From Animal Magnetism to Modern Hypnosis: How a Royal Investigation Changed Psychology

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Today, hypnosis is recognized as a legitimate psychological tool that can help manage pain, reduce anxiety, and treat certain medical and mental health conditions. But its origins are far stranger than most people realize. The story begins not with psychologists or neuroscientists, but with an eighteenth-century physician who believed he had discovered an invisible force flowing through all living things. His name was Franz Anton Mesmer, and his controversial ideas would eventually inspire one of history's first scientific investigations into the power of suggestion—a story that even involves Benjamin Franklin, King Louis XVI, and later, Sigmund Freud.

 

The Birth of "Animal Magnetism"

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Franz Anton Mesmer (1734–1815) was an Austrian physician who believed that an invisible natural force, which he called animal magnetism, flowed through every living creature. Mesmer proposed that illness occurred when this invisible fluid became blocked or unbalanced. By manipulating the magnetic force—sometimes using magnets and later simply his hands or metal rods—he claimed he could restore health. His treatments often produced dramatic reactions. Patients reported warmth, tingling sensations, trembling, emotional outbursts, and sometimes complete relief from their symptoms. As word spread, Mesmer became famous throughout Europe.

His treatment sessions were elaborate affairs. Patients often gathered around a large wooden tub called a baquet, filled with bottles of water and metal filings that Mesmer believed stored magnetic energy. Iron rods extended from the tub so patients could hold them against affected parts of their bodies while music played in the background. Mesmer himself, dressed dramatically, would move through the room making sweeping gestures with his hands or a magnetic wand. To many observers, the recoveries appeared miraculous.

 

King Louis XVI Orders an Investigation

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Mesmer's growing popularity also attracted skepticism. In 1784, King Louis XVI of France appointed two independent scientific commissions to investigate whether animal magnetism truly existed. One commission included some of the greatest scientific minds of the era:

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• Benjamin Franklin, then serving as the American ambassador to France

• Antoine Lavoisier, often called the father of modern chemistry

• Dr. Joseph-Ignace Guillotin, whose name later became associated with the guillotine

• Several other respected physicians and scientists

 

Rather than simply asking whether patients improved, the commissioners asked a more scientific question: What actually caused the improvements?

 

A Brilliant Early Experiment

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The commission designed clever experiments that would feel surprisingly modern today. In one test, participants believed they were being "magnetized" when they were not. In another, they were secretly magnetized without knowing it. The results were striking.

People often experienced dramatic reactions when they believed they were receiving treatment, even if no magnetic procedures had occurred. Conversely, when participants were unknowingly exposed to Mesmer's supposed magnetic force, little or nothing happened.

The commissioners concluded that the patients' experiences were genuine—but they were caused by expectation, imagination, and suggestion, not by any invisible magnetic fluid. Their report stated that the effects were real while rejecting Mesmer's explanation for them. Although the term placebo effect would not be coined for many years, the commission had documented one of the earliest scientific demonstrations of the powerful influence that expectations can have on human experience.

 

The Birth of Scientific Suggestion

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Although Mesmer's theory was discredited, the investigation revealed something equally fascinating. The human mind could produce genuine physical and psychological changes simply through belief and suggestion. Rather than ending the study of hypnosis, the commission inadvertently launched an entirely new field of inquiry. Over the next century, physicians and psychologists began exploring hypnosis without invoking mysterious magnetic forces. Researchers increasingly understood hypnosis as a psychological state involving focused attention, heightened suggestibility, and altered awareness rather than supernatural energy.

 

Freud's Early Interest in Hypnosis

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Nearly a century later, hypnosis influenced another towering figure in psychology: Sigmund Freud. In the 1880s, Freud traveled to Paris to study with the famous French neurologist Jean-Martin Charcot, who used hypnosis while treating patients with hysteria (a historical diagnosis no longer used in modern psychology). Freud later worked with physician Hippolyte Bernheim, whose research emphasized the role of suggestion rather than hypnosis itself. Bernheim argued that many hypnotic phenomena could be explained by the power of expectation and suggestion—ideas that echoed the conclusions reached by Franklin's commission a century earlier.

 

Early in his career, Freud used hypnosis to help patients recall distressing memories and relieve psychological symptoms. However, he soon became frustrated because many patients could not be hypnotized deeply or consistently. These limitations led Freud to develop a different therapeutic approach. Instead of relying on hypnosis, he encouraged patients to say whatever came to mind without censorship, a technique known as free association. This method became one of the defining features of psychoanalysis, helping shape modern psychotherapy. Although Freud eventually abandoned hypnosis, his early experiences with suggestion profoundly influenced the development of his theories about the unconscious mind.

 

What Does Modern Science Say About Hypnosis?

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Today, hypnosis is no longer viewed as mysterious mind control or evidence of hidden magnetic forces.

Instead, researchers define hypnosis as a state of focused attention accompanied by increased responsiveness to suggestion. Brain imaging studies suggest that hypnosis can alter activity in brain regions involved in attention, pain perception, and self-awareness. Clinical hypnosis has been shown to be helpful for some people in managing:

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• Chronic pain

• Medical procedures

• Dental anxiety

• Irritable bowel syndrome

• Smoking cessation (with mixed evidence)

• Stress and anxiety

 

Importantly, hypnosis is not mind control. People generally remain aware of their surroundings and cannot be forced to act against their deeply held values simply because they are hypnotized.

 

Why This Story Matters

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The story of Mesmer reminds us that science often advances in unexpected ways. Mesmer's explanation for his patients' improvements was incorrect. There is no evidence that "animal magnetism" exists. Yet his work inspired one of history's earliest controlled scientific investigations into human belief, expectation, and suggestion. The commission's careful experiments helped demonstrate that psychological factors can produce real experiences—a concept that continues to influence psychology, medicine, and neuroscience today. It also serves as an important reminder that observations can be genuine even when the explanation is wrong.

 

The Bottom Line

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Franz Mesmer believed he had discovered an invisible healing force flowing through the human body. A royal commission led by Benjamin Franklin found no evidence that such a force existed. Instead, they uncovered something arguably more remarkable: the extraordinary power of suggestion. That discovery helped lay the foundation for scientific research on hypnosis, placebo effects, and the relationship between mind and body. Decades later, hypnosis would influence Sigmund Freud's early work before he developed psychoanalysis, making Mesmer's unusual legacy an unexpected chapter in the history of psychology.

 

Learn More

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• The Reports of the Royal Commission of 1784 on Mesmer's Systems of Animal Magnetism and Other Contemporary Documents (English translation edited by Robert Darnton). This collection includes the original reports from the commissions appointed by King Louis XVI and provides a fascinating firsthand look at one of history's earliest scientific investigations.

• Stanford Encyclopedia of Philosophy: Franz Anton Mesmer and Animal Magnetism
  https://plato.stanford.edu/

• Encyclopaedia Britannica: Franz Anton Mesmer
  https://www.britannica.com/biography/Franz-Mesmer

• American Psychological Association: Hypnosis
  https://www.apa.org/topics/hypnosis