Study: Computers Can Now Predict What You're Seeing

March 6, 2008— -- If you're paranoid, you might want to look the other way — according to a new study, someone hoping to peer into your thoughts may one day have an interesting tool to help them do just that.

Researchers at the University of California at Berkeley have developed a computer program that can predict what a person is looking at by analyzing his or her brain activity.

In a letter published in the journal Nature, Jack L. Gallant and his colleagues report their computer program correctly identified which single picture out of 120 photos a person was looking at 72 to 92 percent of the time.

In the same circumstances, a random guess would only be correct 0.8 percent of the time.

But rest assured, drive-by mind reading is a long way off for now. In order to predict what someone is looking at, the computer program has to get to know the person.

"Your brain looks different from my brain — at the fine scale it looks totally different," said Frank Tong, professor and researcher at Vanderbilt University in Nashville, Tenn., who was not associated with the study.

The researchers described their study as "analogous to the classic 'pick a card, any card' magic trick," except that each card is a unique photo.

First the researchers showed test subjects hundreds of stock photos of natural objects — trees, horses, fruits. Meanwhile the researchers simultaneously measured the person's brain activity with a brain scan called functional magnetic resonance imaging, or fMRI.

The researchers then used computer programs to analyze the differences between the brain scan of a person when he was looking at, say, a photo of a horse versus a photo of an orange.

When a person was tested again with a brand new set of photos, the computer program could guess which of the photos the person was now looking at based on their brain activity when they were looking at the other photos.

"The more they [could] measure your brain activity — for hours on end for months and months — they would get a better and better at predicting what you're looking at," Tong said.