While the world celebrates the 500th anniversary of the painting of Mona Lisa, by Leonardo da Vinci, and continues to wonder whether she is smiling or frowning, neuroscientist Margaret Livingstone of Harvard University Medical School today revealed some of the science behind human visual perception of art at the 2003 American Association for the Advancement of Science (AAAS) Annual Meeting.

What makes objects appear in certain ways, in certain situations? Livingstone used artworks as examples to explain the difference between the luminance and flat-reflecting mediums, as well as between central and peripheral vision. For example, in a recent trip to Paris, Livingstone measured the luminance of the sunrise seen in Monet's Impression: Sunrise, and found that, contrary to what we perceive, the yellow sun is actually no brighter than the dark blue sky containing it.

"The reason is that in the color version the sun is interpreted as a type of brilliance; it's so striking because there is a disconnect in our visual system between the color and luminance pathways," Livingstone said.

Luminance refers to the quality of how light something appears, independent of color. It is equivalent of what appears in black and white photos (grayscales), so in a picture, if two objects are different colors, but the same luminance, they will both appear the same shade of gray.

That is exactly what happened when Livingstone took a black and white photo of the painting: the sun disappeared altogether and melted into the same gray as the sky. To the naked eye, in Impression: Sunrise, an orange sun deceives the senses and appears to shift and flicker in the middle of a dark blue
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15-Feb-2003