Bill de Blasio's and Bill Bratton's relationship has been under the microscope recently with the choking death of Eric Garner by a NYC police officer and the subsequent protests it sparked. This past weekend a substantial fraction of New York City's police officers turned their backs on the Mayor during the wake/funeral services for Rafael Ramos who along with his partner Wenjian Liu, was killed in the line of duty allegedly in retaliation for Garner's death.
The expression on Mayor de Blasio's face here can be understood by breaking down its two major components: his eyes/periorbital region and his mouth/jaw.
First note de Blasio's mouth. His lips are configured in what is known as a "Tight Forward Lip Purse".
A forward lip purse (in distinction to a lateral lip purse) indicates that a person has either a clandestine plan or a clandestine disagreement with what is being spoken, read or observed. The mayor does not agree with what Chief Bratton is saying here. There may be some subsequent disagreement voiced, but most (or all) of this will NOT be spoken aloud - but kept to himself. Moreover the forward lip purse indicates that a person feels that at least, with the matter at hand, he holds a distinct advantage and thus perceives himself to be an alpha relative to the beta of the other person or group. In addition, when a person displays a forward lip purse, they also believe they have a good chance at success with their covert intentions.
The interpretation of Mayor de Blasio's lip purse is modified by its tightness. This tension indicates a substantial component of anger. When a forward lip purse is tightened, the surreptitious nature of it is lessened (inversely proportional to the anger level). People cannot keep their own secrets nearly as well when they are further from their emotional baseline - particularly in the context of anger.
Next scrutinize de Blasio's eyes and the tissue around them. His lower central forehead is contracted together - along with his eyebrows. His forehead and brows are also vectored downwards. His upper and lower eyelids are also partially closed with a moderate amount of tension. This nonverbal cluster of the Mayor's eyes is highly indicative of anger - which is further demonstrated and nuanced by his tight variation of the forward lip purse.
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