MAZE STUDIES WITH THE WHITE RAT 263 



B. Alteration of conditions while running the maze 



Degree of Hunger. After the maze was mastered, periods of 

 four days of heavy feeding were alternated with similar periods 

 of normal feeding.. We thus have the rats coming to the maze 

 with different degrees of hunger, the object of the test being to 

 determine the effect of strength of motive upon the accuracy 

 of a well automatized act. Rats differ very materially in the 

 length of the feeding period necessary to keep in good condition 

 and to give consistent daily records. These individual differences 

 are due to the rate of eating and the amount of food required. 

 The normal time allowed for eating ranged from 5 to 7 minutes. 

 The periods of heavy feeding were 15 to 20 minutes in length, 

 the animals being allowed to gorge themselves to their utmost 

 capacity. Ten rats were tested. Heavy feeding multiplied the 

 average error record by twenty. All rats were affected in vary- 

 ing degrees. Disturbance was present in but one-third of the 

 trials. The degree of the disturbance was highly irregular from 

 trial to trial. In general the effect increased at first and then 

 decreased. Complete adaptation was never secured. 



Cleansing Maze. During the course of a long experiment, 

 the maze will accumulate considerable filth in spite of the glass 

 cover. This filth consists of faeces, wisps of cotton, shells of 

 sunflower seeds, trackings of milk, and urine deposits. These 

 were allowed to accumulate for considerable time and the maze 

 was thoroughly cleansed and washed. The animals were tested 

 on subsequent days to determine the effect of this alteration 

 of conditions upon the accuracy of the maze habit. Ten rats 

 were tested, and eight were affected. The greatest effect occurred 

 on the second trial. Adaptation was secured in four trials. 

 Errors were present in but 60 per cent of the tests. The average 

 error record per trial for those affected was 1.75. 



Covering Maze. The rats were allowed to master the un- 

 covered maze. The .canvas top described in the introductory 

 section was then placed over the maze. In one case the interior 

 of the top was illuminated when the rats were tested, and with 

 another group it was not. A homogeneous maze environment 

 was thus substituted for the customary heterogeneous one, 

 and the illumination was either decreased or altered in character. 

 Eighteen rats were subjected to these changes while running 

 the maze, and none were disturbed in the slightest degree. This 



