这貌似是一个奇怪的反应：当你高兴的时候会流泪。不过，一些心理学家称，他们发现了其中的原因，喜极而泣很有可能是身体恢复“情感平衡”的方式。

这些心理学家称，通过消极情绪对势不可挡的积极情绪做出回应，人们能够从强烈的情绪中更好地恢复过来。

耶鲁大学的心理学家测试受试者对不同场景的情绪反应，包括欢聚和面对可爱孩子的场景。他们发现，用消极反应表达积极消息的人能够更快地缓和其强烈的情感，在孩子毕业典礼上最可能哭的人最可能想捏一个可爱的孩子的脸颊。

他们引用了人们用消极情绪回应积极经历的其他例子，包括乐迷在他们的偶像出现时惊恐地尖叫和彩票赢家喜极而泣。

心理学家还表示，有一些证据表明强烈的消极情感也可能引起积极的表情。例如，当人们紧张或者面对困难或可怕的境遇时，他们经常会大笑。

It may seem like a strange response: to break down in tears when you are happy.

But now a group of psychologists say they have found the reason why, and that crying tears of joy may well be the body’s way of restoring “emotional equilibrium”.

The psychologists say that, by responding to an overwhelmingly positive emotion with a negative one, people are able to recover better from strong emotions.

Oriana Aragon, the lead author of the report which will be published in the journal Psychological Science,said: “People may be restoring emotional equilibrium with these expressions.

“They seem to take place when people are overwhelmed with strong positive emotions, and people who do this seem to recover better from those strong emotions.”

The psychologists from Yale University examined subjects’ emotional responses to different scenarios, including happy reunions and “cute” babies.

They found individuals who expressed negative reactions to positive news were able to moderate their intense emotions more quickly.

They also found people who are most likely to cry at their child’s graduation are also most likely to want to pinch a cute baby’s cheeks.

They cited other examples of where people responded to a positive experience with a negative emotion, including concert goers screaming in horror at the presence of their idol and lottery winners breaking down in tears.

The report authors said: "To give an example, upon winning the lottery, one might appraise the event as an incredibly good thing; feel overwhelmed with happiness, smile and cry.

"One’s appraisal that winning is a good thing, intense happiness and verbal expression would easily be described as positive, yet there is also an expression of crying which normatively expresses sadness.

"This expression is not inherent to the situation, the appraisal, or the positive emotions. The negative expression might be merely a facial display, or it might reflect actual negative emotions."

Miss Aragon said: "I was surprised no one ever asked why that is."

Miss Aragon, a postdoctoral associate at Yale, said the research went some of the way to explaining a common response that most people did not understand.

“These insights advance our understanding of how people express and control their emotions, which is importantly related to mental and physical health, the quality of relationships with others, and even how well people work together,” she said.

The psychologists claimed that there was also some evidence that the reverse was also true and that strong negative feelings may provoke positive expressions.

For example, people often laugh when they are nervous or confronted with a difficult or frightening situations. They cite previous studies where psychologists found some subjects smiled at times of extreme sadness.

The study called Dimorphous Expressions of Positive Emotion: Displays of Both Care and Aggression in Response to Cute Stimuli, will be published this month.

（来源：Daily Telegraph 编辑：祝兴媛）