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No. 106: Jul-Aug 1996

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Does the human brain compute, or does it do more?

Of course, the human brain can add and subtract, but does it perform all of its functions by manipulating 1s and 0s, as a PC does?

The recent confrontation between G.K. Kasparov, boasting two hemispheres of gray matter, and IBM's Deep Blue chess-playing computer, with its boards of silicon chips, suggests that the human brain may do things somewhat differently. Consider that in the 3 minutes allotted for each move, Deep Blue could evaluate 20 billion moves. This means that it could examine every possible move and countermove for twelve sequences ahead and, in addition, selected lines of attack for 30 sequences. Kasparov was obviously doing no such computation. Yet, he won two, drew two, and lost only one game. IBM's A.J. Hoane, Jr., remarked that chess geniuses like Kasparov "are doing some mysterious computation we can't figure out."

Hoane's use of the words "mysterious computation" tells us that he is a reductionist. The implication is that everything mental can be reduced to manipulating those 1s and 0s. In reality, Kasparov's brain may have been innovating, working out new strategies, discerning Big Blue's weaknesses. These "higherlevel" functions are needed when the problem (chess) is too complex for a computer to evaluate all possible moves. (A computer can always win or draw at checkers -- a simpler game.) Of course, we do not know how "higher-level" functions are "mechanized" -- perhaps they are not, and there is "something else" going on in the human brain.

Another interesting fact, incidental to the Kasparov match, is that Big Blue. Blue, when faced with identical chess boards, will sometimes make different moves! Maybe even Big Blue's behavior is not always reducible to 1s and 0s.

(Horgan, John; "Plotting the Next Move." Scientific American, 274:16, May 1996)

From Science Frontiers #106, JUL-AUG 1996. � 1996-2000 William R. Corliss