Luis von Ahn has a lofty vision and a short attention span. The 29-year-old computer scientist at Carnegie Mellon University prefers short stories to novels, TV shows to short stories, and the Internet to all of the above. If others share his liabilities, so much the better: he plans to harness his generation's fabled impatience to change the world.
"The grandest projects of humanity took on the order of 100,000 people," he says. "The Panama Canal, the pyramids of Egypt. Now, for the first time in history, we can easily get more people than that working together. Imagine what we could do with 500 million people."
The trick is getting them all to cooperate. Like Tom Sawyer, von Ahn has found a simple and mischievous solution: turn the task into a game. Computer solitaire eats up billions of man-hours a year, he points out, and does nobody any good. But he says his "games with a purpose" will accomplish all sorts of useful tasks. Players will translate documents from one language to another or make it easier for blind people to navigate the Web—all while having fun. And unless they pay attention to the fine print, they may not even know they're doing good.
So far, von Ahn has three games up and running on the Web (peekaboom.org; peekaboom.org/phetch/; espgame.org). When you play the ESP Game, a Carnegie Mellon computer pairs you with another player and sends a randomly selected image, such as the White House, to both screens. Each player tries to describe the picture, and, at the same time, tries to guess what words the other player will choose to describe it. As soon as both players use the same word—"president," for example—the computer rewards them with points and downloads another image.
The game is surprisingly addictive. Players develop strong feelings about their anonymous partners, and some play for hours at a time, e-mailing von Ahn to complain if a glitch interrupts them. And while the players are getting acquainted and trying to read each other's minds, they're labeling the Internet's millions of pictures. The images, paired with their key words, go into a database that von Ahn plans to make available to scientists studying how to make computers think more like people.
What excites researchers about von Ahn's "human computation" work, as he calls it, is less the prospect of getting people to accomplish boring, repetitive chores than the promise of training computers to do the chores themselves. Many tasks that are easy for people are surprisingly difficult for computers, especially those that children learn easily, such as classifying objects, recognizing faces, learning verbal languages and reading handwriting. "We're biologically programmed to teach our kids," says Manuel Blum, a Carnegie Mellon computer scientist and von Ahn's former adviser. "We don't have the patience to teach computers the same way, by answering question after question."
Michael Kearns, a computer scientist at the University of Pennsylvania, says, "There are lots of people studying the hard problem of teaching computers to learn, and lots of other people seeing the entertainment value of the Web. But it's rare to find somebody like von Ahn, who has thought deeply about how to combine the two."
Von Ahn grew up in Guatemala City, where his mother, a physician, gave up her medical practice to raise her son. She and her 11 older brothers and sisters inherited their mother's candy company, Caramelos Tropicales, among the largest in Guatemala. (His father, a professor of medicine, separated from his mother when von Ahn was a toddler.) When von Ahn was 8, his mother bought him a Commodore 64 computer, and he was hooked. He says that as a high-school student working a summer job at his aunt's marshmallow factory, "sometimes my cousins would go in the back room and nap, but I networked the computers." He developed his business sense in part by listening to his uncles and aunts squabble. "They're always fighting about how to run the factory, whether to fire the manager, and on and on," he says. "There are 12 of them, and they can never agree about anything."
The lessons paid off. Google licensed the ESP Game to improve its image-search program. His "big goal," von Ahn says, is to make computers able to do anything that people can do. "I think it'll happen, definitely. If not in 50 years, then 100."
"More like 1,000," says his fiancée, Laura Dabbish, a Carnegie Mellon social scientist.