No, people are not either left-brained or right-brained

A theory claiming humans have a dominant side of the brain has been circulating for decades. Left-brained people are thought to be more analytical, logical and better at math, while right-brained people are thought to be more creative and artistic. In recent years, left-brained vs. right-brained tests have been popping up online claiming they can help people determine which side is most dominant. 

VERIFY viewer Judy emailed us asking if online tests like this one, which claims people who see the horse walking backward are right-brained and people who see it walking forward are left-brained, are valid.

THE QUESTION

Are people either left-brained or right-brained?

THE SOURCES

• Johns Hopkins University Science of Learning Institute
• Smithsonian Science Education Center
• Organisation for Economic Co-operation and Development
• Roger Beaty, Ph.D., professor of psychology at the Pennsylvania State University
• Indre Viskontas, Ph.D., professor of psychology at the University of San Francisco

THE ANSWER

No, people are not either left-brained or right-brained.

WHAT WE FOUND

There is no scientific evidence that shows individuals use one half of their brain more than the other or that being left-brained or right-brained determines a person’s personality, learning style, or strengths, according to the Johns Hopkins University Science of Learning Institute. The Smithsonian Science Education Center agrees.

“While it’s true that certain mental processes tend to occur in either the right or left hemisphere of the brain, research into the topic has found no evidence that people have stronger networks on one side of the brain or the other,” the Smithsonian Science Education Center said. 

Johns Hopkins University and the Smithsonian Science Education Center said the right-brained vs. left-brained idea is actually considered a “neuromyth” that originated from research conducted by neuropsychologist Roger Sperry. Neuromyths are common misconceptions about brain research.

In the 1970s and early 1980s, Sperry’s research team tracked individuals who had undergone operations to sever the corpus callosum — the main structure connecting the two halves of the brain — as a treatment for epilepsy. The researchers found that the two hemispheres of the brain are specialized for different functions; however, the Smithsonian Science Education Center explained that “misinterpretation of these findings led to associations between specific brain functions and personality types, and gave rise to the popular neuromyth of ‘left-brained’ and ‘right-brained’ people.”

When it comes to the legitimacy of right-brained vs. left-brained online tests, like the one with the horse, University of San Francisco psychology professor Dr. Indre Viskontas told VERIFY the direction that a person sees the horse moving is not a result of the right or left half of their brain. Instead, Viskontas says it has more to do with the visual cortex in a part of the brain called the occipital lobe, which stretches into both cerebral hemispheres.

“It just turns out that maybe there's one part of your visual cortex that made the decision for you to see the horse moving forward or moving backwards,” said Viskontas. “I don't think there's any evidence that extrapolates to any other aspect of the way you think or the way you behave or the things that you value.” 

Pennsylvania State University psychology professor Dr. Roger Beaty has a suggestion if you see one of these tests on social media.  

“Click the X button,” Beaty told VERIFY. “I just think a lot of times these tests are not going to be telling you that much, so I would be very skeptical.”

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