Hans the clever is a horse that lived in Berlin between the end of the 19th and the beginning of the 20th century, which was so called because for a long time it was believed that it was capable of performing arithmetic operations and other tasks, and responded by stamping his hooves or pointing with his paws or snout. The horse’s fame was immense and it became a phenomenon acclaimed by the public. However, it was a psychologist, Oskar Pfungst, who discovered what the “trick” was behind this incredible ability: the horse did not respond due to mathematical ability, but because it was able to interpret behavior (apparently) involuntary of his master or of the audience who, with small movements perhaps due to the excitement for the correct answer, actually indicated to him what he should answer.
Who was Hans, the horse that mattered: his story
Performances of Hans the Intelligent began in 1891 to Berlin and were led by its master, Wilhelm with Osten. Wilhelm showed him signs showing mathematical operations and two possible solutions, and with his hoof the horse was able to indicate the correct result, or the owner verbally indicated possible solutions to the questions and tapping his hoof the horse was capable of identify the answer.
With this method, Hans amazed not only the audience, but also the psychologists of the timewho found no trick in Hans’ abilities and indeed, remained amazed by the fact that he was able not only to perform arithmetic functions, but also identify colors, understand the calendar, identify musical notes and even light. To do this, he was placed in front of signs bearing specific words, and when someone said the word in question, Hans shook his head.
It was only in 1911 that a German psychologist, Oskar Pfungsthe managed to figure out what the secret behind Hans’ abilities.
The investigation that discovered the “trick”
Until that moment, psychologists had not found any “trick” because the horse was able to answer questions even when its owner was not present. The psychologist Pfungst, however, noticed that even if Hans could respond even without his master, however, he was unable to answer when not even the audience knew the correct answer. Furthermore, Hans couldn’t answer if he couldn’t see who was asking the question (and therefore knew the answer). This made Pfungst realize that the horse evidently didn’t really know the answer, but he succeeded somehow to read it by its master or by the public.
Pfungst’s conclusion was that the horse skill they were not so much arithmetic or reading, but of interpretation of behavior. In fact, Hans was able to answer because he was capable of interpreting the involuntary signals that the person asking the question showed when faced with the correct question. In all likelihood, such was the excitement over the possible correct answer that the body and expressions of the person asking the question were readable by the horse. In short, the horse was really intelligent, but not in the way the public thought, but rather because it was able to perceive even very subtle body signals.
