In the 19th century, Wilhelm von Osten owned a horse named Hans. Von Osten trained Hans in mathematics and other tasks. Von Osten called him “Clever Hans.” Hans gave his answers to math problems and other questions by tapping out the answers with his hoof.
Decoding Clever Hans’ Abilities
German psychologist Oskar Pfungst agreed to study Hans. When a human showed him a problem or question, Hans generally answered correctly with his hoof.
Pfungst asked the right question. Could Hans recognize the answer to the problem in front of him if his trainer didn’t know the answer?