Artificial Intelligence is a vastly important field in Computer Science today. It’s also one of the few fields that gives and receives knowledge from other fields, such as maths, biology, psychology, sociology and other social sciences. From it’s assumed beginning in 1956 it has built itself into its own discipline off of other discoveries, although work has already begun in the field. Probably the most famous person in AI is Alan Turing, the inventor of the Turing test. For those that do not know the Turing test was based off his landmark 1950 paper Computing Machinery and Intelligence and was a proposed test to see if a machine could replicate intelligence. To achieve this one person (the interrogator) must have a text-only conversation with another person and a computer, both trying to act human. If the interrogator cannot figure out which one is the human then the machine is said to possess intelligent behaviour. It drags forward the dualist and materialist wars that have been fought over history as to whether the mind was a physical entity that could be replicated.

It seems today we’re trying to reverse the classic test, to see if we can figure out who is the human.

We are doing this ‘Reverse Turing Test’ through what we know as a CAPTCHA. For those that don’t know what a CAPTCHA is, it is a special field in a form (online or offline) that shows you an image with letters, numbers or a full word inside it, and your job is to type that out in the text field accompanying it. By doing this you prove that you are human and not a script intended to send automated spam messages around the Internet.

reCAPTCHA - The recommended CAPTCHA for websites.

The CAPTCHA has become a very important part of websites over the past couple of years. Thanks to evil spammers and malicious users this is the best possible way of keeping viagra adverts away from our websites. On a personal note this website has already received thirteen spam messages and several mentions on Blogs intended only for spam. Wordpress has the beloved Akismet spam filter running within the software to stop spam posts appearing on websites, but as a learning script it’s always going to be one step behind the spammers. It’s a good solution for a Blog as there is no need for tight security, but
for websites like event ticket websites security is essential to their business, and they have enough trouble with touts trying to claim all the tickets to major music and entertainment festivals around the world!

However, as many of you have already figured out (the title of this post gives it away), the CAPTCHA suffers from one major flaw, and that’s its inaccessibility flaws. The CAPTCHA was once a method to safeguard important websites across the Internet, like online banking sites. However, those that break these security gates are those who will benefit the most from it, meaning that hired programmers and brute-force methods could be used easily to break a CAPTCHA. Now that the Internet has become more mainstream and can be used by people from all walks of life there is a need for accessible design, including the CAPTCHA. A user with visual-impairment would not be able to see the CAPTCHA image, so the next best thing for a visually-impaired user would be sound, so these CAPTCHA’s are accompanied with a sound file.

The real issue here is now that the CAPTCHA has made it to small-time Blogs and Forums hundreds of thousands of users could be missing out on many fantastic websites. Thankfully many have taken the effort to add sound in, but this will never be a permanent solution to the problem. What we need is a way of stopping spammers and general users from breaking the system for longer than a couple of weeks.

So, is all lost? Can we stop spammers/malicious users and keep our websites accessible to everyone?

A lot of research is going into ways of beating the computer, and the CAPTCHA ‘motto’ from the Google Tech Talk on Human Computation by Luis von Ahn is “…generate and grade tests that only humans can pass, and current computer programs cannot”. This represents a movement against spammers that will most likely go on for a long time until a breakthrough has been reached.

In a way, this is a return of the Turing Test, where spammers and security enthusiasts are trying to thwart the Turing Test. From something seemingly bad like spam we have revived an age-old question and brought a corporate and business agenda to Artificial Intelligence.

The W3C has written an extensive guide on what you’ve just read here, and I recommend all those that are interested in the development of the CAPTCHA to go there to read more. On top of this I highly recommend you all check out the master of the CAPTCHA, Lius von Ahn.