We have been trying to decipher for centuries The Gioconda. With his portrait, Leonardo seems to challenge us to guess what emotion his muse feels. At the University of Amsterdam, neuroscientists subjected the picture to analysis using emotional recognition programs. The computer looks for differences with respect to a neutral expression: nasal widening or wrinkles in the eyes. They concluded that La Gioconda showed 83% happiness. They also detected other emotions: 9% disgust, 6% fear, and 2% anger.
These computer programs are still rudimentary because they do not capture nuance, hints of desire, or disappointment. In contrast, the human brain has evolved to capture any change in facial expression, however minimal. Here, the human being is superior to the machine.
We are so incredibly good that we guess emotional traits, even if they are hidden under a neutral expression, or poker face. It is a key social skill, so the mystery challenges us, human beings.
The code that Freud tried to crack
From the beginning the Renaissance were surprised by that captivating smile. In the 19th century the poet and playwright Théophile Gautier he was among the first to raise this problem. A portrait that smiles mysteriously, whose enigma has not been solved. After observing it for hours, we continue looking for the emotion it transmits. Or rather, the mix of emotions involved, as dynamic as if it were alive.
Freud thought that the smile was reminiscent of his mother, from whom Leonardo separated early. In the 21st century, neuroscience has given some answers. The neurobiologist Margaret Livingstone He noticed that La Gioconda seems to be smiling, especially from afar. Up close, looking into her eyes, he still smiles. However, when looking directly at the mouth, the smile is not found. The lips are contracted, without the typical curvature of joy. Where is it hidden?
Central and peripheral vision
The human eye has two types of vision: central and peripheral. Central vision has higher resolution due to the concentration of cone photoreceptors in the center of the retina, in the fovea. Therefore, it specializes in high spatial frequencies. That is, strong lines and contrasts. The central view captures specific details.
Instead, peripheral vision detects low frequencies in blurred areas. Your goal is not to perceive details, but large areas. The final result of the visual processing looks like a photograph of a well-defined face in the foreground, while the surrounding landscape is blurred.
The neuroscientific explanation
Leonardo painted the smile with soft brush strokes using a new technique, the nuanced. I applied very thin layers of pigment, very diluted. These layers are superimposing translucent tones, building a subtle expression.
Consequently, the smile is not perceptible with our central vision, which detects defined features. The smile emits low frequencies and is only captured by peripheral vision, out of the corner of the eye.
Leonardo developed this technique during his last years, starting in 1513. He kept the painting until his death, as if it were his laboratory. He experimented with new ways of grading the shadows, sometimes with his fingers. This is how he managed to make his Mona Lisa smile in an elusive way. When we want to catch the smile, focus on it closely, we lose it. It vanishes into the air like a soap bubble. Central vision, no matter how hard you look, does not detect the low frequencies of a blurred smile.
Da Vinci described the sfumato as “without lines or edges, like smoke,” or “beyond the plane of focus.”
But how did you achieve this finding? Was it a mixture of observation and intuition, perception and logic? It is not only art, but also science obtained after a lifetime of research.
Why doesn’t the magic smile appear in the Prado?
At the same time as La Gioconda in the Louvre, the Prado version was painted in Leonardo’s Florentine workshop. The restorer Ana González-Mozo considers that it was executed by a close disciple, under the supervision of the teacher and in parallel. Reflectographs show that the same hidden details and corrections appear in both paintings. However, by then Leonardo had not fully developed sfumato.
Around 1506, these twin paintings began divergent paths. La Gioconda del Prado was finished and delivered to the client. In it, the corners of the mouth are marked and the transition of the shadows is less delicate. The rictus is more serious. This lady seems to be waiting for a music band to cheer her on, as the painter used to say. Giorgio Vasari.
On the contrary, Leonardo continued to work on the Mona Lisa in the Louvre until he suffered paralysis in 1517. It was a work in progress, his living will (perhaps a self-portrait). Somehow, the Mona Lisa and Leonardo grew old together. Today, in unison, both continue to question us.
Leonardo’s question remains valid. Neuroscience tries to find out how the recognition of emotions works, a cognitive process essential for our social interactions. If we do not recognize the emotional expressions of others well, we will have interpersonal difficulties. According to Leonardo, obvious features are important, but so are subtleties, such as a smile about to emerge or in danger of fading.
José T. Boyano is Associate Professor of Psychology. Educational Counselor, University of Malaga
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