CONCEPTUAL THOUGHT 173 



the human nervous system. Modern computing machines 

 have become incredibly elaborate and are capable of mem- 

 ory, association, choice, and many other brain functions. 

 The chess-playing machine that no human chess player will 

 ever beat is just around the corner. 



It becomes more and more clear as this new science of the 

 mathematical machine advances that we can say, as Wiener 

 does, that the human brain behaves very much like the ma- 

 chine. The more complex problem-solving mechanisms ac- 

 tually are giving us a better understanding of how the brain 

 operates— even to the assumption that the nerve cell (neu- 

 ron), which is known to carry an electrical potential, acts 

 like the vacuum tube in the machine, and that the reception 

 of a signal by a neuron corresponds to the "tripping" of the 

 relay in an electric circuit. Indeed, in humans the energy of 

 nerve stimulus is changed into electrochemical energy; fun- 

 damentally, these electrochemical impulses flitting around in 

 our brains constitute all that we know about the universe. 

 In general, psychology concurs in all this. 



The forerunners of the great electronic calculators of our 

 day (some have as many as 18,000 vacuum tubes and many 

 information recordings on tape) go back to the early Chi- 

 nese abacus, to the Lully (1235-1315) calculator, and to the 

 famous arithmetic machine which Pascal constructed in 

 1642. Not until World War II, however, were the great 

 contrivances which are capable of "thinking" developed. In 

 these the distinguishing characteristic is the incorporation of 

 the "feed-back" mechanism, which regulates the activities 

 of the machine (slowing down or accelerating it) as infor- 

 mation is fed into it during operation. As Wiener points out, 

 this is similar to what happens when man decides to pick up 

 a pencil. He wills the general act, and the nervous system 

 carries it out through use of feed-back information. That is, 

 at each instant the nervous system must know by how much 

 the pencil is not yet picked up— the information which is 

 fed back through the sensory system. In man a failure of the 



