The guessing game 20 Questions might be won with a quick scan of an opponent's brain. Researchers have developed a way to measure how the human brain reacts to pictures—and to predict what images people are gazing at.
Though a long way off, the technology could help scientists reconstruct dreams or repressed memories, says Jack Gallant, a neuroscientist at the University of California, Berkeley, who led the study, published in the March 20 Nature.
As a first step, two members of Gallant's team viewed hundreds of black-and-white photos from everyday experience, such as people, animals, and fruits, while a functional magnetic resonance imaging (fMRI) scanner recorded the activity of their brains. By analyzing the activity patterns that the images sparked, the researchers made a model that could predict how the brain might respond to any image.