“Facial expressions can exacerbate a conflict. Rolling eyes, smirky smiles or grimaces, and deep frowning all convey contempt or disdain and certainly can heighten defensiveness and worse any conflict.
Sometimes you may not want a colleague to know that she is getting to you. You can communicate power with an expressionless countenance – that we call the ‘stone face’ – that seems to communicate a lack of empathy.
Women in powerful positions often adopt this expression because they must convey power in this way among men. Using a stone face with other women, however, can lead to defensiveness, because women expect one another to be empathetic.”