Known anonymously as “SM,” this woman suffers from an unknown disease that has caused her amygdala (part of the brain that controls fear) to completely deteriorate. Now a mother of three, SM is not able to feel fear, no matter how scary the situation is. In a study that tested her fearing abilities, SM watched the scariest of scary movies and touched a snake’s tongue.

When SM was a child, however, she remembers being afraid of the dark, but by the time she’d reached early adolescence, her amygdala was already destroyed. In fact, she even describes an encounter with a man when she was walking through a park at night. He ran up to her and put a knife to her throat. Instead of being terrified, she calmly told him he would have to go through her guardian angel first, which scared him off. Today, she describes the experience as “strange.”