" Who’s that?” I asked James. “Essi Viding,” he said. “What does she study?” I asked. “Psychopaths,” said James. I peered in at Essi. She spotted us, smiled and waved. “That must be dangerous,” I said. “I heard a story about her once,” said James. “She was interviewing a psychopath. She showed him a picture of a frightened face and asked him to identify the emotion. He said he didn’t know what the emotion was but it was the face people pulled just before he killed them. "

― Jon Ronson , The Psychopath Test: A Journey Through the Madness Industry