144 THE HORSE OF MR. VON OSTEN 



lings. During the first series, he was well disposed, and 

 was able to concentrate effectively, while during the 

 second, he was nervous and easily diverted. This dif- 

 ference in intensity of concentration in the case of the 

 two series is attested, not only subjectively by Mr. Schil- 

 lings's introspective statement, but may be measured 

 objectively by means of the number of final taps which 

 the horse gave with his left foot during these two series. 

 We saw (page 94) that these final taps were always a 

 sign of intense concentration and, as a matter of fact, 

 one-half of the horse's responses to Mr. Schillings during 

 the first series were made in this way; whereas, in the 

 second series, only one-third were of this sort. (I, my- 

 self, was never able to get, without conscious control, a 

 greater number of this type of response.) We may 

 therefore say that, in the first series we had a high degree 

 of tension, or concentration, whereas, in the second 

 series, we had a low degree. The errors distribute them- 

 selves over the two series as follows : 



+ r +2 —1 —2 

 Series I (31 tests) 



Correct responses : 87% 



Incorrect " : 0% 0% 13^ 0% 



Series II (40 tests) 



Correct responses : 40^. 



Incorrect " 40^ Z% z.%,% 0% (and 9.si< 



other liinds of errors.) 



We find in Series I no " + i " errors, but only " — i " 

 errors; in series II, on the other hand, the errors are 

 almost exclusively of the " + i " category, equaling the 

 number of correct responses, and there is only one 

 " — I " error. A series obtained in the case of Mr. von 

 Osten is almost as satisfactory an illustration. When he 



