What Do Christmas Cracker Puns Influence Our Minds?

"How much did Father Christmas's sleigh cost? Nothing, it was on the house."

This joke is met by moans that resonate through a warehouse in London.

This describes a joke-testing session with a company that makes supplies for social events. Its catalogue includes festive crackers.

The firm's founder smiles, almost apologetically at the gag. But the pun has been selected and will feature in future crackers.

"You measure the joke by the volume of moans and the intensity of the groans around the table," she says.

The secret to a great Christmas cracker pun is not the same as a good joke in itself. It is entirely about the setting - in this instance, the shared amusement of the holiday dinner table with elders, children and potentially friends.

"The goal is for the gag to be something that unites the eight-year-old in harmony with the 80-year-old," she adds.

The Neuroscience Behind Shared Amusement

Gathering to enjoy shared laughter is not only ancient, scientists say, it is likely to be older than humanity.

"Therefore when you are laughing with others at the holiday table you are engaging in what's almost certainly a really primordial mammalian social vocalisation," explains a neuroscience expert.

Communal laughter, she says, helps forge and strengthen social bonds between individuals.

Scientists have found that a lack of these social exchanges can significantly damage mental and physical health.

"The people you talk to, and laugh with, it results in increased levels of endorphin uptake," the professor continues.

Endorphins are the body's "happy chemicals" and are produced both to alleviate stress and pain and in response to enjoyable activities, such as laughing with loved ones over a truly terrible festive cracker gag.

"You're not just chuckling at a silly joke with a Christmas cracker," she says. "You are in fact performing a lot of the truly important work of building, preserving the social bonds you have with those you love."

What Happens In the Mind?

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

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

Employing functional magnetic resonance imaging (fMRI), a kind of neural imager which indicates which areas of the brain are more active, researchers have been able to map the areas that receive more blood.

Testing involves scanning the brains of volunteer subjects and then subjecting them to a collection of humorous phrases, accompanied by either a non-emotional sound, or pre-recorded chuckles.

"During the study we observed a really interesting activation pattern of activation," says the professor.

A gag activates not just the areas of the mind responsible for hearing and interpreting language, but also neural regions involved in both preparation and initiating motion and those linked to sight and memory.

Combine these elements as a whole, and individuals listening to a joke have a complex set of brain responses that support the amusement we hear.

The Contagious Power of Chuckles

Scientists found that when a funny phrase is paired with laughter there is a greater response in the brain than the same phrase when accompanied by a neutral sound.

"This was in parts of the brain that you would use to contort your expression into a smile or a laugh," the professor explains.

It indicates we are not just reacting to funny words, they are reacting to the laughter that follows them.

Laughter, says the professor, can be infectious.

So what does this mean for the laughter found around a Christmas table?

"People laugh more when you are familiar with people," she says, "and you laugh further when you are fond of them or love them."

When it comes to festive cracker jokes, she explains, the positive factor is more probable to be triggered not by the joke in itself, but from the reaction to it.

"The laughter is key. The gag is the terrible Christmas cracker joke, and it's just a reason to chuckle together."

The Search for the Perfect Festive Pun

Will we ever find the perfect joke?

Probably not, but that has not prevented researchers from trying to.

In 2001, a professor set up a scientific search for the planet's most humorous gag.

Over tens of thousands of gags submitted, with scores lodged by hundreds of thousands of participants globally, he has a clearer understanding than most as to what works and what fails.

The ideal Christmas cracker joke must be short, he says.

"But they also need to be bad gags, jokes that make us moan," he adds.

The more "awful" the gag, he says the better.

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

"The fascinating part about the holiday cracker jokes is that none of us find them humorous.

"It creates a common experience at the table and I believe it's lovely."