You’re familiar with captchas, the “are you a real person?” tests at the bottom of online forms that are sometimes decipherable, sometimes not – but essential to cut down on spam, at least of the computer-generated type. Unfortunately, the act of making text unreadable for computers often makes it just as hard for people. But there are a couple of very cool alternatives circulating.

First, one I just read about yesterday – an advertising-based tool that would require users to type in some words related to the ad to “pass the test”. The idea is that they would require some sort of analytical thought to get through, rather than just repeating verbatim what’s presented. In the example shown, for instance, users are asked to enter the quoted text – which requires that they know which text is in quotes. The brilliance in this approach, of course (assuming it works), is the additional revenue it could generate.

The second is an older one, but also very cool and worth pointing out. It’s called recaptcha and is a form of crowdsourcing. Basically, when old books are being scanned and digitized through OCR (optical character recognition) technology, some errors will inevitably creep up. Recaptcha takes these hard-to-read (for computers) words and turns them into a captcha test so that the time spent solving captchas can be put to good use.
What are your thoughts on captchas? Have you used either of these technologies on your site? Do you know of any other alternatives?