Micro-Expression
An involuntary facial expression lasting between 40 and 200 milliseconds that reveals an emotion a person is trying to conceal or has not yet consciously acknowledged.
Micro-expressions are very brief facial movements — typically 1/25th to 1/5th of a second — that leak across the face before the brain's social filter can mask them. They were first documented by researchers Haggard and Isaacs in 1966 and popularized by Dr. Paul Ekman's later work.
Because micro-expressions occur faster than conscious control, they are widely considered the most honest external signal of an emotional state. They are used in clinical psychology, intelligence and law enforcement training, negotiation, and high-performance coaching.
Detecting micro-expressions reliably with the naked eye requires extensive training. Computer-vision systems built on FACS can identify and intensity-score them in real time, at frame rates the human visual system cannot match.
Related terms: macro expression, facial action coding system, paul ekman, seven universal emotions
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