Sometimes I just want to give up. I really don’t know why I bother with my epic quest for truth, science and reason.

You are such a right-brain thinker’, she yelled.

I probably should not have said she was so wrong. Maybe I should not have added that she was being a ‘meme sustaining poptart psychologist’ and ‘both neuro-scientifically and anatomically inaccurate’. Like the time she came in when I was watching the cricket and said, “It’s over” and I replied, “No, 3 balls left”.

Despite what you may have been told, you are not left-brained or right-brained. From books to television programs, you may have heard the phrase mentioned numerous times or perhaps you’ve even taken an online test to determine which type best describes you. From self-help and business success books to job applications and smartphone apps, the theory that the different halves of the human brain govern different skills and personality traits is a popular one.

According to this (wrong) theory of left-brain or right-brain dominance, each side of the brain controls different types of thinking. Additionally, people are said to prefer one type of thinking over the other. For example, a person who is labelled left-brained is often said to be more logical, analytical, and objective, while a person whom is labelled right-braine is said to be more intuitive, thoughtful, and subjective. So what exactly did this theory suggest?

The Right Brain Nonsense: According to the left-brain, right-brain dominance failed theory, the right side of the brain is best at expressive and creative tasks. Some of the abilities that are popularly associated with the right side of the brain include:

  • Recognising faces
  • Expressing emotions
  • Music
  • Reading emotions
  • Colour
  • Images
  • Intuition
  • Creativity

The Left Brain Nonsense: The left-side of the brain is (not) considered to be adept at tasks that involve logic, language and analytical thinking. The left-brain is often described as being better at:

  • Language
  • Logic
  • Critical thinking
  • Numbers
  • Reasoning

Too bad it’s not true. Short of having undergone a hemispherectomy (removal of a cerebral hemisphere), no one is a left-brain only or right-brain only person.In pop psychology, the theory is based on what is known as the lateralisation of brain function. So does one side of the brain really control specific functions? Are people either left-brained or right-brained? Like many popular psychology myths, this one grew out of observations about the human brain that were then dramatically distorted and exaggerated.

To try and put this to bed forever, a new two-year study published in the journal Plos One, University of Utah neuroscientists scanned the brains of more than 1,000 people, ages 7 to 29, while they were lying quietly or reading, measuring their functional lateralisation – the specific mental processes taking place on each side of the brain. They broke the brain into 7,000 regions, and while they did uncover patterns for why a brain connection might be strongly left or right-lateralised, they found no evidence that the study participants had a stronger left or right-sided brain network. Jeff Anderson, the study’s lead author and a professor of neuroradiology at the University of Utah says:

It’s absolutely true that some brain functions occur in one or the other side of the brain, language tends to be on the left, attention more on the right.

But the brain isn’t as clear-cut as the myth makes it out to be. For example, the right hemisphere is involved in processing some aspects of language, such as intonation and emphasis. Where has this come form because I am pretty sure you will have heard it? Experts suggest the myth dates back to the 1800s, when scientists discovered that an injury to one side of the brain caused a loss of specific abilities. The concept gained ground in the 1960s based on Nobel-prize-winning split-brain work by neuropsychologists Robert Sperry, and Michael Gazzaniga. The researchers conducted studies with patients who had undergone surgery to cut the corpus callosum – the band of neural fibres that connect the hemispheres – as a last-resort treatment for epilepsy.

They discovered that when the two sides of the brain weren’t able to communicate with each other, they responded differently to stimuli, indicating that the hemispheres have different functions.Both of these bodies of research tout findings related to function; it was popular psychology enthusiasts who undoubtedly took this work a step further and pegged personality types to brain hemispheres.

Brain function lateralisation is evident in the phenomena of right- or left-handedness and of right or left ear preference, but a person’s preferred hand is not a clear indication of the location of brain function. Although 95% of right-handed people have left-hemisphere dominance for language, 18.8% of left-handed people have right-hemisphere dominance for language function. Additionally, 19.8% of the left-handed have bilateral language functions. Even within various language functions (e.g., semantics, syntax, prosody), degree (and even hemisphere) of dominance may differ.

Additionally, although some functions are lateralised, these are only a tendency. The trend across many individuals may also vary significantly as to how any specific function is implemented. The areas of exploration of this causal or effectual difference of a particular brain function include its gross anatomy, dendritic structure, and neurotransmitter distribution. The structural and chemical variance of a particular brain function, between the two hemispheres of one brain or between the same hemisphere of two different brains, is still being studied.

Researchers have demonstrated that right-brain/left-brain theory is a myth, yet its popularity persists. Unfortunately many people are likely unaware that the theory is outdated. Today, students might continue to learn about the theory as a point of historical interest – to understand how our ideas about how the brain works have evolved and changed over time as researchers have learned more about how the brain operates. The important thing to remember if you take one of the many left brain/right brain quizzes that you will likely encounter online is that they are entirely for fun and you shouldn’t place much stock in your results. According to Anderson:

The neuroscience community has never accepted the idea of ‘left-dominant’ or ‘right-dominant’ personality types. Lesion studies don’t support it, and the truth is that it would be highly inefficient for one half of the brain to consistently be more active than the other.

We love simple solutions (see also 21 days to break a habit) Human society is built around categories, classifications and generalizations, and there’s something seductively simple about labeling yourself and others as either a logical left-brainer or a free-spirited right brainer. The problems start, however, when the left-brained/right-brained myth becomes a self-fulfilling prophecy. What research has yet to refute is the fact that the brain is remarkably malleable, even into late adulthood.

It has an amazing ability to reorganise itself by forming new connections between brain cells, allowing us to continually learn new things and modify our behavior. Let’s not underestimate our potential by allowing a simplistic myth to obscure the complexity of how our brains really work.

Be Amazing Every Day.

Nielsen, J. A., Zielinski, B. A., Ferguson, M. A., Lainhart, J. E., & Anderson, J. S. (2013). An evaluation of the left-brain vs. right brain hypothesis with resting state functional connectivity magnetic resonance imaging.

Rogers, M. (2013).Researchers debunk myth of “right brain” and “left-brain” personality traits. University of Utah, Office of Public Affairs. Retrieved from http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0071275