Injormation Processing Theory 35 



approach. Students of behavior still exhibit a propensity to describe 

 the human system in terms of the engineer's handiwork. In the 

 first half of this century, and still today, psychological models 

 took a form remarkably similar to the telephone switchboard, with 

 incoming signals being routed through connections, strengthened, 

 by degrees, through use, to trigger a response, with scarcely a 

 "by-your-leave" to their brothers under the skin. Psychology 

 moved back the boundaries of the mind as emphasis withdrew 

 from the mechanical procedures which performed the motions, 

 and moved toward the control procedures which decided what 

 motions would be made. The mechanical monster seemed too 

 clumsy, and an electrical monster was substituted. 



As the preceding papers have indicated, the recent years have 

 seen some new tools, both conceptual and actual, added to the 

 engineer's gadget bag. These years have also seen some further 

 friendly borrowing of these tools by students of biology and 

 behavior. The new tool with which I am most impressed and 

 with which I hope to impress you is the digital computer. A great 

 deal of work has been directed in the last decade toward the 

 understanding of the neural bases of the control processes which 

 interest the psychologist, and a fair number of psychologists have 

 decided that switchboards are perhaps not the best model for 

 neurological processes. So now we hear that people are really 

 like electronic monsters. 



We are not quite as physiologically naive as was Descartes. 

 We know that humans are not really made up of transistors, 

 resistors, or even electric wire. What, then, do we mean when we 

 say that humans are like computers? 



Humans and other animals make decisions, behave, solve prob- 

 lems, and learn. Machines — digital computers — also do these 

 things. Superficially, at least, humans are like machines. C'an we 

 be more specific? If a machine does the same things that a human 

 does and fails in the same things in which humans fail, then 

 machine and man are alike at a more basic level of description. 

 The more details which can be replicated by the machine, the 

 closer is the comparison. 



Once the basic features of a computer are pointed out to some- 

 one who has seriously attempted to analyze the human system, 



