Clever Hans (The Horse of Mr. Von Osten) / A contribution to experimental animal and human psychology

An investigation scrutinizes claims that a horse could perform arithmetic by tapping, using systematic observations and controlled experiments to determine how answers were produced. The researcher records public demonstrations, intimate introspections, and laboratory tests, and shows that the animal responded to imperceptible, involuntary movements and signals from human questioners rather than independent calculation. The book explains the genesis of the reaction, outlines instructional procedures, and discusses implications for studies of animal awareness, human suggestion, and rigorous experimental technique, supplementing the account with commission reports and methodological notes.