This is incredibly cool. Last year, I wrote a piece for Wired about how Yahoo was stopping spambots by creating a reverse Turing Test: Before you can get a free Yahoo email account, you have to prove you’re a human. How do you do that? By asking users to answer a simple visual-recognition question — i.e. recognizing the text in a graphic image. Even a five-year-old can easily do this, but almost no robots can, because visual recognition is something that’s incredibly hard for machines to do.

Since then, I’ve written more about this topic; recently, I posted an interaction with a customer-service bot where I successfully determined that I was in fact talking to real, live person. And during a particularly cool discussion here about phones, Franco suggested a very cool Reverse Turing Test to use to thwart telemarketers — by demanding anyone who calls you out of the blue prove that they’re human:

I’ve been thinking about how to do this with email for a while now. The charge doesn’t have to be that high to deter systematic marketers without posing much problem for random contacts. The key, though, is to make it virtually painless for almost anyone to contact you out of the blue.

With email, another idea is to simply authenticate humanness with something like the reverse turing test blogged here a while back (http://www.collisiondetection.net/mt/archives/000164.html). I’ve thought about automatically bouncing unrecognized email with such a test and asking the sender to resend with the answer to a reverse turing test kind of question. I suppose it’s probably not that hard to do that with a phone these days, either, but it’s much harder to generalize it to any phone that might be calling you. Maybe an audible turing test: you get a recording that asks you to pass some simple test, like dial a specific 2 digit number. However, the test is read by a stuttering drunk.

So today’s big news is … Earthlink is going to try precisely this technique as a way of thwarting spam! According to today’s USA Today:

Here’s how it works: Anyone who sends e-mail to a challenge-response user quickly receives an e-mail asking them to prove they are a live person. They do so by copying a series of numbers displayed on their computer screen and returning the message. Their original message is then allowed through. Verification needs to be performed just once, and future e-mails from the same e-mail address are recognized. Blocked messages are sent to a suspect mailbox, which customers can view.

The system lets users create approved e-mail address lists so family, friends and business associates are spared e-mail challenges. It also has a feature to generate additional e-mail addresses to purchase goods online.Many vendors send sales-confirmation notices via e-mail.

I love this. As we live in a world populated by more and more bots, we’ll be developing increasingly more techniques for figuring out who’s real and who isn’t. Some of it may even become experiential, rather than technological. We may find that a crucial technique for navigating the everyday world is a sort of “bot-sense” — being able to intuit whether someone who’s talking to us on the phone, sending us an email, or chatting with us online, is truly a human.