STUDENTS facing exams this month, take heart: your companions can smell your fear, and they empathise.

    That's the implication of a study by Bettina Pause at the University of Dusseldorf, Germany, and colleagues. They put absorbent pads under the armpits of 49 university students an hour before they took their final oral exam and again as the same students exercised. Another set of students then sniffed the sweat samples while having their brains scanned.

    None perceived a difference between the two types of sweat, but the pre-exam sweat had a different effect on brain activity, lighting up areas that process social and emotional signals, as well as several areas thought to be involved in empathy （PLoS One, DOI: 10.1371/journal.pone.0005987）.

    The researchers conclude that anxiety prompts the release of a chemical that bypasses conscious experience, automatically triggering similar feelings in anyone who sniffs it. This may allow fear to spread quickly and speed our ability to flee danger. A previous experiment found that sweat from skydivers activated anxiety circuits in sniffers' brains.

    學(xué)生們本月要面臨考試，鼓起勇氣吧：你的同伴可以聞出你的恐懼來(lái)，他們也會(huì)產(chǎn)生同樣的恐懼。

    這是德國(guó)杜塞爾多夫大學(xué)的貝蒂娜·鮑絲與其同事所做一項(xiàng)研究的結(jié)論。他們?cè)?9位大學(xué)生參加期終口試之前，把吸水巾在學(xué)生的腋下放置一個(gè)小時(shí)，在這些學(xué)生參加書面考試之前再做同樣的測(cè)試。另一組學(xué)生隨后嗅聞這些取樣的汗水，同時(shí)對(duì)這組學(xué)生的大腦進(jìn)行掃描。

    無(wú)人理解這兩種汗水有何區(qū)別，但前一種考試的汗水對(duì)大腦活動(dòng)的影響有所不同，它會(huì)使處理社會(huì)和情感信號(hào)的腦域興奮起來(lái)，也會(huì)使若干被認(rèn)為與同情有關(guān)的腦域興奮起來(lái)（《公共科學(xué)圖書館綜合》，文章號(hào)碼： 10.1371/期刊。發(fā)行條碼0005987）.

    研究人員得出的結(jié)論是，焦慮不安會(huì)引起一種化學(xué)物質(zhì)的釋放，這種化學(xué)物質(zhì)繞過(guò)神志清醒的感受，可以自動(dòng)觸發(fā)嗅聞?wù)叩耐�類情緒。這可能讓恐懼迅速蔓延，并讓我們能夠加速逃離危險(xiǎn)。此前的實(shí)驗(yàn)發(fā)現(xiàn)，高空跳傘運(yùn)動(dòng)員的汗水會(huì)激活嗅聞?wù)叽竽X中的焦慮神經(jīng)。