A better world through games

Computer Scientist Luis von Ahn is dedicated to using the Internet to harness free labor and the power of the human mind.

“While people are playing computer games, they’re using their brains,” says the assistant professor at Carnegie Mellon University in Pittsburgh. “I want to make good use of that time for something productive.”

How does he do this? By building online games that link thousands of people around the world to help make computers smarter.

There’s the ESP game, where two randomly paired people with no way to communicate are shown the same image. Without seeing what the other person is typing, they each list words to describe the picture. Working against the clock, the players try to get as many word-matches as they can to earn points.

These words turn out to be very accurate descriptions that the Web can use to label images. The game is so effective that Google licensed the idea two years ago to improve its search engine.

More than 200,000 people have played the ESP game since it launched in 2004, generating 65 million labels for 10 million images.

Playing on a similar theme, Mr. von Ahn’s Tag a Tune game has players listen to songs and type words that describe the music. Another game helps train computers to find objects within images. And Verbosity collects factoids, such as “milk is white” and “cats have four legs.”

“If we collect millions of these facts, we can teach computers a little bit of common sense,” says von Ahn.

The Matchin game orders images from most to least beautiful. “If you have enough data, you can train a computer to recognize which images are prettier than others,” he says. “Eventually your digital camera can tell you when you take a picture, ‘that’s not a very good picture.’"

Von Ahn is working on a new game where players accurately translate sentences, even if they know only one of the languages.

“As people are playing these games, they’re actually solving problems for us,” he says.

For more on von Ahn's work, check out the full story: "reCaptcha: How to turn blather into books"