To recall memories, your brain travels back in time via the ultimate Google search, according to a new study in which scientists found they can monitor the activity and actually predict what you'll think of next. The work bolsters the validity of a longstanding hypothesis that the human brain takes itself back to the state it was in when a memory was first formed. The psychologist Endel Tulving dubbed this process "mental time travel." How it works Researchers analyzed brain scans of people as the test subjects watched pictures on a computer screen. The images were divided into three categories:...