Pop psychology tells us we’re all either left brain dominant or right brain dominant. Really?
Perhaps the most pervasive popular belief that people associate with neuroscience is the idea that we all tend to be either left-brained or right-brained, based on traits like creativity or analytical ability. It’s well known that certain brain functions are localized in various parts of the brain, so it would seem to make sense that some of our individual strengths and weaknesses can be quantified based on brain hemisphere dominance. Quite a few companies even sell products intended to analyze your brain sidedness, promising a variety of personal development benefits. But is this belief — so widely held — good science, terrible science, or some mixture of the two?
Once in college, I took an Honors Colloquium class that was supposed to expose us to a wide variety of ideas and experiences. It was taught by three professors who were presented to us as being the smartest, most well-rounded guys on campus. One of our exercises was to take a test that was supposed to reveal our brain sidedness. The questions were similar to what you might get in a personality test, asking about whether you prefer math or art, privacy or crowds, planning ahead or working on the fly. Some days later we each received our results: a two-axis radar chart, showing a skewed diamond with its left and right corners representing the levels to which we depended on our left brain or right brain, and the top and bottom corners showing the degree to which we depended on our anterior or posterior parts of our brain. It was explained to us that these results could be used to help us self-assess our aptitudes at various skills. Would we be good at sales, leadership, or education? What areas of ourselves could we work on to improve ourselves? What kind of value could we add to an organization with our particular brain map?
Most students had crazily shaped radar charts that showed a strong dependence on one brain area or the other. The horizontal axis had a range of zero to 120 on both sides. We all thought that anyone who had a chart exceeding 100 on either side must be extraordinarily talented according to the popularly believed norms: if you were over 100 on the left you were a math or analytical genius; if you were over 100 on the right you were the next Mozart or Rembrandt. I was very proud that mine was the only one that was symmetrical, 94 on both sides; but after later reflection, I recalled that many of the questions had to do with the classes we were taking. At the time my idea was to double major in computer science and film directing, so I’d given a lot of answers that indicated I was both analytical and creative. I hadn’t had much experience in scientific skepticism at that point, but if I had, I might well have realized that the test was grossly unscientific and relied completely on self-reported answers that might have changed from one day to the next, depending on mood, terminology, context, and many other variables.
Looking at the same test now, I realize that was only the tip of the iceberg. Brain sidedness as a predictor of either preferences or aptitudes is unscientific for a very good reason: it’s virtually entirely wrong.
Let’s go back to that popular public assumption that the left brain is analytic and the right brain is creative, upon which so many of the questions in my Honors Colloquium test focused, and upon which the whole class based the entirety of their analyses of their test results. The natural inference is that people whose left brains are dominant must be good at analytical skills, and people whose right brains are dominant must be good at creative skills. The reverse would also be true: If you are a mathematician or engineer, we might deduce that you are left-brained; and if you’re an artist or poet, that you’re right-brained.
Where did this idea come from?