Wednesday, June 9, 2010

What’s the secret behind Mona Lisa's enigmatic smile?

Art critics, art enthusiasts, experts on paintings, especially those who spend considering amount of time in studying the hidden secrets of da Vinci creations, always wondered about one of the charms of the world's most famous painting, Mona Lisa: she appears smiling one moment and then becomes serious and sardonic the next moment. While one viewer will feel her radiant, the other will perceive her mood as something different. It is rather mysterious, most people have always felt.

But in October 2009, scientific research offered an explanation to Mona Lisa’s changing moods, “Our eyes send mixed signals to the brain”. The scientists proved that Mona Lisa's smile depends on which cells in the eye’s retina pick up the image and which channel the image is transmitted through in the brain. To make it clearer, when one channel wins over the other you see the smile, sometimes other channels take over and you do not see the smile.

It is well-known that different cells in the eye are designed to pick up different colors, contrasts, backgrounds and foregrounds. Some eye cells deal with central vision while others with peripheral vision. So, what cells pick up the image first depends on what channel they are sent to the brain for interpreting the image. These channels decode the data about an object's size, clarity, brightness, distance and location in our visual field.

"Sometimes one channel wins over the other, and you see the smile, sometimes others take over and you don't see the smile," said Dr Luis Martinez Otero, a neuroscientist at the Institute of Neuroscience in Alicante, Spain, who conducted the study, the New Scientist had reported.

To get a clear idea of the reasons behind Mona Lisa's vanishing smile, Dr Martinez Otero changed various aspects of Mona Lisa that are processed by different visual channels, and then asked the volunteers whether they saw a smile or not. Next, the volunteers were asked to look at Mona Lisa in different sizes from varying distances. Based on the volunteers’ responses, they found the closer you were to the painting, the more likely you could see Mona Lisa’s smile.

Dr Martinez Otero's team also compared how light affects our judgment of Mona Lisa's smile. Two kinds of cells determine the brightness of an object relative to its surroundings, ‘on-centre’ cells which are stimulated only when their centers are illuminated and allow us to see a bright star in a dark night, and ‘off-centre’ cells which turn on only when their centers are dark, and help us to pick out words on a printed page.

Dr Martinez Otero jammed these channels by showing either a black or white screen for 30 seconds, followed by a picture of Mona Lisa. The experiment showed that black would mute ‘off-centre’ cells while the while affects ‘on-centre’ cells. It indicated the volunteers were more likely to see Mona Lisa's smile after they had been shown the dark screen, making Martinez Otero to conclude that it is these ‘on-centre’ cells that sense Mona Lisa's smile.

Eye gaze also affects how volunteers see the smile, according to Dr. Martinez Otero, whose team used software to track where in the painting the 20 volunteers gazed while they rated whether or not Mona Lisa's smile became visible or not. With one full minute to gaze at the painting, the volunteers tended to focus on the left side of her mouth when they judged her as smiling. It was further evidence that off-centre vision picks out Mona Lisa’s smile. When the volunteers had only a fraction of a second to discern her smile, their eyes tended to focus on her left cheek, showing that peripheral vision plays a role too.

Now the question is: did Leonardo da Vinci intend to create so much confusion in the brains of viewers? Yes, absolutely, Martinez Otero contends, "He wrote in one of his notebooks that he was trying to paint dynamic expressions because that's what he saw in the street." After all, Leonardo da Vinci was no ordinary painter or genius. Leonardo was the rare archetype of the Renaissance man, an extraordinary genius whose unquenchable curiosity was equaled only by his powers of invention. And his range of expertise and professions spanned a wide range of subjects, as he was renowned as a painter, sculptor, architect, musician, scientist, mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist, writer, and many more.

Leonardo's studies in science and engineering were as innovative as his artistic work, recorded in notebooks comprising some 13,000 pages of notes and drawings, which fused art and natural philosophy, which was the forerunner of modern science. Interestingly, Leonardo wrote with his left hand, and his notes were mostly written in mirror-image cursive handwriting, which has led many people to speculate that he did so for reasons of secrecy.

Dr Luis Martinez Otero’s research finding on the mystery of the smile of Mona Lisa was originally presented at the Society for Neuroscience's annual meeting in Chicago.

This is not the first time scientists have deconstructed Leonardo da Vinci's masterpiece, Mona Lisa. In 2000, Margaret Livingstone, a neuroscientist at Harvard Medical School with a side interest in art history, showed that Mona Lisa's smile is more apparent in peripheral vision than in dead-centre vision.

Perhaps, no other artist’s works underwent the scrutiny of scientists and investigators looking for mysteries and hidden secrets as in da Vinci’s works. Another of his magnum opus that has intrigued scientists, investigators and others including the best selling author Dan Brown is The Last Supper, based on which Brown built up the plot of The da Vinci Code, which was made into a blockbuster movie.

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