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Re: Usability and accessability

From: Al Gilman <asgilman@iamdigex.net>
Date: Fri, 03 Nov 2000 11:35:36 -0500
Message-Id: <Version.32.20001103093237.042e1990@pop.iamdigex.net>
To: sifyalok@sify.com, WAI Interest Group <w3c-wai-ig@w3.org>
At 08:35 AM 2000-11-03 +0000, sifyalok@sify.com wrote:
>Dear all,
>
>What all is there (if defined categories are 
>there) in usability apart from accessability? 
>(talking primarily in web context)
>

Two concepts have appeared repeatedly in discussions of this question.

One concept is that it's not accessibility if the usability defect applies to
all, and does not have a discriminatory effect on people with disabilities.

The other concept has to do with differences in usability that make a task
longer or harder to do, but do not materially decrease the likelihood of task
completion.  In this circumstance, that is likely to provoke comments of
"that's usability, not accessibility."  This creates a distinction between
'accessible' and "equal access."  It may take longer to roll your chair up the
ramp than to run up the stairs, but that is the reasonable-accomodation
balance
point or tradeoff on access to buildings.

It may help to think of usability as a _quantitative_ assessment of how _easy_
a task is, and accessibility as a _discrete_, discussion of cases and remedies
where the easiness degrades to failure levels under person-with-disability
condition.  

Accessibility is in this view is metaphorically a special case of FRACAS -
Failure Reporting and Corrective Action System.

This gets sticky when dealing with cognitive issues, because cognition is deep
in the human processing of the human:computer dialog, and the associated
functional impairments tend to be diffuse and gradual, not as sharply
localized
in interaction phenomenology as those of sensory or actuation failure modes.

Al

>Cheers
>alokjain
>Cognitive Consultant
>Satyam Infoway Ltd
>India
>
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Received on Friday, 3 November 2000 11:07:16 GMT

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