HABIT FORMATION IN THE DOG 27 



Although these results taken at their face value seem to con- 

 firm those of Kalischer and Rothmann, yet they were not wholly 

 satisfactory. The experimenter had been in the room, near the 

 dogs, throughout the experiment. While he was not yet trained 

 to observe and to guard against the giving of less noticeable 

 secondary cues, yet on casting the results it was easy to recall 

 many times when an animal had changed her reaction if the 

 operator happened to turn his head, shift his body-weight from 

 one foot to the other, or catch his breath. Also, that if the 

 stimulus-tone was not damped as soon as the animal had se- 

 lected her feeding-place, she would sometimes go hastily to 

 the other. Further there was room for doubt whether the order 

 of presentation had been sufficiently irregular, as in the records 

 of the animal's work on the first two problems, there were shown 

 only the number of right and wrong reactions respectively to 

 each stimulus-tone, the order of presentation not being given. 

 These facts being considered it seemed better not to rely on the 

 results at hand until other tests could be made in which these 

 possible disturbing factors were eliminated. 



Accordingly in the summer of 1911 the same two animals 

 were subjected to control tests, which, through the kindness of 

 Professors Angell and Carr, were performed in the laboratory 

 of the University of Chicago. The two stimulus-tones chosen 

 were middle c-256 d.v. and e'-320 d.v. It was believed that 

 the animals would quickly learn to discriminate between these 

 and that other tones could then be introduced, to which yet 

 different reactions could be made. 



In these tests the stimulus-tones were struck on standard 

 forks by an assistant^* who sat in a room twelve feet away, 

 separated from the animal-room by two partitions, one of which 

 was a nine -inch brick wall. A wooden tube four by six inches 

 in cross-section was used to convey the sound into the animal- 

 room. Between stimuli the animal was confined in a cage just 

 under the sound-pipe, and when the stimulus-tone was struck, 

 was released by the experimenter's pulling a string from where 

 he stood, in the room adjoining, by which act the door of the 

 cage was noiselessly released. In the opposite corner of the 



^^ This part of the experiment was conducted with the assistance of Mr. J. 

 W. Shields, then a graduate student in the University of Chicago, to whom my 

 thanks are due. 



