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Artificial Intelligence. The Turing Test. Ian Gent ipg@cs.st-and.ac.uk. Artificial Intelligence. The Turing Test. Part I : Turing’s Imitation Game Part II: Some sample games from the 60’s to the 90’s. Alan M Turing, Hero. Helped to found theoretical CS

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Artificial intelligence l.jpg

Artificial Intelligence

The Turing Test

Ian Gent

ipg@cs.st-and.ac.uk


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Artificial Intelligence

The Turing Test

Part I : Turing’s Imitation Game

Part II: Some sample games

from the 60’s to the 90’s


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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 …


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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


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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”


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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


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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


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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”


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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


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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 (!)


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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


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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


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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


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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”


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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


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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”


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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.”


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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