1. The Social Use of Space 17 



5. Avoidance of a Strange Field 



During the pursuit of these studies on behavior in a one-dimensional 

 habitat, a few rats failed to emerge into the alley until after the lapse of 

 several hours. ]VIost frequently such rats were members of subgroups 

 having had less opportunity to adjust to novel stimuli. This suggested 

 that the less opportunity an animal had to make adjustments to strange 

 stimuli, or the more novel was the strange environment, the more likely 

 it would be avoided. 



New alleys were constructed to permit exploration of this hypothesis. 

 These alleys consisted of an 8 X 8-inch channel 15 feet long. At one end a 

 home nest box could be attached from which the rat gained access to the 

 alley by way of a 3 X 3-inch door. At the opposite end of the alley, light 

 from two 60-watt lamps shone through a ground glass plate. Unless other- 

 wise modified, the floor was stationary. A photoelectric cell at each 3-foot 

 interval along each alley initiated a signal to an Esterline-Angus event 

 recorder each time a rat passed. This apparatus is called the "NIH Emo- 

 tional Activity Alley." 



Each of the 7(i subjects, Osborne-]Mendel male rats, was housed alone 

 for 3 months from weaning in a smaD cage precluding the visual perception 

 of any object outside the cage. Cages were not opened. Food and water 

 were delivered into the cage through channels making it unnecessary to 

 open them. These procedures minimized opportunity for adjusting to new 

 configurations of stimuli. In the terminology of Section XIV, G, 1, the 

 isolation cage represents an Ei configuration of stimuli. Under this termi- 

 nology El • • ' En represent a series of discrete configurations of stimuli 

 which an individual may encounter for the first time in that order. 



Twenty rats were transferred directly from the isolation cages into the 

 activity alley for a 2-hour exposure. Of the remaining 56 rats, 24 were ex- 

 posed to an E2 configuration for 2 hours for 10 days prior to being placed 

 in the alley. Similarly, 16 others were exposed to an E-^ configuration, while 

 the remaining 16 were exposed to E2 for 2 hours, then immediately exposed 

 to Es for 2 hours for 10 days. Three days after these exposures, which pro- 

 vided opportunity to adjust to the new stimuli of E2, E:^, or Ei and £"3, 

 each rat was given a 2-hour trial in the activity alley, which represented 

 an Ei configuration. Half of each of these four groups were placed in the 

 alley with a stationary floor, an Eu. configuration; while for the other half 

 the alley contained sections of tilting floor, an E^v, configuration, which 

 clanged when the rats passed over them. 



Greater detail of these studies are presented in Section XIV, G, 4 and in 

 Table lib. However, the results presented in Table Ila suflfice for the 

 present purposes. Both aspects of the hypothesis were confirmed. The 



