病菌会传染，情绪也会传染。你发唠叨，就会把心中的不快传开去，这种现象叫”emotional contagion”。 Contagion是名词，解the communication of disease from one person or organism to another by close contact，接触传染、感染、蔓延。 Contagion也解the spreading of a harmful idea or practice，一些不良的思想或做法蔓延开去。
Contagious是形容词，解spread from one person or organism to another, typically by direct contact，接触传染的、接触传染性的；例如︰Chicken pox is a contagious disease.(水痘是经接触传染的疾病。)情绪怎样人传人？这是可以想象得到，无端端被人恶骂，当然会影响自己的心情，心情受影响，自己也可能会发脾气。但实际的emotional contagion传播方式不只是这样。
University of Hawaii心理学教授Elaine Hartfield解释，emotional contagion是”tendency to automatically mimic(模仿) and synchronize(使同步) facial expressions, vocalizations, postures, and movements with those of another person and, consequently, to converge emotionally”。
原来与人接触，我们会不自觉地互相mimic和synchronize大家的表情、语气、姿态和动作，最后令情绪也趋于一致。 Elaine Hartfield是Emotional Contagion一书的作者之一，她说这种反应是人类互动的基础，对生存有用处。
Primitive(原始的) emotional contagion is a basic building block of human interaction. It helps us coordinate and synchronize with others, empathize with them, and read their minds – all critical survival skills.
Gary Slutkin医生是非牟利机构Cure Violence的创办人与行政总裁，他从公众健康的角度看emotional contagion，关心的是”anger that erupts into violence”(愤怒爆发为暴力)。整个社会气氛差，个人就难以独善其身。不过，防卫不断受别人恶劣情绪轰炸是有办法的。
Anger management(愤怒管控)专家、犯罪学教授Raymond Chip Tafrate说︰”Emotional contagion is an autopilot(自动驾驶) phenomenon. We encourage people to get off of autopilot and learn some skills.”
Ask yourself, “With whom do I feel good? Who reinforces(巩固、加强) my strengths and best qualities? With whom am I the best version of myself?”
另有专家说：”The ideal person is not someone who is ‘positive’ as much as someone who is level-headed(头脑冷静的) and willing to engage with you, including with your darker thoughts.”
Never take anything personally on social media. People have their issues(问题) and they have nothing to do with you. Do not encourage or even engage with bad behavior online, or anything that doesn’t feel right. Bad behavior breeds(滋生) bad behavior: If you send out calm, positive signals, you are less likely to attract negative people.
Judith Orloff的Emotional Freedom: Liberate Yourself from Negative Emotions and Transform Your Life，教你怎样筑构情绪防线。