DISTRIBUTION OF EFFORT IN LEARNING IN WHITE RAT 5 



this was because it was early noticed how eager the rats were 

 to feed when the operator entered the room for the first time, 

 and how this eagerness subsided after he had been present for 

 a time. This association of the operator with the securing of 

 food was seized upon as an advantageous time for work. Of 

 course, when there were from five to ten groups of rats under 

 observation, it was impossible to reach the last of them before 

 this eagerness was dissipated. This was partly overcome by 

 instituting a system of rotation in handling the groups, whereb}' 

 a different set was taken first each morning. 



In the beginning of the work on this problem it was thought 

 necessary, when taking rats at forty days old, to give a few 

 preliminary runs in the Porter maze before actual experimen- 

 tation. This was done to familiarize 3^oung rats with strange 

 surroundings, and to accustom them to being handled. This 

 early preparation was continued in all the work with the latch 

 box when used alone, but abandoned as unnecessary with the 

 other problems, the circular maze and the inclined plane box. 

 It was discovered that the rats were quite ready to solve these 

 problems without such preparation. They were active at all 

 times and not unduly disturbed by the change from the environ- 

 ment of the cage. After the preliminary runs in the maze, the 

 rats were fed for two days in the problem box, after which they 

 were for the first time given the problem to solve. 



At first an entrance box was taken to the cage in which the 

 rats were confined, and then a transfer was made to the hood, 

 but this method was soon abandoned, as it was found exceed- 

 ingly difficult to tame the rats without some handling. An un- 

 trained and naturally excitable rat became greatly disturbed 

 when carried in a closed cage, and it usually required several 

 minutes before it became calm, and, of course, such disturbances 

 could produce nothing but undesirable results. A new procedure 

 was, therefore, adopted. Rats were carried by hand to the 

 entrance box of the hood and then admitted. At no time were 

 they petted or coddled. In fact they were handled as little as 

 possible. When a rat was greatly excited or very timid, it was 

 left in the entrance box until it became calm before it was per- 

 mitted to enter the hood. 



One group of 17 rats was given one trial, another group of 

 1 1 three trials, and a third group of 1 1 five trials daily. Rats 



