HABIT FORMATION IN THE ALBINO RAT 11 



that the day before beginning the problem, the rat had been 

 fed for five minutes in the food box of the maze. 19 Two things 

 were accomplished by this procedure. 1st: The rat was ren- 

 dered quite hungry, a necessary step since food was the stim- 

 ulus used, but the shock which would have resulted from entire 

 absence of food was avoided. 2nd: It became accustomed to 

 some extent to experimental conditions. 



On the day when the problem was actually begun, the tem- 

 porary partition was removed from the maze, a dish of milk- 

 soaked bread placed at the center and the rat put into the 

 starting box (S. B. Fig. 1). The instant it emerged into the 

 maze proper, the door (indicated but not shown in the illustra- 

 tion), was closed behind it, making return into the starting 

 box impossible, the stop watch was started and the tracing 

 begun. Twelve or fourteen minutes might be required to reach 

 the food', and as many as sixteen sheets of paper have been 

 necessary to trace the pathway during a single trial. At the 

 moment of entrance into the food box (F. B.), the watch was 

 stopped, the time noted, and the animal at once removed. This 

 constituted one trip or one trial. The rat was immediately 

 introduced for a second trial, in which the same procedure was 

 followed except that on reaching the food it was allowed to eat 

 for five minutes before being removed. The feeding period was 

 carefully timed with the purpose of keeping the hunger stimulus 

 as uniform as possible. A short ration of grain was thrown into 

 the living cage, and no more food was allowed until the next 

 day's work. Basset 20 had given grain only twice a week, and 

 noted in consequence a disturbance in behavior on the day 

 following that on which grain was given. Ulrich 21 fed his ani- 

 mals in the cage after work, which may account for their slow- 

 ness in learning the maze as compared with the rats used in this 

 problem. 



Two trials were given each day until the problem was learned, 

 i. e., until in six trips made on three consecutive days no error 

 was made from start to finish. In both Basset's and Ulrich 's 

 work, a time norm was set, and, although no useless movements 

 were made, unless the act was performed within the limits of 



19 Grain was given in the cage each day at the end of the feeding period. 



20 Basset, G. C. Habit Formation, etc. Behavior Monograph, 2 ('14), no. 4. 



21 Ulrich. Behavior Monographs. Vol. II, No. 5. 



