The World Wide Web Consortium (W3C) issued on Wednesday a draft criticising visual verification tests that Web-based email services and other Internet businesses use. The tests are designed to prevent software robots from registering numerous accounts and harvesting information for spam schemes and the like.
The tests, which have incensed the visually impaired and their advocates, have popped up on some of the Web's most trafficked sites, including Microsoft's and Yahoo's free email services. Other sites using the tests include VeriSign's Network Solutions, which protects its Whois database of domain names with a test, and Ticketmaster.
None of those companies was available for comment.
Microsoft also uses a visual verification test to register people with its .Net Passport service, which lets people sign into a wide range of sites, including eBay, MSN, Monster.com, the Nasdaq, Pressplay, USA Today and Starbucks. And CNET News.com publishes some of its public email addresses in a graphical, computer-unreadable form in order to throw off spam address harvesters.
Often called a "Turing test" (after computer scientist Alan Turing, who famously described the requirements for a test to distinguish between a computer and a person), the visual verification test requires a person to read and type a series of characters camouflaged in a bitmap image a computer can't decipher.
The problem, the W3C warned in its draft, "Inaccessibility of Visually-Oriented Anti-Robot Tests," is that the visually impaired can't decipher it, either.
"This type of visual verification comes at a huge price to users who are blind, visually impaired or dyslexic," W3C Web accessibility specialist Matt May wrote in the draft. "Naturally, this image has no text equivalent accompanying it, as that would make it a giveaway to computerised systems. In many cases, these systems make it impossible for users with certain disabilities to create accounts or make purchases on these sites."
Some sites do offer a work-around for the visually impaired. Hotmail, for example, offers an audio alternative. And the report refers to an alternative Yahoo provides that lets people who can't pass the visual test call the company for verification through its customer service department, with a maximum 24-hour delay. But on Thursday, that option did not appear on Yahoo's sign-up page.
Even the work-arounds pose problems. A day's delay could cause a concertgoer to miss buying a ticket, the W3C pointed out. And the audio work-around, which requires some distortion to prevent computers from passing it, has a tendency to stymie humans.
In an informal test, three out of four members of the CNET News.com staff failed Hotmail's audio Turing test. That was a slight improvement over the results of a similar test staffers took in July, in which Hotmail mistakenly pegged four out of four as software robots.
In the draft, the W3C outlined various alternatives to the controversial verification tests, including biometric devices, logic tests and credit card verification.
But the draft also outlined flaws to each of these and did not recommend one of them over the other or over the common visual tests.
"There is no clear single solution for this," the WC3's May said in an interview. "What we attempted to do was provide a way to help people think through the problem they're trying to solve and to point out that the (visual verification) solution may not be the solution they think it is."
May held out the highest hope for so-called federated identity systems, such as those in the works by Microsoft and by the competing Liberty Alliance. Such systems let people establish online identities that are difficult to spoof and that work in various online contexts.
The W3C said the issue of Turing tests and accessibility was capturing more attention internationally from industry, standards and accessibility groups, as the use of such tests proliferates and that the W3C is trying to capitalise on that interest as it hones its draft.
"We would like to collect community feedback and collaborate with groups that are working on different aspects of the problem," said Judy Brewer, director of the W3C's Web Accessibility Initiative (WAI). "We've heard from the Antispam Research Group of the IRTF, as well as groups in the disability community who are working on this and industry groups. There's a lot of buzz on this topic in a number of different countries. We're trying to get out in front of it before it creates an even larger accessibility problem."
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