 In 2015, Shuman Ghosemajumder, former click fraud czar of Google, stated that there were cybercriminal sites that would defeat CAPTCHA challenges for a fee, to enable various forms of fraud.Another variation is described as the subject-matter expert Turing test, where a machine's response cannot be distinguished from an expert in a given field.This is also known as a "Feigenbaum test" and was proposed by Edward Feigenbaum in a 2003 paper.