1. The Social Use of Space 179 



adjustment so that at the re-exposure the E eUcits a DMA comparable to 

 that of the initial exposure. Because of the limitations of time and space in 

 which any individual's activities must transpire, maximizing A" demands 

 an active seeking of new £"s. This seeking, I term v". It represents a kind 

 of velocity difficult to distinguish from the normal velocity, v, unless one 

 is aware of the history of an individual with reference to its pattern of 

 repeating specific dMA. In empirical experimental situations the relative 

 magnitude of v'/ may be determined by observing the probability of ap- 

 proaching a new E introduced into an individual's home range so that nor- 

 mal movements will produce exposure. Ecologists concerned with con- 

 trolling the density of species which damage human property or serve as 

 hosts for diseases transmittable to man have been aware of v" in a negative 

 sense. They (e.g., Chitty and Southern, 1954) have noted the avoidance of 

 new objects, such as poison baits or traps. This avoidance has been termed 

 "the strange-object response." 



3. Active Rejection of New Configurations 



Distinct from the relative attraction to or avoidance of a new configura- 

 tion is the phenomenon of physically rejecting or psychologically blocking 

 awareness of new £"s. Processes included under this phenomenon of rejec- 

 tion may be designated as d". A grasp of the -types of phenomena subsumed 

 under d" may be obtained through considering a case observed in my 

 laboratory. 



Large "life-space" cages, LSC, were designed to provide an optimum 

 situation for the breeding of the very sensitive wild Norway rats in the 

 laboratory. A 16 X 25-inch floor provided access to an activity wheel on 

 one side and a lever on the other, which when pressed, provided a drop of 

 water. From this floor two ramps led to a partitioned second floor of eciual 

 dimensions. From one side of the second floor rats had access to one 8 X 

 8 X 6-inch nest box, while two next boxes w^ere accessible from the other 

 side of the second floor. One male and two female adult rats lived in each 

 of six cages. At the time in question three of these cages each also contained 

 a recently weaned litter. Up to this time the water-providing lever apparatus 

 had not been delivered by the manufacturer. In its place the adults were 

 provided water through a drinking tube from a bottle, as had been the 

 practice since they were captured in the wild as juveniles. When the lever 

 apparatuses became available, one was inserted into each cage and the 

 water bottle was remo^xd. By the following morning when the cages were 

 next examined, the situation in each cage was identical; all movable ob- 

 jects available to the rats, paper used as nesting material and orange peels, 

 had been piled over the lever, completely hiding it. 



