Why does the Mona Lisa seem to be smiling and not smiling at the same time? For more than 500 years, the portrait Leonardo da Vinci painted in the early 16th century has puzzled visitors to the Louvre.
Science, art history and synergology each offer their own answer. And they don’t contradict each other as much as you might think.
Key takeaways
- In 2005, University of Amsterdam emotion-recognition software read her face as 83% happy, 9% disgusted, 6% fearful and 2% angry.
- According to Harvard neuroscientist Margaret Livingstone, the smile is mostly seen in peripheral vision, which is why it seems to come and go.
- Synergology offers another reading: facial asymmetry, with each half of the face expressing a different emotion.
- A study published in Science in 1978 showed that emotions are expressed more intensely on the left side of the face.
What does the Mona Lisa really feel, according to science?
Mostly happiness. In December 2005, a University of Amsterdam team working with the University of Illinois ran the painting through emotion-recognition software. The result: 83% happy, 9% disgusted, 6% fearful and 2% angry (Al Jazeera, 2005).
The software compared her face with a neutral reference expression, looking in particular at the curve of the lips and the creases around the eyes. The researchers themselves called it a fun demonstration rather than a rigorous experiment: the tool can’t detect subtle emotions, or the irony many people see in her gaze.
Why does her smile seem to appear and disappear?
Because of the way we see. In 2000, Harvard neuroscientist Margaret Livingstone analysed the painting by its spatial frequencies (Livingstone, Science, 2000). The blurry shadows around the mouth and cheeks, picked up by peripheral vision, suggest a smile. When you look straight at the mouth, central vision only takes in the sharp details, and the smile fades.
The result: the more you look for the smile, the more it slips away. As she put it to Discover magazine, the expression really does change, but the change happens in your eye, not in the paint.
What does an asymmetrical face reveal, according to synergology?
Two states of mind at once. For synergology, when you split a face in two, each half can show a different emotion. The right side would show what the person wants to convey to others; the left side, what they’re really feeling.
This reading echoes a scientific finding. In 1978, researchers showed in the journal Science that emotions are expressed more intensely on the left side of the face (Sackeim, Gur and Saucy, Science, 1978).
Note: when we say right and left, we always mean the right and left of the person being observed, not yours.
The Susan Smith case: when the two halves of a face disagree
In 1994, in South Carolina, Susan Smith pleaded on television for the kidnapper to return her two sons. She even had a composite sketch made of the man who had supposedly taken them. On the right side of her face, the pain is obvious: you can even see a tear forming under her right eye.
On the left side, the synergological reading is very different: a genuine smile, as if the person were thinking “everything’s going fine, I’m getting away with it”. A few days later, Susan Smith confessed that she herself had drowned her children. The “act” played out on the right; the real emotion, on the left.
What do the two halves of the Mona Lisa's face show?
Neutrality on one side, genuine satisfaction on the other. Let’s apply the same grid to the famous portrait.
The right side: what is shown to others
The right half of the face is neutral. The lips turn neither up nor down, showing neither sadness nor pleasure. Probably at the painter's request: “Please don't smile.”
The left side: what is truly felt
The woman is being painted by the greatest painter of her time, and she feels great satisfaction about it. That's what the left half expresses: the lip turns upward, a sign of pleasure and well-being.
Another example: Serge Chapleau on Tout le monde en parle
Cartoonist Serge Chapleau, a guest on the Quebec TV show Tout le monde en parle, takes on Raël, the leader of a sect who claims to have met extraterrestrials: “Excuse me, my man, but: Claude, this is a joke!”
On the left side of his face, one half is privately amused: what he’s really feeling. On the right, one half is meant to be threatening, the one attacking Raël: what he’s showing the other person.
Can you trust the reading of an asymmetrical face?
Yes, as a starting point, not as a verdict. Every face is a little asymmetrical, and a still photo only captures one moment. The synergological reading helps you spot a gap between what a person says and what they seem to feel, then check it by listening and asking questions.
That’s exactly what we practise in training: observe, form a hypothesis, then validate it. To practise, try our free quizzes or read our article on how to recognise a real smile.
Frequently asked questions about the Mona Lisa's smile
Is the Mona Lisa happy?
Mostly, according to emotion-recognition software tested in 2005 by the University of Amsterdam: 83% happy, 9% disgusted, 6% fearful and 2% angry. The researchers presented this result as a playful demonstration, though, not as scientific proof.
Why does the Mona Lisa's smile seem to change?
According to Margaret Livingstone (Harvard, 2000), the smile is mostly visible in peripheral vision, thanks to the blurry shadows around the mouth. When you stare straight at the mouth, central vision no longer sees those shadows and the smile seems to vanish.
What does an asymmetrical face reveal?
For synergology, each half of the face can show a different emotion: the right side would show what we want to convey, the left side what we feel. A study published in Science in 1978 also showed that emotions are expressed more intensely on the left side of the face.
Can you learn to read emotions on a face?
Yes, with practice. Studying photos and videos, combined with a reading grid like synergology’s, helps you spot gaps between what people say and what they feel more quickly. Our training and free quiz are a good place to start.
Go further: test your knowledge with our free non-verbal communication quiz or explore our synergology training.
