After outsourcing call centers, rote financial work, and programming, why not comment spam? This reporter’s blog comment filter was working, yet:

…so far it’s stopped 10,000 spams while allowing 377 human comments. So why had this got through? The electronic trail explained: the “captcha” (Completely Automated Public Turing test to tell Computers and Humans Apart) had been filled in.

The captcha is the junk filter’s last resort. Because it’s easy and cheap to program machines to post any sort of junk on blogs, a captcha (which puts numbers or letters in an image, which a machine in theory can’t read) shows whether you’ve got a real live person giving their thoughts, or just a dumb machine trying to up some spammer’s search-engine ranking.

If the captcha was filled in, it must have been done by a person; if it had been done by a machine, the spammers would have cracked the problem of solving captchas and would be busily spamming every blog they could find.

The price of humans who’ll spam blogs is falling to zero, Charles Arthur, The Guardian Thursday November 23, 2006

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