At one point in our history, the most impressive example of artificial intelligence was a computer that was really, really good at chess. Today, various pieces of software can do everything from chat with us on Facebook Messenger to guiding the Mars rover Curiosity while its human engineers catch a nap. Now, a team of scientists from Carnegie Mellon University have developed an AI that can do something once thought impossible: read the human mind. The group's new software takes a novel approach to guessing what is going on inside a human brain, using data gathered from brain scans via fMRI to predict human thoughts by seeing how the pattern of brain activity that produces them, then detecting it in reverse. "One of the big advances of the human brain was the ability to combine individual concepts into complex thoughts," lead researcher Marcel Just explains.