<P> Professor Margaret Livingstone of Harvard University has argued that the smile is mostly drawn in low spatial frequencies, and so can best be seen from a distance or with one's peripheral vision . Thus, for example, the smile appears more striking when looking at the portrait's eyes than when looking at the mouth itself . Christopher Tyler and Leonid Kontsevich of the Smith - Kettlewell Institute in San Francisco believe that the changing nature of the smile is caused by variable levels of random noise in the human visual system . Dina Goldin, Adjunct Professor at Brown University, has argued that the secret is in the dynamic position of Mona Lisa's facial muscles, where our mind's eye unconsciously extends her smile; the result is an unusual dynamicity to the face that invokes subtle yet strong emotions in the viewer of the painting . </P> <P> In late 2005, Dutch researchers from the University of Amsterdam ran the painting's image through "emotion recognition" computer software developed in collaboration with the University of Illinois at Urbana - Champaign . The technology demonstration found the smile to be 83% happy, 9% disgusted, 6% fearful, 2% angry, less than 1% neutral, and 0% surprised . </P> <P> In 2004, experts from the National Research Council of Canada conducted a three - dimensional infrared scan . Because of the aging of the varnish on the painting it is difficult to discern details . Data from the scan and infrared were used by Bruno Mottin of the French Museums' "Center for Research and Restoration" to argue that the transparent gauze veil worn by the sitter is a guarnello, typically used by women while pregnant or just after giving birth . A similar guarnello was painted by Sandro Botticelli in his Portrait of Smeralda Brandini (c. 1470 / 1475), depicting a pregnant woman on display in the Victoria and Albert Museum in London . Furthermore, this reflectography revealed that Mona Lisa's hair is not loosely hanging down, but seems attached at the back of the head to a bonnet or pinned back into a chignon and covered with a veil, bordered with a sombre rolled hem . In the 16th century, hair hanging loosely down on the shoulders was the customary style of unmarried young women or prostitutes . This apparent contradiction with her status as a married woman has now been resolved . </P> <P> Researchers also used the data to reveal details about the technique used and to predict that the painting will degrade very little if current conservation techniques are continued . During 2006, Mona Lisa underwent a major scientific observation that proved through infrared cameras she was originally wearing a bonnet and clutching her chair, something that da Vinci decided to change as an afterthought . </P>

According to critics the woman in mona lisa seems to be in two places at the same time