We all know about those authentication blocks of text called CAPTCHAs, perhaps too well. (Today's fun trivia: The acronym stands for Completely Automated Public Turing Test to Tell Computers and Humans Apart.). A new idea from PlayThru is to embed a small Flash or HTML5-based game that a human plays with a mouse to prove he or she really is a carbon-based life form. It is intriguing, potentially less annoying, and has captured (if you will excuse the pun) a few supporters already. The service is just getting started, and it is free to try out.

The CAPTCHA process was developed in 2000 by several computer scientists at Carnegie Mellon University. It has since spread like kudzu to various websites, where site owners try to prevent automated bots from bombarding their pages.

The original thought of Alan Turing with his namesake test was to develop some way for a human to tell when it was talking to a computer. The CAPTCHA is actually this process in reverse: It is administered by a machine, but tries to distinguish humans. It hasn't been working all that well, though. Many spammers employ a variety of techniques to defeat them, such as by paying low wages to actual humans or running optical character recognition software to ferret out the CAPTCHA codes.

In the process, as so often happens with the Internets these days, the bad guys are making for a miserable user experience for the rest of us. The codes have gotten harder to read by ordinary humans, and many users will abandon a Web page rather than try to enter the right code. Updates such as user refreshes to get a new code or audio translators haven't helped much.

Enter PlayThru's attempt. Their service, perhaps the first game-based CAPTCHA, invites users to solve a game by identifying and interacting with dynamic objects, such as dragging and dropping toppings onto a pizza or food items into a refrigerator. You can see an example here.

Beta deployments of PlayThru are seeing submission rates increase by up to 40% over text-based CAPTCHAs, and in a company-sponsored survey of 100 people, 98% of the users preferred PlayThru over traditional text-based CAPTCHAs. Granted, that isn't a scientific sample, but it's still an indication of how much we all hate the regular CAPTCHAs, and of how much opportunity there is for their replacement.

PlayThru isn't the first company to invent a better CAPTCHA. Oregon-based Vidoop came out with their own innovation a few years ago, but it hasn't caught on.

But this just illustrates the problems in fighting spammers and still making our computer systems usable for the rest of us who just want to go about our business and get work done. The spammers always seem to have ways to defeat the latest technology, no matter how sophisticated. The PlayThru game-based CAPTCHAs could turn into a miniature Space Invaders or World of Warcraft as the automated tools used by the bad guys get better, which would make the simple originals useless. In the meantime, though, try out the demo on PlayThru's site, and let us know what you think of the idea.