Hans, the thinking horse from Elberfeld

Ethicist Dr. Heike Baranzke on the phenomenon of a "smart" animal

The story of a horse named Hans is still exciting and amusing for scientists and animal lovers alike, even a good century after the actual events. It begins in Berlin and ends in - Elberfeld!
The ethicist Heike Baranzke knows its history and the many errors and confusions that have been preserved in the cultural memory of the people until today. But from the very beginning...

A skull of significance

"Kluge Hans` was a stallion in Berlin that caused a worldwide sensation at the beginning of the 20th century. He belonged to the retired elementary school teacher Wilhelm von Osten. The latter first had a horse, Hans I, which he was convinced was very intelligent and could think," the scientist begins this incredible story. When this horse died in 1895, the passionate pedagogue wanted to find out whether he could also teach a horse. He bought a new stallion in 1900, whose particular skull shape was significant. "He then chose a second Hans, and a Russian Orlov trotter with a very specific skull shape," Baranzke reports, "because in the 19th century, the theory of the skull, known as phrenology, had been developed by Franz Joseph Gall (phrenology attempted to determine mental characteristics and states in delimited brain areas, editor's note), and it said that the shape of the skull could be used, so to speak, to read off the intelligence abilities of living beings." Von Osten began to systematically teach Hans II the elementary school subjects of reading, writing and arithmetic according to the reform pedagogical method of Friedrich Adolph Wilhelm Diesterweg of the time. The astounding successes he achieved in his small Berlin backyard were then first shown to his neighbors. Now von Osten was beating the press drum because he wanted to have his results scientifically investigated. "Because of the persistent press echo, the Ministry of Culture forced the head of the Psychological Institute, philosophy professor and Privy Councillor Carl Stumpf, to take a closer look at the horse's apparent intelligence achievements," says Baranzke. "Wilhelm von Osten really courted scientific recognition of his teaching success from this famous psychologist."

Science is embarrassed

'Kluge Hans`, as the horse was called from then on, answered the tasks set for him by tapping a hoof or nodding/shaking his head. In this way, he could solve mathematical problems, spell and count objects or people. A scientific sensation took off, reported even in the New York Times. But science was initially very hesitant. "In the middle of the 19th century, modern natural science really took off as an empirical science, ultimately replacing romantic natural philosophy, which was still arguing metaphysically and spiritually. It was a fiercely fought worldview battle at the time," the scientist explains. Research was in a state of upheaval. "The scientific ideal was the exact sciences, first and foremost physics," she continues, "In medical training at that time, the philosophical course was replaced by the physics course. The exact sciences promised to be the solution to all problems." And psychology, too, was in the process of trying to see itself as an exact natural science. "The concept of soul had come into crisis because anatomists and surgeons were unable to find a soul. But among the people it still played a major role. Against the background of this time of upheaval, the request of a popular school teacher to a respected psychological researcher, anxious to preserve his scientific reputation, to look at supposed powers of thought and intelligence of an animal, was a rather embarrassing affair." For fear of losing their scientific reputation, the scientific institutions were therefore coy and did not even want to deal with 'Kluge Hans'. But the growing public interest in the clever animal - also on the part of the German emperor - forced a scientific statement.

Investigative commission to expose tricks

"Carl Stumpf was in a bind," Baranzke explains, and even the formation of an investigative commission proved difficult. Stumpf also built ahead by framing the investigation as a preliminary question that would simply clarify whether von Osten had used trickery. "He then surrounded himself with all sorts of capacities from various biological disciplines as well as recognized non-scientific horse experts from the military and circus world. Among them were the famous ornithologist Oskar Heinroth, the well-known Berlin zoo director Ludwig Heck, as well as majors, because the military in imperial times had many more horses and these gentlemen were considered good horse experts. Other members included circus trainers who had an eye for it because they worked with horses themselves."

Expert opinion prepared by student

"The result of this 13-member mixed September commission was to clarify whether von Osten was a trickster or not," Baranzke explains. "However, no trickery could be discerned, so the matter could not be dismissed as a stroke of genius by a shrewd attempt at deception. However, as Carl Stumpf emphasized and really impressed upon all those involved, nothing else was to be said to the press than that the question of how the horse had come to behave in this way had not yet been clarified, because this now required the establishment of a second commission." This now consisted of only three participants from the Institute and Stumpf delegated the preparation of the expert opinion to his student assistant at the time, Oskar Pfungst, as well as another colleague. "This Pfungst, who describes himself in the expert opinion he wrote as a "vivisector of the soul," didn't have much to lose scientifically and was known for having a rather unsentimental relationship with animals, so he was pretty sharp about it, too." But the finished report also raises many questions today. For a student to publish the fruits of his professor's and assistant's labor and base his fame on it is already a rarity in the annals of science. "The nice thing was, now with this opinion, you could say the case is settled for science," Baranzke says. "If criticism came, you could always say it was the opinion of a Mr. Pfungst, who was not yet a recognized scientist. Established science was out of the line of fire as a result." The fact is, Oskar Pfungst became famous with this expert opinion, which has been reissued again and again to this day. It proves, for one thing, that there had been no fraud, and it remains important in cognitive psychology to this day. "What Pfungst also showed was that there was no willful dressage, that is, that Wilhelm von Osten also did not train his stallion in the conviction that he would train him. Von Osten was convinced that he had actually taught his stallion like a schoolboy." Pfungst came to the conclusion that it had been an involuntary, i.e., unintentional, dressage that von Osten had, namely, "by the smallest, unintentional physical twitches, changes, inclinations, etc., not noticed by oneself."

“Smart Hans" and the Darwinian biologists

For science the matter seemed to be settled, von Osten withdrew deeply frustrated, but the Elberfeld jeweler Karl Krall, who had followed the development of the story with interest, did not let the case of Hans rest. He went to faraway Berlin to take a look at the trotter himself. "Krall had always been an amateur physicist, especially in optical fields. He also owned a small laboratory," Baranzke knows. In Berlin, he now joins a group of Darwinian-minded biologists for whom the human-animal similarity debate was far from over. "On the background of two and a half thousand years of anthropological discussion with the question of what distinguishes humans from animals, on the background of a hierarchically graded order of soul faculties, at the top of which were the human faculties of reason, it was clear from tradition," Baranzke explains, "that above all the domestic animals, i.e., horses and dogs - but at that time, too, the animals, too, were the most important species. that such animals, which man had drawn into his circle, were most likely to illustrate the debate about difference and similarity between man and animal. At the beginning of the 20th century, more and more stories of knock-talking dogs, horses, and even pigs became known in the circle of the animal protection movement supported by the middle classes. Darwinist-oriented biologists, in turn, looked with great interest on anecdotes of this kind, because they wanted to prove the continuity of man with the animal kingdom."

'Kluger Hans' comes to Elberfeld

"When Wilhelm von Osten died embittered, he had bequeathed Hans II to Karl Krall, and the latter transferred the stallion to Elberfeld." There he set up an animal psychology laboratory in the stable of the Privy Councillor of Commerce von der Heydt 'Am Mäuerchen` in Elberfeld. He made quite systematic experiments, not only with Hans, but also with eleven other horses, two donkeys, a pony and an elephant. "Among others, he had a blind cold-blooded horse named Berto, on which he tried in principle to disprove Pfungst`s thesis of visual perceptions, which he recorded and the result of which he would have liked to publish." However, this was denied him because the publishers did not want to get into the reputation of unscientificness, so he deposited his manuscript in the Kaiser Wilhelm Institute, the predecessor institution of the Max Planck Institutes in Berlin. "Karl Krall was not entirely on the losing end, because against the backdrop of the rise of the new Darwinian worldview, there were definitely sympathizers with only a gradual human-animal difference, and these included intellectuals from a wide variety of disciplines and arts," says Baranzke, who went on to meet in Elberfeld. "Among them were zoologists such as the famous "German Darwin" - as the Jena physician and zoologist Ernst Haeckel was known - or his student Heinrich Ernst Ziegler, who later became a zoology professor at the Technical University of Stuttgart, and corresponded by letter with the Mannheim terrier Rolf." And Baranzke names other luminaries. "They included a whole host of psychologists and psychiatrists, such as the Swiss psychiatrist Gustav Wolff, who spoke enthusiastically about the animals' performance in arithmetic, tapping, and recognizing people in photographs. And even the Nobel Prize winner for literature, Maurice Maeterlinck, was lured to Elberfeld by Kluge Hans. The latter then published a report entitled 'The Horses of Elberfeld`. The critics of Karl Krall only shot their arrows from a distance."

The 'Kluge Hans-Effekt' and its effect until today

Eventually, Krall gave up his investigations, moved to Munich and henceforth became involved in occultism. "It seems so abstruse," says Baranzke, "but all the differentiations in psychology were only just beginning. There was also in the early days around 'Kluge Hans` another psychologist, Albert Moll, then chairman of the Psychological Society of Berlin and one of the first scientists who had taken the trouble to seek out von Osten and his horse in person. He was on the trail of other perceptive faculties besides our known five senses, and had brought into play "N-rays" of the human brain as involuntary signaling. Extrasensory phenomena are in the strict sense of the word first of all such phenomena which are not limited to our known senses. One must remember that there are also sensory perceptions which only we humans do not have, and then one is not so far away from occultism." The echo sounder in bats or the electric eel, after all, were all still being discovered.
After all, Krall's estate is now housed in the Psychology History Research Archive at Fernuni Hagen. "His investigations for science have shown above all that there is an involuntary influencing of creatures by humans, and that the whole body language also works with higher animals." In scientific animal behavior research, he said, this has led, for example, to the separation of experimental animal and experimenter in order to exclude such involuntary 'Kluge-Hans effects`. "Transferred to these involuntary signals," Baranzke continues, "this means that an involuntary twitch signals: 'Now you have to stop tapping your hoof!' This led to the separation of the experimenter and the test animal, so that during the experiment, when the experimenter knew the result, he would not influence the test animal in its behavior through involuntary signals." The Pfpfungsgutachten is still a criterion in the discussion about the speech and thinking ability of apes today. Indeed, he said, it matters whether gorillas, chimpanzees or orangutans are capable of conceptual thought or not. "There's a fierce argument raging about that to this day."

In the human-animal relationship, humans set the rules

In summary, nevertheless, amazing achievements of the trotter remain. "He certainly couldn't do arithmetic or speech or solve root-calculation problems," the researcher knows, "but it's incredible how fine the interpretive powers of animals are in relation to human behavior."  But not enough research is being done on these other sensory perceptions, she says. There have been studies on sensing atmospheres or tensions, where the entire body is used for sensory perception, she said. "That would take quite a bit more discovery." Not doing so for a long time, he said, was a kind of avoidance story that prevented looking more extensively at the perceptual and communication abilities of animals. "It is, after all, a fascinating matter that also opens up interesting communication spaces for us," emphasizes Baranzke, who also always intends a fundamental behavioral question. "In what ways may we treat animals, the more we learn about how similar they are to us? To that extent, these findings certainly inform us about how we can adequately interact with animals. But the decision on how we want to shape the relationship is not something we can leave to animals; it is our decision of will. And that is specifically human."
The trail of 'Kluge Hans` gets lost in the turmoil of war. "In 1916 we are in the middle of the First World War and it was still considerably contested by the participation of horses," she says at the end. "Quite a few horses died there. One suspects that 'Kluge Hans` also took his way there." The poet Jan Wagner has dedicated an elegy to 'Kluge Hans', and thus set a monument to him in our cultural memory, even if he does not mention his Elberfeld stay in it.

Uwe Blass (conversation from 03.08.2021)

Dr. Heike Baranzke is a lecturer in theological ethics of Catholic theology in the Faculty of Humanities and Cultural Studies at Bergische Universität.