This is “human computation,” the art of using massive groups of networked human minds to solve problems that computers cannot. Ask a machine to point to a picture of a bird or pick out a particular voice in a crowd, and it usually fails. But even the most dim-witted human can do this easily. Von Ahn has realized that our normal view of the human-computer relationship can be inverted. Most of us assume computers make people smarter. He sees people as a way to make computers smarter.
Odds are you’ve already benefited from von Ahn’s work. Like when you type in one of those stretched and skewed words before getting access to a Yahoo email account or the Ticketmaster store. That’s a Captcha, which von Ahn developed in 2000 to thwart spambots. Or there’s von Ahn’s picture-labeling games, which have lured thousands of bored Web surfers into tagging 300,000 photos online — doing it so effectively that Google bought his idea last year to improve its Image Search engine.