INTEGRATION OF MOVEMENTS IN LEARNING IN THE RAT 481 



before the plane is plunged, and other increases in the number 

 of movements and in time appear before there occurs an im- 

 provement in the effectiveness of responses leading to the ap- 

 pearance of directive integration. 



These repeated advances to the plane with an increase in 

 time to plunge it, not only help to facilitate direct progression 

 first to the plane, but also do so first to the door before directive 

 integration is fully established. When reflex excitability is 

 manifest only after the plane is plunged, increases in the number 

 of advances and in the time to plunge the plane lead to the 

 effective performance of movements, and to the facilitation of 

 direct progression first to the door and not to the plane. This 

 same effective performance of movements leading to direct 

 progression to the door of the problem occurs after the problem 

 remains for one or two trials unsolved. The effect produced 

 by numerous movements in this last instance is not so imme- 

 diate, but is noticeable in a trial or two after the problem is not 

 solved. On the other hand, when reflex excitability is manifest 

 before the plane is plunged, and even when an increase in excit- 

 ability is again manifest after the plane is plunged, then the 

 cumulative effect of all movements leads to the facilitation of 

 direct progression first to the plane and not to the door. With 

 early manifestation of reflex excitability, effective movements 

 appear at any trial the moment a rat is admitted to the problem, 

 whereas, when excitability must be aroused, by the plane going 

 down, effective movements appear at the end of a trial. 



Not alone is directive integration facilitated with repeated 

 advances to the plane, but these advances are made to one side 

 of it and a constant method to plunge the plane is used. When 

 progression is to one side of the plane and one method to plunge 

 it occurs, then that side of the plane actually determines the 

 direction of progression from the entrance box to the plane. 

 This advance to one side of the plane is usually facilitated 

 whether direct progression is facilitated first to the plane, or 

 first to the door; but at times when direct progression to the 

 door is not readily facilitated, progression may be to the right 

 or to the left of the plane for many trials. Usually, then a 



