Page 47 - Foundations of Cognitive Psychology : Core Readings

Can Machines Think? 45

medical problems, to analyze geological data, to analyze the results of scientific
experiments, and the like. Some of them are very impressive. SRI in California
announced in the mid-eighties that PROSPECTOR, an SRI-developed expert
system in geology, had correctly predicted the existence of a large, important
mineral deposit that had been entirely unanticipated by the human geologists
who had fed it its data. MYCIN, perhaps the most famous of these expert sys-
tems, diagnoses infections of the blood, and it does probably as well as, maybe
better than, any human consultants. And many other expert systems are on the
way.
All expert systems, like all other large AI programs, are what you might call
Potemkin villages. That is, they are cleverly constructed facades, like cinema
sets. The actual filling-in of details of AI programs is time-consuming, costly
work, so economy dictates that only those surfaces of the phenomenon that are
like to be probed or observed are represented.
Consider, for example, the CYRUS program developed by Janet Kolodner in
Roger Schank’s AI group at Yale a few years ago (see Kolodner, 1983a; 1983b,
pp. 243–280; 1983c, pp. 281–328). CYRUS stands (we are told) for Compu-
terized Yale Retrieval Updating System, but surely it is no accident that CYRUS
modeled the memory of Cyrus Vance, who was then secretary of state in the
Carter administration. The point of the CYRUS project was to devise and test
some plausible ideas about how people organize their memories of the events
they participatein; henceitwas meanttobea‘‘pure’’AIsystem, ascientific
model, not an expert system intended for any practical purpose. CYRUS was
updated daily by being fed all UPI wire service news stories that mentioned
Vance, and it was fed them directly, with no doctoring and no human inter-
vention. Thanks to an ingenious news-reading program called FRUMP, it could
take any story just as it came in on the wire and could digest it and use it to
update its data base so that it could answer more questions. You could address
questions to CYRUS in English by typing at a terminal. You addressed them in
the second person, as if you were talking with Cyrus Vance himself. The results
looked like this:
Q: Last time you went to Saudi Arabia, where did you stay?
A:In a palace in Saudi Arabia on September 23, 1978.
Q: Did you go sightseeing there?
A:Yes, at an oilfield in Dhahran on September 23, 1978.
Q: Has your wife even met Mrs. Begin?
A:Yes, most recently at a state dinner in Israel in January 1980.

CYRUS could correctly answer thousands of questions—almost any fair
question one could think of asking it. But if one actually set out to explore the
boundaries of its facade and find the questions that overshot the mark, one
could soon find them. ‘‘Have you ever met a female head of state?’’ was a
question I asked it, wondering if CYRUS knew that Indira Ghandi and Mar-
garet Thatcher were women. But for some reason the connection could not be
drawn, and CYRUS failed to answer either yes or no. I had stumped it, in spite
of thefactthatCYRUScould handle ahostofwhatyou mightcallneighboring
questions flawlessly. One soon learns from this sort of probing exercise that it is