What Do Festive Cracker Gags Do to Our Minds?

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

This quip is greeted with groans that echo through a storage facility in London.

We're at a joke-testing meeting with a company that makes products for social events. Its repertoire includes Christmas crackers.

The company's founder grins, almost sheepishly at the gag. But the pun has made the cut and will feature in future crackers.

"You measure the gag by the volume of groans and the loudness of the groans at the table," the founder says.

The key to a great Christmas cracker joke is not the identical as a good joke per se. It is entirely about the context - in this case, the communal laughter of the Christmas dinner table with grandparents, kids and potentially neighbours.

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

The Neuroscience Behind Communal Laughter

Coming together to experience communal amusement is not only nothing new, experts say, it is likely to be pre-human.

"Therefore when you are laughing with people at the Christmas table you are engaging in what's very likely a truly primordial mammal play sound," says a professor.

Communal amusement, she explains, aids in forge and strengthen social bonds between individuals.

Researchers have found that a lack of these interactions can significantly harm mental and physical health.

"Those you converse with, and share laughter with, it results in increased amounts of 'happy chemical' release," she continues.

These natural chemicals are the body's "feel-good compounds" and are released both to reduce stress and pain and in response to enjoyable experiences, such as laughing with loved ones over a truly terrible festive cracker gag.

"It's not simply chuckling at a foolish joke with a Christmas cracker," she says. "You are in fact performing a lot of the truly important work of building, preserving the connections you have with those you care about."

Which Happens In the Mind?

But what is truly happening within the brain when we hear a gag?

A tremendous amount happens in response to comedy, it turns out.

Employing functional magnetic resonance imaging (fMRI), a type of neural imager which shows which areas of the brain are working harder, scientists have been able to map the areas that get more blood flow.

Testing involves scanning the minds of volunteer subjects and then subjecting them to a database of funny words, accompanied by either a non-emotional sound, or recorded laughter.

"In the scanner we got a really fascinating activation pattern of neural activity," notes the neuroscientist.

A gag activates not just the parts of the mind in charge of auditory processing and understanding language, but also brain regions involved in both preparation and initiating movement and those involved in sight and recall.

Combine all of this as a whole, and individuals listening to a joke have a complex set of neural reactions that underpin the amusement we experience.

The Infectious Power of Chuckles

Researchers found that when a humorous phrase is paired with chuckles there is a stronger response in the mind than the identical word when accompanied by a neutral sound.

"This was in parts of the mind that you would employ to contort your face into a grin or a chuckle," she says.

It indicates people are not just reacting to humorous jokes, they are responding to the laughter that follows them.

Laughter, according to the expert, can be contagious.

So what does this mean for the laughter heard at a holiday gathering?

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

When it comes to festive cracker puns, she says, the feel-good effect is more probable to be caused not by the joke itself, but from the response to it.

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

The Quest for the Ideal Cracker Joke

Will we ever find the ultimate gag?

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

Years ago, a professor established a scientific search for the planet's funniest gag.

Over tens of thousands of jokes submitted, with ratings provided by 350,000 participants around the world, he has a better understanding than most as to what succeeds and what does not.

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

"But they also be poor jokes, puns that make us groan," he adds.

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

"This is because if nobody laughs – it's the joke's fault, not your own.

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

"That's a shared moment around the gathering and I think it's wonderful."