action item: why structure is an accessibility issue

Structured content is important for users with disabilities who have to use
serial media" such as screen readers, or highly magnified screens. Reading
content that doesn't have structure is much slower for such users.

How much? This is a brief thought experiment in the absence of proper data:

I can look at approximately 1000 words in a glance, pick out the headings and
links in under a second, and read them in about 1-5 seconds (lower for a page
of actual content than for something like search engine output).  Using a
fast speech synthesis system that takes about two minutes. If navigating
content by recognising these things is 5 percent of using the web, that makes
it between about 2 and 6 times as slow overall.

(I am not sure what there difference is with braille because I don't know how
fast that goes, but the same calculations can be done for screen
magnification. Essentially visual recognition is much faster, and
comprehension requires recogition first).

Similar arguments apply to navigation of content, using input systems such as
sip-puff controllers, very limited keyboards, and so on. If the user can
rapidly access navigation controls providing outlines, link lists, etc. then
the difference is reduced to actual reading and "keying" speed.

Both of these things are important to accessibility. The importance for
content is reflected in the fact that structure is required by WCAG, and the
importance for navigation is that navigation of structure is required (in
several ways) by UAAG.

cheers

Charles McCN

-- 
Charles McCathieNevile    http://www.w3.org/People/Charles  phone: +61 409 134 136
W3C Web Accessibility Initiative     http://www.w3.org/WAI    fax: +1 617 258 5999
Location: 21 Mitchell street FOOTSCRAY Vic 3011, Australia
(or W3C INRIA, Route des Lucioles, BP 93, 06902 Sophia Antipolis Cedex, France)

Received on Tuesday, 14 August 2001 08:01:43 UTC