“The average person uses 10% of their brain capacity,” says the movie poster. Scarlett Johansen’s piercing eyes stare at you from beneath the tagline, “…imagine what she could do with 100%”.

Wow, what a prospect. Can she do really fast algebra? Compose great musical compositions or find the solution to world peace, perhaps?

No, none of these – at least according to the plot line of Lucy, a recent sci-fi blockbuster directed by the acclaimed Luc Besson. Rather, ‘Lucy’ does martial arts, moves objects with her mind and makes people collapse at the flick of a finger. Ah yes, of course.

I know what you’re thinking, “...imagine what she could do with 100%” doesn’t make for the most electrifying of action movie straplines. But it grabs us because, if we’re honest, we would all love to be just a little bit smarter (although perhaps not in ways quite like Lucy).

A surprising number of people I speak to believe the ten per cent theory to be true. But it patently isn’t – and it’s one thing we would all do well to forget.

It’s not difficult to see why the ten percent idea caught on. Just look at some modern-day super-brains: Daniel Tammet, the British writer who knows the number Pi to 22,513 decimal points, speaks ten languages and learnt Icelandic in a week; Flo and Katherine Lyman, the identical twins who instantly know the day of the week for any date in history (October 17, 1683 is a Sunday, for example); and Derek Paravicini, who was born blind and a musical prodigy, able to recite any piano piece after hearing it once.

However, gifts like these usually come at a cost. More often than not, those who have an intellectual superpower have impairments in other areas – often lacking social skills or creative thinking.

The brain isn’t an underutilised engine, ticking over at 10 per cent power; but is a living device that plays a continuous balancing act.

Rather than think of your brain as being capable of “100 per cent”, consider it as a truly incredible bit of machinery that holds all its parts and abilities in a wonderful harmony. And it is not a piece of kit that is prefabricated and fixed, but is a highly adaptable organ – able to learn and adapt to all a manner of remarkable challenges.

Seven years ago, I lost an egg-sized chunk of my grey matter to a tumour. I had effectively lost about 10 per cent of the ‘thinking’ part of the brain. But nature played its part, and the remaining brain neurons rewired to adapt around the missing bit. The result is that I now live without disability and can function at near my pre-illness status.

Similarly, when anyone taxes their brain with new challenges (say, learning a language or taking up art), they force neurons to rewire in positive ways – effectively ‘growing’ their abilities.

Obviously, no-one will ever be like ‘Lucy’. Nor will you be Daniel Temmet, Derek Paravicini, Katherine or Flo. For your brain is unique to you. To be like them would probably mean disabling other parts of your thinking brain – losing a part of who you are.

What you can do, however, is shape how your brain changes and adapts over time. You can do this every day of your life, with how you choose to live, the things you learn, and the journeys you take.

But don’t worry (spoiler alert), just know that no matter how smart you get, you won’t ever have to fear melting into a pile of black goo, disappearing into the space-time continuum and popping up on a French detective’s phone. Because that’s just silly.