Chapter 13 Artificial Intelligence 1 Artificial Intelligence Artificial

Chapter 13 Artificial Intelligence 1

Artificial Intelligence Artificial: humanly contrived often on a natural model Intelligence: the ability to apply knowledge to manipulate one's environment or to think abstractly as measured by objective criteria Clearly, intelligence is an internal characteristic. How can it be identified? 2

Thinking Machines o A computer can do some things better --and certainly faster--than a human can: n n Adding a thousand four-digit numbers Counting the distribution of letters in a book Searching a list of 1, 000 numbers for duplicates Matching finger prints 3

Thinking Machines o o Figure 13. 1 A computer might have trouble identifying the cat in this picture. BUT a computer would have difficulty pointing out the cat in this picture, which is easy for a human. Artificial intelligence (AI) The study of computer systems that attempt to model and apply the intelligence of the human mind. 4

In the beginning… o o In 1950 Alan Turing wrote a paper titled Computing Machinery And Intelligence, in which he proposed to consider the question “Can machines think? ” But the question is “loaded” so he proposed to replace it with what has since become known as the Turing Test. “Can a machine play the Imitation Game? ” 5

The Imitation Game 6 Skip detailed description

The Imitation Game The 'imitation game' is 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. 7

The Imitation Game 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. The object of the game for the third player (B) is to help the interrogator. 8

The Imitation Game 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? 9

The Imitation Game 10

The Turing Test (objections) o o There authors who question the validity of the Turing test. The objections tend to be of 2 types. n The first is an attempt to distinguish degrees, or types of equivalence… 11

The Turing Test (objections) o o Weak equivalence: Two systems (human and computer) are equivalent in results (output), but they do not arrive at those results in the same way. Strong equivalence: Two systems (human and computer) use the same internal processes to produce results. 12

The Turing Test (objections) o o o The Turing Test, they argue, can demonstrate weak equivalence, but not strong. So even if a computer passes the test we won’t be able to say that it thinks like a human. Of course, neither they, nor anyone else, can explain how humans think! So strong equivalence is a nice theoretical construction, but since it’s impossible to demonstrate it between humans, it would be an unfair requirement of the Turing Test. 13

The Turing Test (objections) o o o The other objection is that a computer might seem to be behaving in an intelligent manner, while it’s really just imitating behaviour. This might be true, but notice that when a parrot talks, or a horse counts, or a pet obeys our instructions, or a child imitates its parents we take all of these things to be signs of intelligence. If a parrot mimicking human sounds can be considered intelligent (at least to some small degree) then why wouldn’t a computer be considered intelligent (at least to some small degree) for imitating other human behaviour? 14

Turing’s View o “I believe that in about fifty years time it will be possible to programme computers with a storage capacity of about 109 to make them play the imitation game so well that an average interrogator will not have more than 70 per cent chance of making the right identification after five minutes of questioning. ” 15

Context o In 1950, computers were very primitive. n o UNIVAC I was the first commercial computer made in the United States. It was delivered to the United States Census Bureau on March 31, 1951! At a time when the first computers were just being built, to suggest that they might soon be able to think was quite radical. 16

Objections Turing Foresaw 1. 2. 3. 4. 5. 6. 7. 8. 9. Theological Objection The 'Heads in the Sand' Objection The Mathematical Objection The Argument from Consciousness Arguments from Various Disabilities Lady Lovelace's Objection Argument from Continuity in the Nervous System The Argument from Informality of Behaviour The Argument from Extra-Sensory Perception 17

Can Machines Think? o No machine has yet passed the Turing Test. o Loebner Prize established in 1990 n $100, 000 and a gold medal will be awarded to the first computer whose responses are indistinguishable from a human's 18

Aspects of AI o Knowledge Representation n n o o Semantic Networks Search Trees Expert Systems Neural Networks Natural Language Processing Robotics 19