I recently described an encounter with a robot which set me thinking about the Turing Test. These days it’s not just people who need to distinguish between people and computers. Computers have to too.
I’m thinking about all those web forms designed to foil spam-bots: sum these numbers, answer this question, type the letters hidden in this image. The intelligence behind these forms is entirely mechanical, and the odd thing is that most of the tests are the kind of things that robots are capable of doing well; whereas, being colour-blind, it usually takes me a few goes to pass the hidden-text tests. I guess this first line of defence is simply a way to make a site less attractive to spam-bots, in the hopes they’ll buzz off and annoy another computer.
It turns out that this spin on the Turing Test is known as a CAPTCHA — a Completely Automated Public Turing test to tell Computers and Humans Apart. I discovered this in a roundabout way, when I chanced upon an anti-captcha. Being human I instantly recognised this as a funny joke. Hah!