S.M., sometimes referred to as SM-046, is an American woman with a peculiar type of brain damage that physiologically reduces her ability to feel fear.
First described by scientists in 1994,[1] she has had exclusive and complete bilateral amygdala destruction since late childhood as a consequence of Urbach–Wiethe disease.
revealed no fear in response to exposure and handling of snakes and spiders (including tarantulas), a walk through a haunted attraction (Waverly Hills Sanatorium, specifically), or fear-inducing film clips (e.g., The Blair Witch Project, The Shining, and The Silence of the Lambs), eliciting instead only interest, curiosity, and excitement, though she expressed emotions appropriate to the film content such as happiness and disgust when viewing non-fear-inducing film clips.
is not immune to all fear, however; along with other patients with bilateral amygdala damage, she was found to experience fear and panic attacks of greater intensity than the neurologically healthy controls in response to simulation of the subjective experience of suffocation via carbon dioxide inhalation, feelings which she and the others described as completely novel to them.
is described as very outgoing, extremely friendly, and uninhibited, as well as "somewhat coquettish" (playfully flirtatious) and having an abnormally high desire and tendency to approach others.
appears to experience relatively little negative emotion,[3] whilst simultaneously experiencing a relatively high degree of positive affect, despite great adversity in her life.
shows a lack of a sense of personal space, and experiences virtually no discomfort standing extremely close to strangers, even nose-to-nose with direct eye contact.
She has been held up at both knifepoint and gunpoint, was almost killed in a domestic violence incident, and has received explicit death threats on multiple occasions.
has had a history of adversity in her life, including alienation, hardship, teasing, shunning and abuse from authority figures.