🔗 Share this article

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

This quip is greeted with groans that resonate through a storage facility in the capital.

We're at a humor-evaluation session with a company that makes supplies for gatherings. Its catalogue includes festive crackers.

The company's founder smiles, nearly sheepishly at the joke. But the joke has made the cut and will feature in upcoming crackers.

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

The secret to a great Christmas cracker pun is not the identical as a good joke in itself. It is all about the setting - in this instance, the communal laughter of the Christmas meal with elders, kids and potentially neighbours.

"You want the joke to be something that unites the eight-year-old together with the grandparent," she states.

The Neuroscience Of Shared Amusement

Gathering to experience communal amusement is not only ancient, scientists say, it is probably to be pre-human.

"Therefore when you are laughing with people at the Christmas table you are dropping into what's almost certainly a really primordial mammal social sound," explains a neuroscience expert.

Communal amusement, she explains, helps make and maintain social bonds between people.

Researchers have found that a absence of such interactions can seriously damage mental and physical well-being.

"The people you converse with, and laugh with, it leads to increased amounts of endorphin uptake," she continues.

Endorphins are the brain's "happy chemicals" and are released both to reduce tension and discomfort and in response to enjoyable activities, such as laughing with loved ones over a particularly terrible festive cracker gag.

"It's not simply laughing at a silly pun with a Christmas cracker," the expert says. "You are actually performing a lot of the really important work of making, maintaining the connections you have with those you love."

Which Happens In the Mind?

But what is truly taking place inside the brain when we listen to a joke?

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

Using functional magnetic resonance imaging (fMRI), a kind of neural imager which indicates which parts of the brain are more active, scientists have been able to map the regions that get more blood.

Testing entails imaging the brains of volunteer participants and then exposing them to a database of humorous words, accompanied by either a neutral sound, or recorded laughter.

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

A joke activates not just the parts of the mind in charge of hearing and interpreting language, but also neural regions involved in both planning and starting motion and those linked to sight and recall.

Put all of this together, and people hearing a pun have a sophisticated series of brain reactions that underpin the laughter we hear.

The Infectious Nature of Chuckles

Scientists found that when a humorous word is paired with chuckles there is a greater response in the mind than the same phrase when accompanied by a non-emotional sound.

"This was in parts of the brain that you would use to contort your expression into a grin or a laugh," she says.

It indicates people are not just responding to humorous jokes, they are responding to the amusement that accompanies them.

Amusement, according to the professor, can be infectious.

So what does this imply for the chuckles found at a holiday table?

"People laugh more when you are familiar with others," she says, "and you laugh more when you are fond of them or care for them."

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

"It's the laughter. The joke is the terrible Christmas cracker pun, and it's just a reason to laugh as a group."

The Quest for the Ideal Cracker Joke

Is it possible to discover the ultimate gag?

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

In 2001, a psychologist set up a scientific search for the world's most humorous joke.

Over 40,000 jokes submitted, with ratings lodged by hundreds of thousands of people globally, he has a clearer understanding than most as to what succeeds and what fails.

The perfect festive cracker pun needs to be brief, he explains.

"They must also be poor jokes, puns that cause us to groan," he continues.

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

"The reason is that if no-one laughs – it's the joke's fault, not yours.

"What's interesting about the Christmas cracker jokes is that not one person considers them humorous.

"It creates a shared experience around the table and I believe it's wonderful."