"People genuinely think they are mostly laughing at other people's jokes, but within a conversation, the person who laughs most at any one time is the person who is talking," she told the BBC.
The University College London professor's current research aims to distinguish the difference between fake laughs used during conversation, and involuntary giggles.
She has carried out brain scans on volunteers listening to expressions of disgust, a real belly laugh and a realistic fake one.
So far, her research has found that volunteers were almost always able to identify a false laugh.
She has also discovered that less authentic tones are more nasal, and belly laughs never come through the nose.
Laughter is the best medicine
Researchers from Indiana State University found that with laughter can boost the immune system by up to 40 per cent.
The study tested 33 healthy women.
Half of the women watched a comedy video together while the others watched a dull video on tourism.
When the films were over, scientists took samples of the women's immune cells, known as natural killer cells, and mixed them with cancer cells to see how effectively they attacked the disease.
They found that the women who had found the comedy funny enough to laugh out loud had significantly healthier immune systems afterwards than those who had watched the tourism film.
Meanwhile, MRI scans revealed how hearing real and fake laughter activates two different areas of our brains.
Fake laughter triggers more brain activity - in the medial prefrontal cortex, associated with problem-solving - as we try to work out why the person is doing it.
Genuine laughter simply activates auditory areas in the temporal lobe - where we process all sound.
But both activate the brain's mirror regions that mimic other's actions, and she says this is the reason behind why laughing can be so contagious.
"You are 30 times more likely to laugh if you're with someone else," she claims.
To further her work, Scott has recently set up an experiment at London's Science Museum, where she will be asking visitors to judge the authenticity of different clips of people laughing.
And she believes far more research needs to be done on this cultural tic.
"If you search on the Web of Science database for papers on the emotion of fear, you'll get back 6477 published papers," Professor Scott writes on Ted.
"Search for papers on laughter and you'll get a paltry 175. Why the disparity? Well, one reason might be that laughter, like other positive emotions, feels less important than negative emotions.
"Sometimes people think that laughter is a ridiculous, trite, pointless topic to research...I think it's a fascinating social behaviour, it is essential to study."
In a separate study last year, 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."
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- Daily Mail
