DESIGN FOR A BRAIN 



14/6 



14/6. The process can readily be demonstrated, almost in 

 truistic form, on the Homeostat (which is here treated as a system 

 whose variables include 4 position of uniselector ' so that it has 

 many states of equilibrium, differing from one another according 

 to the uniselector's position). 



The process is shown in Figure 14/6/1. Two units were joined 



Time 



Figure 14/6/1 : Homeostat tracing. At each D, l's magnet is displaced 

 by the operator through a fixed angle. 2 receives this action through 

 its uniselector. When the uniselector's value makes 2's magnet meet 

 the critical state (shown dotted) the value is changed. After the 

 fourth change the value causes only a small movement of 2, so the value 

 is retained permanently. 



1 — > 2. The effect of 1 on 2 was determined by 2's uniselector, 

 which changed position if 2 exceeded its critical states. The 

 operator then repeatedly disturbed 2 by moving 1, at D. As 

 often as the uniselector transmitted a large effect to 2, so often 

 did 2 shift its uniselector. But as soon as the uniselector arrived 

 at a position that gave a transmission insufficient to bring 2 to its 

 critical states, that position was retained. So under constant 

 stimulation by D the amplitude of 2's response changed from 

 larger to smaller. 



The same process in a more complex form is shown in Figure 

 14/6/2. Two units are interacting: 1 ^± 2. Both effects go 





Time 

 U 



3l 



Figure 14/6/2 : Homeostat arranged as ultrastable system with two units 

 interacting. At each D the operator moved l's magnet through a fixed 

 angle. The first field such that D does not cause a critical state to be 

 met is retained permanently. 



188 



