Equine intelligence, long described in myths and anecdotes, has been the subject of scientific study since the early 20th century. The worldwide fascination for clever horses, such as Clever Hans, gave rise to a long-running controversy over the cognitive abilities of horses. The discovery of the Clever Hans effect, followed by the development of ethological studies, has progressively revealed a high level of social intelligence evident in horse's behavior. The scientific discipline that studies equine cognition, at the crossroads of ethology and animal psychology, is cognitive ethology.
Although the existence of consciousness among horses is yet to be proven, their remarkable memory has been recognized for centuries. Because of their wild herd lifestyle, horses also exhibit advanced cognitive abilities related to the theory of mind, enabling them to understand interactions with other individuals. They can recognize a human by their facial features, communicate with them through body language, and learn new skills by observing a person's behavior. Horses are also adept at categorizing and conceptual learning. In terms of working intelligence, horses respond well to habituation, desensitization, classical conditioning, and operant conditioning. They can also improvise and adapt to suit their rider. Understanding how horses' cognitive abilities function has practical applications in the relationship between domesticated horses and humans, particularly in areas such as training, breeding, and day-to-day management, which can ultimately improve their well-being.
The perception of horse intelligence varies across cultures. This intelligence is often portrayed as human-like in tales and legends about wise, talking horses, such as the Kyrgyz epic Er-Töshtük and the Russian tale of The Little Humpbacked Horse, as well as in novels, films, comics, and series for young people, including The Black Stallion, Jolly Jumper, and Black Beauty.
History The horse has played an important socio-economic role across various historical periods, serving humans in labor, combat, sports, therapy, consumption, and religious practices. However, the intrinsic qualities of horses have sometimes been overlooked, with a variety of cultural narratives and perceptions surrounding them. Humans have shown interest in horses since prehistoric times, prior to their domestication, and horses have inspired written works since antiquity. Vanina Deneux-le Barh observes a recurring theme in equestrian literature, both technical and literary: humans can train horses to become skilled fighters. This suggests that, in their shared lives with humans, horses are believed to demonstrate situational intelligence.
Many equestrian authors have expressed a desire for horses to demonstrate intelligence and dedication to work. Despite this, horses have often been subjected to harsh treatment. The oldest known equestrian treatise, written by Kikkuli of the kingdom of Mittani in the 14th century BC, is an instruction manual for the training of chariot horses. This text is characterized by its stringent selection methods.
Xenophon (430-355 B.C.), the first European author whose equestrian writings have survived, frequently discussed horses in his works. He recognized situational intelligence in warhorses of Athens and strongly advocated against using violence in training:
From the Middle Ages to modern times
A significant portion of medieval technical literature consists of treatises on veterinary care. Arab and Muslim scholars made notable contributions to the knowledge of equine medicine, education, and training, in part due to the contributions of the translator Ibn Akhî Hizâm, who wrote around 895, and Ibn al-Awam, who advocated for non-violent training methods and pioneered the application of habituation methods.
There are historical accounts of horses reported to be extraordinarily intelligent, such as the Catalan knight Giraud de Cabrières' horse, described by the medieval English chronicler Gervais de Tilbury as both refined and invincible in races, capable of dancing, and even advising its knight and helping him in his victories by communicating with him through a secret language. Similarly, the English horse Marocco (), nicknamed "The Thinking Horse" or "The Talking Horse," was trained and performed in public shows.
During the Renaissance, the printing press revolutionized the production and dissemination of equestrian literature. Writings primarily focused on methods to achieve obedience and maneuverability in horses. The Italian horseman Federico Grisone, for instance, promoted the use of physical punishment to control horses he considered difficult to train.
With the rise of philosophical debates in France, René Descartes' concept of the "animal machine" contrasted with Michel de Montaigne's perspective, which viewed animals as possessing intelligence and virtues. Antoine de Pluvinel, influenced by Xenophon, acknowledged the sensitivity, individuality, and psychology of horses, emphasizing the importance of understanding the brain. François Robichon de La Guérinière (1733) also recognized a form of intelligence in horses, noting that some horses exhibited challenging behaviors or appeared indecisive. According to Sophie Barreau and zootechnician-sociologist Jocelyne Porcher, Guérinière was among the first to reject harsh methods, prioritizing the horse's cooperation over submission.
In the 19th century
From the 19th century onwards, numerous equestrian treatises acknowledged the intelligence of horses. People who interacted with horses daily observed their ability to communicate and their sensitivity. The era's interest in animal intelligence was reflected in the organization of numerous horse-focused performances, which became a common circus feature during the mid-19th century, especially at Victor Franconi's circus, which was inaugurated in Paris in 1845. In 1868, the Spanish writer Carlos Frontaura observed the "great intelligence" (gran inteligencia) of the horses pulling Parisian omnibuses, praising their initiative.
François Baucher included a detailed discussion of the term "intelligence" where he expressed his firm belief in the horse's intelligence:
The structured training system promoted by Baucher emphasized engaging with the horse's intelligence. Similarly, zoologist Ernest Menault also recognized "signs of intelligence" in horses, though his observations were less grounded in scientific evidence. Gustave Le Bon was one of the early researchers in horse psychology, and his 1892 equestrian treatise acknowledged the horse's intellectual abilities.
According to Jocelyne Porcher, 19th- and 20th-century zootechnicians applied the "animal machine" hypothesis to horses, drawing on the ideas of René Descartes, Nicolas Malebranche, and Francis Bacon. This perspective held that horses could not think, feel pain, or possess consciousness and emotions. Social pressures discouraged researchers from challenging these views, as their findings might not be well received, given that the "animal machine" concept was easier to defend in the context of industrialized farming practices. In 1892, T. B. Redding reported on a societal divide: some attributed intelligence and reason to horses, while others dismissed their actions as purely instinctual.
Additionally, misconceptions persisted. One of the most widely disputed misconceptions, according to equestrian journalist Maria Franchini, was the belief—circulating since at least 1898—that a horse's obedience stems from seeing humans as seven times taller than they actually are.
The worldwide popularity of "Learned Horses"
Until the mid-20th century, discussions about animal intelligence were framed through ontological comparison with human cognition. In 1901, French military veterinarian Adolphe Guénon published a comparative psychology study titled L'Âme du cheval, where he characterized the horse's brain as relatively simple compared to that of humans. Starting in the late 19th century, there was a global interest in animals believed to demonstrate intelligence. These horses, described as "calculating," were equipped with specially designed tools—such as cubes, sticks, and boards—and demonstrated patience in performing tasks.
Numerous journalists wrote articles about the intelligence of horses. In 1904, C. Mader questioned the view of the horse as a "living machine". In 1912, Remy de Gourmont commented on the growing fascination with horse intelligence in a society that had previously considered horses to be of average intellect at best. In 1913, a writer for The New York Times published an article asking whether horses were capable of "thinking".
The case of Clever Hans () is a notable example of this interest. This black horse, raised in Germany, became an international sensation in the early 20th century due to his supposed ability to solve complex arithmetic problems by tapping his hoof to indicate answers:
Belgian philosopher Vinciane Despret notes the prolonged scientific debate sparked by Hans's abilities, questioning whether horses possess conceptual intelligence. German psychologist Oskar Pfungst later revealed that Hans was not actually calculating but was instead highly attuned to human body language, stopping his hoof taps when he detected subtle cues. This discovery contributed to the development of the Clever Hans Effect.
Another notable example is Beautiful Jim Key, a horse which was trained to perform complex tasks and gained widespread fame in the early 20th century. Similarly, the case of the mare Lady Wonder sparked a debate about whether horses could communicate telepathically with humans. Despite doubts, some individuals continued to believe in equine telepathy well into the 1970s.This is particularly the case of Henry Blake, in his work "I speak to horses... They answer me."
Implications of the Clever Hans case for equine cognition research
Dutch primatologist and ethologist Frans de Waal discusses the relevance of Morgan's Canon—a scientific principle stating that animal behavior should not be attributed to higher mental faculties if it can be explained by simpler processes—illustrated by the case of Clever Hans. According to Jocelyne Porcher, Morgan's Canon had a lasting impact on research into animal cognition.
De Waal also observes that the experiments on Hans were interpreted in ways that undermined his intelligence, even though the experiments demonstrated his ability to read and interpret human body language. Ethologist Léa Lansade emphasizes that, at the time and up until the 1960s, animals were considered "intelligent" only if they demonstrated human-like abilities—such as calculating or learning sign language—even though these skills were not necessarily aligned with their natural behaviors.
The Clever Hans case had a significant impact on subsequent studies of animal cognition, contributing to the adoption of more rigorous experimental protocols. As Deneux-Le Barh notes, "experimental sciences aim to minimize the influence of the mètis (cunning intelligence) of the individuals being studied."
In the first half of the 20th century, research was primarily focused on behaviorism. Over time, this field divided into two main currents: ethology and cognitive animal psychology, which later converged into cognitive ethology.
Highlighting the cognitive faculties of the horse