Annual Meeting Reports Plenary Address: Human Computation

Speaker: von Ahn said that many people The partners see the same image at the Luis von Ahn spend hours playing computer and video same time. Each partner guesses what label Carnegie Mellon University games and that more than 200 million the other would give to the image. When , are typed every day by people both partners type the same words, they around the world. To transform this typing earn points, and another image is pre- Reporter: into useful work, he has introduced the pro- sented. Some images have “taboo words” Bernard Appiah gram reCAPTCHA (www..net) that players must avoid. When an image Texas A&M University to digitize printed materials. von Ahn said has more taboo words, a series of matches College Station, Texas that his project gives CAPTCHAs free to leads to more points. During the game, Yahoo, , Facebook, and many other partners must learn to think the same. It It can be annoying. You want to log onto online companies. The CAPTCHAs origi- has been found that the series of words a Web site or get ready to purchase an nate from print sources to be digitized. He on which the two players agree are usually item online, but before you can proceed, explained that words in older publications good labels for an image. von Ahn said you are instructed to type specified funny often cannot be recognized accurately by that more than 200,000 players have made “words”. The scientist behind these words computerized optical character-recogni- 50 million agreements in the ESP Game. is Luis von Ahn, an assistant professor tion systems. Such words are presented as He noted that many people play more than of computer science at Carnegie Mellon CAPTCHAs. When a CAPTCHA is con- 20 hours a week. University, whose interests include using sistently translated into a particular word, Although people may be playing the humans “cheaply” to address problems that that word is assumed to be the original game for fun, its importance is huge. “5,000 computers cannot solve. word. von Ahn said that through the use of people playing simultaneously can label “The inscription you type before you CAPTCHAs, the digitization of The New all the images on in 2 months!” proceed to a desired Web page is called a York Times published from 1851 through von Ahn said. He also described a similar CAPTCHA,” said von Ahn, who invented 1980 would be completed in 2009. game called Audio ESP, which encourages CAPTCHAs. “Computer programs cannot von Ahn also discussed computer proj- partners to listen to sounds and type what identify CAPTCHAs, so they are used to ects that use humans to label images on they hear. verify that only humans are using certain the Web. He termed them “games with a von Ahn said his interests in com- Web sites.” von Ahn said that people purpose” (GWAPs). GWAPs have been puting include treating human brains as usually type CAPTCHAs as part of secu- applied in such fields as security, computer processors in a distributed system, each rity measures on Web sites to allow only vision, Internet accessibility, adult-content performing a small part of a massive com- humans access, but he noted that spam filtering, and Internet searching. One such putation. He therefore uses online games companies have employed humans to type game, the ESP Game (www.espgame.org), to encourage participation in the process. CAPTCHAs and thus circumvent this shows how humans, as they play, can solve The plenary address indeed showcased a measure. “CAPTCHAs are generating jobs problems that computers cannot yet solve. new era of human computing and its use for some people,” he joked. “Such people The ESP Game randomly pairs players. in Internet security. earn $2.50 per hour.” Players do not know each other’s identity.

4 • Science Editor • January – February 2010 • Vol 33 • No 1