Microexpressiveness

We've been watching the new TV series, Lie To Me, which makes much of the fact that deceivers do an imperfect job of squelching their true feelings.

A microexpression is a brief, involuntary facial expression shown on the face of humans and chimpanzees when one is trying to conceal an emotion. They consist of and completely resemble the 6 universal emotions: disgust, anger, fear, sadness, happiness, and surprise.

Detecting such things can be disturbing, as when someone keeps making disturbing jokes.

When he makes impromptu quips
the mask of kindness often slips
and a scowl crosses his lips.