What is CAPTCHA? Those annoying little boxes

Chances are you have bought something online or participated in an online chat at some point in your life. You probably saw one of those little boxes come up where you had to type in what it said in the box. Those are annoying aren’t they? No one really seems to like them but yet they are still there. Is that a capital letter? Is that a 1 or an L? Why do I have to do this? Why?

Those boxes are called CAPTCHA, or Completely Automated Public Turing test to tell Computers and Humans Apart. Got that? For the most part, that is straight forward. It is there to make sure that you are indeed a human sitting behind the keyboard and not an automated bot. The Turing test is something developed by Alan Turing in the 1950s to judge a machine’s ability to exhibit human intelligence. Yes, the same Alan Turing who helped to break the Enigma code during World War 2.

CAPTCHA dates back to 1997 when it was developed by Mark Lillibridge, Nicholas Hopper, Krishna Barat, and Andrei Broder while working at Alta-Vista. CAPTCHA tests require three things, invariant recognition, segmentation, and parsing to complete them. All three tests are difficult at best for an artificial intelligence to complete, much less do all three in one test, whereas humans are able to complete that with ease (in theory of course!).

The developers know that many people struggle with these. So why not develop something easier, like say a picture or just a check box? The check box can be overcome by an artificial intelligence. If the test would be to identify something in a picture, what would be the correct answer? Think of a busy city street. What is the primary focus of the picture? A person, a taxi, a car, a building? Also what may be identified as one thing in New York might be known as something else in California or Texas, much less in another country. To some degree pictures are being used so this is beginning to be overcome by selecting portions of a picture where a certain item is shown. It has hardly been perfected.

So, the next time you get a CAPTCHA test, don’t complain. It is there for a very good reason and for your own safety. If you can’t read it just click the option for the next one. Eventually you will get one that you can read!

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