IN THE end, the robots won. On December 3rd, Google announced that it was radically changing its ReCAPTCHA system, the sort of prove-you’re-a-human-and-not-automated-software test that has become all but ubiquitous online.
In April, Google researchers published a paper showing that their computer-vision software could decipher their own squashed and twisted images 99.8% of the time.
For many, it comes as little surprise that algorithms can now nearly always beat a CAPTCHA. This is a tortured acronym that stands for “completely automated public Turing test to tell computers and humans apart“, and refers to a notional test devised by Alan Turing, a British code-breaker and computer-science pioneer, in which humans test a machine to see if it can think. CAPTCHAs are the reverse, administered by a machine to make sure the user is of the thinking sort.
It was inevitable that computer-vision research would advance to a point that CAPTCHA text that was in any way legible to humans would also be legible to the machines they had taught. In 2009, Luis von Ahn, the founder of ReCAPTCHA (the sort that presents two images, one of which is designed to make the user extract useful bits of text from an image, such as a scan of a newspaper page or a house number in a photograph), told The Economist that “it will be possible for software to break text CAPTCHAs most of the time within five years.” He was spot on.
The April paper came out of work on text recognition in images from the firm’s Street View archive, and of course on ReCAPTCHA’s arms race to defeat increasingly sophisticated artificial intelligence. Vinay Shet, the product manager for the service, said that the outcome was proof that decrypting squiggly text alone was no longer enough to separate the men from the ‘bots. However, Mr Shet says, Google had already developed a sophisticated risk-analysis system that could do the same job by different means.
The solution—which may seem fantastically simple by comparison to some of the textual hoops web denizens have had to jump through in recent years—is to ask a user to check a box that reads, quite simply, “I’m not a robot”.