What Does the Left-Brain, Right-brain Theory Tell Us?

Tracy Smith, LPC, NCC, ACS
April 24, 2019

The human brain is comprised of two hemispheres that are connected by a grouping of nerve fibers called the corpus callosum.  The corpus callosum functions to help both sides of the brain communicate with each other.  The left hemisphere generally directs features of language and judgment, while the right hemisphere handles spatial orientation and visual understanding.

brain left right

The two hemispheres are the subject of the left-brain, right-brain theory, which contends that one side of the human brain is dominant over the other, thus having significant impact on an individual’s personality, thoughts, and actions. The theory also alleges that the left and right hemispheres operate differently from each other.

Roger Sperry conducted research in the 1960’s regarding the outcomes of epilepsy.  During his research, Sperry found that seizures could be decreased or eliminated completely by cutting the corpus callosum.  In addition to studying seizure activity, Sperry noticed that there were some differences in cognitive functioning in both hemispheres.  Sperry concluded that language was largely managed and maintained by the left side of the brain after finding that patients were only able to name objects processed by the left side of the brain as opposed to the right side.

An individual with a dominant left hemisphere is referred to as “left-brained” and is representative of a person who is strong in mathematics and logic.  A left-brained person has methodical, logical, and systematic attributes.  A left-brained person is attentive to facts and details and is good with numbers.  They have a powerful command of language, can think critically, and display strong reasoning skills.

A person with a dominant right hemisphere is termed as “right brained” and denotes a person who is largely imaginative, artistic, and creative.  The left-brain, right-brain theory states that the right side of the brain is adept at emotional and innovative tasks.  A right-brained person is thoughtful and an independent and visual thinker.  They respond strongly to music, color, portraying and reading emotional expressions, identifying faces, and following their intuition.

Research conducted on the left-brain, right-brain theory fully disproves its hypothesis.  Study outcomes have shown that the two hemispheres of the brain are not as independent as the theory contends.  While the abilities of each hemisphere are indeed different, the way that the hemispheres process information is where the true differences are.  Research has shown that both hemispheres work together and communicate through the corpus callosum to accomplish a vast array of tasks.

While the left hemisphere specializes in sounds and language rules, the right hemisphere is perceptive to emotional aspects of language, such as inflection and tone.  Other studies have shown that while brain activity can sometimes be more active in certain parts of a hemisphere, activity in both hemispheres remain mostly equal on average.  Dominance is not asserted if operations occur more fully in one hemisphere over the other, as the connections are what hold a higher importance.

Despite the fact that the left-brain, right-brain theory has been disproven, it is still prevalent in our society.  Many people do not know that this theory is merely a myth, which further perpetuates its popularity.  The left-brain, right-brain theory is often referenced in television, magazines, books, and in movies.  It is not uncommon to find a quiz in a magazine or an online test to help people determine which part of their brain is more dominant.  At the end of the day, we know that neither hemisphere is more dominant and that both sides of the brain always work together.  Because of this fact, results from these quizzes and tests should be taken lightly and only be utilized for fun.

Tracy Smith, LPC, NCC, ACS

Tracy is a Licensed Professional Counselor and is a clinical supervisor for the Community YMCA, Counseling & Social Services branch. Tracy has over 12 years of experience working in many settings including partial care hospitalization and intensive outpatient programs, community agencies, group practice, and school-based programs. Tracy works with clients of all ages, but especially enjoys working with the adolescents. Tracy  facilitates groups using art therapy, sand play and psychodrama.

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