Why Psychologists Study The Duchenne Smile

Our facial expressions can tell people a lot about our emotions. When we speak of human smiles, our first thought may be a smile of pure happiness or true enjoyment. There are other smiles, too, though. Not all smiles are created equal or show a positive emotion: there's the smile of fear, the smile of embarrassment, even the smile of anger. These smiles have their distinct physical characteristics and may be considered false smiles.A Duchenne smile is a genuine and often involuntary smile that involves both the muscles around the mouth and the eyes, indicating true happiness and authenticity.

The Duchenne smile is a very unique type of human smile that psychologists have been studying for over a century. In short, Duchenne smiling is considered to be a genuine, often involuntary smile of happiness and may display authenticity.

What is the Duchenne smile?

A Duchenne smile is a natural smile that conveys enjoyment and involves contraction of the zygomatic major muscle (the muscle that runs along your cheekbone) and the orbicularis oculi muscle (the muscle that lines the top of your lip). It’s often involuntary and experienced during times of genuine happiness or enjoyment.

A smile associated with positive emotion

When you see someone displaying a Duchenne smile, you are likely to naturally feel positive emotions for the person smiling. The smile is distinctive and reveals each Duchenne marker in the region involved: the mouth turning up, the cheeks lifting, and the eye sockets crinkling to create “crow's feet.” 

This smile does not look forced and is not available on command; it’s a smile that happens when something prompts a person to feel happy and positive.

What makes this facial expression special?

The Duchenne smile is different from other smiles in several ways. First, it uses both the zygomatic major and the orbicularis oculi, while a false smile doesn’t involuntarily engage the zygomatic major as much or at all but resides only on and around the lips. A false smile can be described as a smile that “doesn’t reach the eyes” as it does not engage the muscles around the eyes and only pulls up on the outside corners of the mouth.

Second, the Duchenne smile is considered a natural smile of enjoyment. In the past, the consensus among researchers was that a true smile couldn't be faked. More recent research calls that into question. Now, researchers spend more time trying to find out how we benefit from and how we can produce the Duchenne smile.

Early studies of smiles

Smiles have also been a subject of scientific interest for at least a century. To many researchers, the Duchenne smile is the most interesting, partly because of the question about whether we can produce it on command.

Guillaume Duchenne had an unusual way of conducting research. Using people at a psychological hospital as subjects, Duchenne produced various expressions by stimulating facial muscles with an electrical current. The procedure was said to be extremely painful, so his later methods were often macabre, involving severed heads from cadavers. 

Eventually, he published a book explaining what he found through his studies. The book is called  'Mécanisme de la Physionomie Humaine,’ and was published in French in 1862. 

Darwin on facial expressions

During the same historical period when Duchenne did his work, Charles Darwin studied facial expressions and their role in the survival and evolution of humans. In 1872, Darwin published a book called, 'Expression of the Emotions in Man and Animals,’ which delved into the types of expressions we use, what they look like, and what purposes they serve in the communication and cohesiveness of groups.

Diagrams within this book show the muscles responsible for making our facial expressions. Darwin goes on to discuss his interpretations of expressions like the smile of joy, which roughly correlates to the Duchenne smile. In fact, within this text, Darwin mentions Duchenne and gives him credit for successfully explaining how those muscles create that distinct smile.

Carney Landis and the subtleties of emotion in faces

A psychology student at the University of Minnesota, Carney Landis, conducted what are widely considered to be bizarre and overall unethical experiments to study human facial expressions. He put his subjects in unexpected situations and photographed them. Some of the situations included putting their hand in what turned out to be a bucket of frogs, watching porn, smelling ammonia, and even being asked to decapitate rats (which 1/3 of participants did, while the other 2/3 who refused were made to watch as Landis did it for them). Landis’ study was published in 1924, in the Journal of Comparative Psychology, and his work quickly caught on within the field of psychological research.

A lingering problem with Landis' study is that he failed to recognize the subtleties of how different facial expressions can indicate different emotions. He didn't recognize the Duchenne smile and said that smiles—genuine or fake—were common in any situation. He saw no relation between the smile and a sense of enjoyment or satisfaction.

However, Landis did accomplish something meaningful with his work. He asked a question that would be the subject of study for the next 90-plus years: Do emotions cause expressions, is it the other way around, or can both be true?

Ekman and Friesen

In the 1970s, Paul Ekman and Wallace Friesen brought back the idea of the Duchenne smile. They also cataloged 3,000 facial expressions in their coding system called the Facial Action Coding System, which has been an extremely helpful tool for researchers studying the Duchenne smile and other expressions. 

The FACS shows photos of each expression, its description, and the facial muscles used to produce it. In the guide, you can see the action of both the zygomatic major and the orbicularis oculi muscle, although each is shown separately.

Psychologists' goals for studying the Duchenne smile

There are a number of reasons why psychologists are interested in examining the Duchenne smile.  The Duchenne smile impacts and is impacted by the specific situation the smiler is in, so it can help further understanding of social interactions. The smile is also an indicator of emotion, a subject that's incredibly important to psychologists. Below are some of the more specific reasons researchers have focused on it.

To better understand how the brain processes a facial expression

When we see someone's facial expressions, how do we know what emotion they're expressing? Neuroscientists recently took electroencephalogram (EEG) recordings of people smiling to learn if their brains would process other people's emotions differently depending on their expressions.

The subjects were told to smile or hold a neutral face. Then, they were then shown photos of people with neutral faces. When the subjects smiled, their brains demonstrated different processes than when they held a neutral face and viewed the photos. This study on smiling, published in 2015, didn't specifically address the Duchenne smile.  However, in a related meta-analysis of the Duchenne smile, it was determined that people respond more positively when others smile a genuine smile compared to a polite one.

In another study, titled Proximity Begins with a Smile, But Which One? Associating Non-Duchenne Smiles with Higher Psychological Distance, researchers showed that a false smile was a reliable marker of a more distant relationship, while a Duchenne smile indicated a close relationship. 

To test the facial feedback hypothesis

The facial feedback hypothesis states that the way you move the muscles of your face can change your emotional state. This hypothesis has been tested in many studies, including one by Robert Soussignan published in 2002. 

This research targeted Duchenne smiles specifically. When the subjects produced a Duchenne smile - fake though it was - they had a more pleasant experience, indicating that the facial feedback hypothesis might be correct. Associating false smiles with unhappiness may not be entirely accurate either, a person may smile and feel happy, it just might not be so overwhelming that a Duchenne smile is present.  

To better understand how the Duchenne smile interacts with a person’s thoughts

Scientists don't just want to know the neurological components that the smile involves. They also want to know how our thoughts affect how we express ourselves and how our expressions change not just our emotions but also our conscious thoughts. A part of the reason why psychologists study facial expressions is to understand our emotions better. The more complete their understanding of these emotions, the better they can help their clients.

Not only do therapists need to understand emotions to help their clients directly, but they also need to be able to identify emotions by reading facial expressions as clues to inner states. This interpretation helps them better understand clients' reactions so they can respond appropriately.

To learn about the role duchenne smiles have in child development

Researchers have also studied the intersection of child development and facial expressions. One study by Ruiting Son, Harriet Oliver, and Malinda Carpenter investigated the process of learning to recognize a genuine Duchenne smile. The study indicated that by age three, children look more often at people showing the Duchenne smile. By age four, the children could verbally point out a “real” (Duchenne) smile and a “fake” (non-Duchenne) smile. At ages four and five, the children expected the person with the Duchenne smile to be more friendly and helpful than the person with the fake smile.

To understand differences across cultures

Psychologists look for both similarities and differences across cultures and among individuals. Researchers studied the differences between countries like the U.S. and South Africa where smiling is more acceptable and countries like Russia where smiling is more discouraged.

In a multicultural study, people who smiled were considered more intelligent than others by people in countries where smiling is encouraged, but less intelligent by people in countries where smiling was discouraged. These multicultural studies are important to help people of different cultures better understand and, ideally, get along with each other.

Individual differences in smiling have also been studied. For example, in a study by K.L. Schmidt and J.F. Cohn, some people showed partly non-Duchenne characteristics even though they were enjoying themselves.

The positive effects of Duchenne smiles

From their significant research into the topic, academics, sociological professionals, and scientists have been able to discover some remarkable effects of the Duchenne smile on both physical and mental health.

Improves mood and social relationships

The Duchenne smile creates good feelings unexpectedly. Since past studies have indicated that smiling releases hormones and endorphins that can improve mood, it stands to reason that seeing a happy face will boost your mood as well.

In a recent study, researchers Javier Elkin and Dr. Parashkev Nachev found just that. They sent a photo of a happy face to subjects via smartphone. Subjects reported feeling better afterward; these results suggest that smiling may improve low moods.

Smiling can impact your relationships, be they platonic or romantic. What's more, as research shows, smiling can make you seem more attractive. If you're a woman, smiling can also make you seem more trustworthy. All of these factors can improve your personal and social relationships dramatically.

Increased persuasiveness

The Duchenne smile, even when applied deliberately rather than involuntarily, makes it easier to persuade someone of something. You can use this fact not only to convince someone that something is true, but you can carry it further and potentially convince them to buy something from you if you’re running a business or working in sales. Smiling has also been shown to impact customer tipping behavior in a service relationship, which may be why “service with a smile” is a mantra in many industries.  

One study published in the Journal of Advertising Research showed that celebrities who flashed a Duchenne smile during product endorsements were seen in a more positive light. This means that if you can produce a Duchenne smile, you may be able to influence others more easily.

Boosts enjoyment and positive emotion

Our modern world doesn't always lend itself to pleasant experiences or letting go and just enjoying the moment. However, sporting a Duchenne smile can enhance your ability to feel pleasant, positive emotions. Simply put, it’s possible that you could enjoy your life more by smiling more often.

Genuine facial expressions and the duchenne smile

Many researchers now believe you can voluntarily produce a Duchenne smile. To create a Duchenne smile, start by thinking of something happy. Picture someone you love or remember a happy event. Some people prefer to think of something humorous. Sometimes, just changing the way you're thinking at the moment is enough.

If not, try mirror practice. Think of that happy thought as you look in a mirror. Then, try to smile, focusing on lifting the skin around your lips, cheeks, and eye muscles. When you see you've produced a genuine-looking smile, notice what muscles you're using. The more you practice, the better you may become at producing the smile, and the more easily it may come in the future.

How online therapy can help

When smiling seems impossible, you may need some extra help to put a Duchenne smile back on your face, and that’s okay. You can talk to a therapist anytime you're ready. Licensed counselors are available at BetterHelp for online therapy at a time and place that's convenient for you.

Online therapy can be a useful, effective tool for a broad variety of people. If you’re struggling to smile, it might help to know that 70% of BetterHelp users experienced notably decreased depression symptoms, while 98% of all users across a wide range of conditions had significantly improved their conditions and mental health after treatment. What’s more, 78% of users classified as having “severe depression” before online treatment were no longer classified as such after three months of treatment, with 15% of them now being classified as having mild depression.

If your schedule is packed, you live in a rural setting too far away to commute to sessions, or you prefer virtual communication, online therapy can be beneficial. All you need is an internet connection to get started! You can have sessions with a licensed therapist via phone, video chat, texting/instant messaging, live voice recording, or any combination of the above. Additionally, because there is no designated office, online therapy is often a more affordable option than face-to-face therapy.