Luis von Ahn

Luis von Ahn is an assistant professor in the Computer Science Department at Carnegie Mellon University, where he also received his Ph.D. in 2005 under the supervision of Manuel Blum. Previously, von Ahn obtained a B.S. in mathematics from Duke University in 2000. He is the recipient of a Microsoft Research Fellowship, and became a MacArthur Fellow (a.k.a., the "genius award") in 2006. His research includes CAPTCHAs and Human-based computation. He was born in Guatemala City, Guatemala.

Von Ahn's early work was in the field of cryptography. With Nick Hopper and John Langford, he was the first to provide rigorous definitions of steganography and to prove that private-key steganography is possible. He has also worked with the cryptographer Josh Benaloh.

In 2000, he did early work in CAPTCHA, a computer-generated test that humans can pass but computers cannot. The device is used by websites to prevent bots from automatically registering large numbers of accounts. The CAPTCHA brought Luis his first widespread fame among the general public due to its coverage in the New York Times, USA Today, Discovery Channel, and other mainstream outlets.

His Ph.D. thesis, completed in 2005, was the first treatise recognizing the importance of human-based computation within computation generally. It is also the first work on Games with a Purpose, which are games played by humans that produce useful computation as a side-effect. The most famous example is the ESP Game, a game in which two people are simultaneously given an image of the same picture, with no way to communicate. Each then lists a number of words/phrases that describe the picture within a time limit, and are rewarded with points for a match. This match turns out to be an accurate description of the picture, and can be successfully employed in a database for more accurate image search technology. The ESP Game has been licensed by Google in the form of the Google Image Labeler, and is used to improve the accuracy of the Google Image Search. Other games include Peekaboom, a game for locating objects within an image, Verbosity, a game for collecting common-sense facts about the world, and Phetch, a game for annotating web images with explanatory text. Von Ahn's games brought him more coverage in the mainstream media, as well as numerous honors including the MacArthur Fellowship, Microsoft New Faculty Fellowship, Technology Review's TR35: Young Innovators Under 35, and Popular Science Magazine's Brilliant 10. His thesis won the Best Doctoral Dissertation Award from Carnegie Mellon University's School of Computer Science.

More recently, von Ahn developed reCAPTCHA, a new form of CAPTCHA that also helps digitize books. In reCAPTCHA, the words displayed to the user come directly from old books that are being digitized; they are words that OCR could not identify and are therefore sent to people throughout the Web to be proofread.