Google has made several improvements to the reCAPTCHA anti-bot service after San Francisco-based start-up Vicarious claimed that its artificial intelligence (AI) software can crack the Turing test.

CAPTCHA is the acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart." These are quixotic codes which have to be entered into websites to enable them to decipher and automatically determine that it is a human and not a bot which is keying them in.

Google has made the anti-bot service smarter barely days before Vicarious claimed that its AI software could crack the test.

"Vicarious, a startup developing artificial intelligence software, today announced that its algorithms can now reliably solve modern CAPTCHAs, including Google's reCAPTCHA, the world's most widely used test of a machine's ability to act human," touts the start-up's press release.

"Understanding how brain creates intelligence is the ultimate scientific challenge. Vicarious has a long term strategy for developing human level artificial intelligence, and it starts with building a brain-like vision system. Modern CAPTCHAs provide a snapshot of the challenges of visual perception, and solving those in a general way required us to understand how the brain does it", said Vicarious co-founder Dr. Dileep George.

Google had updated the reCAPTCHA that will make it easier for users to type in the random codes the app uses, since it will now be able to establish if the visitor is human or a bot.

"For over a decade, CAPTCHAs have used visual puzzles to help webmasters keep automated software from engaging in abusive activities on their sites," wrote Vinay Shet, product manager for reCAPTCHA, on the Google Online Security blog. "However, over the last few years advances in artificial intelligence have reduced the gap between human and machine capabilities in deciphering distorted text. Today, a successful CAPTCHA solution needs to go beyond just relying on text distortions to separate man from machine."

Now per Shet, reCAPTCHA is more "adaptive" and better prepared to identify users vis-à-vis automated software. For this Google has created "different classes" of CAPTCHA for different users.

"The updated system uses advanced risk analysis techniques, actively considering the user's entire engagement with the CAPTCHA-before, during and after they interact with it," wrote Shet. "That means that today the distorted letters serve less as a test of humanity and more as a medium of engagement to elicit a broad range of cues that characterize humans and bots."

Most users will find it easy to decipher the codes, whereas bots will see CAPTCHA that is "considerably more difficult" and will be barred from getting access.