Amazon's Mechanical Turk allows users to sign up for quick, low paying, online-based jobs like writing with photo captions, allowing other large Web companies including Twitter to crowdsouce the labor they don't want to have their full-time staff doing. But now a new study has found that while many users thought their work was anonymous, Amazon actually links it to their public Amazon profiles, identifying them. The researchers warn this could be combined with other information to identify people who don't necessarily want to be outed online.

"Users of Amazon Mechanical Turk generally believe that the workers are anonymous."

"Users of Amazon Mechanical Turk generally believe that the workers are anonymous, identified only by a long obscure identifier like A3IZSXSSGW80FN," wrote one of the researchers behind the study, MIT associate professor of computer science Rob Miller, in a blog post on the findings. "But it isn’t true. Many MTurk workers are rather easy to identify."

Miller stumbled across his own Mechanical Turk public profile on Amazon containing his full name. That led his team to look for more. They now estimate 50 percent of the website's 500,000 workers have been linked to public Amazon user profiles, and about 30 percent list workers' first and last names. Yet when they surveyed the workers, researchers found 80 percent of a group of 1,000 were unsure of or didn't think job posters had access to their real names, and that 95 percent "placed relatively high value on the security of their first and last name."

An estimated 50 percent of Mechanical Turk's 500,000 workers have a public profile

The researchers conclude: "While neither the Amazon Profile or the WorkerID are individually a problem, it is still unsettling whenever such linkage occurs in ways that seem surprising to users." They advise the company to warn users more clearly going forward, or risk damaging its appeal as a trustworthy crowdsourced labor platform. The Verge has reached out to Amazon for a response to the study and will update when we hear anything.