She apparently hasn't felt fear as an adult, not even 15 years ago in an incident described by the researchers. A man jumped up from a park bench, pressed a knife to her throat and hissed, "I'm going to cut you."
SM, who heard a church choir practicing in the distance, looked coolly at him and replied, "If you're going to kill me, you're going to have to go through my God's angels first."
The man suddenly let her go. She didn't run home. She walked.
"Her lack of fear may have freaked the guy out," Feinstein said.
But it also got her into that situation in the first place, he noted. SM had willingly approached the man when he asked her to, even though it was late at night and she was alone, and even though she thought he looked "drugged out."
SM's actions are clearly irrational--because rationality is a pattern woven in the fabric of emotion. Or perhaps there's a more fitting analogy. Regardless, those who would try to isolate reason from the texture of emotions discount both.
Related: when a tumor makes you utilitarian.