288 HARVEY CARR 



environment. The maze is now covered with the canvas top. 

 A uniform but darkened environment is substituted for that 

 present while the maze was mastered. If the rat is relying 

 upon these visual objects as directive stimuli in threading the 

 maze, their sudden removal should disrupt the act. No animals 

 were disturbed in this test, and we are forced to conclude that 

 vision possessed no directive function after the maze was mas- 

 tered. We may also assume that the alteration did not operate 

 as a distraction because the new environment was homogeneous 

 and poorly lighted. In the opposite experiment of uncovering 

 the maze, we may conclude that vision of the extraneous en- 

 vironment possessed no directive function because the condi- 

 tions were such that no possibilities were present for its de- 

 velopment. The maze was mastered in a homogeneous optical 

 environment. Removal of the top and the introduction of a 

 well illumined and heterogeneous environment resulted in dis- 

 turbances. Evidently these novel conditions were effective only 

 as distractions. If we cpuld generalize from these experiments, 

 we would be forced to conclude that all disturbances due to 

 alterations after the maze is learned and while the rat is run- 

 ning are the result of distractions. 



There is but one possible exception to the above formula- 

 tion, — certain characteristics of behavior when the sideless maze 

 was rotated. After rotation the animals frequently drifted to 

 that corner at which the food box had formerly been located. 

 This fact would indicate that the rats can orient themselves 

 in reference to the position of the food box in terms of stimuli 

 emanating from the extraneous environment. The same be- 

 havior was occasionally noted in the rotation of the standard 

 maze when the extraneous environment near the food box pos- 

 sessed unusual features, as an open window giving good light. 

 Granted that this fact indicates a directive function, yet it is 

 by no means certain that it was mediated through vision rather 

 than smell or some other sense, for no blind animals were em- 

 ployed as controls in this experiment. The fact can be inter- 

 preted, however, in terms of the distractive function. It is pos- 

 sible that certain unusual features in the environment near the 

 position of the food box operated as a distractive stimulus and 

 that the rats reacted to it in a positive manner. We may then 

 safelv conclude that alterations instituted after the maze is 



