Left is right. Science is art. Right-brain/left-brain theory loses ground.

By Christine Jasoni 31/08/2013

I am not an artistic person. My drawing, if you can even call it that, consists of stick figures. I cannot paint, sing, or dance. In school, I studied Science. I found it fun to think and learn about, and I was pretty good at it. My mother is a dancer, she teaches ballet, and can paint or draw anything she sees. In school, she studied the Fine Arts. This scenario is familiar to many of us, and in popular culture the terms right-brained, for the creative and thoughtful, and left-brained, for the logical and scientific, have been used to categorise these two types of people. For some reason this theory is appealing to us, maybe it satisfies some need we have to neatly categorise the world around us, but we actually know very little about what the brain does to make us good painters or good scientists. So there is, in fact, no scientific evidence to support or refute this idea. Until now.

We do know a little bit about this puzzle already. Some functions or mental processes that our brains perform happen more on one side than the other (1, 2). Our skills in language – putting together words that make sense, understanding words that others may speak or write – occur because of the activity of groups of nerve cells located mainly on the left side of the brain. By contrast, attention (as in ‘are you paying attention?’) is due mainly to the activity of nerve cells on the right side of our brains. This happens pretty much the same in all of us; in you and me, and in Einstein and Picasso alike. So if we think about language and attention, at least, there is no right-brain versus left-brain difference – Picasso’s language was driven by the left side of his brain, and Einstein’s attention by his right. Thinking about it this way should probably give us a hint that right-brain left-brain theory has some holes in it, or at least it is perhaps a bit too simplistic to explain complex behavioural differences such as creative versus logical thought. To address this quandary and delve more deeply into the neural mechanisms of what makes us who we are, Neuroscientists examined over 7000 areas in the brains of over 1000 people (3). To do this, they used fMRI (functional Magnetic Resonance Imaging), a technique that can reveal the connections that brain cells make to one another in a living human brain either at rest or while performing a particular action or task. The researchers then asked: can we find evidence that some peoples’ mental processes are driven more by the nerve cells on the right side of their brain and others more by the left side?

When Neuroscientists did this investigation, they found no evidence for right side or left side dominance. What they did find was that many places in the brain are similar to the language and attention areas – mainly on one side where the nerve cells make connections with other cells near them to control a particular mental process. It’s a bit like neighborhoods that each have their own identity, and maybe even social activities, that result from interactions among the people that live near one another. To me this makes good sense: many very creative people are also logical and vice versa. Einstein was an exquisite violinist.

Because the study participants ranged in age from 7-29 this allowed the researchers to understand better when the connections on each side are made and whether there may be differences in right- versus left-side dominance that change with age. If you’ve ever worked with children you may have found that you can often tell whether a child is artistic or likes to take things a part. So, you might wonder whether left- versus right-brain dominance may be present early, when these behaviours are beginning to show in children. If this asymmetry were present, then right- versus left-brain dominance may somehow initiate the different behaviours. However, this does not seem to be the case either. Children as young as 7 years old show essentially the same local right or left side brain networks as people well into their 20s and no right- versus left-brain dominance.

Creative versus logical is not the only way that we try to categorise one another. We frequently hear that “Men are from Mars, Women are from Venus” (4), so it does seem reasonable to imagine, or hypothesise, that there could be differences in the connections within the brains of men and women. Bu if we apply the same logic to this question as we did to the creative vs scientific question, we probably would not expect male female differences to be so general as to be right- versus left-sided either. Not surprisingly, this was what the researchers found – no evidence for large-scale differences in left- or right-side brain activity between men and women. A more directed approach with a more specific hypothesis about how and where in the brain men and women may differ is probably more likely to reveal a difference. Indeed, we do know already that men’s and women’s brains differ in several key ways, mainly in regions that regulate sexual behaviour and aggression (5), but this current study did not have the correct design to look specifically at these regions.

One dimension that the study lacked is that it did not test the participants for their personality traits, so the researchers were not able to associate specific patterns of brain activity with broad classifications of creative versus quantitative ability. Instead the researchers reasoned that because there were over 1000 subjects in the study and a mix of men and women, that there was probably also a good mix of creative versus logical thinkers. This seems a reasonable assumption, but some data to back this up would have added a bit of strength to their argument.

Finally, there was one additional inspiration for the study, which had to do with understanding mental illness. People with autism spectrum disorders (ASD) and schizophrenia have symptoms that suggest that they may have right- versus left-side differences from the neurologically normal population (6, 7). This study did not examine individuals with schizophrenia or ASD, but it may be interesting to perform such a study in order to inform us better how brain function and mental processes are disrupted in these disorders. Also, it may be useful to point out that the average age of onset for schizophrenia is 18-25, so some fraction of the younger participants in this study could eventually develop schizophrenia.

The results of this study is study are both fascinating and complicating. Now that creative vs logical thought cannot be explained by a simple right- versus left-brain dominance, scientists and non-scientists alike will need to think of far more complicated mechanisms to explain how the brain achieves this amazing feat even though it is so easy for us to characterise people in such simple terms. This fascination that our brains have with breaking our world up into overly-simple categories probably has evolutionary advantage. Simply put, the first things we need to assess about someone or something new that we meet are: Will it hurt me? Can I eat it? Can I have sex with it? For most of us modern society takes care of those questions, yet our brains still retain vestiges of our past that manifest themselves in quirky habits and beliefs that are engrained so deeply in us that they can be difficult to give up. Understanding how to lose these habits in the face of new knowledge is a challenge for everyone, scientists and non-scientists alike. Figuring out how they come about in the first instance is one step along this exciting path.