WHITE RAT AND THE MULTIPLE CHOICE METHOD 227 



trial and the rat, when ready, was admitted again into the re- 

 action-chamber for another trial. The time from the entrance 

 into the reaction-chamber until the arrival at the food was meas- 

 ured with a stop-watch. 



PRELIMINARY TRAINING 



The rats were placed in the apparatus in groups of two or 

 three with all the doors open and with food in the food-dish. 

 They were left there for three hours. This procedure was re- 

 peated for three days. 



Then with all the entrance doors of the nine compartments 

 open, a rat was admitted to the reaction-chamber. When he 

 entered any compartment the door was closed behind him and 

 the exit door immediately raised and he found his way to the 

 food. He was allowed to eat for a few seconds, then pushed 

 into the entrance box and readmitted to the reaction-chamber 

 with all the entrance doors open. This was repeated for half 

 an hour. Such preliminary training was continued until the 

 animal made ten choices in half an hour. .This necessitated in 

 most cases only two or three series, of half hour's length, a day 

 apart. 



The following day the rat was given the opportunity to secure 

 success at each of the nine boxes. No. 1 was the only door 

 open on the first trial, No. 2 on the second, etc. The next day 

 this was reversed, No. 9 being the only door open on the first 

 trial, No. 8 on the second, etc. The rats by this time had the 

 food-association well formed and appeared to be in a state of 

 uniform preparation for the regular experiments. 



RESULTS OF EXPERIMENTS 



As it is essential to present the data for each trial in the series 

 of experiments, tables I, II, III, IV, V, and VI have been con- 

 structed after the following manner. At the head of each table 

 stand the several settings, the letter S serving as an abbreviation 

 for setting and the number following it designating the place 

 of the setting in the series. Immediately under the number of 

 the setting appear the numbers of the doors open, with the one 

 to be chosen (correct one) in bold face type. The column at 

 the left gives the date. The second column gives the number 

 of the various trials in the whole series. Following these num- 



