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Why you're not 'left-brained' or 'right-brained'

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It's a well-established scientific fact that each hemisphere of the brain serves different functions in the body. That fact led to the popular belief that some people are more right-brained or left-brained in their personality. However, neuroscientific research proves that this theory is entirely false.

Dr. Jeff Anderson, assistant professor of radiology at the University of Utah’s School of Medicine, discussed his work with “Take Care,” which proves that though each side of the brain serves separate purposes, there is no connection between personality and which side of the brain is more active.

“The neuroscientific community has never believed that personality is based on dominance of one hemisphere or the other,” Anderson said.

The misconception stems largely from research done in the 1960s to cure epilepsy, according to Anderson. Scientists cut the corpus callosum -- the part of the brain connecting the two hemispheres -- in several patients, resulting in a significant decrease in seizures. A side effect was that scientists could then present stimuli to one side of the brain separately from the other, which revealed small differences in hemispheric functionality.

“Popular psychologists sort of just took it and ran with it, and we’ve kind of been in that position ever since,” Anderson said. “It’s almost impossible to quash at this point, in spite of the fact that every single day, in every major medical center in the country, we have experiments that are disproving it.”

"The neuroscientific community has never believed that personality is based on dominance of one hemisphere or the other."

The real science that resulted from the epilepsy experiments revealed that the left side of the brain primarily processes language, while the right side largely controls attention. Anderson said each hemisphere responds to stimuli on the opposite side of the body as well.

Intrigued by this established science, Anderson focused his research on the strength of individual connections in different brain regions to hopefully develop a tool to help doctors diagnose conditions like autism and schizophrenia. The results showed that those conditions, as well as a person’s personality, have nothing to do with which side of the brain is more active.

“The complex personality traits -- things like creativity or pattern recognition, logic -- these are complex processes that involve the interaction of many brain regions on both sides of the brain more or less equally,” Anderson said.

Anderson said that though hemispheric activity does not largely impact neurological conditions, there is evidence that those with conditions such as autism, epilepsy and schizophrenia process language in both hemispheres as opposed to the typical left hemisphere. It is still mostly processed in the left side, but the amount of right hemispheric contribution to language is higher in individuals with a whole range of different types of neurological or psychiatric conditions, according to Anderson.

Left-handedness can also contribute to a different distribution of language processes, Anderson said. About 5 to 10 percent of individuals are left-handed, which can lead to having language processed on both sides of the brain or mostly on the right side instead of the left.

The most important thing to remember, Anderson said, is that though the idea of right- and left-brained personality types is a fun and tempting idea, it's not based in any scientific fact.

“It’s complete nonsense,” Anderson said. “We love to have little games or tests that tell us something about ourselves, but it really has absolutely nothing to do with the left and the right side of the brain.”