Microexpressions are like any other facial expression, but they are very subtle and occur incredibly quickly, coming and going in several hundred milliseconds.
Paul Ekman, largely known for his discovery that many facial expressions of emotion were universal, has been particularly keen on researching microexpressions in recent years.
It is thought that these fleeting expressions give away the inner emotional state (and maybe whether someone is lying), because they are under less conscious control than more obvious facial expressions.
The other freely available article is on the gestures we make when talking, that potentially give an insight into the hidden psychology that belies our words.
Our body movements always convey something about us to other people. The body “speaks” whether we are sitting or standing, talking or just listening. On a blind date, how the two individuals position themselves tells a great deal about how the evening will unfold: Is she leaning in to him or away? Is his smile genuine or forced?
The same is true of gestures. Almost always involuntary, they tip us off to love, hate, humility and deceit. Yet for years, scientists spent surprisingly little time studying them, because the researchers presumed that hand and arm movements were mere by-products of verbal communication. That view changed during the 1990s, in part because of the influential work of psycholinguist David McNeill at the University of Chicago.