Artificial Intelligence

1. Artificial Intelligence The Turing Test Ian Gent ipg@cs.st-and.ac.uk

2. Artificial Intelligence The Turing Test Part I : Turing’s Imitation Game Part II: Some sample games from the 60’s to the 90’s

3. Alan M Turing, Hero • Helped to found theoretical CS • 1936, before digital computers existed • Helped to found practical CS • wartime work decoding Enigma machines • ACE Report, 1946 • Helped to found practical AI • first (simulated) chess program • Helped to found theoretical AI …

4. Can Machines Think? • Computing Machinery and Intelligence • Alan M Turing • Mind, Vol LIX, Number 236 (1950) • Can be found reprinted in many places • e.g. Computers and Thought

5. Can Machines Think? • Turing starts by defining machine & think • Will not use everyday meaning of the words • otherwise we could answer by Gallup poll • Instead, use a different question • closely related, but unambiguous • “I believe the original question to be too meaningless to deserve discussion”

6. The Imitation Game • Interrogator in one room • digital computer in another room • person in a third room • From typed responses only, can interrogator distinguish between person and computer? • If the interrogator often guesses wrong, say the machine is intelligent. • Usually done with one machine/person at a time

7. A sample imitation game • Turing suggests some specimen Q & A’s: • Q: Please write me a sonnet on the subject of the Forth Bridge • A: Count me out on this one, I never could write poetry • Q: Add 34957 to 70764. • (pause about 30 seconds) • A: 105621 • Q: Do you play chess? • A: Yes • Q: I have K at my K1, and no other pieces. You have only K at K6 and R at R1. It is your move. What do you play? • (pause about 15s) • A: R-R8 mate

8. What did Turing think? • Turing (in 1950) believed that by 2000 • computers available with 128Mbytes storage • programmed so well that interrogators have only a 70% chance after 5 minutes of being right • “By 2000 the use of words and general educated opinion will have altered so much that one will be able to speak of machines thinking without expecting to be contradicted”

9. Objections and Responses • Turing discusses responds to some objections • Some of them can be dealt with quite quickly • The Theological Objection • Man has a soul, machines do not • AT: Can we deny His power to give a soul to a machine • Heads in the sand • I don’t like the idea so I will ignore it • Argument from various disabilities • No machine can X (e.g. tell right from wrong) • AT: Becomes a less powerful argument each day

10. Some more objections • Lady Lovelace’s [Ada’s] objection • computers do whatever we know how to order them to perform , so computers cannot do anything really new • AT: Machines constantly surprise us. • Argument from informality of behaviour • impossible to write down formal rules for every situation • AT: Scientifically impossible to prove people not driven by rules • Argument from ESP • Telepathy would let humans win imitation game • AT: Put competitors in ‘telepathy-proof’ room (!)

11. Three more serious objections • Argument from Consciousness • “No mechanism could feel pleasure, grief … • AT: Danger of Solipsism • AT: Imitation game exists now - in oral exams • Probably the most contentious objection • Argument from continuity in the nervous system • the brain does not operate digitally • AT: computers can simulate continuous behavior, eg. Statistically

12. Three more serious objections • Mathematical Objection • Godel’s theorem, Halting problem, etc, show that machines cannot do ‘meta-reasoning’. • AT: We too often give wrong answers ourselves to be justified in being very pleased at fallibility of machines • The mathematical, consciousness, and continuity arguments deserve further discussion, … • … but that’s another story

13. Some Famous Imitation Games • 1960s ELIZA • Rogerian psychotherapist • 1970s SHRDLU • Blocks world reasoner • 1980s NICOLAI • unrestricted discourse • 1990s Loebner prize • win $100,000 if you pass the test

14. The problem with ELIZA • Eliza used simple pattern matching • “Well, my boyfriend made me come here” • “Your boyfriend made you come here?” • Eliza written by Joseph Weizenbaum • Weizenbaum so upset at credibility of users… • his secretary wanted to use it only in private • psychotherapists excited at prospect of Eliza-booths • … he wrote a book to debunk the possibilities • “Computer Power and Human Reason”

15. The problem with SHRDLU • SHRDLU had a very limited domain • “Look-ma-no-hands” AI • hard to abstract lessons learnt • natural language processing intermingled with planning, etc • SHRDLU written by Terry Winograd • with this and later work, he made major contributions to AI • especially in natural language processing

16. The problem with NICOLAI • NICOLAI was not a computer program! • Doug Hofstadter conducted dialogue, believing NICOLAI was electronic • (Almost) passed the Reverse Turing Test • Tricks like the occasional dumb answer • but “too much cleverness in these weird responses”

17. The problem with the Loebner Prize • Jason Hutchens programmed the 1996 winner • Then wrote an article • “How to pass the Turing test by cheating” ! • “Turing’s imitation game in general is inadequate as a test of intelligence, as it relies solely on the ability to fool people, and this can be very easy to achieve, as Weizenbaum found.”

18. Summary: The Turing Test • The Turing test turns a philosophical question ... • Can Machines think? • … Into an operational one • Can machines play the imitation game? • We are not near writing programs to pass the test • The Turing test does NOT drive much AI research • Improving the capabilities of computers DOES