Right-Brain / Left-Brain: Fact, Theory or Myth?

What is the right-brain/left-brain theory?

The basic premise of right-brain/left-brain (pop-) psychology is that each side of the brain is said to control different types of thinking. For each of us, one side of the brain is supposed to be dominant. So if the left side of you brain is dominant, by the theory, you would be a logical, methodical, objective, analytical scientific kind of person. However if the right side of your brain is dominant you would a more creative, artistic, intuitive, expressive, subjective kind of person. Knowing what side of brain is dominant is presumably helpful in explaining why we might meet problems with certain tasks and indeed what we might do to balance out the ‘one-sidedness’. The theory of brain-dominance is something that frequently crops up in discussions in my confidence-building workshops. Sometimes these kind of theories provide comfort because on first glance seem to offer a way to explain and structure our experience. So let’s look at the evidence.

Considering the evidence for the right-brain-left-brain

Supporters of the theory might argue that this is supported by scientific evidence, and yes of course, as with many pop-psychology theories there is a grain of truth. However, when reviewing evidence, it depends on how old the research is, whether up-to-date research has challenged initial findings, whether the original research is generalizable to the general population and who is interpreting the evidence. It’s common to see newspaper journalists report evidence-based research in a headline grabbing way. There is no space for the fine detail.

The right-brain-left-brain theory is based on the work of Roger W. Sperry in the 1960s. In psychology it’s known as  the the lateralization of brain functionOur brains are comprised of two hemispheres connected by a structure called the corpus callosum which facilitates inter-hemispheric communication. So it the normal, undamaged brain, there is ‘dialogue’ between the two sides. Sperry studied epilepsy patients and discovered that seizures were reduced or ceased when the corpus callosum was cut. Through a series of experiments, Sperry (and others) were able to determine which parts of the brain were involved in various functions, including language, maths, drawing and so on.

This is the basis for the pop-psychology theory. I heard one self-styled new age guru claim that ‘old psychology is dead’ and we need to usher in the new psychology. Apparently he didn’t see the irony of citing research from the 1960s. It’s also important to correct the misnomer of two brains. A neuroscientist would not use this terminology, unless to criticise the theory. We have one brain with two hemispheres. So if you see or hear someone waxing lyrical about ‘right brain’ this and ‘left brain’ that, chances are they probably don’t have any qualifications in neuroscience or psychology.

Apart from the passage of time, there is another key point to be made here. The research was based on people with epilepsy and who had their corpus callosum cut, therefore ending communication between the two brain hemispheres. This hardly sounds like a sample representative of the general population. It’s a pretty select group.

So what does up-to-date research have to say?

Contemporary evidence for the right-brain/left-brain theory

Inevitably there has been a wealth of research published on neuroscience since the 1960s. Unfortunately, much of this will not find its way into newspaper headlines of pop-psychology books.

In an attempt to better understand brain lateralization with a view to treating medical conditions (rather than myth-busting), scientists at the University of Utah in analysed more than 1000 brains to see if people had dominant sides. They found no evidence. On average, both sides of the brain were essentially equal. The study’s lead author, Jeff Anderson, explains that while it is true some brain functions occur in one side or the other (language: left; attention:right), ‘[P]eople don’t tend to have a stronger left- or right-sided brain network. It seems to be determined more connection by connection’.

The overall conclusion from this an other up-to-date research is that the two sides of the brain communicate through the corpus callosum to work together to perform a variety of tasks.

Why does the popularity of the right-brain/left-brain theory persist?

Searching online I found some interesting and amusing exchanges between the supporters of the right-brain/left-brain theory and its critics. In response to a discussion of up-to-date, peer-reviewed research from leading neuroscientists, the striking thing is that supporters of the theory offer personal anecdotes to ‘disprove’ the research. The subtext is, ‘that’s all very interesting but it doesn’t apply to me’. Here’s one example:

When I am studying math or chemistry intensely I find the left side of my brain hurts, Whereas when I am writing a report or something along the lines of literature, the right side of my brain hurts. It’s a nice pain though. I was not aware of this right brain left brain theory until I started noticing this happening and researched it for myself. Amazing really.

This inspired a particular pointed (cruel) response:

You should see a doctor. It’s not amazing, it sounds more like you’ve sustained a stroke.

In a follow-up comment, the same ‘wag’ makes another important point:

Wow, from some of the posts . . . you would think the world is full of neuroscientists that are all incapable of doing a simple internet search for information.

This last comment is quite telling, It highlights a phenomenon in social psychology, in particular the subject of stereotypes. A stereotype is a generalized, over-simplified packet of knowledge about something. We can see in the realms of prejudice where are a stereotype can act as a filter for new information. Anything that contradicts the stereotype is rejected. So, yes, all this neuroscience may be very interesting but if it contracts a strong belief in the right-brain/left-brain theory, then the scientists must have made errors. The results have to be rejected. The fact that the research went through a rigorous review process does not matter. At the same time the supporter of the right-brain/left-brain theory will overlook the lack of a generalized sample for Sperry’s research. By time the belief is firmly held, the whole question of research may not even matter anymore. ‘My head hurts on the left hand side when studying maths, that’s good enough for me’.

There is also the question of exposure to information. Magazines and reality TV pundits like to offer a ‘bit of science’. For the purpose the ‘science’ needs to be easy to comprehend. So idea of right-brain/left brain keeps popping up. The more a thing is repeated leads us to question whether ‘there must be something in it’.

How to interpret right-brain/left-brain tests

Common magazine pencil-and-paper test of right-brain/left-brain begin with the assumption that there is specialization. This is written into each of the questions in these tests. The results are foregone conclusions. Reducing human experience to a binary is always problematic. Nature never creates a dichotomy. That’s something we do to help explain thing. Black and white categories are easier to process. Rarely do these over simplifications map onto real-world experience. So at the very best, treat these tests as a bit of fun

A better strategy is to spend time taking stock of your own abilities and strengths. It’s easy to look for evidence to contradict the test’s verdict. Instead, balance things out and look for any evidence that contradicts the result. Think of your life experience. The longer you spend on this phase, the more evidence you will find to contradict the results and the more you will realize is what modern neuroscience tells us: you’re using both sides of your brain pretty much equally. What you will have is a better picture of yourself as resourceful, psychologically rounded human being.

Book Cover: Unlock Your Confidence by Dr Gary WoodThat’s got to be a boost to your confidence and self-esteem. Much better than believing you’re living only half of the human experience.



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