12 



John B. Calhoun 



5 



o 1000 



DISTANCE FROM HOME IN FEET 

 FROM WHICH OBJECTS WERE TAKEN 



Fig. 4. Frequency of transporting nesting material and food into the home com- 

 partment from points at successively greater distance from it. A, 3810 strips of paper; 

 B, 3551 pellets of food. See Table la. 



It is therefore concluded that structuring the environment with items 

 inducing responses leads to a reduction of the distance from home at which 

 trips are terminated. 



3. The Prob.\bility of Terminating Trips 



The two prior sections merely demonstrate an effect produced by struc- 

 turing the environment. They do not further our understanding of the 

 underlying biological process. 



The behavior of rats in the structured environment provides the clue. 

 During any period of intensive transportation, one trip almost immediately 

 followed the preceding one. And yet the distance at which a particular 

 trip terminated bore no relationship to the distance at which the previous 

 or following one terminated. It was as if the rat w^as blind to its surroundings 

 on the outward trip until some neural switching mechanism became acti- 

 vated in a random fashion with reference to the time of the trip's initiation. 

 This switching on (or off?) placed the rat in a perceptive phase at which 

 time it responded by picking up the nearest relevant object and trans- 

 porting it into the home compartment. Therefore, it will be helpful to deter- 



