As a favor to friends in my academic department, I have frequently been a guinea pig in the functional magnetic resonance imaging (fMRI) scanner. In most of these cases, I fight valiantly against slumber as the stimuli flash on the small screen in front of me and the hypnotic, high-pitched beeps of the scanner reverberate all around. This time, though, it was different. Martin Monti, a fellow neuroscientist at the MRC Cognition and Brain Sciences Unit in Cambridge, England, was going to read my mind. As the bed I lay on slid robotically into the giant doughnut-shaped scanner, I had a strange sensation that I was about to be seen naked—mentally, at least.