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CS 484 – Artificial Intelligence 1

Announcements

• The Thinking Machine airs • Today (9/6) at 4PM on channel 53• Monday (9/10) at 3 and 8PM on channel 53

• Homework 1 due Tuesday, 9/11 – write up on The Thinking Machine

• Lab 0 due Thursday, September 13

Introduction to Artificial Intelligence

Lecture 2


What is Artificial Intelligence?

• Systems that think like humans

• Systems that act like humans

• Systems that think rationally

• Systems that act rationally


What has AI accomplished?


What will AI accomplish?


The Beginnings

• 1942 – Isaac Asimov publishes the three laws of robotics

• 1950 – Alan Turing publishes the Turing Test, a means of determining if a machine can think

• 1956 – The term Artificial Intelligence is coined at a meeting at Dartmouth College


The Turing Test

• Uses the "Imitation Game"• Usual method

• Three people play (man, woman, and interrogator)• Interrogator determines which of the other two is a

woman by asking questions• Example: How long is your hair?

• Questions and responses are typewritten or repeated by an intermediary

• Turing Test• Machine takes the part of the man


Strength of the Test

• "The new problem has the advantage of drawing a fairly sharp line between the physical and the intellectual capacities of a man" (Turing, 1950)


Debating the question "Can machines think?"

• The Theological Objection• Thinking is a function of man's immortal soul

• The "Head in the Sand" Objection• The consequences of machines thinking would be too

dreadful

• The Mathematical Objection• Given the limitations to the powers of discrete-state

machines, there are some questions to which it will either give the wrong answer or fail to answer



• The Argument from Consciousness• "Not until a machine can write a sonnet or compose a

concerto because of thoughts and emotions felt, … could we agree that machine equals brain" (Jefferson, 1949)

• Arguments from Various Disabilities• "I grant you that you can make machines do all the

things you mentioned but you will never be able to make one do X"

• X = be kind, resourceful, friendly, …



• Lady Lovelace's Objection• "The Analytical Engine has no pretensions to originate

anything. It can do whatever we know how to order it to perform"

• The Argument from Continuity in the Nervous System• Given that the nervous system is not a discrete-state

machine, you cannot mimic the behavior of nervous system with a discrete-state machine.



• The 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. Thus it is not possible that humans are machines.

• The Argument from Extrasensory Perception• Assuming the woman has ESP, she could perform

better on a test of clairvoyance than the machine

• Use a telepathy-proof room


Recent Experiment

• Spring, 2005 3 undergrads from Simon’s Rock College (Bard, MA) conducted the first “gender-twisting” Turing Test

• Setup• Round 1: Participant has 5 minutes to chat with

a woman and a man masquerading as a women• Round 2: Participant has 5 minutes to chat with

a woman and ALICE • Female chat bot developed by Richard Wallace


Sample interaction

Subject: What do girls do at sleepovers?

Bot: They do their own thing.

Subject: Do you wear skirts?

Bot: Only when I dress up.

Subject: You are a female.


Outcomes

• 42 participants• 23 didn’t give any indication that they suspected

ALICE was not a real person

• Some did suspect ALICE• Subject: Are you a computer?

• Bot: Would it matter to you if I were metal instead of flesh?

• Question that tripped up men and bot• Subject: What size panty hose do you wear?


What does it mean if a computer passes the Turing Test?

• Can the computer think?

• Does the computer have a mind in exactly the same sense that you and I have minds?


Chinese Room

• Thought experiment purposed by John Searle in 1980• Given that we have constructed a machine that

behaves as though is understands Chinese, it convinces a Chinese speaker that it speaks Chinese

• Given Chinese symbols, it consults a look-up table and produces other Chinese symbols as output


Chinese Room substitution

• Machine is replaced by Searle sitting in a room where he receives Chinese symbols, looks them up on a look-up table, and returns the Chinese symbol indicated by the table• English speaker can now give correct answers to

Chinese questions without understanding Chinese

• Since Searle doesn't understand Chinese, how can it be said that the computer understands Chinese?


Systems Reply

• Although Searle himself doesn't understand Chinese, it is reasonable to say that Searle plus look-up table understand Chinese

• Counter example: he memorized the look-up table before entering the room


Robot Reply

• The reason that we don't want to attribute understanding to the room, or a computer is that the system doesn't interact properly with the environment

• Solution: put the computer in a robot so that it can interact with the world

• Reply: Cognition is not symbol manipulation. Second, Searle could be inside the robot and still not understand Chinese


Chinese Room Conclusion

• The mind is not a computer• Thus the Turing Test is inadequate


How would you show that a machine can think?


Additional Sources• Generation5's interview with John Searle (2001).

• http://www.generation5.org/content/2001/searle.asp• Eliasmith, C. Chinese room.

• http://www.artsci.wustl.edu/%7Ephilos/MindDict/chineseroom.html• McCarthy, J, et al. A proposal for the Dartmouth Summer Research

Project on Artificial Intelligence. 1955.• http://www-formal.Stanford.EDU/jmc/history/dartmouth.html

• Moravec, H. Robot: Mere Machine to Transcendent Mind. Oxford University Press, Inc. 1999.

• Tompson, C. The Other Turing Test. Wired, 13.07, 2005.• http://www.wired.com/wired/archive/13.07/posts.html?pg=5

• Turing, A. Computing machinery and intelligence. Mind, 59, 433-460.• http://www.loebner.net/Prizef/TuringArticle.html

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