Answer: Alan Turing

In the mid-20th century, early computer scientist Alan Turing invented what would go on to become a critical component in the philosophy of artificial intelligence: the Turing test. The basic premise of the Turing test is that when communicating via text (so as to not put the computer at a body language/speech disadvantage), a computer capable of passing the test should be able to communicate with a human being such that the human being is unable to distinguish whether the computer is a human or not.

Nearly fifty years after Turing introduced the Turing test in his paper “Computing Machinery and Intelligence”, the test was turned on its head with the introduction of CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart). Unlike the original Turing test which was intended to test if a computer could pass as a human, CAPTCHA puzzles were designed so that a computer could tell if a human could pass as human (and weed out spam scripts and malicious bots). When you complete a CAPTCHA puzzle like picking out all the pictures in the grid that have waterfalls or deciphering fuzzy text on a fuzzy background, you’re proving to the machine gate keeper that you’re a human user.