Friday, August 10, 2012

Computer Activities with a Purpose

If you use the Internet at all, odds are you've been asked to complete a "CAPTCHA". These are the distorted "words" that a human is able to read and type but are supposed to stump computers. Captcha's were invented in 2000 by Luis Von Ahn, Manual Blum, and others at Carnegie Mellon University and stands for "Completely Automated Public Turing test to tell Computers and Humans Apart".

In a talk at, Luis Von Ahn said he felt guilty about Captchas and the time lost in filling them out. They are needed to prevent computer spamming but could there be a better use of people's time? So Von Ahn created reCAPTCHA which looks the same but instead of random, distorted words, reCAPTCHA uses words that stumped OCR (optical characters recognition) while digitizing books in the public domain for the Gutenberg project. Each reCAPTCHA is shown to hundreds(?) of people and the majority vote is used to update the word in the digital copy of the book. With 100 million reCAPTCHAs every day, the service has been able to digitize thousands of books.

Von Ahn's PhD thesis was devoted to Games With A Purpose, or GWAPs. Can people have fun on the Internet and accomplish something useful at the same time? One example is the ESP game. Two random people are show the same photo via the Internet. They receive points for how closely their description of the photo matches. The best matching descriptions are saved by Google to help identify photos for future image searches.

Von Ahn's newest project is His team thought, why not learn a language and help translate the Internet at the same time? The online lessons in English, Spanish, German, and French are free. My wife & I have learnt a lot. With duoLingo you earn points by translating actual websites in foreign languages and rating the translations of others. Give it a try!

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