The image above (and the cropped close-up below) shows one of the few currently available photos of Salman Abedi - the alleged perpetrator of the recent bombing during at an Ariana Grande concert in Manchester, England. Tragically, 22 victims were killed and at least 120 others were injured.
Note the expression on Abedi's face - it's a mixture of both Contempt and Disgust. The elevated "snarl" appearance on HIS left side (e.g. the well-defined nasolabial fold [the furrow running from the side of the nose to the corner of the mouth]), is particularly emblematic of Contempt. His mid-face tightness (in the "mustache area") is consistent with both of these emotions (although also more accentuated on his left - ergo contempt). His "droopy eyelids", while perhaps longstanding (e.g., congenital ptosis) - here serve as an amplifier of contempt and disgust. Abedi's backward head tilt also acts to intensify each of these emotions.
As human beings, we all occasionally feel - and thus display each of these feelings - but hopefully not very often or too intensely.
However, those who make such facial expressions frequently have a dramatically increased likelihood of having impulse control disorder (colloquially known as a "short temper"). Therefore in the context of significant disagreements, these individuals will tend to use physical force and outright violence to solve problems - rather than dialog, diplomacy, and reason.
Moreover, if we evaluate the real-time behavior and/or social media behavior record of the people who perpetrate terrorist activity or mass-shootings - we will observe a dramatic frequency of disgust and contempt - as well as anger (often there exists a mixture of these emotions)
With this in mind, it's not surprising that a senior person at the mosque which Abedi attended (the Manchester Islamic Centre aka Didsbury Mosque) reported that Salman Abedi looked at him with a "face of hate" after the imam gave a sermon denouncing terrorism and preaching against ISIS.
Summary: Careful observation of Nonverbal Behavior plays a crucial role in Threat Assessment and preventing violence. The perpetrator of the 2017 Manchester Bombing, Salman Abedi, is yet another example of an individual who exhibited such body language red flags. And while certainly not all of those who display chronic expressions of anger, contempt, and/or disgust will perpetrate terrorist activity - they will virtually always have impulse control disorder (thus you don't want to date them, hire them, be hired by them, vote for them, etc.).
My sincere condolences for all those who have suffered in this horrific event.
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