Duchenne de Boulogne (right) and a colleague use electrical probes to manipulate the facial muscles of one of their test subjects.Adrien Tournachon/Wikimedia Commons
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"Pleasure"Adrien Tournachon/Wikimedia Commons
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Duchenne de Boulogne and a colleague use electrical probes to stimulate the facial muscles of a test subject.adoc-photos/Corbis via Getty Images
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"Astonishment, stupefaction, amazement"Adrien Tournachon/The Metropolitan Museum of Art
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"Ferocious cruelty"Adrien Tournachon/The Metropolitan Museum of Art
Duchenne de Boulogne (right) and a colleague use electrical probes to stimulate the facial muscles of one of their test subjects.Adrien Tournachon/Wikimedia Commons
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"Scene of coquetry"Adrien Tournachon/The Metropolitan Museum of Art
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Duchenne de Boulogne poses with one of his test subjects.Adrien Tournachon/The Metropolitan Museum of Art
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"Nun saying her prayers"Adrien Tournachon/The Metropolitan Museum of Art
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Adrien Tournachon/The Metropolitan Museum of Art
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One of the machines that Duchenne de Boulogne used to stimulate the faces of his test subjects with electrical currents.Museo Galileo/Wikimedia Commons
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"The grimice produced is similar to a tic of the face"Adrien Tournachon/The Metropolitan Museum of Art
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"Whimpering and false laughter"Adrien Tournachon/The Metropolitan Museum of Art
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"Expression proportionally more pained"Adrien Tournachon/The Metropolitan Museum of Art
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"Painful weeping and forward looking"Adrien Tournachon/The Metropolitan Museum of Art
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Duchenne de Boulogne and a colleague use electrical probes to stimulate the facial muscles of a test subject.adoc-photos/Corbis via Getty Images
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"Gaiety expressed by the ideas of lustfulness, cynicism, and lewdness"Adrien Tournachon/The Metropolitan Museum of Art
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Duchenne de Boulogne and a colleague use electrical probes to stimulate the facial muscles of a test subject.adoc-photos/Corbis via Getty Images
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"Expression of severity"Adrien Tournachon/Wikimedia Commons
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"The attention attracted by an object that provokes lascivious ideas and desires"Adrien Tournachon/The Metropolitan Museum of Art
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"Strong expression of cruelty"Adrien Tournachon/The Metropolitan Museum of Art
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Duchenne de Boulogne places electrical probes on the face of one of his test subjects.Adrien Tournachon/Wikimedia Commons
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"Pain and despair"Adrien Tournachon/The Metropolitan Museum of Art
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"Scornful laughter and scornful disgust"Adrien Tournachon/The Metropolitan Museum of Art
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Duchenne de Boulogne uses an electrical probe to stimulate the facial muscles of a test subject.adoc-photos/Corbis via Getty Images
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"A suggestion of...weeping"Adrien Tournachon/The Metropolitan Museum of Art
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"Fright"Adrien Tournachon/The Metropolitan Museum of Art
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"Terror, semiprofile"Adrien Tournachon/The Metropolitan Museum of Art
Haunting Photos From One Of The Most Horrific Looking Human Experiments Ever Conducted
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Whether you know it or not, you have given plenty of Duchenne smiles throughout your life. They are, after all, the most joyous and genuine kind of smile.
What sets the Duchenne smile apart from the other kinds is not in the mouth, but instead in the eyes. While a polite, calculated smile (known as a Pan Am smile, named for the superficial smiles that that airline's flight attendants were required to give each passenger) engages only the zygomatic major muscle to raise the corners of the mouth, a Duchenne smile engages both the zygomatic and the orbicularis oculi muscle to raise the cheeks and form crow's feet around the eyes.
We know this because of the pioneering research conducted by the man for whom the Duchenne smile is named: Guillaume-Benjamin-Amand Duchenne de Boulogne.
This French neurologist carried out several electrophysiological studies between 1854 and 1856 that determined precisely how the muscles in the human face work to produce facial expressions.
As innocent as that sounds — and as pleasant as it is to have the most authentic of human smiles named in your honor — Duchenne de Boulogne's work has, in recent years, elicited new interest because of just how grotesque and horrific some of his studies' photos appear to be.
Collected and published in 1862's The Mechanism of Human Physiognomy, these photos show Duchenne de Boulogne and colleagues holding electrical probes to the faces of their test subjects in order to produce haunting expressions of terror, pain, and horrified surprise.
While Duchenne de Boulogne did indeed shock his subject's facial muscles to produce certain expressions, neither the shocks themselves nor the experiments as a whole were as torturous and ghastly as these surviving photos lead many to think.
In fact, if anything, Duchenne de Boulogne's work advanced the fields of neurology and electrotherapy in ways that have helped countless patients in the century and a half since his death. He was, for example, the first clinician to conduct muscle biopsy and his work went on to influence seminal Charles Darwin writings on the influence of genetics on human behavior.
Nevertheless, joining these significant accomplishments — and his eponymous smile — in Duchenne de Boulogne's modern legacy are the seemingly horrific electro probe photos collected in the gallery above.
John Kuroski is the editorial director of All That's Interesting. He graduated from New York University with a degree in history, earning a place in the Phi Alpha Theta honor society for history students. An editor at All That's Interesting since 2015, his areas of interest include modern history and true crime.
Savannah Cox holds a Master's in International Affairs from The New School as well as a PhD from the University of California, Berkeley, and now serves as an Assistant Professor at the University of Sheffield. Her work as a writer has also appeared on DNAinfo.
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Cite This Article
Kuroski, John. "Haunting Photos From One Of The Most Horrific Looking Human Experiments Ever Conducted." AllThatsInteresting.com, June 1, 2017, https://allthatsinteresting.com/duchenne-de-boulogne. Accessed February 12, 2025.
