The Language of Faces

If you are at all familiar with the early history of neurology, you have likely heard of Dr. Guillaume-Benjamin-Amand Duchenne (de Boulogne).  Born in Boulogne in 1806 (which is why "de Boulogne" is often added in brackets after his name), Duchenne defied his father's dream that he become a sailor like the rest of his family.   Instead, Duchenne would pursue his own dream  to study medicine instead (sorry, Dad).  After qualifying as a medical doctor in 1831, he returned to Boulogne where he opened a practice and married for the first time.   This marriage ended tragically with his wife's death from pueperal fever followed by rumours about being responsible for his wife's death. And this may well have been true since he had done the delivery and this was in the era before Ignasz Semmelweiss demonstrated the need for doctors to wash their hands before delivering infants.  Whatever the reason for his wife's death, her family took charge of Duchenne's son and he would not see him again until shortly before his own death in 1875.

250px-Guillaume_Benjamin_Amand_Duchenne[1]Eventually moving to Paris (and enduring an unhappy second marriage), Duchenne began experimenting with the use of electric shocks to stimulate the muscles of patients.  Through his methodical research and determination, he eventually established himself as one of Europe's leading neurologists.   He also trained some of the most eminent neurologists of the 19th century, including Jean-Martin Charcot.    Duchenne is also remembered for first identifying the condition now known as Duchenne muscular dystrophy.

Still, the most unique area of research for which Duchenne is remembered is in the neurology of facial expressions.   As one of the first serious researchers to use photography to document his research, Duchenne carefully recorded the different facial expressions which were produced using electrical stimulation of the facial muscles.   In studying the physiology of smiling, he determined that "true" smile due to happiness involved both the eye muscles and mouth muscles.   This is why the term "Duchenne smile" is still used to describe this complete smile of happiness.  His 1862 book, Mecanisme de la physionomie Humaine (The Mechanism of Human Facial Expression),  contained a wide range of photographs, all featuring the bizarre facial expressions which were produced in his subjects by electrical stimulation to the various facial muscles.    220px-Smiling_girl[1]

But Duchenne wanted to understand more about facial expressions.  He believed that observing how the facial muscles produced different expressions could be used to measure emotions and personality.   During the 19th century, physiognomy, or the assessment of a person's character by observing their outward appearance was in vogue.   Even Robert Fitzroy, the Captain of the HMS Beagle was an amateur physiognomist and this nearly doomed Charles Darwin's chances of joining the Beagle expedition.    On first meeting Darwin, Fitzroy decided that the shape of the young biologist's nose meant that the he had a serious "lack of determination"  (Fitzroy later relented though).   

As for Duchenne, he developed what he described as a complete system for reading an "accurate rendering of the soul's emotions" based on different facial expressions.   He would announce in his 1862 book:

In the face our creator was not concerned with mechanical necessity. He was able in his wisdom or – please pardon this manner of speaking – in pursuing a divine fantasy … to put any particular muscles into action, one alone or several muscles together, when He wished the characteristic signs of the emotions, even the most fleeting, to be written briefly on man's face. Once this language of facial expression was created, it sufficed for Him to give all human beings the instinctive faculty of always expressing their sentiments by contracting the same muscles. This rendered the language universal and immutable

Based on the actions of different facial muscles, Duchenne identified thirteen primary emotions that could be expressed by one or more muscles.   To express frank joy, for example, Duchenne wrote that this involved a combination of the zygomaticus major muscle and the orbicularis oculi, "the first obeys the will but the second is only put into play by the sweet emotions of the soul;  the...fake joy, the deceitful laugh, cannot provoke the reactions of this latter muscle...The muscle around the eye does not obey the will; it is only brought into play by a true feeling, by an agreeable emotion.  Its inertia, in smiling, unmasks a false friend." 

Using applied electric shock to stimulate facial muscles, Duchenne captured the "idealized" expressions of his subject which he then recorded in his book using photographs.    A facial expression could be either partial or combined depending on the arrangement of muscles involved.  He used six living models for his book though his primary model, known only as "the Old Man" was described as an "old toothless man, with a thin face, whose features, without being absolutely ugly, approached ordinary triviality."    Referring to the different facial expressions as the "gymnastics of the soul,"  Duchenne argued that his research demonstrated the "conditions that aesthetically constitute beauty."  250px-Guillaume_Duchenne_de_Boulogne_performing_facial_electrostimulus_experiments[1]

He intended far more than simply listing different possible facial expressions, though.   What he wanted was to uncover a universal language of faces that remained the same across different cultures.  As he wrote in his book, "I have established the fact that it is always a single muscle which executes the fundamental movement which represents a given mental operation.  This law is so rigorous that man cannot change or modify it.  Had it been otherwise, it must have happened that the language of the face must have shared the language of speech;  each country, each province, would have painted the passions of the face after its own way, and possibly caprice would have caused the facial expression to vary infinitely in each city, or in each individual." 

Despite his ambitious research, Duchenne came under fire for how he used the subjects in his book, especially the "Old Man".   The various photographs showing an elderly patient with a series of bizarre expressions on his face (all induced through electric shocks) raised concerns about medical ethics.   In defending himself, Duchenne stated that the Old Man suffered from a complete loss of sensation to the face.  Since his facial muscles were unaffected, this allowed Duchenne to experiment on him without any pain.   He also argued that allowing the patient to show the full range of his emotions was aesthetically pleasing.   With another subject, a vision-impaired young woman, he also displayed the emotions that could be read from looking at only one side of the face, or seeing the complete face.

Though his great dream of creating a language of faces never really materialized, Duchenne's research into facial expression has been highly influential.   Along with with his other contributions to neurology, Duchenne's work with electrical stimulation of muscles would establish him as one of the pioneers of electro-physiology.  While his book was not that well-known outside of France (it wasn't translated into English until 1990),  Charles Darwin drew heavily on Duchenne's facial research in writing his own 1872 book, The Expression of Emotion in Men and Animals, and even corresponded with Duchenne for a time.    Duchenne's most famous discovery, the "Duchenne smile" is still considered to be a classic "tell" in identifying real versus fake emotions.  

Paul Ekman, among others, has written extensively on how the Duchenne smile can be used to detect deception.  It was Ekman who first coined the term "Duchenne's smile" and discovered, among other things, that even ten-month-old infants were more likely to show these smiles on seeing a mother's face as opposed to to seeing a stranger and that schizophrenics were less likely than non-schizophrenics to show Duchenne smiles. 

It was through Duchenne's research with facial expression, and the later work of his pupil Jean-Martin Charcot who did very similar research with his own psychiatric patients, that inspired many aspects of Sigmund Freud's psychoanalytic theory as well as modern treatment methods such as psychodrama.  Whether or not facial expressions can really be regarded as th "gymnastics of the soul,"  Dr. Guillame Duchenne would ensure that we would never see facial expressions in the same way again.






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