Brain Scanner Can Tell What You're Looking At

By Brandon Keim

March 05, Wired

Tell me what you see.

On second thought, don't: A computer will soon be able to do it, simply by analyzing the activity of your brain.

That's the promise of a decoding system unveiled this week in Nature by neuroscientists from the University of California at Berkeley.

The scientists used a functional magnetic resonance imaging machine -- a real-time brain scanner -- to record the mental activity of a person looking at thousands of random pictures: people, animals, landscapes, objects, the stuff of everyday visual life. With those recordings the researchers built a computational model for predicting the mental patterns elicited by looking at any other photograph. When tested with neurological readouts generated by a different set of pictures, the decoder passed with flying colors, identifying the images seen with unprecedented accuracy.

"No one that I know would ever have guessed our decoder would do this well," study co-author Jack Gallant said.

As the decoder is refined, it could be used to explore the phenomenon of visual attention -- concentration on one part of a complicated scene -- and then to illuminate the dimly understood intricacies of the mind's eyes.

"One day it may even be possible to reconstruct the visual content of dreams," Gallant said.

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photo: Scientists have developed a computer model that predicts the brain patterns elicited by looking at different images -- a possible first step on the path to mind reading (Image: University of California at Berkeley)