Left or Right brained: it's a myth!

26 February 2016

Interview with

Dr Kat Arney, The Naked Scientists

Kat Arney, wraps her brain around the latest bit of bad science: the claim that people can be "left- or right-brained"...

Kat - If you've been killing time on social media sites such as Facebook, you've probably had a go at some of the tests and quizzes that pop up from time to time, from 'What country describes your personality?' to "What shaped pasta would you be?' One that's been recently doing the rounds claims to be able to tell whether someone is more 'right-brained' or 'left-brained' and, in turn, how this affects their personality and character, how we go through life and the decisions we make.

According to the typical blurb, left-brain people are more organized and systematic while right-brain people are more creative and intuitive. Known as 'hemisity' according to some psychology researchers, t's an attractive idea - especially if you want to blame your lack of bright ideas or organisational skills on the sidedness of your brain. But is there any scientific truth to these tests and what they claim to be able to tell us?

It's obvious from looking at the anatomy of our grey matter that the brain is divided into two halves, or hemispheres, and neuroscientific studies have shown that specific cognitive abilities - that's things like vision, movement, languages and much more - can be found in three different types of patterns in the brain.

Some tasks, such as general attention, are done equally in both halves of the brain, as is the wonderfully-named 'executive function' - the ability to plan and control the things you do. Other abilities, such as vision, are found in both halves of the brain, but specific to the opposite side of the body - for example, the motor cortex in the left sides of your brain controls the movement of the right side of your body.

And then there are some tasks that are specific to one hemisphere - for example, language and mathematical skills seem to be localised to the left side of the brain, for people who are right-handed (meaning their left hemisphere is dominant). But music and spatial processing - being able to figure out shapes and spaces - is usually found in the right side of the brain.

It's this discovery that seems to have led to the idea that left-brained people are good at maths and analytical skills, while right-brain people are better at all the creative stuff. But in fact this is a vast oversimplification of the way that both sides of the brain work together. And it's certainly not true that someone's general personality is located in one half of their brain rather than the other.

For a start, there's a huge amount of inter-connectedness between the two halves of the  brain, and information flows seamlessly between them through a thick cable of nerves known as the corpus callosum. And a 2013 study using fMRI brain scanning showed that there doesn't seem to be a neuroscientific basis for the idea that people are predominantly left or right-brained, based on brain scans from more than a thousand people aged from 7 to 29. While there were local examples of certain different tasks tending to be done by the left or right brain, there was no overall bias to either side.

So does it matter? Surely social media quizzes are just a bit of fun to pass the time during a lunchbreak, and nobody takes it seriously. But I think it does. We like to put people into boxes, but giving someone a simple label like left or right-brained doesn't really reflect the underlying plasticity we all have to tackle life in a range of ways. Telling someone they're "right brained, so they're going to be no good at maths", or "left-brained so they'll never be creative" is limiting and not based on sound science. So let's stop trying to label our brains, and label this particular idea as a myth.

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