DESIGN FOR A BRAIN 8/8 



the pattern of impulses sent to the muscles does not cause that 

 pedal movement which would lower the voltage on the grill. 

 These high excitations in the brain will cause some step-mech- 

 anisms to change value, thus causing different patterns of body 

 movement to occur. The step-mechanisms act directly only at 

 stage 6, but changes there will (S. 12/9) affect the field of all 

 six groups of main variables. These changes of field will continue 

 to occur as long as the high excitation in the brain persists. 

 They will cease when, and only when, the linkages at stage 6 

 transform an excitation of skin receptors into such a bodily 

 movement as will cause, through the pedal, a reduction in the 

 excitation of the skin receptors; for only such linkages can stop 

 further encounters with critical states. The system, that is, 

 will change until there occurs a stable field. The stability will 

 be shown by an increase in the voltage on the grill leading to 

 changes through skin, brain, muscles, and pedal that have the 

 effect of opposing the increase in voltage. The stability, in 

 addition, has the property that it keeps the essential variables 

 within physiological limits; for by it the rat is protected from 

 electrical injury, and the nervous system from exhaustion. 



It will be noted that although action 3 has no direct con- 

 nexion, either visually in the real apparatus or functionally in the 

 diagram of immediate effects, with the site of the changes at 6, 

 yet the latter become adapted to the nature of the action at 3. 

 (The subject was discussed in S. 5/13.) 



This example shows, therefore, that if the rat and its environ- 

 ment formed an ultrastable system and acted purely automati- 

 cally, they would go through the same changes as were observed 

 by Mowrer. 



Training 



8/8. The process of ' training ' will now be shown in its relation 

 to ultrastability. 



All training involves some use of ' punishment ' or ' reward ', 

 and we must translate these concepts into our form. i Punish- 

 ment ' is simple, for it means that some sensory organs or nerve 

 endings have been stimulated with an intensity high enough to 

 cause step-function changes in the nervous system (S. 7/19 and 

 9/7). The concept of ' reward ' is more complex. It usually 

 involves the supplying of some substance (e.g. food) or condition 



110 



