1. The Social Use of Space 15 



The amount of structuring used here increased the probability of stopping 

 by 32% [i.e., (0.240 - 0. 182) /0. 182]. The extent to which this difference 

 modifies the use of a field may be visualized by considering the following: 

 Of every 1000 trips arriving 1 foot from home in the unstructured alley, 30 

 would stop at the tenth foot and 134 would continue farther, whereas in 

 the structured environment only 20 would stop at the tenth foot and only 

 64 would continue farther (see Fig. o). 



In closing this section it should be emphasized that the probability of 

 stopping is basically a function of time. In the particular situation, the p's 

 refer to the time required for the rats to travel a distance of 1 foot. 



A further question may be asked: "How does structuring increase the 

 probability of stopping if the animals are perceptually 'blind' to specific 

 stimuli to the extent of being unable to exhibit directed responses to them?" 

 One may visualize the situation in general terms: There is some assembly 

 of neurons which provides a signal terminating an ongoing behavior, such 

 as outward locomotion from home. The magnitude of this signal neces- 

 sary for behavioral termination reciuires simultaneous firing of some x 

 number of neurons. This assembly of neiu'ons may be called a "governor." 

 It must be located anatomically in some subcortical portion of the brain 

 precluding conscious awareness of its functioning. During any ongoing 

 behavior all perceivable stimuli unrelated to the ongoing behavior initiate 

 impulses which arrive at the behavior terminating governor. Each unit of 

 impulse causes an increase in the rate of firing of the neuronal net forming 

 the governor. The greater the intensity of such stimuli, or the greater the 

 number of stimuli of a given intensity, the more rapidly will the neurons 

 of the governor fire and thus the shorter will be the interval between emis- 

 sion of effective signals by the governor. This signal both terminates the 

 ongoing behavior and produces awareness of stimuli appropriate to eliciting 

 those responses appropriate to initiating some other behavior. 



4. Initial Hyperactivity in a Strange Environment 



For the rats discussed in Section III, A, 1 the level of activity in terms 

 of trips per rat per hour (Fig. 3 and Table la) was approximately six times 

 as high during the first 150 minutes of exposure to a strange environment 

 in comparison with the later periods following adjustment. This observa- 

 tion requires postulation of a second governor, one which determines the 

 probability of initiating trips. Initiating trips is here considered to be 

 synonymous with initiation of periods of diffuse undirected motor activity. 

 Examination of the expression of hyperactivity during the first 2-2| 

 hours of exposure to a strange environment provides insight into the func- 

 tioning of this governor of trip-initiations. 



