The Cost of Turing Tests

The other day, I had the pleasure of visiting my aunt and uncle. When I was over there, I showed them my the website I had created for the National Honor Society at Mountain View High School, as well as my blog. We came upon the topic of Facebook. They were interested in what it was all about, so I logged in to my account, and showed them around.

One thing that arose was them wanting to click on things that would appear to other people as if I had done, and, for obvious reasons, this was undesirable. My uncle proposed that my aunt create an account, as it requires very little effort to do so. She entered the necessary information, but the page came back saying that she had typed the CAPTCHA incorrectly. At that point, she decided that she did not want to create a Facebook account -- for my aunt, the marginal benefit of having an account was less than the marginal cost of typing in the CAPTCHA.

The purpose of a CAPTCHA is to tell humans and computers apart. It is basically a Turing test. A Turing test is supposed to be a task that is trivial for a human to do, but nearly impossible for a computer to do. As it turns out, they are often onerous for humans to do, and computers have been able to do them in all cases with at least some success. In this case, Facebook lost a potential user due to the difficulty of their CAPTCHA.