lecture 2cse 140 - intro to cognitive science1 the turing test: simulating intelligence

Lecture 2 CSE 140 - Intro to Cognitive Science 1

The Turing Test: Simulating Intelligence


Alan Turing (1912-1954)

The Turing machine and the mathematization of the notion computable function

The halting problem Colossus & breaking the Enigma code ACE: England’s first large scale general

computing machine Developed an influential mathematical model

of embryological development

Hodges, Andrew (1983) Alan Turing: The Enigma. Simon and Schuster, New York


Computing Machinery & Intelligence (1950)

“I PROPOSE to consider the question, 'Can machines think?' This should begin with definitions of the meaning of the terms 'machine‘ and 'think'.”


“Think”: The Imitation Game

“It is played with three people, a man (A), a woman (B), and an interrogator (C)…. 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.”

“The interrogator is allowed to put questions to A and B….”

“It is A's object in the game to try and cause C to make the wrong identification….”

“ In order that tones of voice may not help the interrogator the answers should be … typewritten.”


The Imitation Game II

“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?' “


“Machine”: An Electronic Computer

“The question which we put in § 1 will not be quite definite until we have specified what we mean by the word 'machine‘”

“… the present interest in 'thinking machines' has been aroused by a particular kind of machine, usually called an 'electronic computer' or 'digital computer'. Following this suggestion we only permit digital computers to take part in our game.”


Summary of Turing’s Test

Can an appropriately programmed digital computer consistently deceive a critical observer given that:

1. The observer is free to ask the computer any question;

2. The machine is free to lie;

3. The observer distinguishes the machine from a human at chance.


The Turing Test: A Sufficient Test

“May not machines carry out some-thing which ought to be described as thinking but which is very different from what a man does? This objection is a very strong one, but at least we can say that if, nevertheless, a machine can be constructed to play the imitation game satisfactorily, we need not be troubled by this objection. “


A Key Implicit Claim

A perfect simulation of intelligence would be indistinguishable from the real thing so that we would have no reason to say that the simulation is not intelligent.


What Is a Computing Machine?

Motivation: A human “computer” doing arithmetic, e.G. Adding two large numbers.

The human computer: Follows fixed rules, “stored in a book altered when he

is put on to a new job.” Has an unlimited supply of paper.


A Computing Machine Consists of

An executive unit, which carries out a fixed set of simple rules.

A store, which is used as a “notepad.”• To write down the results of its

calculations.• To remember which rules to use in which

order. A control, which makes sure that the

instructions are carried out correctly and in the right order.


Turing’s Question:

Given that this model can simulate ANYANY digital computer (!!),

Is human intelligence inside the set of computable functions; That is, the set of functions that can be computed by an algorithm


Will Computers Pass the Turing Test?

Turing’s belief: in about 50 years (last year!!) It will be possible to program computers

With a storage capacity of 109 bits (~100 megabytes)

Guessing error rates of 30% After 5 minutes questioning


Potential Objections Raised by Turing


The Theological Objection

“Thinking is a function of man’s immortal soul. God has given an immortal soul to every man and woman, but not to any other animal or to machines. Hence no animal or machine can think.”

“Should we not believe that He has the freedom to confer a soul on an elephant if he sees fit?”

“We are in either case [constructing machines or procreation] instruments of His will providing mansions for the souls that He creates.”

“Such [theological] arguments have been found unsatisfactory in the past.”


The “Heads in the Sand” Objection

“The consequences of machines thinking would be too dreadful. Let us hope and believe that they cannot do so.”

Alas….


The Mathematical Objection

Gödel’s theorem “states that there are certain things that [a digital] machine cannot do. If it is rigged up to give answers to questions as in the imitation game, there will be some questions to which it will either give a wrong answer, or fail to give an answer at all…”

“It has only been stated, without any sort of proof, that no such limitations apply to the human intellect.”


The Argument from Consciousness

“Not until a machine can write a sonnet or compose a concerto because of thoughts and emotions felt, and not by the chance fall of symbols, could we agree that machine equals brain… No mechanism could feel … pleasure at its successes, grief when its valves fuse, be warmed by flattery, be made miserable by its mistakes, be charmed by sex, be angry or depressed when it cannot get what it wants”

By this argument, “the only which by which one could be sure that a machine thinks is to be the machine and to feel oneself thinking.”


Arguments from Various Disabilities

“… you will never be able to make one to do X.” where X can be: make mistakes, enjoy strawberries and cream, do something novel, fall in love, make someone fall in love with it, tell right from wrong…

For each X, we are faced with an analytical problem. Is it really true that X lies outside our power to create algorithms for simulating X? As it stands, this objection simply asserts that something is impossible without offering any proof.


Lady Lovelace’s Objection

“The Analytical Engine has no pretensions of originate anything. It can do whatever we know how to order it to perform.” (1842)

One reading: machines will not surprise us. But “Machines take me by surprise with great frequency.”

This is due to “the [false] assumption that as soon as a fact is presented to the mind all consequences of that fact spring into the mind simultaneously with it.”

Otherwise, Good Point!!! Turing presents a framework for machine learning that is still with us today.


Argument from Continuity in the Nervous System

“The nervous system is not a discrete-state machine [which the computing machine surely is].” Because it has continuous states, a discrete state machine cannot simulate a nervous system.

This presupposes that the nervous system is capable of making infinitely fine distinctions which is false. We can digitize all sorts of continuous phenomena (witness CDs and DVDs); why can’t we similarly digitize the signals of the nervous system?


Argument From Informality of Behavior

“It is not possible to produce a set of rules purporting to describe what a man should do in every conceivable set of circumstances…To attempt to provide rules of conduct to cover every eventuality…appears to be impossible.”

The argument seems to be “If each person had a definite set of rules of conduct by which his or her life is regulated, then people would be no better than machines. There are no such rules, so people are not machines.”

No! Compare: If it is snowing, then I will be cold. It isn’t snowing, so I’m not cold.


Argument from ESP (!!)

“Unfortunately the statistical evidence, at least for telepathy, is overwhelming.” A telepath might guess, for example, what card someone is holding, more often than a machine.

“To put the competitors in a ‘telepathy-free room’ would satisfy all requirements.”


ELIZA Written by Weizenbaum in 1966 Simulated a non-directive psychotherapist Sample Dialogue:

Men are all alike. IN WHAT WAY? They're always bugging us about something or other. CAN YOU THINK OF A SPECIFIC EXAMPLE? Well, my boyfriend made me come here. YOUR BOYFRIEND MADE YOU COME HERE He says I'm depressed much of the time. I AM SORRY TO HEAR YOU ARE DEPRESSED It's true. I am unhappy


ELIZA …

DO YOU THINK COMING HERE WILL HELP YOU NOT TO BE UNHAPPY

I need some help, that much seems certain.

WHAT WOULD IT MEAN TO YOU IF YOU GOT SOME HELP

Perhaps I could learn to get along with my mother.

TELL ME MORE ABOUT YOUR FAMILY

My mother takes care of me.

WHO ELSE IN YOUR FAMILY TAKES CARE OF YOU

My father.

YOUR FATHER

You are like my father in some ways.

WHAT RESEMBLANCE DO YOU SEE


Recent Objections Compiled by David J. Chalmers, Department of Philosophy,

University of Arizona, Tucson AZ 85721. E-mail: [email protected].

Block, N. 1981. A look-up table could pass the Turing test, and surely isn't intelligent. The TT errs in testing behavior and not mechanisms.

Moor, J. H. 1976. The basis of the Turing test is not an operational definition of thinking, but rather an inference to the best explanation

Searle, J. R. 1980. Implementing a program is not sufficient for mentality, as someone could e.g. implement a "Chinese-speaking" program without understanding Chinese. So strong AI is false, and no program is sufficient for consciousness.

Maudlin, T. 1989 Computational state is not sufficient for consciousness, as it can be instantiated by a mostly inert object.

http://www.u.arizona.edu/~chalmers/

http://www.u.arizona.edu/~chalmers/

mailto:[email protected]





lecture 2cse 140 - intro to cognitive science1 the turing test: simulating intelligence

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