I was watching a presentation called Human Computation by Luis Von Ahn from Carnegie Mellon University. In it he describes his invention of "Captchas" those distorted words you have to type so that scripts can't get some service such as a free email a/c. "Captcha: A program that can generate and grade tests that most humans can pass but current computer programs cannot pass." (CACM Crypt)

He noted that nine thousand million hours of Solitaire was played across the world in 2003. The Empire State building took seven million person hours (ie 6.8 hours of world solitaire play) and the Panama Canal took twenty million person hours (ie less than a day of world solitaire play). All right these aren't feasible because of the logistics but what if you used the internet?

A project he's been working is the ESP game. In the game, players are randomly paired and shown an image. Each player has to type a word or phrase. If there is a match they both get points and move to the next image. There's a bit more to it but apparently the game is fun and even addictive. The global purpose is to label images on the web. One million images have been labelled so far. The ESP game is a symmetric game since both players respond equally. He also has been working on asymmetric games such as peekaboom where one player shows a portion of an image the other guesses what is being shown. The words and phrases used come from the ESP game. Another game is verbosity where words and phrases and corresponding commonsense facts are matched. "Milk" is usually near cereal in a bowl. Skynet here we come.

One interesting side issue is what happens if a player's net connection goes down. Apparently the software stores images and already recorded timed responses so the player can keep going. What if the pre-recorded player was the examiner who knows the correct answers and the other player a student sitting an exam then we can evaluate the student against a standard and give them a grade.