"Natural liars" may be aware of their ability to control microexpressions, and so may those who know them well; they may have been "getting away" with things since childhood due to greater ease in fooling their parents, teachers, and friends.[27] People can simulate emotion expressions, attempting to create the impression that they feel an emotion when they are not experiencing it at all. A person may show an expression that looks like fear when in fact they feel nothing, or perhaps some other emotion.[28] Facial expressions of emotion are controlled for various reasons, whether cultural or by social conventions. For example, in the United States many little boys learn the cultural display rule, "little men do not cry or look afraid."