Artificial Intelligence - strong and weak
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Artificial Intelligence - strong and weak
Turing and his test
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Turing and his test


Alan Turing was a pioneer of AI and invented the test of the same name!

Alan Turing was an early pioneer of many aspects of computing and was one of the earliest proponents of AI. He argued that the only real test of strong AI was to see if anyone could tell the difference.

He suggested that a human was hidden behind a screen and communicated with a judge using whatever methods the AI program used. If the judge could tell that there was a human or a program behind the screen then the AI program was not a thinking conscious entity equivalent to a human. On the other hand if the program could fool the judge into believing that there really was a human behind the screen then by all practical definitions of human intelligence that is what the program possesses. This is the Turing Test for strong AI and it has caused a great deal of controversy.

Philosophers have argued for years about whether or not the Turing test is valid. Essentially one group of philosophers argue that it takes more than just equivalence of performance to make something intelligent and conscious. Most of the arguments come down to the supposed mind/brain split. In this model the brain isn’t just the machinery that creates human intelligence, it is also the residence of the mind, which is some how different and separate. If you believe in this worldview then strong AI is doomed to failure.

This is a big argument that is more about religion and belief than hard facts and it is best avoided!

Notice however that the Turing test is a weak AI approach to the problem of proving strong AI. Turing proposed an operational definition of what intelligence is that is every bit as mechanical as a Watt governor. There is no attempt to bring any aspect of "how it works" into the picture and this is, of course why it is so simple.

Oh Eliza!

Originally the Turing Test was nothing more than a theoretical plaything but in 1990 Hugh Loebner set up an annual contest to win a $3000 annual prize and a Grand Prize of $100,000 plus a Gold Medal for any program that could pass the Turing Test.

The contest has been run every year and so far the results have been either poor or impressive depending on your understanding of what is going on. The programs chat with humans – you can try some of them out if you want to at Chatbots or Pandorabots.

As with all aspects of AI, what seems to be intelligent quickly loses its magic once you know how it works.

So far all of the test competitors have been based on the Eliza model. Eliza was a very early attempt at AI and all it did was to scan the input text, pick out key words and respond with vaguely connected phrases.

For example, if you type “I feel ill” it might well trigger on the word “ill” and respond “I’m sorry to hear that”. It also used simple rules for turning phrases around to create new ones. For example you might type “I like cars” and it would transform this into “Why do you like cars?”

What is surprising about Eliza is that it seems to work! People are fairly convinced that there is an intelligence behind the program even though the program makes no attempt to analyse or understand in any sense what is being said. In fact once you know that this is the approach it is very easy to create conversations that reveal how the program is working and how it lacks understanding.

Many new Eliza programs attempt to cover their lack of understanding by being “quirky”. If you ask them a direct question such as “what is 2 times 2?” or “What colour is the sky?” they respond with something like “That’s boring, let’s talk about something else.” Of course a human could respond in this way because humans are quirky but if you press the human they will eventually tell you that the answer is four or the sky is blue (sometimes). Of course once a comment like "chatbots can't do 2+2" appears in public most chatbots quickly acquire the answer. But if you try something similar they will go back to the ploy of being quirky.


What Eliza and the current attempts at passing the Turing test reveal more clearly than anything else is how willing humans are to share their intelligence with non-intelligent things. We all do it. When you car doesn’t start you attribute it a malicious intent, we talk to plants, animals and machines as if they understood and it all seems very natural.






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