Why is Donald Trump (or any politician) a good liar? One (of several) nonverbal reasons for his increased ability to deceive is his "mask". The less variability a person has in their facial expressions (or other body language signals), the less likely they are to be caught in a lie. Thus they have a "go to" or default facial expression which they use a disproportionately high percentage of time. This behavior is akin to a person putting on a mask and moreover helps them to suppress facial expression "tells" and therefore lowers the chances of being caught lying.
The image below is Trump's primary default facial expression - Donald's main "mask". Those individuals with Antisocial Personality Disorder (Sociopaths, etc.) have a much higher frequency of facial mask behavior.
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