By Evan Thomas
Art historians say Leonardo da Vinci hid an optical illusion in the Mona Lisa's face: she doesn't always appear to be smiling. There's question as to whether it was intentional, but new research into a second painting attributed to da Vinci suggests yes, it was."Portrait of a Young Fiancée," which is thought to be of an Italian girl named Bianca, shows the same almost-smile depending on viewing distance and sharpness of the image.
"When she is viewed from close-up the mouth appears to have a downwards slant, making her look melancholic, unhappy and hostile, but when viewed from further away, her mouth appears to take an upward, smile-like appearance making her appear happy and cheerful," a researcher said. The researchers also found the smile — or frown — appears to change, depending on where it is in a viewer's peripheral vision. They simulated this effect on test subjects using blur. The blurrier Bianca was, the happier she appeared to be.
