Spam blockers blind to the blind
An increasingly popular technique for preventing e-mail abuse is frustrating some visually impaired Net users, setting the stage for a conflict between spam busters and advocates for the disabled.
Many companies have recently begun requiring users to pass a verification test in order to access their services--typically by typing into a Web form a few characters that appear on the form in a guise that prevents a computer or software robot from recognizing and copying them. The technique, now used by Web giants Yahoo, Microsoft, VeriSign and others, seeks to block software bots from signing up for Web-based e-mail accounts that can be used to launch spam and from scraping e-mail addresses from online databases.

The scheme is winning high marks in the battle against unwanted junk e-mail. But it is also increasingly hindering the progress of Web surfers with visual disabilities--raising the ire of advocates for the blind, spurring plans for alternatives from a key Web standards group, and eliciting warnings from legal experts who say that the practice could expose companies to lawsuits brought under the Americans with Disabilities Act.

"It seems that they have jumped on a technological idea without thinking through the consequences for the whole population," said Janina Sajka, director of technology research and development for the American Foundation for the Blind in Washington, D.C. "These systems claim to test whether there's a human on the other end. But it's only technology that can challenge certain human abilities. So someone who doesn't have that particular ability is excluded from participation. That's really inappropriate."

Efforts to create tests aimed at distinguishing humans from machines go back decades, with the most famous formulation of the problem posed in 1950 by the English mathematician and World War II "Enigma" code breaker Alan Turing. Turing's controversial hypothesis was that a machine could be defined as "intelligent" if a questioner could be fooled into believing it was a person.

Visual tests in a sense turn that theory on its head, assuming that a machine is defined by its inability to perform a task that is easy for most humans to accomplish.

The increase in use of visual tests--Yahoo in recent weeks has started springing them on users of its mail service--comes as Internet service providers and other companies are acknowledging and attacking the spam problem with unprecedented energy. Assaults on spam have come fast and furious this year on the litigation, legislation and technology fronts.

Companies that have implemented the technique call it a winner. Microsoft last month said it had achieved a 20 percent reduction in e-mail account registrations after implementing the test.

Some Web sites using visual tests provide work-arounds for the visually impaired; some don't. But existing work-arounds are less than perfect and less than universally implemented.

The increasingly popular visual test, and the difficulty of using current work-arounds, has raised enough hackles among advocates for the disabled that working groups within the World Wide Web Consortium's (W3C) Web Accessibility Initiative have begun discussions on how to standardize an alternative.

Two WAI working groups are hashing out proposals to guide Web sites in designing blind-friendly bot repellants, and the WAI hopes to address the issue in the next working draft of its Web Accessibility Guidelines, Version 2.0, which is due by year's end. So far, published working drafts of the guidelines are silent on the issue.

"What visual verification is testing is whether someone is a sighted human, even if that's not the intent of the organizations using it," said Judy Brewer, director of the WAI. "This has been a known problem for several years, and I know that we've received different complaints about it. But it's not necessarily an easy problem to solve."

Brewer did not specify what alternatives the WAI working groups were debating.
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