1 definition by 200lies.com
A nano-expression is a very brief, involuntary facial expression shown on the face of humans according to emotions experienced. They usually occur in high-stakes situations, where people have something to lose or gain. Unlike regular facial expressions, it is difficult to fake nanoexpressions.
Nano-expressions express seven universal emotions as microexpressions: disgust, anger, fear, sadness, happiness, surprise, and contempt. They can occur as fast as 1/05 to 1/14 of a second.
by 200lies.com December 17, 2010