46 Information Storage and Neural Control 



what coding rules are assumed, provided that the coding results 

 in a ranking of words by cost. 



Substituting this last equation in our first result yields 

 Pr = P ijr -\- my , 

 which reduces to the standard equation when w = and B = — 1 . 

 The additional parameters allow closer fit; but since each has a 

 "physical interpretation," we are not really cheating. 



My purpose is not to compare the adequacy of these three 

 particular theories — this has been argued elsewhere: Simon (12, 

 13, 14), Mandelbrot (15, 16), Rapoport (17) — but to contrast 

 the theoretical style. The procedure of Mandelbrot, then, is to 

 start from ceitain assumptions and to deduce the resulting prop- 

 erties. In his case, the assumptions were stated in information 

 theoretic terms and the deductions were analytic. 



My final example illustrates the information processing ap- 

 proach. Unfortunately, as I rhentioned earlier, it does not deal 

 with the same data, although it is concerned with verbal pro- 

 duction. Hence, we may contrast the underlying notions even if 

 we cannot compare theoretical validity. 



This description is due to Yngve (18) who has attempted to 

 explain some of the salient features of English grammar. As a 

 starting point, Yngve has pointed out that English often provides 

 several grammatically correct and semantically equivalent ways 

 of saying the same thing, and that some of these ways are quite 

 complicated. On the other hand, the grammars of formal mathe- 

 matical notations, such as that of algebra, impose severe limits 

 on the number of forms permitted, and yet these restrictions do 

 not hamper expressive power nor limit "sentence" length. Let 

 us consider just two examples. In English the standard form of 

 modification places modifiers before that which is modified. Thus, 

 we have such phrases as "the big, happy man." But we may also 

 reverse this order — which logically should be completely ade- 

 quate — in such phrases as "a man as tall as a circus giant." Why 

 do we not avoid such discontinuous constituents (some modifiers 

 in front, some behind) and use the more consistent form "an as 

 tall as a circus giant man" or "an as a circus giant tall man"? 



Secondly, note that English provides both active and passive 

 voices: "Johnny gave the ball to Billy" and "The ball was given 



