US Patent 9767263 Turing test via failure

Current CAPTCHA tests are designed to be difficult for a bot and simple for a human-user to answer; however, as artificial intelligence improves, bots are more capable of using techniques such as optical character recognition to resolve current CAPTCHAs in similar manners as human-users. By providing a CAPTCHA challenge from a library or set of challenges that are designed in a manner that causes or likely causes a human-user to trivially get the answer to the challenge wrong, helps to confirm that a user is a human-user, as a bot would answer the challenge correctly.