Researchers have turned to the animal kingdom in an attempt to 'fox' those pesky internet bots.

At Microsoft's annual Techfest research conference, boffins unveiled their plan to use images of cats and dogs as a way to differentiate between human and computerised surfers. Users will be shown a random assortment of pictures of the two species and asked to click on the cats - a simple matter for your average man on the street, but fiendishly difficult for an automated program.

Websites such as MySpace are constantly plagued by automated spamming programs, which sign up for free services and then send out huge volumes of unsolicited advertising. A previous way of dealing with this problem was to show users distorted, concealed arrangements of letters and numbers - but programmers have come up with ways around that system. Humans, meanwhile, often struggle to make out the sequences.

The visual similarities between cats and dogs are so great, and the differences so intuitive and organic, that experts hope the problem may be solved for the immediate future. The database of images is extensive - there are two million - to prevent hackers classifying them individually.

And there's been a happy secondary result of the initiative: one of the homeless cats featured in the picture library has found a new owner.

[Via the BBC.]