150 M. F. WASHBURN AND EDWINA ABBOTT 



after the change. This arrangement of the papers was used in 

 all subsequent experiments with these rabbits: it was used 

 from the beginning in the experiments on three other rabbits 

 (Shadrach, Meshach, and Abednego) ; and was introduced in a 

 few series with the remaining rabbit (Polly) without producing 

 any change in the percentage of correct choices. 



As a routine procedure in all the experiments except the 

 very first ones, where we were habituating the rabbits to the 

 apparatus, we kept out of sight of the animals tested. 



It has been stated that our ordinary practice was to have the 

 door which could be opened on opposite sides in successive experi- 

 ments. It is therefore possible that our rabbits, instead of acquir- 

 ing a habit based on discrimination between two visual stimuli, 

 were, as their records improved, merely acquiring a habit based 

 on kinaesthetic data, of turning to alternate sides in successive 

 experiments. It may naturally be asked why, in view of this 

 possibility, we did not vary the place of the open door less 

 regularly. Our reason for not doing so at the outset lay pri- 

 marily in the very strong tendency of the rabbits to form place 

 associations, and to go to the side at which they had last received 

 food. If they were allowed to get food from the same side twice 

 in succession, a tendency to go to this side would be started, 

 and we wished, of course, to force them to depend on visual 

 clues from the first. In our earlier series we were testing two 

 rabbits alternately, and there seemed little antecedent proba- 

 bility that with the comparatively long interval between suc- 

 cessive tests with the same animal which this involved, a habit 

 of alternating could be formed. Our later experience showed 

 us, as will appear, that even when the tests followed each other 

 immediately no habit of alternating was formed. The tendency 

 was always rather to go to the side that had been found 

 profitable the last time, and the only exceptions to our practice 

 of alternating the positions of the open door occurred when, to 

 break up a habit of going always to the same side, the open 

 door was kept persistently on the opposite side. 



The motive leading the animals to push the door, and to 

 acquire an association with one visual impression rather than 

 with the other, was simply the desire of food. The degree of 

 hunger was certainly not constant. The tests were made almost 

 without exception early in the afternoon, between half past one 



