To check that those signing up for its various services are humans and not machines, Google uses a program called a CAPCTHA. Coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper, and John Langford, CAPTCHA stands for "Completely Automated Public Turing test to tell Computers and Humans Apart." This distinction is useful to protect programs and applications from mechanized attacks, where computers are programmed to simulate human users in order to get access to the sytems. Google thought CAPTCHAs were so important that they bought von Ahn’s company reCAPTCHA. reCAPTCHA exploits the human brain’s superior ability to derive textual information in order to correct errors made by computers when they ‘read’. The program takes words from scanned books and offers them to users as part of traditional CAPTCHAs. The text that users enter is then used to correct the transcripts of the scanned books. By parcelling out the process of correcting transcripts and then making it a game, a task that would otherwise be too laborious to carry out is completed as users go about their day-to-day business.
CAPTCHAs, as a form of Turing Test, go right to the heart of artificial intelligence. If a machine can pass a Turing Test, then it is a little more human. Thinking about such tests, then, is a form of thinking about what makes us distinct from machines.
You can learn more about this here:
- Von Ahn, Luis, Ben Maurer, Colin McMillen, David Abraham and Manuel Blum, ‘reCAPTCHA: Human-Based Character Recognition via Web Security Measures’, Science 321 (2008): 1465–1468 <http://www.cs.cmu.edu/~biglou/reCAPTCHA_Science.pdf>
- ‘CAPTCHA’, Wikipedia (24 September 2011) <http://en.wikipedia.org/wiki/CAPTCHA>
- The Official CAPTCHA Site (2000-2010) <http://www.captcha.net/>
- reCAPTCHA: Stop Spam, Read Books (2011) <http://www.google.com/recaptcha>
- ‘reCAPTCHA’ Wikipedia (28 September 2011) <http://en.wikipedia.org/wiki/ReCAPTCHA>
- ‘Turing Test’, Wikipedia (23 September 2011) <http://en.wikipedia.org/wiki/Turing_test>
- ‘Turing Test’, XKCD (undated) <http://xkcd.com/329/>