The Turing test is a test of a machine's ability to demonstrate intelligence. A human judge engages in a natural language conversation with one human and one machine, each of which tries to appear human. All participants are separated from one another. If the judge cannot reliably tell the machine from the human, the machine is said to have passed the test. In order to test the machine's intelligence rather than its ability to render words into audio, the conversation is limited to a text-only channel such as a computer keyboard and screen.
The test was introduced by Alan Turing in his 1950 paper Computing Machinery and Intelligence, which opens with the words: "I propose to consider the question, 'Can machines think?'" Since "thinking" is difficult to define, Turing chooses to "replace the question by another, which is closely related to it and is expressed in relatively unambiguous words." Turing's new question is: "Are there imaginable digital computers which would do well in the [Turing test]"? This question, Turing believed, is one that can actually be answered. In the remainder of the paper, he argued against all the major objections to the proposition that "machines can think".
In the years since 1950, the test has proven to be both highly influential and widely criticized, and it is an essential concept in the philosophy of artificial intelligence.
The question of whether it is possible for machines to think has a long history, which is firmly entrenched in the distinction between dualist and materialist views of the mind. From the perspective of dualism, the mind is non-physical (or, at the very least, has non-physical properties) and, therefore, cannot be explained in purely physical terms. The materialist perspective argues that the mind can be explained physically, and thus leaves open the possibility of minds that are artificially produced.
In 1936, philosopher Alfred Ayer considered the standard philosophical question of other minds: how do we know that other people have the same conscious experiences that we do? In his book Language, Truth and Logic Ayer suggested a protocol to distinguish between a conscious man and an unconscious machine: "The only ground I can have for asserting that an object which appears to be conscious is not really a conscious being, but only a dummy or a machine, is that it fails to satisfy one of the empirical tests by which the presence or absence of consciousness is determined." (This suggestion is very similar to the Turing test, but it is not certain that Ayer's popular philosophical classic was familiar to Turing.)
Researchers in the United Kingdom had been exploring "machine intelligence" for up to ten years prior to the founding of the field of AI research in 1956. It was a common topic among the members of the Ratio Club who were an informal group of British cybernetics and electronics researchers that included Alan Turing, after whom the test is named.
Turing, in particular, had been tackling the notion of machine intelligence since at least 1941 and one of the earliest-known mentions of "computer intelligence" was made by him in 1947. In Turing's report, "Intelligent Machinery", he investigated "the question of whether or not it is possible for machinery to show intelligent behaviour" and, as part of that investigation, proposed what may be considered the forerunner to his later tests:
It is not difficult to devise a paper machine which will play a not very bad game of chess. Now get three men as subjects for the experiment. A, B and C. A and C are to be rather poor chess players, B is the operator who works the paper machine. ... Two rooms are used with some arrangement for communicating moves, and a game is played between C and either A or the paper machine. C may find it quite difficult to tell which he is playing.
When Turing published "Computing Machinery and Intelligence" he had been considering the possibility of artificial intelligence for many years, though this was the first published paper by Turing to focus exclusively on the notion.
Turing begins his 1950 paper with the claim "I propose to consider the question 'Can machines think?'" As he highlights, the traditional approach to such a question is to start with definitions, defining both the terms "machine" and "intelligence". Turing chooses not to do so; instead he replaces the question with a new one, "which is closely related to it and is expressed in relatively unambiguous words." In essence he proposes to change the question from "Do machines think?" to "Can machines do what we (as thinking entities) can do?" The advantage of the new question, Turing argues, is that it draws "a fairly sharp line between the physical and intellectual capacities of a man."
To demonstrate this approach Turing proposes a test inspired by a party game, known as the "Imitation Game", in which a man and a woman go into separate rooms and guests try to tell them apart by writing a series of questions and reading the typewritten answers sent back. In this game both the man and the woman aim to convince the guests that they are the other. Turing proposes recreating the game as follows:
We now ask the question, "What will happen when a machine takes the part of A in this game?" Will the interrogator decide wrongly as often when the game is played like this as he does when the game is played between a man and a woman? These questions replace our original, "Can machines think?"
Later in the paper Turing suggests an "equivalent" alternative formulation involving a judge conversing only with a computer and a man. While neither of these formulations precisely matches the version of the Turing Test that is more generally known today, he proposed a third in 1952. In this version, which Turing discussed in a BBC radio broadcast, a jury asks questions of a computer and the role of the computer is to make a significant proportion of the jury believe that it is really a man.
Turing's paper considered nine putative objections, which include all the major arguments against artificial intelligence that have been raised in the years since the paper was published. (See Computing Machinery and Intelligence.)
Turing predicted that machines would eventually be able to pass the test; in fact, he estimated that by the year 2000, machines with 109 bits (about 119.2 MiB or approximately 120 megabytes) of memory would be able to fool thirty percent of human judges in a five-minute test. He also predicted that people would then no longer consider the phrase "thinking machine" contradictory. He further predicted that machine learning would be an important part of building powerful machines, a claim considered plausible by contemporary researchers in artificial intelligence.
In a paper submitted to 19th Midwest Artificial Intelligence and Cognitive Science Conference, Dr.Shane T. Mueller predicted a modified Turing Test called a "Cognitive Decathlon" could be accomplished within 5 years.
By extrapolating an exponential growth of technology over several decades, futurist Raymond Kurzweil predicted that Turing test-capable computers would be manufactured in the near future. In 1990, he set the year around 2020. By 2005, he had revised his estimate to 2029.
The Long Bet Project is a wager of $20,000 between Mitch Kapor (pessimist) and Kurzweil (optimist) about whether a computer will pass a Turing Test by the year 2029. The bet specifies the conditions in some detail.
Based on http://en.wikipedia.org/wiki/Turing_test licensed under the Creative Commons Attribution-Share-Alike License 3.0
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