SCIENCE
01/07/2013 07:49 am ET

Neuroscience & Art: Margaret Livingstone Explains How Artists Take Advantage Of Human Visual Processing (VIDEO)

The Mona Lisa is arguably the most famous painting in the world. Have you ever wondered why? Leonardo Da Vinci was masterful at manipulating our own visual shortcomings to make us feel something beautiful, complicated, even unsettling. There's just something about her smile.

Dr. Margaret Livingstone, a visual neurophysiologist at Harvard, knows this all too well. I recently spoke with her about how our visual systems have evolved to process one of the inventions that sets us apart from non-human animals--art.

To learn more, watch the video above or click the link below. And don't forget to sound off by leaving a comment at the bottom of the page. Come on, talk nerdy to me!

CARA SANTA MARIA: Hi everyone. Cara Santa Maria here. The Mona Lisa's arguably the most famous painting in the world. Have you ever wondered why? Leonardo Da Vinci was masterful at manipulating our own visual shortcomings to make us feel something beautiful, complicated, even unsettling. There's just something about her smile. Dr. Margaret Livingstone, a visual neurophysiologist at Harvard, knows this all too well.

ML: Sometimes she looks quite cheerful and sometimes she looks enigmatic and not particularly cheerful. But I noticed, being a visual physiologist, that when I was looking at her eyes or looking at the background, she seemed to be smiling a lot. But when I looked right at her mouth, she seemed to stop. And if you go back and forth systematically, even with a reproduction, not even a particularly good one, but in the original at the Louvre, it’s creepy. Her expression changes depending on how far your gaze is, your center of gaze is, from her mouth.

CSM: Well guess what folks? The elusive Mona Lisa smile can be explained with cold, hard science!

ML: Your central vision is good at tiny detailed things, your peripheral vision isn’t bad it’s just different and it’s better at seeing big blurry things. And the Mona Lisa smile is all in the low spatial frequencies, that is it’s blurry. Leonardo used sfumato, which means he blurred it. So if you filter the Mona Lisa in such a way that you can see what she looked like in just your peripheral vision, she’s grinning from ear to ear, but if you look at it filtered with high spatial frequency pass, bandpass filter, you see that as if you could see her, her whole face with your central vision, which of course you can’t do, she isn’t smiling at all. So as you move your eyes around the painting, her expression changes. So that gives it a dynamic quality, which 500 years ago it was a pretty special thing. And it kind of gives her a coy quality, so you're looking at the background and she’s grinning and you try to catch her smiling and she stops.

CSM: Da Vinci was definitely ahead of his time. But what is it about art that's so special, as far as our brains are concerned? Apparently, not much.

ML: All you’ve got up there are neurons and all they do is fire or not fire. And the whole point of your visual system is to extract information about your environment and art is just part of your environment. It’s not, looking at art is not qualitatively different as far as the visual system is concerned as looking at anything.

CSM: The only real difference is that many artists like Da Vinci have figured out, if only intuitively, how to exploit human visual perception in their work. For example, we can see depth in a painting, even though it exists on a two-dimensional canvas.

ML: Your visual system uses a number of algorithms to compute distance and depth, it uses perspective, shading, relative motion so when you move things that are near more than things that are far away, stereopsis, which is the difference in the images in your two eyes. Your two eyes are just a couple of inches apart and so they get slightly different views of the world.

CSM: And here's a little trick:

ML: When you look at a flat painting, your stereo, if you have normal stereopsis, is telling you that the painting is flat. So the best way to make a painting look three dimensional is to close one eye. And some of our research has shown that many artists have poor stereopsis and that probably helps them to render monocular cues about depth in a flat image.

CSM: I know you're itching to try that out the next time you have a chance to see the Mona Lisa. She's such a tricky girl. I want to hear your thoughts! Reach out on Facebook, Twitter, or leave a comment on The Huffington Post. Come on, talk nerdy to me!

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