DISTURBED SYSTEMS AND HABITUATION 



13/9 



13/8/3. Two units are interacting : 1 ^± 2. Both effects go 

 through the uniselectors, so the whole is ultrastable. At each D, 

 the operator displaced l's magnet through a constant distance. 

 On the first c stimulation ', 2's response brought the system 

 to its critical states, so the ultrastability found a new terminal 



D 



Time 



Figure 13/8/2 : 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 states (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. 



-\rv 



Time 



Figure 13/8/3 : 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. 



field. The second stimulation again evoked the process. But 

 the new terminal field was such that the displacement D no 

 longer caused 2 to reach its critical states ; so this field was 

 retained. Again under constant stimulation the response had 

 diminished. 



13/9. For completeness we will now consider the effects of these 

 disturbances in combination. The combination of repeated 

 constant displacements with small random disturbances yields 

 little of interest. But the combination of an alternation of para- 

 meter-value with small random disturbances is worth notice. 



149 l 



