The Ghoulish Science Behind Micro Expression Research:

How French Revolution Guillotine Experiments Led to Authentic Smiles

By David M. Schneer, Ph.D.

There is a nasty history and science to facial Micro Expressions that we will be discussing in this post. In later essays, we will cover how to spot and decode non-facial body language positions.

If you have an iron gut, read on, and you’ll discover a powerful technique that can help you communicate more effectively. But first, some definitions are in order.

What are Micro Expressions and Why Should You Study Them?

Micro Expressions are involuntary facial movements that last a half second or less. While Micro Expressions are not proof of lying per se, they are reliable signs of emotions that may be tied to falsehoods or anxiety. These faint facial expressions could be early signs of an emotion, the subtle experience of an emotion, or an emotion that is deliberately concealed. There are 7 observable Micro Expressions: happiness, anger, surprise, disgust, contempt, sadness, and neutral.

Why learn to spot these emotions? Consider these advantages:

  • Sales professionals can gauge if their prospect or customer is “buying” their product or service.
  • An HR professional can tell if a candidate is less than authentic about experience or past positions.
  • Senior executives can hone their leadership skills by ensuring that their vision is resonating among employees and colleagues.
  • Lawyers can bolster their sixth sense during jury selection or cross-examination.
  • Police detectives can pick out the Pinocchio in the lineup.
  • Product managers can improve customer feedback.
  • Focus group moderators can decode respondents’ facial expressions for better understanding.

So, what does all this have to do with smiling and the French Revolution? While the guillotine was used as a means of execution long before the French Revolution (even the Nazi’s used it centuries later), the genesis of the French version was originally proposed as a more “humane” alternative to swords or axes, which often left their victims mangled.

Grisly Experiments

Whether the guillotine was actually a kinder/gentler form of execution has long been debated; speculation abounded whether the condemned were conscious after death. Grisly experiments were conducted to test this hypothesis. According to Evan Andrews, a writer, and History Channel contributor, doctors during the French Revolution urged victims “to try to blink or leave one eye open after their execution to prove they could still move.” During the spectacle of public executions, some would scream at the deceased’s head to draw attention. Still, others would expose severed heads to flames or ammonia to elicit a reaction.[1]

An Authentic Smile

Despite these fiendish medieval experiments, one French neurologist made some important discoveries regarding genuine and “fake” smiles. While others before him analyzed the heads of guillotine victims to see how long, if at all, victims lived after being executed, it was Guillaume Duchenne de Boulogne who studied how face muscles worked using electrical stimulus. The Zygomatic muscles he studied span the side of the face and attach to the corners of the mouth. These muscles also are attached to the orbicularis oculi, which are independent muscles that separately pull the eyes back, producing “crow’s feet”. Through his experiments, Duchenne proved that, unlike the “crow’s feet” muscles, we can control the zygomatic muscles to feign happiness or to signal subordination. An authentic smile should be accompanied by wrinkles around the eyes. Say Allen and Barbara Pease, husband and wife body language experts, “insincere people smile only with their mouth.” [2] Today, a true or genuine smile is called the “Duchenne smile”.

The Merrill Institute Mission

Others have built upon Duchenne’s legacy including, but not limited to, Dr. Paul Eckman, Haggard and Isaacs, famed psychologists Wallace Friesen and Dr. David Matsumoto, Swedish physician Carl-Herman Hjortsjö, and The Center for Body Language—to name a few.

We at the Merrill Institute intend to build on this legacy, both in Micro Expressions and Body Language training. Stay tuned to our next blog as we individually analyze the 7 Micro Expressions as well as introduce the concept of the 88 Major Body Language Positions.

Contact The Merrill Institute to learn more about Body Language Training and Micro-Expressions


[1] Andrew Evans, 8 Things you Didn’t Know about the Guillotine,

[2] Pease, Allan & Barbara. The Definitive Book of Body Language (pp. 66-67). Random House Publishing Group. Kindle Edition.