In this task, you're given an article and an answer. Your task is to generate the question for the answer based on the given article.

Article: Face masks are commonly used in ceremonies and performances. They not only hide the real face of the mask wearer but they often evoke powerful emotions in the audience--danger, fear, sadness, joy. You might think, because so many things vary cross-culturally, that the ways in which emotions are displayed and recognized in the face vary too. Apparently they do not. Recent research on masks from different cultures supports the conclusion that masks, like faces, tend to represent certain emotions in the same ways. We now have some evidence that the symbolism used in masks is often universal. The research on masks builds on work done by anthropologists, who used photographs of individuals experiencing various emotions. These photographs were shown to members of different cultural groups who were asked to identify the emotions displayed in the photographs. Emotions were identified correctly by most viewers, whatever the viewer's native culture. Coding schemes were developed to enable researchers to compare the detailed facial positions of individual portions of die face (eyebrows, mouth, etc.) for different emotions. What exactly do we do when we scowl? We contract the eyebrows and lower the corners of the mouth; in geometric terms, we make angles and diagonals on our faces. When we smile, we raise the corners of the mouth; we make it curved. Psychologist Joel Arnoff and his colleagues compared two types of wooden face masks from many different societies--masks described as threatening versus masks associated with nonthreatening functions. As suspected, the two sets of masks had significant differences in certain facial elements. The threatening masks had eyebrows and eyes facing inward and downward and a downward-facing mouth. In more abstract or geometrical terms, threatening features generally tend to be angular or diagonal and nonthreatening features tend to be curved or rounded, a face with a pointed beard is threatening; _ is not. The theory is that humans express and recognize basic emotions in uniform ways because all human faces are quite similar, skeletally and muscularly.
Answer: The uniformity of facial expressions in revealing emotions.
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