134 E. S. BOGARDUS AND F. G. HENKE 



This third maze was altered by placing door 4 at 5 and by open- 

 ing 2. The fourth maze was changed by placing door i at 2 

 and by opening 4. Several important features are to be noted 

 in this series of mazes, (i) Mazes II and III merely shorten 

 successively the true pathway of maze I. The object here is to 

 observe the process of learning to short circuit a familiar path. 

 This short circuiting is not optional on the part of the animals, 

 inasmuch as the former roundabout path has been blocked by 

 the insertion of sliding doors. (2) In mazes IV and V, the animals 

 are forced to enter former blind alleys at the end of which they 

 find themselves upon the old familiar path. (3) All five mazes 

 possess a common or identical true pathway at the beginning 

 and at the end. The mazes differ from each other only in the 

 middle portion. Each maze differs from the preceding one only 

 in one respect, so that each succeeding maze requires the animals 

 to make but one new adjustment. This position may be termed 

 the critical point. In mazes II and III the rats travel the habitual 

 path for a certain distance and then are 'forced by a short cut 

 to strike the old path which they can follow to the end. In 

 mazes IV and V, the animals travel at first over the old path; 

 from this they are forced into a blind alley at the end of which 

 they emerge again onto the old path. In describing the rats' 

 behavior in making these adjustments, we shall need to refer 

 to these three parts of the pathway. 



These mazes were graded for relative difficulty in learning 

 in the following order: I, II, IV, III, V. By relative difficulty 

 w^e mean the order of difficulty which would be encountered 

 by animals with no previous maze experiences. This order was 

 not determined by actual experiment, but was based upon 

 judgments of their apparent complexity. That mazes III and 

 V are much simpler than maze I is evident at a glance. 



The actual order of difficulty encountered in learning them 

 successively was V, IV, III, I, II. This fact is illustrated by table 

 III, the results of which are typical for all of the rats used. This 

 order is almost the reverse of that of their relative complexity. 

 In the successive learning of a series of similar mazes, it is 

 evident that previous experiences are effective upon subsequent 

 behavior and that these effects are advantageous or disad- 

 vantageous according to circumstances. 



As one would expect, the animals ran over the first identical 



