MAZE STUDIES WITH THE WHITE RAT 265 



adaptation to the new conditions, a return to the normal situa- 

 tion effected no disturbance. 



Position of the Experimenter. The experimenter maintained 

 a constant position in reference to the maze while it was being 

 learned. After mastery, this position was varied. After insert- 

 ing the rats in the maze, the experimenter occupied a position 

 on the opposite side of the maze from that in which he formerly 

 had stood. Six rats were tested on successive days until all 

 disturbance had subsided. All members of the group were 

 affected in varying degree. Errors were present in 60 per cent 

 of the tests. The average error record for three successive 

 trials was 2.50 as compared with a previous normal of .11. The 

 disturbance was eliminated in three trials. The total number 

 of errors per rat for the three trials ranged from 2 to 18. The 

 disturbance occurred only at that point in the maze path near 

 which the experimenter stood. The path previous to and after 

 this critical point was traversed normally. All error deviations 

 were in the direction of the experimenter. A disturbance was 

 frequently manifested by slow and hesitant movements and 

 head and body orientations in the direction of the experimenter 

 even when no errors were made. 



Rotation of a Uniform Environment. The maze was covered 

 by the canvas top closed on all sides and the interior was 

 illuminated by the electric light. Under these conditions vision 

 of the objective environment was impossible to the human eye. 

 This top was practically square (3', 9" by 4'), and as a consequence 

 the optical environment was uniform. The top was now rotated 

 90 degrees between trials, the maze itself remaining stationary. 

 Presumably the visual situation was not altered by this pro- 

 cedure. Ten rats were tested, and no disturbance resulted. 



Rotation of Heterogeneous Environment. The maze was 

 learned with the curtain of the canvas top open on one side. 

 This curtain was now closed and that on another side was 

 opened. This procedure was continued until all four sides were 

 opened several times on successive days. The alteration pro- 

 duced a change in the direction and intensity of the light as 

 well as in the character of the optical environment. Seven 

 rats were tested under these conditions, and five were affected 

 by the novel conditions. These five animals made an average 

 error record of 1.90 for six tests, and errors were present in 85 



