APPENDIX 



THE ELBERFELD HORSES 



ALL preconceived opinions as to the limitation of animal in- 

 telligence have been called in question of late years by the 

 experiments of Herr von Osten and Herr Krall with their learned 

 horses. It is impossible for anyone who has not himself seen the 

 horses to make any contribution to the subject that is worthy 

 of attention. I had hoped to have an opportunity of forming 

 an independent opinion upon their performances before revising 

 this work, but events intervened, and I have been compelled to 

 rely on the evidence of others. It may be well, however, to 

 set forth briefly the admitted facts, to indicate the conclusions, 

 or rather the alternative conclusions, to which these point, and 

 to show what bearing they will have on the view of animal 

 psychology arrived at in the preceding chapters. The broad 

 facts are well known, but it will be convenient to summarise 

 them very briefly. 



Herr von Osten had a horse called Clever Hans, which was 

 able apparently to solve arithmetical questions by rapping out the 

 appropriate numbers with his hoof, and to communicate with 

 his master by an alphabetical code, in which a number of raps 

 corresponded to letters. The performances of Hans attracted 

 attention in Germany, and were investigated by a commission of 

 psychologists, who came to the conclusion that he was guided by 

 involuntary signals telling him when to begin rapping and when 

 to stop, and that no further intelligence was involved in the 

 operations of the horse. After Herr von Osten's death, however, 

 the matter was taken up by a believer, Herr Krall, who has 

 trained a number of other horses on similar lines. The alleged 

 arithmetical performances of these horses include the four primary 

 rules, a knowledge of fractions, use of brackets, the extraction of 

 roots to the 4th and 5th root, complex sums involving multi- 

 plication of roots, and the solution of simple equations. They 



447 



