Friday, April 07, 2006

Accessibility Guidance on Gatekeeping and Access Control from WAI

Making websites with limited access service accessible ...

"Inaccessibility of CAPTCHA: Alternatives to Visual Turing Tests on the Web" is a W3C Working Group Note. It's not brand new, but it's still incredibly timely.

The paper discusses the common method of limiting access to services made available over the Web using visual verification of a bitmapped image, a kind of Turing test to stop bots and so on passing through. It points out that this form of control presents a major problem to users who are blind, have low vision, or have a learning disability such as dyslexia.

The document runs through some alternative techniques for identifying real people on the Web and concludes: 'Sites with attractive resources and millions of users will always have a need for access control systems that limit widespread abuse. At that level, it is reasonable to employ many concurrent approaches, including audio and visual CAPTCHA, to do so. However, it must be noted that human users will fall through the cracks in these systems, and it will be necessary for sites like these to ensure that users with disabilities will have some human-operated means of interacting with a given resource in a reasonable amount of time. The widespread use of CAPTCHA in low-volume, low-resource sites, on the other hand, is unnecessarily damaging to the experience of users with disabilities."   continued ...   (Via Usability News, W3C)

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