The Impact of Holiday Cracker Gags Influence Our Brains?

"How much did Santa's sleigh cost? Zero, it was on the house."

This quip is greeted with moans that echo through a warehouse in London.

This describes a joke-testing session with a company that makes products for social events. Its catalogue features Christmas crackers.

The firm's founder grins, almost sheepishly at the joke. But the pun has made the cut and will appear in future crackers.

"The success is gauged by the joke by the number of moans and the intensity of the groans at the table," the founder explains.

The secret to a great holiday cracker pun is not the same as a good joke per se. It is entirely about the setting - in this case, the shared laughter of the Christmas meal with grandparents, kids and potentially friends.

"You want the gag to be a thing that brings the child together with the grandparent," she adds.

The Neuroscience Of Shared Laughter

Gathering to enjoy communal laughter is not only ancient, scientists argue, it is probably to be pre-human.

"So when you are laughing with people at the Christmas dinner you are engaging in what's very likely a really ancient mammalian play vocalisation," says a neuroscience expert.

Shared laughter, she says, helps make and maintain social bonds between people.

Scientists have found that a absence of such social exchanges can significantly harm mental and physical health.

"Those you talk to, and laugh with, it results in increased levels of 'happy chemical' uptake," she adds.

Endorphins are the brain's "happy chemicals" and are released both to reduce stress and pain and in reaction to pleasurable activities, such as chuckling with loved ones over a particularly terrible Christmas cracker joke.

"You're not just laughing at a silly joke with a Christmas cracker," she says. "You are in fact performing a lot of the truly vital work of making, maintaining the connections you have with the people you care about."

What Occurs Inside the Brain?

But what is actually happening inside the brain when we hear a joke?

An awful lot occurs in reaction to humour, it transpires.

Employing brain scanning technology, a type of neural imager which indicates which areas of the brain are more active, scientists have been able to map the regions that get more blood flow.

Testing involves scanning the minds of healthy subjects and then subjecting them to a database of funny words, paired with either a neutral sound, or recorded laughter.

"During the study we got a very fascinating activation pattern of neural activity," says the neuroscientist.

A gag activates not just the parts of the mind responsible for hearing and understanding speech, but also neural areas associated with both preparation and starting motion and those linked to sight and recall.

Put these elements together, and people listening to a joke have a complex set of neural responses that support the laughter we experience.

The Contagious Power of Laughter

Researchers discovered that when a funny phrase is combined with chuckles there is a greater response in the brain than the identical word when accompanied by a neutral sound.

"This was in parts of the brain that you would use to contort your face into a smile or a chuckle," the professor says.

It means people are not just responding to funny words, they are responding to the laughter that follows them.

Laughter, according to the professor, can be contagious.

So what does this mean for the chuckles found around a holiday gathering?

"People laugh harder when you know people," she notes, "and you laugh further when you like them or love them."

When it comes to Christmas cracker jokes, she says, the positive effect is more likely to be caused not by the joke itself, but from the response to it.

"The laughter is key. The joke is the dreadful holiday cracker pun, and it's just a pretext to laugh as a group."

The Search for the Perfect Festive Pun

Will we ever find the ultimate joke?

Likely not, but that has not prevented experts from attempting to.

In 2001, a professor set up a research project for the planet's funniest joke.

Over tens of thousands of jokes submitted, with scores lodged by hundreds of thousands of people globally, he has a clearer understanding than many as to what succeeds and what fails.

The perfect Christmas cracker joke needs to be brief, he explains.

"But they also be poor gags, jokes that cause us to moan," he continues.

The increasingly "terrible" the gag, he says the more effective.

"This is because if no-one laughs – it's the joke's fault, not yours.

"What's interesting about the holiday cracker jokes is that none of us find them funny.

"That's a shared experience around the table and I think it's wonderful."