horse from Germany, owned by Wilhelm II seemed to know how to count, say the days of the week, and even understand the German language. At first, many believed this to only be a big lie for Wihelm II to attract attention. Hans, the clever horse, had become famous worldwide for his unexplained abilities. William von Osten exhibited his extraordinary horse in 1891, and the two attracted a lot of people flocking to see this phenomenal horse.
His great teacher
Behind every great student, there is also a great teacher by the name of Herrn von Osten, who was a lesser-known German mathematician that saw the potential in Hans as well as an opportunity to get some attention from the abilities the horse had. Since the horse could not speak (that would have been a sensation), he was communicating by stomping his foot on the ground. If Hans was asked how much five plus two, he would hit the ground seven times; if asked what day came after Monday, he would be asked to stomp once with his foot for Tuesday, two times for Wednesday, and so on.
The whole of Germany was aware of Hans the cleaver horse, and the population started seeing him as a sort of national treasure. He became so famous in 1892–1893 that many people would travel across the world to see Hans do his maths so that they could see it for themselves, as no one in the right mind would believe that a horse could do basic maths.
What was the secret?
Was it a farce or a truly unique horse, an extraordinary specimen who seemed as smart as a first-class child? In 1904, a group of researchers announced that they did not find any evidence to prove that it was a hoax. However, Professor Carl Stumpf and one of his students, Oskar Pfungst, would finally solve the mystery. They noted that Hans could only very rarely answer questions to which his master did not know the answer, suggesting that there must be a connection between the two.
Through careful tests and observations, they realized that Hans was responding to very subtle, even unconscious, cues given by his trainer. For example, when Hans was asked how much was two plus three, von Osten or the one who asked the question (standing right in front of the horse) bowed a little in front after Hans kicked five times and before making this gesture for the sixth time.
Von Osten was very careful of the horse, but Hans was also watching the master carefully. Each time the horse reached the correct number of signs with his foot, the trainer made subtle movements (sometimes just a simple change of facial expression or posture) that told the horse to stop. Hans was obviously rewarded for the correct answers, thus getting used to this kind of behavior. Hans was obviously a smart horse, but not as smart as the public thought.