A test devised by the English mathematician Alan M. Turing to determine whether or not a computer can be said to think like a human brain. In an attempt to cut through the philosophical debate about how to define "thinking," Turing devised a subjective test to answer the question, "Can machines think?" and reasoned that if a computer acts, reacts and interacts like a sentient being, then call it sentient. The test is simple: a human interrogator is isolated and given the task of distinguishing between a human and a computer based on their replies to questions that the interrogator poses. After a series of tests are performed, the interrogator attempts to determine which subject is human and which is an artificial intelligence. The computer's success at thinking can be quantified by its probability of being misidentified as the human subject.