More on ReCaptcha
Mr. Ahn calls this “human computation” — using human brainpower to help computers solve problems they can’t solve on their own. The New York Times, for one, has used ReCaptcha to help scan its 150-years-deep archives. And Google has worked with Mr. Ahn before to harness human intelligence, with its Image Labeler, a game in which Internet users compete to add descriptive tags to photographs, which ends up making those photos more identifiable and searchable in Google’s index.
Now Google recognizes that humans might help in its vast and controversial Google Book Search project. It has been scanning old books from libraries for more than five years and runs character recognition software on those scans to convert them to plain text, so they can be easily searched and displayed on mobile devices. The next time you solve a captcha puzzle to log into a Web site, you may be helping that effort.