LITERARY NOTICES. 



Pfungst, Oskar. Das Pferd des Herrn von Osten (Der kluge Hans). Ein Beitrag zur experiment- 

 ellen Tier- und Menschen-Psychologie mit einer Einleitung von Prof. Dr. C. Stumpf sowie 

 einer Abbildung und fiinfzehn Figuren. Pp. 193. Leipzig: Verlag von Jmbrosius Barth. 

 1907. 



Clever Hans has been in the pubhc eye for four or five years and many charming 

 magazine stories have been written about his wonderful and supermundane powers. 

 Hans and his master, Herr von Osten, apparently were first brought to scientific 

 and world-wide popular notice by the zoologist. Schillings. So wonderful were 

 the attainments of the horse that a "Hans commission" of thirteen men was chosen 

 from widely different scientific fields and asked to solve the question as to whether 

 there was any secret means of rapport between horse and master. The commission 

 reported that Herr von Osten did not. at least consciously, control the responses 

 of the animal by means of signals. 



Stumpf's investigations of the behavior of Hans began on the thirteenth of 

 October and were continued until November 29, 1904. Herr O. Pfungst and 

 Dr. E. V. Hornbostel were present during these observations. The main conclu- 

 sion reached was to the effect that visual signs of one kind or another were utilized 

 by the horse in making the proper responses. 



0. Pfungst then continued the work in two ways. First, he made a thorough 

 test of the various acts of Hans, then determined the sensory cues to which the horse 

 reacted: Second, he substituted human subjects for Hans, who were required to 

 answer questions (similar to those put to Hans) by utilizing the same kind of data 

 which Hans employed. 



The experimental work was conducted partly in an open court and partly in a 

 large, white tent. Carrots, sugar and bread were the rewards for correct answers. 

 All questions asked were put in such a form that the answers could be given by 

 tapping a certain number of times with the foot. 



1. Can Hans read numbers.? Printed or written numbers were placed on 

 cards and exhibited to Hans. Hans was supposed to tap the appropriate number 

 of times. Two methods were tried. First, the questioner himself was ignorant of 

 the number displayed; second, the questioner knew the correct answer. When 

 the questioner was ignorant of the answer, only 8 per cent of correct responses was 

 returned. On the other hand, when the questioner knew the answer, 98 per cent 

 of correct answers was returned. 



2. Can Hans read words .? Such words as "Hans," "Stall," etc., were printed 

 on placards and arranged in a numbered series on a board. The horse was asked 

 to indicate by tapping on which placard any chosen word lay. When the word 

 chosen was unknown to the experimenter, no correct answers were returned, when 

 known to the experimenter, 100 per cent of correct answers was given. 



