研究發現 微笑能給人造成壓力也能緩解壓力

New research finds that smiles can be used to both soothe or attack - at least, as far as the brain's stress pathways are concerned.
新研究發現，微笑既可用於安撫，也能產生傷害，至少對於大腦的應激通路確是如此。

The study, published by researchers from the University of Wisconsin-Madison and Bar-Ilan University, looked at the interaction between nonverbal feedback and the activity of the hypothalamic-pituitary-adrenal axis, our body's central stress response system.
威斯康星大學麥迪遜大學和巴伊蘭大學的研究人員發表的這項研究，對非語言反饋與下丘腦-垂體-腎上腺軸，即我們身體的主要壓力應對系統之間的互動進行了調查。

The authors report that individuals with higher heart-rate variability showed the widest range of responses to different smiles.
作者報告稱，心率可變性大的人對不同笑容的反應差異性也更大。

Higher heart rate variability has previously been correlated with a higher ability to recognize facial expressions.
此前，心率可變性大就被認爲與辨認面部表情的能力更強有關。

"The findings provide further evidence for the view that smiles do not necessarily constitute positive nonverbal feedback, and that they may impact social interactions by affecting the physiological reaction of people who perceive them," the authors write.
作者們寫道：“研究結果進一步爲以下觀點提供證據，即微笑並不一定就是正面的非語言反饋。通過影響了解其含義的人的身體反應，微笑有可能對社交互動模式產生影響。”

"In addition, cortisol appears to support the detection of social threat and coordinate biological activity needed to adequately respond to the threat."
“此外，皮質醇似乎能夠支持對社交威脅的檢測，並協調需要被用於應付威脅的生物學活動。”

The findings help patch in our understanding of the depth of nonverbal communication in human language -- as a tool to unnerve, a hand to soothe, and as an outside effect on our psychological state.
這項研究增加了我們對人類之間的非語言溝通的理解深度，非語言溝通能夠作爲使人焦慮和給人安慰的手段，也是對我們心理狀態產生作用的外部因素。

However, the team cautions that because of the small sample of exclusively male participants, the findings shouldn't be generalized until replicated.
但是，該團隊提醒道，因爲該研究的樣本較小，而且只有男性受測者，所以這項發現在被複現之前不能推廣到所有人羣。

Thus, further research will need to explore whether or not men and women react differently to the same kind of smile, and to test more overt (both negative and positive) facial expressions.
因此，還需要進一步的研究來探究男性和女性對相同種類微笑的反應是否相關，並測試更多種類（消極與積極的）的面部表情。