How Do Christmas Cracker Gags Affect The Brain?

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

This one-liner is met by moans that echo through a storage facility in the capital.

This describes a joke-testing meeting with a firm that produces products for social events. Its repertoire includes festive crackers.

The company's founder smiles, nearly apologetically at the gag. But the pun has made the cut and will appear in upcoming crackers.

"The success is gauged by the joke by the number of groans and the loudness of the groans at the table," she says.

The key to a good holiday cracker pun is not the identical as a stand-up gag per se. It is entirely about the setting - in this case, the shared laughter of the Christmas dinner table with grandparents, kids and possibly neighbours.

"You want the joke to be a thing that brings the child in harmony with the 80-year-old," she adds.

The Science Of Shared Laughter

Coming together to experience shared laughter is not only ancient, scientists argue, it is likely to be pre-human.

"So when you are laughing with others around the Christmas dinner you are engaging in what's very likely a truly primordial mammal play vocalisation," says a neuroscience expert.

Shared amusement, she explains, helps forge and strengthen social bonds between individuals.

Scientists have found that a lack of such social exchanges can significantly harm mental and physical well-being.

"Those you talk to, and laugh with, it results in enhanced amounts of endorphin uptake," she continues.

These natural chemicals are the brain's "feel-good compounds" and are produced both to alleviate stress and pain and in reaction to enjoyable experiences, such as laughing with loved ones over a particularly awful festive cracker joke.

"It's not simply chuckling at a foolish joke with a Christmas cracker," she states. "You are in fact doing a lot of the really important work of making, maintaining the social bonds you have with those you care about."

What Happens In the Mind?

But what is actually happening within the brain when we listen to a gag?

A tremendous amount occurs in response to humour, it transpires.

Using brain scanning technology, a type of neural imager which shows which areas of the brain are working harder, researchers have been able to map the areas that receive more blood.

Testing involves imaging the minds of healthy participants and then subjecting them to a database of humorous phrases, paired with either a non-emotional sound, or pre-recorded chuckles.

"During the study we got a really interesting pattern of neural activity," notes the professor.

A joke activates not just the areas of the brain in charge of auditory processing and interpreting language, but also brain areas associated with both preparation and initiating motion and those involved in vision and memory.

Put all of this together, and people listening to a pun have a complex set of brain responses that underpin the laughter we hear.

The Contagious Power of Laughter

Scientists discovered that when a funny phrase is paired with laughter there is a stronger reaction in the mind than the same word when followed by a neutral sound.

"This activation occurred in areas of the mind that you would employ to contort your face into a grin or a laugh," the professor says.

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

Amusement, according to the professor, can be infectious.

So what does this mean for the laughter found at a holiday table?

"People laugh harder when you know people," she says, "and you laugh more when you are fond of them or love them."

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

"It's the laughter. The gag is the terrible holiday cracker pun, and it's just a pretext to laugh together."

The Search for the Ideal Festive Pun

Is it possible to discover the ultimate joke?

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

Years ago, a professor set up a scientific search for the planet's most humorous joke.

Over 40,000 jokes later, with scores provided by hundreds of thousands of people globally, he has a better understanding than many as to what succeeds and what fails.

The perfect festive cracker pun must be short, he says.

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

The more "awful" the joke, he says the more effective.

"This is because if no-one finds it funny – it's the joke's fault, not your own.

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

"That's a shared moment around the table and I believe it's wonderful."