i8 



THE QUARTERLY REVIEW OF BIOLOGY 



present in addition to Mr. Herbert and 

 the writers. We watched the dog per- 

 form for half an hour or so — remarkably 

 well it seemed to us in spite of our chronic 

 skeptical attitude. We noted that no 

 attempt was made by the owner to use 

 identical phrases in the commands cover- 

 ing the same preformance, nor was any 

 set order followed in the performances. 

 The commands were given in a natural 

 conversational tone as if the owner were 

 holding a conversation with the dog. We 

 were quite convinced before the examina- 

 tion was over that the performance of the 

 dog was far above the level of routine so 

 characteristic of the usual animal trained 

 for purposes of exhibition. Even when 

 we, ourselves, determined the order of the 

 commands in a hit and miss manner the 

 performance was perfect. Our opinion 

 that the different acts were quite isolated 

 from one another and involved no element 

 of routine whatsoever has been fully borne 

 out by all later tests. 



The problem as to the nature of the 

 stimulus cues determining the responses 

 of the dog could not, of course, be so 

 easily disposed of. The first point to 

 settle was whether the essential stimuli 

 were actually auditory or not. For after 

 all the dog might be depending upon 

 unintentional gesture, or other visual cue 

 so long as he performed always in the 

 presence of his master. The possibility 

 of the "Clever Hans" error must be 

 effectually ruled out in view of the fact 

 that Johnson (zo) had found it to be a 

 complicating factor in his work on audi- 

 tory sensitivity in dogs. Certain pitch 

 discrimination habits, or what seemed to 

 be such, broke down entirely when the 

 experimenter absented himself from the 

 room during the experiment. 



In the absence of a screen, Mr. Herbert 

 was stationed in the bathroom of the suite 

 and gave his commands through the closed 



door while the writers remained in the 

 room with the dog to observe and to give 

 the necessary signals for the successive 

 commands. We were very careful not to 

 aid Fellow in any way by movements of 

 body, head or eye. Although not perfect, 

 the dog's performance was on the whole 

 quite satisfactory, and especially so in 

 view of the fact that the arrangement of 

 having the master absent was entirely 

 new, and the commands were noticeably 

 less audible. It was evident that visual 

 cues from Mr. Herbert were quite un- 

 necessary to successful response in many 

 cases at least, the essential stimuli being 

 auditory in character. 



It would have been desirable to run a 

 series of control tests to determine more 

 precisely the nature of the auditory cues 

 and particularly what, if any, language 

 elements were involved. We were handi- 

 capped at this point, however, by the 

 fact that Fellow is a one-man dog and has 

 been trained not to respond to the com- 

 mands of others than his master. Such 

 training is perhaps necessary if an animal 

 is to play his part well on the stage or in a 

 cinema role. It was impossible to carry 

 out our original intention, therefore, of 

 making systematic tests in which the 

 commands should be given by other per- 

 sons with varying pitch and different 

 intonation. We had thought of introduc- 

 ing a woman's voice in this connection. 

 We did find that Fellow would obey the 

 commands of persons with whom he has 

 been associated for some time, after 

 getting a nod of approval from his master. 

 Furthermore, Mr. Herbert varied his own 

 voice in pitch, intensity and intonation — 

 sometimes giving the commands in a 

 monotone — without disturbing the dog's 

 performance. 



It was evident that the dog has associ- 

 ated certain sounds, of the human, verbal 

 pattern type, with definite responses, but 



