On: What's up, bot? Google tries new Captcha method

[Goladus]

The best you'll ever get is human to human contact.

But that doesn't scale cheaply.

[shader → Goladus]

And there is the essence of the need for captchas ;)

You need to scale, so you employ computers instead of people. Now you have to have computers run a reverse turing test. Otherwise, it's much easier for spammers to scale as well.

It's easy to cut down on spam if you don't accept any incoming mail.