A blank expression is a facial expression characterized by the neutral
position of facial features and implies a lack of strong emotion. It may
be caused by a lack of emotion, boredom, slight confusion (such as when
someone refers to something which you do not understand) or a deliberate
attempt to disguise one's emotions, such as when playing poker.
In poker, this expression is referred to as a "poker-face"
(shortened to a po-face). In poker one does not want others to know if
one is holding a good or bad hand, hence the need for a blank expression.
