HABIT FORMATION IN THE DOG 41 



FURTHER EXPERIMENTS ON TONAL DISCRIMINATION WITH 

 IMPROVED APP.ARATUS 



In the fall of 191 1, the experiments on pitch-discrimination 

 were continued in the Johns Hopkins laboratory, with the im- 

 provement in method just suggested. The two tones to be 

 discriminated remained c-256 d.v. and e-320 d.v. They were 

 sounded on "tandem-driven" forks mounted with Kong reso- 

 nators, as described above. The reaction to the c-fork was a 

 turn to the left at the end of alley B, and the choice of food- 

 compartment F ; that to the e-fork, a turn to the right and 

 choice of food-compartment F'. The experiments had to be 

 conducted at night — from 10 to 2 o'clock, when a quiet build- 

 ing could be had. In addition to Dogs i and 2, two normal 

 female puppies, littered June i, 191 1. of which Dog 2 was the 

 dam, were introduced as a control. These animals are referred 

 to hereafter as Dogs 3 and 4. 



The first two or three days of work was spent in feeding the 

 animals in the stimulus-cage, and getting them accustomed to 

 passing through the doors without hesitation. After they had 

 become apparent^ "at home" in the new environment, each 

 animal was "put through" the proper reactions to the two 

 tones for three series of fifteen trials each, and then left to work 

 out the problem for herself. Punishment was not introduced 

 until the twenty-first day of training. The results were not 

 satisfactory. The animal's reactions were greatly retarded in 

 every case, and a certain disturbance resulted which none of 

 the animals entirely overcame. A shock too weak to be dis- 

 agreeable or even to be perceived when applied to the human 

 subject's dry hand, would often cause great disturbance in an 

 animal which had ignored it for several series. Care was always 

 taken, too, to weaken the current still more if the dogs' feet 

 were wet.^" 



For se\-eral weeks Dog i would go to grill G', mount with 

 the left foot the sill on her right, and reaching under the left 

 fore-leg with her right forepaw, would scratch the grill vigor- 

 ously for as long as five minutes, sometimes, barking furiously 

 all the while. The stimulus-tone was being sounded continu- 

 ously — or at intervals of one second from the time she was 



^" Breed, in his work on vision in the chick minimized changes in shock con- 

 ditions by having the floor of the home-box covered with moistened material so 

 that the animals' feet were always wet. This precaution seems well taken. 



