Scientists Discover a Second ‘Mona Lisa Smile’

By K. N. Smith | August 14, 2015 10:41 am


Researchers have unraveled the mystery of the Mona Lisa’s enigmatic smile, with help from another Leonardo da Vinci painting that uses the same clever technique.

The Mona Lisa has captivated people for centuries because her smile is so elusive; from one angle, she seems to be smiling, but when you look directly at her lips, her smile appears to flatten. It’s really a clever visual trick, in which subtle blending of colors exploits our peripheral vision.

And now it appears da Vinci had used the trick before. A recently discovered earlier da Vinci portrait, “La Bella Principessa,” uses the same visual effect to create the impression of an elusive smile.

Left, Mona Lisa, and right, La Bella Principessa.

Left, Mona Lisa, and right, La Bella Principessa.

La Bella Principessa

The girl in the portrait is Bianca, the illegitimate daughter of Ludovico Sforza, who ruled Milan during the 1490s. Her father commissioned the painting in 1496, in honor of Bianca’s upcoming wedding to a commander of the Milanese army. She was 13 years old.

Bianca’s portrait conveys all the tension and complexity of her situation. When viewed from a distance, Bianca seems to be smiling. But up close, her mouth seems to tilt downward, giving her a grim, melancholy look. And like the Mona Lisa, Bianca’s smile appears more readily in viewers’ peripheral vision, and fades when viewers look directly at her lips.

“As the smile disappears as soon as the viewer tries to ‘catch it’, we have named this visual illusion the ‘uncatchable smile,’” researchers Alessandro Soranzo and Michelle Newberry of Sheffield Hallam University wrote in a paper published in the journal Vision Research.

The Uncatchable Smile

To find out how da Vinci’s subtle illusions worked, Soranzo and Newberry set up a series of experiments in which people either viewed the portraits from a distance or saw blurred versions to simulate peripheral vision. (We see things in the center of our field of vision more sharply than we see things on the edges.)

People agreed that the Mona Lisa and “La Bella Principessa” appeared more content, on a numerical scale from one to seven, from a distance than when viewed up close, but distance didn’t make a difference for “Portrait of a Girl,” painted in 1470 by Piero del Pollaiuolo, who didn’t use da Vinci’s visual illusion. Digitally blurred copies of the images created the same effect as distance.

Next, to test how precisely this ambiguity was achieved, researchers showed subjects copies of the paintings with black rectangles over the subjects’ eyes, mouth, or both.

With the mouths covered, the ambiguity vanished. That indicated that the subjects’ shifting expressions were originating from their mouths.

Here’s the Trick

"Virgin of the Rocks," by da Vinci.

“Virgin of the Rocks,” by da Vinci.

The portraits’ mouths seem to change their slant thanks to a technique called sfumato, which blends colors and shades to produce soft, gradual transitions between shapes, without any clear outlines. In both the Mona Lisa and “La Bella Principessa,” da Vinci used sfumato to soften the outlines of the mouth, so there’s no clear line between the lips and the rest of the face.

When a viewer focuses on the subject’s eyes, the sfumato technique creates the illusion of the lips slanting upward. But when you look at her lips themselves, they seem somewhat pursed.

That’s why the Mona Lisa seems to smile more when you’re not looking at her mouth.

Soranzo told Discover, “Given da Vinci’s mastery of the technique, and its subsequent use in the Mona Lisa, it is quite conceivable that the ambiguity of the effect was intentional.” And da Vinci may have experimented with the technique even earlier, in his 1483 work “Virgin of the Rocks,” although that hasn’t been proven yet.

“Many of Leonardo’s followers used a similar technique, but without they haven’t been able to achieve the same result,” said Soranzo. Soranzo next intends to analyze da Vinci’s work in comparison to his followers’ in order to better understand the secrets of that subtle smile.

CATEGORIZED UNDER: Mind & Brain, top posts
  • Reinaldo Martinez

    I think that the “sfumato” argument has very little ground. To start with the sfumato technique has nothing to do with lips. Sffumato is what we do to smooth a transition between any two shades of color or “chiaroscuro”.

    All artists who have worked drawing and painting human faces know that some people just do not have perfect chiseled lip lines. For some of us who have also done some research in physiognomy ans symbolism of the human face, there are two different kinds of archetypical faces: Priestesses (no chiseled lip lines) and Venuses, with very sharp ridges in their lip lines. This also indicates the sort of temperament women -and in general people- possess. Priestesses tend to be grave love study, reading, music and art; and are rether cold, stable, self disciplined kind of women. Venuses are sensual, strongly erotic and elegant, loving parties and are easy laughing and extroverted. There are some sub categories too, but basically this is rather clear for those who have studied Tarot and their archetypes.

    • saymwah

      Of course. Every woman is either a Jackie or a Marilyn.

      • Reinaldo Martinez

        Exactly, mate. Is an archetypal kind of personality. Mona Lisa was indeed a “Jackie”, like the “Girl with Ermine” (Leonardo). But “The Girl with the Pearl Pendant” (Van Eyck) and all the “PreRafaelite” women are all “Marylins”. Thanks.

        • Reinaldo Martinez

          “Oops” Vermeer, I meant. Not Van Eyck. Sorry.

          • saymwah

            I guess you didn’t see that episode of Mad Men.

      • Maia

        I hope that’s sarcasm. If not, it’s nonsense.

      • ellen kelleher

        hunh??? does that Work for you? and what, all guys are John Wayne or-heretofore- Bruce Jenner ? (btw- imo-thé John Wayne shtick’s your problèm- and you don’t Know he was gay) i have had the Immense honor to visit La Jaconda numérous times, again last month -She IS Smiling ~smirking even ? She KNOWS Something. Also, not mentioned, she’s looking to her left, not son discretely. For more clues look at his other paintings. As well, Poussin. Thé Truth IS out there, in plain view ~for those «with eyes to see»..

    • Glenn Jones

      There is a real sense that the Mona isa is holding something in regardless of how she is viewed. But the article makes interesting reading, as do your comments Mr Martinezz. Thank you to both of you.

    • Emmanuel Gonzalez

      Yea I got bounced here from another article that said:

      By blending color pigments to deceive our peripheral vision, Da Vinci made the shape of the model’s mouth shift down or up depending upon which angle the painting is viewed from. The technique is called “sfumato,” and according to the researchers both the Mona Lisa and La Bella Principessa paintings utilize the optical illusion

      So I was glad to see someone else felt compelled to more accurately define the word.

  • M. Peters

    This was a fascinating article – and one which spawned *so many* plot bunnies…. Thanks so much for the read! Another excellent, informative article by an amazing writer!

    • Sterling Running Stream philli

      Its late , so I will be brief. If you paint the shadow of the pouting or discontented mouth first. It is just a matter of glazing in at an angle that hides the shadow by catching the light in such a way as to blend out the the expression and only leave just enough to convey an almost smile. There isnt much room for wild differences in emotional tone. But enough. Uße the glare off the tiniest of ridges created by the bristles t hide shadows that will become apparent when the eye shifts enough to focus beyong the glare. I think…..see, Brief .

  • YagsidoG

    That is nice and all, but

  • NavyBlue1962


    • Reinaldo Martinez

      “The bull lies always in the beholder”. Metuselah.

  • TheLegendary87

    Mona Lisa looks like she’s smiling to me at all times, whether I look directly at her lips or not. It’s the slightest of smirks.

  • AsIfUknow

    I found this very interesting. I have always wondered what the big deal is with what’s behind her smile. I think it is probably far more powerful IN PERSON & if one is studying the work(s) scientifically.

    I don’t think it matters what kind of lips she had (defined line or not) the important aspect of sfumato as a technique is something most realist painters try to achieve and that is to make it look like the human face and not as if the lips were drawn on. It’s important probably the most heard comment in painting classes throughout time, “blend, blend, blend! there are no lines in nature!” Now the fact that da Vinci was gifted enough to use sfumato to create an illusion few others have is what made him the gifted artist & scientist few others have been (or ever will be again).

  • Indro

    It seems to me that there is a tight link between the Mona Lisa and the Buddha Smile.

  • Gale

    No one has commented on the checks. Checks can also give to the smile and aid in the appearance of a weak smile.

    • Skuser

      And the eyes.

  • Skuser

    News value for art historians: close to zero. The sfumato technique and its effects are very well-known.

    On a side note: “We see things in the center of our field of vision more sharply than we see things on the edges” should be NEAR the center of our field of vision, because IN the center of our vision is our blind spot.

  • Vil Vaitas

    She has the smile that lights up your soul no matter which way you view her. It not the pigment that provides the come hither smile, it is the talent of the artist.

  • Avia

    My question is … what happened to her eyebrows?

  • Wright A Ken

    I’m am art historian who in many attempts to draw
    the eye away from the subject true to the image ! The optical illusion of The Mona Lisa sfmutao is a true illusion as the author of the portrait disassembly points out there is a lack of defining line to subdue the eye towards the eye’s in the The
    Mona Lisa as to aline Miss Mona Lisa ‘s lip line with the peripheral view of the viewer’s gaze ? Thanx Leonardo the only illustration of life imitating art with a smile on! wrightaken.url

    • EnigmaV8

      Wow that sure was a lot of verbose dribble to sound intelligent.



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