So what’s going on? Are there really two separate minds in a bilingual brain? That’s what the snowflake experiment was designed to find out. I’m a little nervous of what my fumbling performance will reveal about me, but Athanasopoulos assures me I’m similar to others who have been tested – and so far, we seem to be validating his theory.

In order to assess the effect that trying to understand the Syntaflake language had on my brain, I took another test before and after the snowflake task. In these so-called flanker tasks, patterns of arrows appeared on the screen and I had to press the left or right button according to the direction of the arrow in the centre. Sometimes the surrounding pattern of arrows was confusing, so by the end of the first session my shoulders had been hunched somewhere near my ears and I was exhausted from concentrating. It’s not a task in which practice improves performance (most people actually do worse second time round), but when I did the same test again after completing the snowflake task, I was significantly better at it, just as Athanasopoulos has predicted.

“Learning the new language improved your performance second time around,” he explains. Relieved as I am to fit into the normal range, it’s a curious result. How can that be?

The flanker tasks were exercises in cognitive conflict resolution – if most of the arrows were pointing to the left, my immediate impulse was to push the left button, but this wasn’t the correct response if the central arrow was pointing right. I had to block out my impulse and heed the rule instead. Another example of cognitive conflict is a test in which the names of colours are written in different colours (“blue” written in red, for example). The aim is to say which colour each word is written in, but this is tricky, because we read the word much quicker than we process the colour of the letters. It requires considerable mental effort to ignore the impulse just to say the word we can’t help but read.

The part of the brain that manages this supreme effort is known as the anterior cingulate cortex (ACC), part of the “executive system”. Located on the frontal lobe, it is a toolbox of mental attention skills that enables us to concentrate on one task while blocking out competing information, and allows us to switch focus between different tasks without becoming confused. It is the executive system that tells us to go when we see a green light and stop for a red, and it is the same system that tells us to ignore the meaning of the word we read but concentrate on the colour of the letters.

The snowflake test prepared my ACC for the second flanker task, just as speaking more than one language seems to train the executive system more generally. A steady stream of studies over the past decade has shown that bilinguals outperform monolinguals in a range of cognitive and social tasks from verbal and nonverbal tests to how well they can read other people. Greater empathy is thought to be because bilinguals are better at blocking out their own feelings and beliefs in order to concentrate on the other person’s.

“Bilinguals perform these tasks much better than monolinguals – they are faster and more accurate,” says Athanasopoulos. And that suggests their executive systems are different from monolinguals’.

Mental muscles

In fact, says cognitive neuropsychologist Jubin Abutalebi, at the University of San Raffaele in Milan, it is possible to distinguish bilingual people from monolinguals simply by looking at scans of their brains. “Bilingual people have significantly more grey matter than monolinguals in their anterior cingulate cortex, and that is because they are using it so much more often,” he says. The ACC is like a cognitive muscle, he adds: the more you use it, the stronger, bigger and more flexible it gets.

Bilinguals, it turns out, exercise their executive control all the time because their two languages are constantly competing for attention. Brain-imaging studies show that when a bilingual person is speaking in one language, their ACC is continually suppressing the urge to use words and grammar from their other language. Not only that, but their mind is always making a judgement about when and how to use the target language. For example, bilinguals rarely get confused between languages, but they may introduce the odd word or sentence of the other language if the person they are talking to also knows it.

“My mother tongue is Polish but my wife is Spanish so I also speak Spanish, and we live in Edinburgh so we also speak English,” says Thomas Bak. “When I am talking to my wife in English, I will sometimes use Spanish words, but I never accidentally use Polish. And when I am speaking to my wife’s mother in Spanish, I never accidentally introduce English words because she doesn’t understand them. It’s not something I have to think about, it’s automatic, but my executive system is working very hard to inhibit the other languages.”

For bilinguals, with their exceptionally buff executive control, the flanker test is just a conscious version of what their brains do subconsciously all day long – it’s no wonder they are good at it.