Digression 2: the 'imitation game'

The classic case of ELIZA fooling its user is that, quoted in Boden (1986, p.96), of a vice-president of a computer company not realizing he was on-line to the program. The user seems truly to have believed that he was conversing with his flesh and blood(y-minded?) colleague:

VP: Do you think that I can use the computer this morning?
ELIZA: Why do you ask?
VP: I might be able to make some additional telcomp sales.
ELIZA: Why aren't you sure?
VP: My prospective cistomers have never seen a demonstration of the system.
ELIZA: Does this mean very much to you?
VP: Of course it does.
ELIZA: You seem very positive about that.
VP: This is ridiculuous.
ELIZA: What do you mean this is ridiculuous?
VP: Is there any reason why I can't use the computer now?
ELIZA:Tell me more about your prospective customers.
VP:Please dial me up on 491-1850

It is something like this scenario that forms the basis of the so-called 'Turing Test', named after the Cambridge mathematician and computer pioneer, Alan Turing (1912-1954), and proposed in a visionary paper first published in 1950. Turing asks his reader to imagine a game -- the 'imitation game' -- played with three people, a man (A), a woman (B), and an interrogator (C) who may be of either sex. The interrogator stays in a room apart from the other two. The object of the game for the interrogator is to determine which of the other two is the man and which is the woman. He knows them by the labels X and Y, and at the end of the game he says either "X is A and Y is B" or "X is B and Y is A". It is A's object in the game to try to cause C to make the wrong identification; while the third player B is to help the interrogator. C may ask any questions he wishes, e.g. "Will X please tell me the length of his or her hair?" If X is B, then she will obviously answer truly; if X is A, the man, he will obviously concoct an answer designed to convince the interrogator that he is the woman. If A succeeds, then he has won the game.

Now let a machine take the place of A. 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? If he does, then the machine has passed the Turing Test.

Clearly ELIZA is very impressive, but would it pass the Turing test? If not, why not? At least the following two reasons suggest themselves. (a) despite its apparent passivity in allowing the patient to explore his own problems for himself, ELIZA in fact manages to retain the initiative for nearly all the interaction; in the imitation game, it is the interrogator who endeavours to retain the initiative, but even in mixed initiative dialogues -- such as that between ELIZA and the vice-president -- the latter would very probably, had the conversation gone on much longer, have had his doubts about his interlocutor. Which leads us on to: (b) ELIZA can 'talk' appropriately in only one domain -- non-directive psychotherapy; ask it to write a sonnet or to comment on the state of British football, and it will become at the very least unco-operative.

The imitation game arose as a response to the question posed at the end of the 1940s, "Can computers think?" Turing remains non-committal as regards the answer to the question, beyond offering the imitation game; but the thrust of his argument seems to be that the question is fundamentally a non-starter. A more meaningful question would have been, "Is the intentional stance the most appropriate stance to take in dealing with this system?" When we feel we have answered that, perhaps we should ask a second question: "Is it important that a machine pass the Turing test?"

Boden, M. A. (1986). Artificial Intelligence and Natural Man. [Second Edition]. Brighton: Harvester Press and Basic Books.