Friday, January 28, 2005

The Art of Seeing Without Sight

Interesting article about a blind painter and how is brain is similar and different from those who see.

We normally think of seeing as the taking in of objective reality through our eyes. But is it? How much of what we think of as seeing really comes from without, and how much from within?

Kennedy put Armagan through a battery of tests. For instance, he presented him with solid objects that he could feel - a cube, a cone and a ball all in a row (dubbed the "three mountains task") - and asked him to draw them. He then asked him to draw them as though he was perched elsewhere at the table, across from himself, then to his right and left and hovering overhead. Kennedy asked him to draw two rows of glasses, stretching off into the distance. Representing this kind of perspective is tough even for a sighted person. And when he asked him to draw a cube, and then to rotate it to the left, and then further to the left, Armagan drew a scene with all three cubes. Astonishingly, he drew it in three-point perspective - showing a perfect grasp of how horizontal and vertical lines converge at imaginary points in the distance. "My breath was taken away," Kennedy says.

So, we ask, how do you know how long these poles should be as they recede? I was taught, he says. Not by any formal teacher, but by casual comments by friends and acquaintances. How do you know about shadows? He learned that too. He confides that for a long time he figured that if an object was red, its shadow would be red too. "But I was told it wasn't," he says. But how do you know about red? He knows that there's an important visual quality to seen objects called "colour" and that it varies from object to object. He's memorised what has what colour and even which ones clash.

Even more intriguing was the way in which drawing activated Armagan's visual cortex. It is now well established that when sighted people try to imagine things - faces, scenes, colours, items they've just looked at - they engage the same parts of their visual cortex that they use to see, only to a much lesser degree. Creating these mental images is a lot like seeing, only less powerful. When Armagan imagined items he had touched, parts of his visual cortex, too, were mildly activated. But when he drew, his visual cortex lit up as though he was seeing. In fact, says Pascual-Leone, a naive viewer of his scan might assume Armagan really could see.
via New Scientist

1 comment:

Randolph Wilburn said...

I hope you are well!

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