Most young kids do it. Michael Jordan was famous for it. And it’s quite possible you do it too. What am I talking about? Sticking your tongue out when you concentrate. It’s incredibly common and over the years there have been a variety of theories attempting to explain the habit. Recent research supports the suggestion it’s connected to the way humans evolved spoken language.

Do you know someone who pokes their tongue out when they’re concentrating? Image credit henry… via Flickr

A quirky tongue?

Next time you have the opportunity, watch a young child who is concentrating hard on doing something with their hands. Chances are you’ll notice their tongue poking out from their mouth. Is it simply a childhood quirk, or could there be more to the humble poking tongue?

Think back to the last time you did something with your hands that required a lot of dexterity. Something like threading a needle or sinking the perfect shot while playing pool. It’s highly likely your tongue was pressed between your lips, perhaps with the tip peeking out. Your tongue is one of the largest groups of muscles in your body and there’s good reason to think our tendency to poke it out when concentrating is more than just a quirk.

Don’t interrupt me!

Research published back in 1974 looked at ‘tongue-show behaviour’ in young children, adults living in a variety of countries and young gorillas. The researchers concluded humans (and other primates) show our tongues to communicate we don’t want to interact with anyone. During the 1980s, a number of researchers explored the idea a tongue poking out works as an effective signal to say “don’t disturb me”.

In one study, 50 university students each took an individual reading comprehension test. The lecturer sat at the front of the room, but wore headphones needed to complete other work. Each student was put in a position in which they had to interrupt the lecturer: one page of the test was clearly missing. Because of the headphones, a student had to either call loudly or tap the lecturer on the arm to get attention.

If the lecturer appeared to be concentrating and had their tongue poking out, it took students on average nearly 20 seconds to interrupt and ask for the extra page. If the lecturer at the front had the same facial expression – but without a visible tongue – students waited on average only seven seconds before interrupting. Interestingly when asked later, none of the students who had seen the tongue were aware it had been part of the lecturer’s facial expression. An extension of this experiment found the same thing: the visible tongue is the important feature. People are much less likely to interrupt you if your tongue is poking out than if you simply look to be concentrating intensely.

Desmond Morris pointed out babies also signal they have had enough to eat by poking their tongue out. Another way of saying ‘leave me alone’. But just because a poking-out tongue functions as a ‘don’t interrupt’ signal, that doesn’t necessarily explain why we do it.

Overloaded

Stop for a moment and become aware of the incredible sensitivity of your tongue. It isn’t just responsible for tasting things but provides you with a detailed and constantly-updated mental map of the inside of your mouth. Your tongue is highly sensitive because it has a big supply of nerves.

You may also find that as you think, your tongue moves to partly form the shape of a word you are thinking. All of this means your tongue is sending lots of information to your brain all the time. So one explanation for why you might do it is that in order to reduce some of this sensory input, you stick your tongue outside of your mouth and hold it still. As a result, you are left with more brainpower to concentrate on a demanding task.

It’s all about language

We know there are strong links between the brain regions responsible for speaking and the control of hands and arms. And many scientists have suggested human speech may have evolved from communication by hand gestures.

In a study published earlier this year, right-handed 4-year-olds were filmed while completing tasks requiring either very fine hand control (opening a padlock with a key), less fine control (playing a game that involved knocking or tapping the table) or no hand control at all (remembering a story). The researchers watched each video for any sign of the kid’s tongue poking out.

All of the children stuck their tongues out while performing the tasks, but more often during some tasks than others. Although we might expect something as challenging as opening the padlock to lead to the most tongue-showing, that’s not what the researchers found. Instead, it was the knock and tap game that resulted in the kids sticking out their tongues most often.

The researchers explain it by the fact the game involved strict rules, rapid turn-taking and the use of defined hand gestures. All of which are the basic and early components of language. To back this up, the researchers noticed that the tongue most often poked out on the right side of the body. That suggests the tongue movement is being controlled by the left side of the body, which is where language centres are usually found in right-handed people, particularly amongst children.

If kids can’t help but stick their tongues out when engaging the language centres of their brains, why don’t more adults do the same? Probably because adults are embarrassed and have trained themselves not to do it.

So next time you see someone’s tongue sticking out as they concentrate, smile by all means and take it as a sign to leave them in peace. But also step back and admire a sign that the complex language we all depend on may well have evolved from simple hand gestures.

Links and stuff

• Research this post is based on
• Why do we look upward when in deep thought?
• Scientific American: Is the tongue the strongest muscle in the body?

Radio on demand

This post accompanies a radio segment on Triple R’s Breakfasters program on Wednesday 24 June 2015.