 This is Hidden Brain. I'm Shankar Vedantam. Psychologist Ethan Cross is the author of the book, Chatter. He has studied the different roles of the voices we hear inside our heads. The harsh judge, the fearful prognosticator, the repetitive ruminator. One of the puzzles that arises from this area of research is this. If our inner voice is consistently a source of anxiety or a driver of depression,