HABIT FORMATION IN THE DOG 9 



other possible changes of posture (e.g., strain and relaxation of 

 neck- or body-muscles), are possible involuntary changes in 

 breathing, etc., any of which the animal could quickly leam to 

 associate with food or with punishment. 



Kalischer indeed attempted two control-tests of the existence 

 of secondary criteria. First, he asserts that he made "some" 

 of his dogs temporarily blind, by sewing their eyelids together. 

 He reports that the accuracy of discrimination was not affected. 

 Now, if this temporary blindness were complete, this result in- 

 deed would show that the secondary cues if there had been any, 

 were not visual cues ; but it would not show that there were 

 no secondary cues of another kind. Changes of tension in the 

 operator's body-muscles, of breathing, etc., can be detected by 

 other than visual avenues. I lay what ma}^ seem undue stress 

 on this possibility, because, as will appear later, there is reason 

 to believe that such cues, involuntarily given, were factors in 

 some tone-discrimination tests which I made on blind dogs. 



Besides this form of control, Kalischer destroyed one cochlea 

 in some other "well-trained dogs." No disturbance is reported. 

 When the other cochlea was destro^^ed, all discrimination ceased. 

 Dogs subjected to extirpation of both cochlea before any train- 

 ing was attempted did not learn to discriminate at all. Kal- 

 ischer regards this as evidence that the other dogs had ignored 

 extra -auditory stimuli. The possibility still remains, however, 

 that in the tests given the normal animals, the experimenter 

 expected them to react when the food-tone was sounded, and to 

 inhibit reaction when other tones were sounded; and that he 

 made "unconscious" movements corresponding to his expecta- 

 tion, to which the animals reacted. On the other hand, in test- 

 ing dogs in which the cochlea had been destroyed, it is possible 

 that the experimenter, believing them to be deaf, did not expect 

 them to react, and hence did not make the movements which 

 one would expect in the opposite situation. The most honest 

 introspection will not enable him to decide w^hether "uncon- 

 scious and involuntary" movehients were made. If would have 

 been much better if Kalischer had applied some form of control 

 tests with the experimenter and others as well out of the room. 



Kalischer, however, was satisfied that the dogs were dis- 

 criminating between "exclusively auditory perceptions," and on 

 that assumption proceeded to operate on the auditory center as 



