下回當你聽到老板講的無聊笑話而硬擠出笑容時，可真要注意了，其實他們能看出來你是在裝模作樣。

倫敦研究人員近日發現，我們在聽到發自內心的笑聲和虛情假意的笑聲時，大腦會呈現出完全不同的反應。

假笑聲會激活大腦中專門用于破譯情感信息的區域。也就是說，聽到假笑聲時，我們會知道那并非真情流露，同時大腦會自動分析假笑的緣由，隱含的意思以及對方的真實想法。

而發自內心的笑聲會激活大腦中與快樂和積極情緒相關的區域。

為了證實這一理論，倫敦大學皇家霍洛韋學院心理學博士卡羅琳·麥格蒂根讓志愿者傾聽YouTube網站上視頻片段中的開懷大笑聲，同時監測他們大腦的反應。并將參與者聽到真笑時的大腦活動與聽到假笑時的反應做對比。

測試結果顯示，參與者在未被告知測試目的的情況下能夠下意識地分辨出假笑聲。

麥格蒂根指出人類大腦對于笑聲中所隱含的社會和情感信息非常敏感。

“在我們的研究過程中，當參與者聽到笑聲，他們會啟動大腦中與心智相關的區域，從而試圖獲知他人的情感或精神狀態。”

Next time your boss tells a bad joke and you feel compelled to laugh, beware - they can tell you're faking it.

Researchers from London have discovered our brains carry out different process when we hear genuine laughter compared to fake chuckles.

When laughter is forced, for example, it activates a part of the brain linked with deciphering emotions.

This means we know it's not a genuine laugh, and we automatically try to work out why they're faking it, what the laugh means and what the they're thinking.

While genuine laughter lights up areas of the brain linked with happiness and positive emotions.

To test the theory, psychologist Dr Carolyn McGettigan from the Royal Holloway University of London measured brain responses of volunteers as they listened to genuine laughter on YouTube clips.

Each participant was asked to pick clips they found funny.

This ranged from comedy shows, such as Flight Of The Conchords, and even the Eurovision Song Contest.

The results were then compared to how their brains responded to fake laughter.

The findings revealed participants, none of which were told the study was about laughter perception, could unconsciously tell when the chuckles were insincere.

Dr McGettigan said: 'It's fascinating to consider the way our brain is able to detect genuine happiness in other people.

'Our brains are very sensitive to the social and emotional significance of laughter.

'During our study, when participants heard a laugh that was posed, they activated regions of the brain associated with mentalising in an attempt to understand the other person's emotional and mental state.'

The study goes a long way to explain why people can easily spot when someone is forcing laughter.

Dr McGettigan added: 'Some of the participants engaged parts of the brain that also control movements and detect sensation.

'These individuals were more accurate at telling which of the laughs were posed, and which were real, when we tested them after their scan.

'This suggests that as listeners, 'trying out' how a laugh would feel if we produced it ourselves might be a useful mechanism for understanding its meaning.'

The study was commissioned for the second annual International Day of Happiness on Wednesday.

Dr McGettigan's findings confirm previous research from scientists at the University of Tuebingen in Germany who investigated the 'laughter perception network' of the brain.

Lead researcher Dr Dirk Wildgruber found that parts of our brains sensitive to processing high-level, social information reacted most to 'joyous' and 'taunting' laughter.

Wildgruber's study said this is proof the brain is able to recognise the difference between types of laughter, and whether we're being laughed at, or laughed with.

Yet, regions of our brain that are more sensitive to picking up and registering more complex sounds reacted most to 'tickling' laughter.

（來源：Daily Mail 編輯：丹妮）