How Do Christmas Cracker Gags Do to Our Brains?

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

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

We're at a joke-testing session with a firm that makes products for social events. Its repertoire features festive crackers.

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

"You measure the gag by the number of groans and the intensity of the groans around the table," the founder explains.

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

"You want the gag to be a thing that unites the child in harmony with the 80-year-old," she states.

The Science Behind Shared Amusement

Coming together to enjoy shared laughter is not only nothing new, experts say, it is likely to be older than humanity.

"So when you are laughing with people around the holiday table you are engaging in what's almost certainly a really primordial mammalian social vocalisation," says a professor.

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

Researchers have found that a absence of these interactions can significantly damage mental and physical health.

"Those you converse with, and laugh with, it results in increased amounts of endorphin release," the professor continues.

Endorphins are the brain's "feel-good compounds" and are released both to reduce tension and discomfort and in reaction to pleasurable activities, such as laughing with loved ones over a particularly awful festive cracker joke.

"It's not simply laughing at a foolish joke with a Christmas cracker," she says. "You are actually doing a lot of the really vital task of building, preserving the social bonds you have with those you care about."

Which Occurs In the Brain?

But what is truly happening inside the mind when we hear a gag?

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

Using brain scanning technology, a type of neural imager which shows which parts of the mind are more active, scientists have been able to chart the regions that receive more blood flow.

Testing involves scanning the brains of healthy participants and then exposing them to a database of funny phrases, paired with either a neutral sound, or pre-recorded chuckles.

"During the study we observed a really fascinating pattern of activation," notes the professor.

A joke stimulates not just the parts of the mind responsible for auditory processing and understanding speech, but also neural regions associated with both preparation and initiating motion and those involved in sight and recall.

Combine these elements as a whole, and people listening to a joke have a complex series of brain responses that underpin the amusement we hear.

The Infectious Nature of Chuckles

Researchers found that when a humorous word is combined with laughter there is a greater reaction in the mind than the same word 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 chuckle," the professor says.

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

Amusement, says the expert, can be contagious.

So what does this imply for the chuckles found at a Christmas gathering?

"You laugh more when you know people," she says, "and laughter increases further when you like them or care for them."

When it comes to Christmas cracker puns, she says, the positive effect is more probable to be triggered not by the gag 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 reason to chuckle as a group."

The Quest for the Perfect Cracker Joke

Is it possible to find the ultimate gag?

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

Years ago, a psychologist set up a scientific search for the world's funniest joke.

More than 40,000 jokes submitted, with scores provided by hundreds of thousands of participants globally, he has a clearer understanding than most as to what works and what does not.

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

"They must also need to be bad gags, jokes that make us groan," he continues.

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

"The reason is that if nobody laughs – it's the joke's shortcoming, not your own.

"What's interesting about the holiday cracker jokes is that none of us considers them humorous.

"That's a shared moment around the table and I think it's lovely."