Produced by Audrey Longhurst, Linda Hamilton and the Online Distributed Proofreading Team at http://www.pgdp.net [Illustration: CLEVER HANS] CLEVER HANS (THE HORSE OF MR. VON OSTEN) _A CONTRIBUTION TO EXPERIMENTAL ANIMAL AND HUMAN PSYCHOLOGY_ BY OSKAR PFUNGST WITH AN INTRODUCTION BY PROF. C. STUMPF, AND ONE ILLUSTRATION AND FIFTEEN FIGURES TRANSLATED FROM THE GERMAN BY CARL L. RAHN _Fellow in Psychology in the University of Chicago_ WITH A PREFATORY NOTE BY JAMES R. ANGELL _Professor of Psychology in the University of Chicago_ [Illustration] NEW YORK HENRY HOLT AND COMPANY 1911 COPYRIGHT, 1911, BY HENRY HOLT AND COMPANY PREFATORY NOTE [BY JAMES R. ANGELL] _The University of Chicago_ It gives me great pleasure to accept the invitation of the publishers to write a word of introduction for Mr. Rahn's excellent translation of "Der Kluge Hans", a book which in the original has been but little known to American readers. The present wave of interest in animal life and behavior renders its appearance peculiarly appropriate. No more remarkable tale of credulity founded on unconscious deceit was ever told, and were it offered as fiction, it would take high rank as a work of imagination. Being in reality a record of sober fact, it verges on the miraculous. After reading Mr. Pfungst's story one can quite understand how sedate and sober Germany was for months thrown into a turmoil of newspaper debate, which for intensity and range of feeling finds its only parallel in a heated political campaign. That the subject of the controversy was the alleged ability of a trained horse to solve complex arithmetical problems may excite gaiety and even derision, until one hears the details. Scientists and scholars of the highest eminence were drawn into the conflict, which has not yet wholly subsided, although the present report must be regarded as quite final in its verdict. As for Hans himself, he has become the prototype of a host of less distinguished imitators representing every level of animal life, and when last heard from he was still entertaining mystified audiences by his accomplishments. But the permanent worth of the book is not to be found in its record of popular excitement, interesting as that is. It is a document of the very first consequence in its revelation of the workings of the animal mind as disclosed in the horse. Animal lovers of all kinds, whether scientists or laymen, will find in it material of greatest value for the correct apprehension of animal behavior. Moreover, it affords an illuminating insight into the technique of experimental psychology in its study both of human and animal consciousness. Finally, it contains a number of highly suggestive observations bearing on certain aspects of telepathy and muscle-reading. All things considered, it may fairly be said that few scientific books appeal to so various a range of interests in so vital a way.