How Do Festive Cracker Gags Influence Our Brains?

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

This joke is met by groans that echo through a storage facility in London.

We're at a humor-evaluation session with a firm that makes products for gatherings. Its catalogue features Christmas crackers.

The firm's founder grins, nearly apologetically at the gag. But the joke has been selected and will feature in upcoming crackers.

"The success is gauged by the gag by the number of moans and the loudness of the groans at the table," she explains.

The key to a great Christmas cracker joke is not the identical as a good gag per se. It is all about the setting - in this case, the shared laughter of the Christmas dinner table with elders, kids and possibly friends.

"You want the gag to be something that brings the child together with the 80-year-old," she adds.

The Neuroscience Of Communal Amusement

Gathering to enjoy shared laughter is not only nothing new, experts argue, it is likely to be older than humanity.

"So when you are laughing with others at the Christmas dinner you are dropping into what's almost certainly a truly primordial mammalian social sound," explains a neuroscience expert.

Communal laughter, she explains, helps make and maintain social connections between individuals.

Scientists have found that a absence of such interactions can seriously damage both psychological and bodily health.

"The people you converse with, and share laughter with, it results in enhanced levels of 'happy chemical' release," the professor continues.

These natural chemicals are the body's "happy chemicals" and are released both to reduce tension and discomfort and in reaction to pleasurable experiences, such as chuckling with loved ones over a particularly awful festive cracker gag.

"You're not just laughing at a silly joke with a Christmas cracker," the expert states. "You are in fact doing a lot of the truly important work of building, preserving the connections you have with the people you care about."

What Happens In the Mind?

But what is actually taking place within the mind when we listen to a gag?

A tremendous amount occurs in reaction to comedy, it turns out.

Using functional magnetic resonance imaging (fMRI), a type of neural imager which shows which parts of the mind are more active, researchers have been able to chart the areas that receive more blood.

The research involves scanning the minds of volunteer participants and then exposing them to a collection of humorous words, paired with either a non-emotional sound, or recorded laughter.

"In the scanner we observed a very interesting pattern of neural activity," says the neuroscientist.

A joke activates not just the parts of the brain in charge of hearing and understanding speech, but also neural regions involved in both preparation and starting movement and those involved in vision and memory.

Put these elements together, and individuals hearing a pun have a complex set of brain responses that support the amusement we experience.

The Infectious Power of Laughter

Scientists discovered that when a humorous word is combined with laughter there is a stronger response in the mind than the same phrase when accompanied by a neutral sound.

"This activation occurred in parts of the brain that you would use to contort your face into a smile or a laugh," she explains.

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

Laughter, says the professor, can be infectious.

So what does this mean for the chuckles heard at a Christmas gathering?

"People laugh harder when you are familiar with others," she says, "and you laugh more when you like them or love them."

When it comes to Christmas cracker puns, she says, the feel-good factor is more probable to be triggered not by the gag in itself, but from the response to it.

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

The Search for the Ideal Cracker Joke

Will we ever discover the perfect joke?

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

In 2001, a psychologist set up a scientific project for the planet's funniest joke.

Over 40,000 jokes submitted, with ratings lodged by hundreds of thousands of participants around the world, he has a clearer idea than most as to what works and what does not.

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

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

The increasingly "terrible" the joke, he says the better.

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

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

"It creates a common moment around the gathering and I think it's wonderful."