Adorable Spambot Killers
Unfortunately captchas are not perfect, and bots are making use of increasingly clever optical character recognition programs to defeat them. In an escalating arms race between bots and captchas, the amount of optical distortion necessary to make a foolproof test unfortunately makes the same test exceedingly difficult to pass by regular humans. We’ve all experienced that moment of wondering whether a twisted I is really an L, and the problem can only get worse.
Enter Oli, and his moment of “thinking outside the text box.” While computers are getting better and better at optical character recognition, one thing that they still have great difficulty doing is recognizing the contents of pictures. Oli, who runs a web site called ThePCSpy.com, realized that a computer would have a great deal of difficulty in telling the difference between different types of fuzzy animals. So he came up with KittenAuth, a test that requires the user to identify which three out of nine pictures contain kittens. The “3 in 9″ grid leaves the poor spambot with only a one in 84 chance of randomly picking the right answer. Larger grids or number of picks can make the chances lower still. Source.