Stealing Cycles from Humans

Karl Anderson kra at
Mon Oct 20 00:23:32 PDT 2003

"The players may not realize it, but the lists of descriptive words that they're generating could eventually be used by search engines such as Google to improve Internet searches for images.

They also are doing something that no computer program has ever managed to accomplish: analyzing an image and accurately describing it in words.

In effect, what von Ahn is creating with his game is a giant, special-purpose supercomputer that uses human brains to do the computing. And the 24-year-old von Ahn, a graduate student in computer science at Carnegie Mellon University, says this approach, which he calls "Stealing Cycles from Humans," could be applied to a wide variety of problems that are too great for any individual but also beyond the capabilities of conventional computers."

"The CAPTCHA tests are simple for humans to pass, but hard for computers. A typical test features a word with fuzzy or distorted letters, or words overlapping each other, or a word superimposed on a complex background; visitors to the site are asked to type a word they see. Yahoo began using the CAPTCHAs on its Web registration form several years ago; other Web sites quickly copied the idea.

But at least one potential spammer managed to crack the CAPTCHA test. Someone designed a software robot that would fill out a registration form and, when confronted with a CAPTCHA test, would post it on a free porn site. Visitors to the porn site would be asked to complete the test before they could view more pornography, and the software robot would use their answer to complete the e-mail registration."

Karl Anderson      kra at 

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