Pick a photo, any photo

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.