Exploring the left brain/right brain myth

This post is the fourth in a periodic series exploring common misconceptions around how students learn. We first touched on these misconceptions in our September 2015 report, The Science of Learning, and will be exploring them in more depth over the next few months.

Today’s post from Dr. Melina Uncapher explores the right-brain/left-brain myth: that people are preferentially “right-brained” or “left-brained” in the use of their brains. This is one of the more prevalent neuromyths, believed by about 80 percent of educators around the world. Uncapher is a neuroscientist, an assistant professor at University of California-San Francisco, a research scientist at Stanford University, and executive director of the nonprofit scienceforgood.org.

Did you know that sprinter Usain Bolt is right-footed? And that’s the reason he’s the fastest runner ever recorded? You haven’t heard this? Good, because it’s not true. Turns out he relied on both his feet to break the world records in the 100- and 200-meter races and to become the first man to set three world records in a single Olympics.

If it sounds silly to you to attribute Bolt’s domination in the running world to just one of his feet, it sounds just as silly to neuroscientists to attribute an individual’s personality to one or the other of his brain hemispheres. As I wrote in a previous neuromyth-busting post, we use 100 percent of our brain 100 percent of the time. Just as we can’t walk or run effectively by favoring one leg, we can’t function effectively by favoring one brain hemisphere instead of using them both an integrated way.

The idea that people rely predominantly on either a rational, logical, “left-brained” cognitive style or a more creative, abstract, “right-brained” style is one of the more prevalent neuromyths, believed by approximately 80 percent of educators around the world (Howard-Jones, 2014, Nature Reviews Neuroscience). A recent empirical study examined this neuromyth using current sophisticated neuroimaging methods. Jared Nielsen and colleagues directly tested the hypothesis that individuals have stronger left- or right-hemispheres, and–as would be predicted by every practicing neuroscientist–failed to find evidence for hemispheric dominance.

In their study, Nielsen and company analyzed the brains of more than 1,000 people, aged 7 through 29, for clues of left- or right-brained dominance. Their highly precise measurement of 7,266 regions throughout the brain revealed some lateralization of function, but only locally, not globally. In other words, there were some regions that seemed to be more active in one hemisphere than another, but in no one was there an overall profile of left- or right-brain activation that dominated the other hemisphere.

Local activation of certain regions is actually the grain of neuro-truth that spawned the left-brain/right-brain myth. Yes, there are some brain regions in the left hemisphere that are more closely associated with, say, language production than the analogous bits in the right hemisphere. This was pioneered in the 1860s by the French neurologist Pierre Broca when he examined the brains of adults who had presented with language difficulties before their deaths. Broca noticed that all these patients had some damage to a specific region in their left frontal lobes while their right frontal lobes remained intact.

But it’s important to note that not every aspect of language is processed in this part of the left frontal lobe (“Broca’s area”). While patients with damage to this area had difficulty in producing language, they could still comprehend the meaning of words, a cognitive function that relies on both hemispheres.

There’s a similar example for math, another aspect of so-called left-brained thinking. Some aspects of math, like counting and reciting multiplication tables, seem to recruit the left hemisphere more than the right, while other aspects, like estimating the quantity of a set of objects, seem to recruit the right hemisphere more than the left.

This illustrates one of the facts we know for sure about the brain: every complex cognitive function is a result of the engagement of a network of multiple regions, distributed throughout both hemispheres, acting in coordinated ways. Many neuroscientists think about brain activity as a sort of neural concert, where individual players may have a stronger role during certain movements, but no one side of the orchestra always dominates.

The widespread belief in left-brained/right-brained thinking styles has led to a proliferation of teaching programs and technology that are designed to help teachers assess the “styles” of their students, and then teach to those styles. As I pointed out in my post on the myth of the 10 percent, this amounts to a massive misallocation of resources in support of programs based on faulty assumptions and no scientific evidence. And as Dylan Wiliam said in his post on the learning-styles myth, learning is actually more effective when it’s hard – so trying to match instruction to a particular style is not only based on faulty assumptions, it may actually reduce learning.

Whenever I discuss this and other neuro-myths with educators, I stress that these myths have likely become popular because they capture what every teacher knows: that students show individual differences in the ways they learn. But are these differences appropriately described by left/right-brained thinking, or by auditory/visual/kinesthetic styles? The science says probably not. Instead, research tells us that thinking about how students make meaning out of the information you’d like them to learn is a more appropriate way to think about individual differences in learning.

References
Nielsen, J. A., Zielinski, B. A., Ferguson, M. A., Lainhart, J. E. & Anderson, J. S. An Evaluation of the Left-Brain vs. Right-Brain Hypothesis with Resting State Functional Connectivity Magnetic Resonance Imaging. PLoS ONE 8, e71275–11 (2013).