NERVOUS DISCHARGES 33 



This mechanism is of especial interest as it illustrates the 

 physiological accompaniment of a form of satisfaction, show- 

 ing how associations may be reinforced or stamped in. Such 

 satisfaction we may say is the antithesis of inhibition. 



To explain, it is thought that where the situation is such 

 that a given response is followed by a new or changed sensa- 

 tion which gives the same response the effect is a form of satis- 

 faction. To illustrate this, if the puppy is induced to suck the 

 teat and the sucking results in a pleasant taste which causes 

 him to suck harder, that is satisfaction. 



The signal SR2 in table V belongs to a class that may be 

 known as counter signals. A counter signal is a signal (or sen- 

 sation) that is due to the reaction of the environment to a given 

 motor response. A counter signal may be inhibiting or rein- 

 forcing or otherwise according to the structure of the nervous 

 channels (or coupling gang). For example, the whine of the 

 infant is a motor response and its counter signal is the offer 

 of the nipple. The sucking is a motor response and its counter 

 signal is a pleasant taste. S2, table I, is also a counter signal. 

 Counter signals or sensations play an important part in the 

 development of nervous channels as has been shown for simple 

 cases of inhibition and satisfaction. It is largely through the 

 effect of counter signals on the nervous system that it is brought 

 into proper correspondence with the creature's environment. 



It is evident that the forms that we have illustrated in the 

 figures and tables could be combined in various ways so that 

 many types of response to situation could be simulated. For 

 example, the arrangement shown in table V may be modified 

 by adding two more key rods on the left and four moie trans- 

 mitters. By suitable connections we will have a two way tan- 

 dem converging gang which will simulate the selection of re- 

 sponses by satisfaction. Whatever system of coupling be em- 

 ployed to control a plurality of movements there will be found 

 the same general principle throughout. Along with the descrip- 

 tion we have incidentally observed how the mechanical action 

 simulated particular nervous developments. As to general 

 analogy of the apparatus with a nervous system we may briefly 

 note: 



A 1, A simultaneous flow in several meterpipes results in a 

 certain movement or movements. 



