390 JOHN LINCK ULRICH 



and the rat permitted to feed within, and then placed in the living 

 cage for a trial the next day. This method was continued for a 

 total of 6 days. If the problem was then unsolved, the rat was 

 considered unfit for solution of the problem and was no longer 

 used. The one trial a day method was adopted throughout all 

 investigations in learning. 



Before the work had proceeded very far, it was clearly evident 

 that the first trial was more important than succeeding trials for 

 the consideration of the integrated movements in learning. During 

 the supposed " initial effort" to solve the problem much of the 

 support for a " trial and error" conception of learning either in 

 its original formulation or in a modified form is obtained. At 

 this time the rat is supposed to "to try" first one way then an- 

 other until by the appearance of some fortunate " successful" 

 movements "it solves" the problem. Diametrically opposite to 

 the "successful" kind of movements, the "unsuccessful" are es- 

 tablished. The latter are clearly the kind which do not produce 

 the results for which we are looking and we regard those that do 

 produce the results as the "successful" movements. The signif- 

 icant thing hi this rating of movements is the regarding of "suc- 

 cessful" movements as important, without consideration of the 

 usual connection of events which lead up to the solution of the 

 problem. In any scientific investigation, previously existing 

 conditions have as great a value for the taking place of a pro- 

 cess and its explanation as the last added. 



When in preliminary feeding the rat is first admitted to the 

 environment of the problem, his behavior is quite different from 

 that when in the living cage. Usually hi an active rat, numer- 

 ous short spurts are made, and the body crouches at intervals 

 and relaxes at the end of each spurt. With less active rats, pro- 

 gression is slow in all parts of the problem. At the termination 

 of each spurt, the body is relaxed and progression is then in any 

 direction. All these movements do not stand out alone, but are 

 accompanied by evident organic changes, reflex excitability, and 

 often with the voiding of execreta. Elliott (7) has shown that 

 animals brought into strange surroundings had a considerably 

 smaller amount of epinephrin in the adrenalin glands than other 



