13/9 



DESIGN FOR A BRAIN 



From S. 11/4 it is known that the alternation of a parameter 

 p between two values, p' and p", will result in the emergence of 

 two stable fields. We might get a pair like A and B of Figure 

 13/9/1. As the parameter p alternates between p' and p", so 



Figure 13/9/1 : Two possible terminal fields : A, when p has the value p' 

 and B, when it has the value p" . (Critical states shown as dots.) 



Figure 13/9/2 : When the parameter is constant at p', the representative 

 point will follow the path from )3 to a ; when at p" the point follows 

 the path from a to j8. 



will the field of the system's main variables alternate between 

 A and B. If p alternates slowly in comparison with the move- 

 ment of the representative point, the point will follow the circuit 

 of Figure 13/9/2, going from a to /? when p is changed from 

 p' to p'\ and returning to a when p is returned to p' . 



Suppose now that small random disturbances are applied to 



150 



