We are data-gatherers and pattern-noticers, we humans. Even as babies we are watching and learning, and trying to make generalizations about the world based on what we've experienced. And while many of those generalizations turn out to be correct -- we wouldn't have lasted long as a species if they weren't -- we sometimes draw incorrect conclusions.
And when we do, we tend to hang onto them like grim death. Once people have settled on a model, for whatever reason -- be it that "it seems like common sense" or that it has gained currency as some kind of "urban legend" -- it becomes extremely hard to undo, even when the science is unequivocal that our beliefs are wrong.
I ran across a particularly good example of that this week. I teach an introductory neurology class, and when we start talking about brain physiology and its role in personality, inevitably someone brings up the phenomenon of brain lateralization -- the fact that, as we develop, one side of the brain exerts more influence over us physically than the other does. This is why most of us have a dominant hand, foot, eye, and so forth.
Most common biological traits can be explained based upon some kind of evolutionary advantage they provide, but the jury's still out on this one. Halpern et al. concluded, in 2005 in The Journal of Neuroscience, in their paper "Lateralization of the Vertebrate Brain: Taking the Side of Model Systems," that the evolutionary advantage of allowing one side of the brain to dominate the motor activity of the body is that it allows the other, non-dominant side to do other things -- something they call "parallel processing." But even they admitted that this was speculation.
One claim that gained a lot of currency, beginning in the 1960s, was that people who were right brain dominant were artistic, creative, and saw things holistically, and that people who were left brain dominant were logical, verbal, mathematical, and sequential.
Now, there may be some truth to the claim that the sensory-processing centers on the two sides of the brain do see the word differently -- studies done on people who have had strokes in the cerebrum, and those with "split brains" (who have had the corpus callosum cut, preventing cross-talk between the two cerebral hemispheres), do seem to support that there is a dramatic difference in how the two sides of the brain interpret what you see. (For an amazing personal account that supports this view, check out Jill Bolte Taylor's talk "A Stroke of Insight.")
The idea that people with intact brains are either artistic right-brainers or logical left-brainers has led to a whole slew of "therapies" meant to allow people to "balance their brains." It has been especially targeted at the left-brainers, who are sometimes seen as cold and calculating.
Many of these treatments require such things as forcing people to write or perform actions with their non-dominant hands, or patching their dominant eye -- the claim being that this will force the poor, subjugated non-dominant side of the brain to feel free to express itself, resulting in an enlightened, fully-realized personality.
All of this, apparently, is pseudoscience.
I've suspected this for a while, frankly. In my neurology class, we do a physical brain dominance test, and someone always asks about brain lateralization's role in personality. When this happens, I have had to do something I am always reluctant to do, which is to say, "Well, I haven't seen any research, but this seems to me to be bogus."
I don't have to say that any more.
Two weeks ago, the peer-reviewed journal PLOS-One published a paper by Jared A. Nielsen, Brandon A. Zielinski, Michael A. Ferguson, Janet E. Lainhart, and Jeffrey S. Anderson entitled, "An Evaluation of the Left-Brain vs. Right-Brain Hypothesis with Resting State Functional Connectivity Magnetic Resonance Imaging." In this paper they describe a series of experiments that looked at the actual structure of the brain, and its connectivity -- and they found that there's no such thing as a "right-brain" personality and "left-brain" personality based upon anything real that is present in the brain wiring. Here's what they said in their discussion section:
In popular reports, “left-brained” and “right-brained” have become terms associated with both personality traits and cognitive strategies, with a “left-brained” individual or cognitive style typically associated with a logical, methodical approach and “right-brained” with a more creative, fluid, and intuitive approach. Based on the brain regions we identified as hubs in the broader left-dominant and right-dominant connectivity networks, a more consistent schema might include left-dominant connections associated with language and perception of internal stimuli, and right-dominant connections associated with attention to external stimuli.So the truth turns out to be more complicated, but more interesting, than the commonly-accepted model. We tend to do that a lot, don't we? After all, what is much of pseudoscience but an attempt to impress order upon nature, to make it fit in neat little packages, to make it work the way we'd like it to? Astrology, for example, would have you believe that there are twelve personality types, and that anything about your behavior that needs explanation can be filed under the heading of, "Oh, but of course I'm like that. I'm a Scorpio."
Yet our analyses suggest that an individual brain is not “left-brained” or “right-brained” as a global property, but that asymmetric lateralization is a property of individual nodes or local subnetworks, and that different aspects of the left-dominant network and right-dominant network may show relatively greater or lesser lateralization within an individual.
But the world is complex and messy, and doesn't care about our desire for order. However, it is also beautiful and mysterious and fascinating, and ultimately, understandable. And science remains our best lens for doing so, for blowing away the dust and cobwebs of our preconceived notions, and helping us to comprehend the world as it is.
And it works regardless of which side of the brain you're thinking with.