A CORU�A, SPAIN.-According to Margaret Livingstone the smile of Mona Lisa �is an illusion that comes and goes due to the way the human eye processes images.� Margaret Livingston made this statement during her participation at the European Congress of Visual Perception taking place at A Coru�a, Spain. This could solve the five-century mystery of the most famous portrait: Mona Lisa by Leonardo Da Vinci.

Margaret Livingston further stated, �Artists have been studying visual processes longer than us, neurobiologists.� Margaret Livingston is a professor at Harvard University. She stated that when Leonardo Da Vinci painted Mona Lisa in the 16th century, he managed to create an effect where the smile disappears when one looks at the painting directly and it only reappears when one focuses on other parts of the painting. He created this illusion �intuitively� using some tricks that we now find have a scientific basis. Her theory is based on the fact that the human eye has a very central vision, very good to recognize details and another peripheral vision, less precise but adequate to recognize shadows.

Margaret Livingstone stated, �Da Vinci painted Mona Lisa�s smile using the shadows that we see best with our peripheral vision. This is the reason why we have to look her in the eyes or somewhere else in the painting to see her smile, so her lips are in the peripheral camp of vision.�

After publishing her theory on the changes in expression of Mona Lisa, Livingstone is now studying how many painting geniuses had some sort of visual deficiency.