26 Information Storage and Neural Control 



Saltzberg: In any communications system which places a very 

 high priority on accuracy, redundancy is frequently employed. 

 In situations where it is not practical to increase the strength of 

 the signal in order to improve accuracy by increasing signal-to- 

 noise ratio, it becomes important to use redundancy to correct 

 the errors due to noise. In digital communication systems, re- 

 dundancy is often employed in the form of error-correcting codes. 

 The accuracy of language communication is greatly enhanced by 

 the redundancy of language. It is easy to get a qualitative feeling 

 for the amount of redundancy in the English language. For 

 example, consider a situation in which a sentence composed 

 of a sequence of symbols is transmitted and the first symbol re- 

 ceived is a t, the second a k, and the third an e. You would 

 have no trouble concluding that the word transmitted is "the" 

 because of the constraints in the language. The language structure 

 tells us that "tke" must be in error since "tke" is not a word. 

 Further, since h very frequently follows t in the English language, 

 there is not much doubt that the first word in the sentence is 

 "the." This is one aspect of how the redundancy of the language 

 increases the accuracy of communication. In fact, in communica- 

 tion systems which are signal power limited, it is necessary to 

 employ redundancy techniques to reduce the errors in com- 

 munication due to noise. 



Ralph W. Gerard (Ann Arbor, Michigan): It was said that 

 maybe an example would illuminate some of the points that 

 would come up, and I think I can give one that might be helpful. 

 Limiting the spectrum in frequency or the interval of time in 

 which the significant signal is to be expected is helpful. Gregory 

 Bateson referred back to that in speaking of a para-signal, which 

 tells the meaning of the signal itself by indicating where in the 

 total space you must look for the signal. I wonder how many in 

 the room will understand the statement, ^^ Cur antrum santrum, 

 ovidiim, ovidum.'' Hands? None. That is because you thought I was 

 talking Latin, whereas I was actually talking German. Now I 

 will repeat it the same way. "'/Tz//? rant rum, Sand rum, ohwiedumm, oh 

 wie dummy Knowing that the language is German is the para- 

 signal; locating the message in the total space is what is meant by 

 having the proper set. 



