汗水中的化學物質可以傳遞積極的情緒

中國科技網4月15日報道（張微 編譯）發表在心裡學協會的期刊《心裡科學》的一項最新研究表明，通過我們的汗味，人類可以傳遞比如快樂這樣的積極情緒。這項研究表明，當我們愉悅的心情被接觸到我們汗水人感受到的時候，我們產生了一種化學化合物或化學信號。

雖然以前的研究表明，恐懼和厭惡這類消極的情緒能夠通過汗液中的化學成分進行傳播，但是很少有研究探討，積極的情緒是否具有相同的傳播功能。

「我們的研究顯示，接觸到心情愉快時產生的汗水時，能夠誘發接收者一種幸福幻影，並引起情緒狀態的蔓延，」荷蘭烏得勒支大學心理學家，這項研究的高級研究員Gün Semin解釋說。「這表明幸福快樂的人會將這種情緒傳染給身邊的人，讓他們有福同享。在某種程度上，幸福的汗水有點像微笑——它是會傳染的。」

為了確定這種情感化學信號是否會延伸成積極的情緒，Semin和同事們檢驗了人們快樂狀態下的汗水是否會影響行為、感知和接觸到汗水的人的情緒狀態。

研究人員招募了12名白人男性，他們為這項研究提供汗水樣本。參與者們不吸煙或服用任何藥物，而且沒有心理障礙。他們被禁止喝酒，性生活，食用有特殊味道的食物，以及在研究期間過度運動。

參與者來到實驗室，清洗並擦乾了腋下，並在腋窩處粘上了吸水墊。他們穿上水洗布t恤坐下來完成研究任務。他們觀看了一個試圖誘發他們情感狀態(恐懼、快樂、中性)的一個視頻短片，還完成了隱性情緒的測量，在這個測量中他們被告知觀察漢語符號並記錄每個人愉快或不愉快。然後移除吸水墊並將其儲存在瓶子里。

在第二部分研究中，研究人員招募了無心理障礙，呼吸系統疾病或其他疾病的36名白人女性。研究人員指出，這部分研究只有女性參與，女性擁有比男性更加敏銳的嗅覺和敏感的情緒表達。這是一樣雙盲研究，研究人員和實驗參與者都不知道在實驗中參與者會接觸到哪一個汗水樣本。

女性坐在椅子上，下巴置於腮托上。裝有汗水樣本的瓶子放置在一個與腮托連接的支架上，在目標任務之前立即打開瓶子。女性接觸到每種類型(恐懼、快樂、中性)的汗水樣本，不同樣本之間有五分鐘的間隔。

最初的數據分析證實，視頻短片確實影響了男性參與者的情緒狀態，觀看恐怖視頻之後男性顯示出負面情緒，而且觀看快樂視頻的男性顯示出積極情緒。

但這些情感狀態會傳遞給女性參與者嗎?行為學的研究結果表明，答案是肯定的。

面部表情數據分析顯示，接觸到「恐懼汗水」的女性顯示出內側額肌肉活動增加，這是恐懼表情的普遍特徵。接觸到「快樂汗水」下的女性顯示出更多的面部肌肉活動，這是真誠笑容的體現，快樂表情的組成部分。在女性的面部反應和他們的界定愉快以及緊張的汗水之間沒有顯著的關聯。

研究人員說這些發現表明，發送者(提供汗水樣本的人)和接收者(接觸到汗水的人)之間的一個「行為同步」。

這些初步的研究成果表明，通過不同的化學信號，比如接收者所產生的發送者情感狀態的模擬，我們就能夠表達出積極和消極的情緒狀態。

這項發現具有廣泛的關聯性——畢竟情感和汗水是人類經歷的兩個核心特徵。快樂通過化學方式傳播的事實，由於其潛在的商業應用價值，可能會引起「氣味行業」的興趣，Semin說。

「我們人體汗液傳播功能的一般模型還有另外一項任務，我們將繼續完善它，了解人體汗液對接觸到這些化合物的人神經系統的影響。」Semin總結道。

A sniff of happiness: Chemicals in sweat may convey positive emotion

Humans may be able to communicate positive emotions like happiness through the smell of our sweat, according to new research published in Psychological Science, a journal of the Association for Psychological Science. The research indicates that we produce chemical compounds, or chemosignals, when we experience happiness that are detectable by others who smell our sweat.

While previous research has shown that negative emotions related to fear and disgust are communicated via detectable regularities in the chemical composition of sweat, few studies have examined whether the same communicative function holds for positive emotions.

"Our study shows that being exposed to sweat produced under happiness induces a simulacrum of happiness in receivers, and induces a contagion of the emotional state," explains psychological scientist Gün Semin of Utrecht University in the Netherlands, senior researcher on the study. "This suggests that somebody who is happy will infuse others in their vicinity with happiness. In a way, happiness sweat is somewhat like smiling - it is infectious."

To determine whether this emotional chemosignaling extends to positive emotions, Semin and colleagues examined whether sweat taken from people in a happy state would influence the behavior, perception, and emotional state of people exposed to the sweat.

The researchers recruited 12 Caucasian males to provide the sweat samples for the study. The participants did not smoke or take any medications, and had no diagnosed psychological disorders. They were prohibited from engaging in alcohol use, sexual activity, consumption of smelly food, or excessive exercise during the study.

The sweat donors came to the lab, rinsed and dried their armpits, and had absorbent pads attached to each armpit. They donned a prewashed T-shirt and sat down to complete the study tasks. They watched a video clip intended to induce a particular emotional state (fear, happiness, neutral) and they also completed a measure of implicit emotion, in which they were asked to view Chinese symbols and rate how pleasant or unpleasant each one was. The sweat pads were then removed and stored in vials.

For the second part of the study, the researchers recruited 36 Caucasian females, with no psychological disorder, respiratory disease, or other illness. The researchers note that only females were included in this part of the study as women generally have both a better sense of smell and a greater sensitivity to emotional signals than men do. The study was double-blind, such that neither the researcher nor the participant knew which sweat sample the participant would be exposed to at the time of the experiment.

The women were seated in a chair and placed their chins on a chin rest. The vial containing the sweat sample was placed in a holder attached to the chin rest and was opened immediately prior to the target task. The women were exposed to a sweat sample of each type (fear, happiness, neutral), with a 5-minute break in between samples.

Initial data analyses confirmed that the videos did influence the emotional states of the male participants - men who watched the fear video showed predominantly negative emotion afterward and men who watched the happiness video showed predominantly positive emotion.

But were these emotions conveyed to the female participants? Some behavioral results suggest the answer is "yes."

Facial expression data revealed that women who were exposed to "fear sweat" showed greater activity in the medial frontalis muscle, a common feature of fear expressions. And women who were exposed to "happy sweat" showed more facial muscle activity indicative of a Duchenne smile, a common component of happiness expressions. There was no observable association, however, between the women"s facial responses and their explicit ratings of how pleasant and intense the sweat was.

These findings, the researchers say, suggest a "behavioral synchronization" between the sender (the sweat donor) and receiver (the sweat smeller).

These findings, while preliminary, suggest that we communicate our positive and negative emotional states via distinct chemosignals, such that the receiver produces a simulacrum of the sender"s emotional state.

The findings have broad relevance - emotion and sweat are two core features of the human experience, after all. But the fact that happiness may be communicated chemically could be of particular interest to the "odor industry," says Semin, due to its potential commercial applications.

"This is another step in our general model on the communicative function of human sweat, and we are continuing to refine it to understand the neurological effects that human sweat has on recipients of these chemical compounds," Semin concludes.