226 HAROLD E. BURTT 



In most cases the rats were given the ten settings in order 

 in a single series of experiments. In a few of the earlier series 

 it was not feasible to give ten trials in immediate succession. 



Both punishment and reward were used as incentives. The 

 punishment consisted of confinement in a compartment after 

 an incorrect choice for 5 (in some cases 10) seconds. The re- 

 ward consisted of food, — cold boiled potato or green corn prov- 

 ing most satisfactory. The rats were given all the food they 

 wished during the afternoon and evening, but always fasted 

 from 10 p. m. until the middle of the next forenoon when the 

 experimental observations w T ere usually made. If trials were 

 made in the afternoon also, no food was given in the interim. 



EXPERIMENTAL PROCEDURE 



The usual procedure in a series was as follows. Sufficient 

 food for 10 trials was placed in small bits in the food-dish. The 

 rat was 1 put into the entrance box through the rear door. The 

 experimenter then took his seat at the table ten feet distant 

 and remained there during the entire series. The proper en- 

 trance doors of the compartments were raised for the first trial, 

 e. g., in Problem 1 doors 1, 2 and 3 w r ere opened and all the others 

 closed. The door leading from E into the reaction-chamber 

 was then raised and the behavior of the rat was recorded in 

 symbols from its entrance into the chamber until its arrival at 

 the food. 



If the animal entered the wrong compartment the door behind 

 it was closed for 5 seconds, —the experimenter counting the tics 

 of the stop-watch. The rat was then allowed to retreat from 

 the compartment and make another choice. This procedure 

 was repeated until the rat entered the correct compartment, 

 wiiereupon the door behind it was closed and the exit-door 

 opened immediately. The rat then ran along the alley to the 

 food-dish. The experimenter immediately pulled a string closing 

 the door across the alley behind the animal. After a few seconds 

 the door from the alley to the entrance box was raised, and the 

 door behind the rat pulled along until it drove or pushed him 

 into the entrance box. Most of the rats, however, soon acquired 

 the habit of picking up a bit of food, waiting until the door in 

 front of them opened and then going into the entrance box to 

 eat at their leisure. Meanwhile the doors were set for the next 



