伦敦研究人员近日发现，我们在听到发自内心的笑声和虚情假意的笑声时，大脑会呈现出完全不同的反应。
假笑声会激活大脑中专门用于破译情感信息的区域。也就是说，听到假笑声时，我们会知道那并非真情流露，同时大脑会自动分析假笑的缘由，隐含的意思以及对方的真实想法。
而发自内心的笑声会激活大脑中与快乐和积极情绪相关的区域。
为了证实这一理论，伦敦大学皇家霍洛韦学院心理学博士卡罗琳·麦格蒂根让志愿者倾听YouTube网站上视频片段中的开怀大笑声，同时监测他们大脑的反应。并将参与者听到真笑时的大脑活动与听到假笑时的反应做对比。
测试结果显示，参与者在未被告知测试目的的情况下能够下意识地分辨出假笑声。
麦格蒂根指出人类大脑对于笑声中所隐含的社会和情感信息非常敏感。
“在我们的研究过程中，当参与者听到笑声，他们会启动大脑中与心智相关的区域，从而试图获知他人的情感或精神状态。”
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.