D Smile! It makes everyone in the room feel better because they, consciously or unconsciously, are smiling with you. Growing evidence shows that an instinct for facial mimicry( 模仿 ) allows us to empathize with and even experience other people’s feelings. If we can’t mirror another person’s face, it limits our ability to read and properly react to their expressions. A review of this emotional mirroring appears on February 11 in Trends in Cognitive Sciences . In their paper, Paula Niedenthal and Adrienne Wood, social psychologists at the University of Wisconsin, describe how people in social situations copy others’ facial expressions to create emotional responses in themselves. For example, if you’re with a friend who looks sad, you might “try on” that sad face yourself without realizing you’re doing so. In “trying on” your friend’s expression, it helps you to recognize what they’re feeling by associating it with times in the past when you made that expression. Humans get this emotional meaning from facial expressions in a matter of only a few hundred milliseconds. “You reflect on your emotional feelings and then you generate some sort of recognition judgment, and the most important thing that results in is that you take the appropriate action—you approach the person or you avoid the person,” Niedenthal says. “Your own emotional reaction to the face changes your perception of how you see the face in such a way that provides you with more information about what it means.” A person’s ability to recognize and “share” others’ emotions can be prevented when they can’t mimic faces. This is a common complaint for people with motor diseases, like facial paralysis( 瘫痪 ) from a stroke, or even due to nerve damage from plastic surgery. Niedenthal notes that the same would not be true for people who suffer from paralysis from birth, because if you’ve never had the ability to mimic facial expressions, you will have developed compensatory ways of interpreting emotions. People with social disorders associated with mimicry or emotion-recognition damage, like autism( 自闭症 ), can experience similar challenges. “There are some symptoms in autism where lack of facial mimicry may in part be due to limitation of eye contact,” Niedenthal says. Niedenthal next wants to explore what part in the brain is functioning to help with facial expression recognition. A better understanding of that part, she says, will give us a better idea of how to treat related disorders.