Neuroscience research shows that left-brain right-brain dominance is a myth. Yet myth-based left-brain right-brain tests exploit public belief for profit.
The left-brain right-brain theory of personality is one of the more persistent myths about the brain.
This theory purports that there are two types of people — left-brained people who are analytical and right-brained people who are creative.
This idea made sense after certain discoveries were made about how the brain works over 100 years ago.
But with rapid advances in neuroscience, the concept of left-brain versus right-brain dominance is obsolete.
How the Left-Brain Right-Brain Myth Began
Our brains are comprised of two distinct halves known as cerebral hemispheres.
However, these hemispheres are not mirror images of each other — our brains are asymmetrical in both form and function.
The two sides of the brain communicate with each other via a band of nerve fibers called the corpus callosum.
In the 1880s, it was noted that damage to half of the brain resulted in predictable changes in behavior and brain function. (1)
It was observed that language abilities resided in structures in the left side of the brain, while areas that governed spatial abilities were found in the right side.
Fast-forward to the 1960s when neurosurgeons performed split-brain surgery on patients with severe epilepsy. (2)
Split-brain surgery involves severing the connection between the two hemispheres.
This drastic procedure worked to stop seizures, but the cost was often loss of specific brain functions. (3)
By carrying out experiments on these split-brained patients, neuropsychologists were able to correlate areas of the brain with their functions.
They discovered that each brain hemisphere was dominant for different kinds of behaviors. (4)
The right side of the brain was thought to be mainly responsible for spatial abilities, facial recognition, visual imagery, and music, while the left side governed calculations, math, and logical abilities.
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The head of this research, Richard Sperry, received a Nobel Prize for this work, bringing the left-brain, right-brain concept to the attention of the public.
According to the left-brain right-brain dominance theory, everyone has a dominant brain hemisphere and this is a major determinant of basic personality type. (5)
Typical right-brain characteristics include creativity, expressiveness, intuitiveness, and emotional and artistic tendencies.
Representative left-brain attributes include being logical, analytical, and good at language, math, and science.
The illustration below sums up the theoretical concept of these two personality types nicely.
Why the Theory of Left vs Right-Brain Dominance Is Obsolete
The concept of left-brain right-brain dominance never did have a strong foundation in science, and now this theory has been totally debunked.
Brain scan technology reveals that the two brain hemispheres communicate through the corpus callosum and work together to perform a wide variety of tasks.
For example, language processing, previously thought to be a left-brain activity, does not take place in any one side or region of the brain.
The left side of the brain processes grammar and pronunciation while the right side processes intonation. (6)
Of course, some people are better at languages than others, but this is not because they are left-brain dominant.
Language involves the whole brain.
(That’s one reason why being bilingual or learning a new language is excellent brain exercise.)
In a recent groundbreaking study, neuroscientists scanned over 7,000 brain regions in more than 1,000 people to analyze brain activity patterns.
They found no evidence of left-brain or right-brain dominance. (7)
So now, the prevailing theory is that we use both sides of our brain as needed depending on the task at hand.
Why the Left-Brain Right-Brain Myth Persists
The scientific case against the left-brain right-brain dominance theory is strong.
It was always considered “pop psychology” by most in the scientific community and was never widely accepted.
While different personality types exist, it’s quite clear they have nothing to do with whether one brain hemisphere is more active, stronger, or more connected than the other. (10)
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And yet this myth persists anyway.
Here are four possible explanations why the world at large won’t let this brain myth die.
1. It takes time for a new idea to go mainstream, so it could just be a matter of time.
It takes an average of 17 years for a new medical discovery to be adopted by mainstream medicine and even longer to trickle down to the general public. (11)
2. Generalizing and categorizing helps us make sense of our world.
Understanding of the brain and human personality is really still in its infancy.
Dividing humanity into two main personality types has a beautiful simplicity to it.
Learn more —
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3. People yearn to understand themselves — why they are the way they are, and how they fit into the world.
They feel that the left-brain right-brain concept helps them do that.
For similar reasons, personality quizzes and daily horoscopes are always popular.
4. An abundance of left-brain right-brain tests, books, and apps found online lends credibility to the myth.
When you see something repeated often enough, you are more likely to believe it’s true.
This is due to a cognitive bias known as the illusory truth effect. (12)
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However, the perpetuation of the brain dominance myth is harmful because it hinders social progress.
Believing you can be good at only one set of skills can become a self-fulfilling prophecy.
It also has us looking at others with a left-brain vs right-brain perspective.
This encourages stereotypical thinking and prejudice — “all artists are bad at math” and “engineers can’t be creative.”
Obviously this is untrue.
Some of the greatest minds of all time were simultaneously analytical and creative.
Leonardo da Vinci was a scientist, mathematician, engineer, and inventor who painted the Mona Lisa, one of the most famous paintings in the world.
Nobel Prize-winning theoretical physicist Albert Einstein was an accomplished violinist with a life-long passion for music.
He believed the theory of relativity occurred to him by intuition, and that music was the driving force. (13)
Learn more —
How Music Affects the Brain
Unfortunately, the left-brain right-brain myth has infiltrated our education system.
Some teachers use it to label students as dominant in just one potential skill area, and have attempted to teach those students accordingly. (14)
By depriving our science-minded students of music lessons, we might be depriving the world of the next Einstein!
World-renowned astrophysicist Neil DeGrasse Tyson is one of the most outspoken champions of science.
He makes an impassioned plea to stop the damaging left-brain right-brain myth in a short but powerful video on FastCompany.com.
Why You Should Be Leery of Left-Brain Right-Brain Tests
The prevalence of bogus brain dominance tests online is a way that marketers keep the public believing in the left-brain right-brain myth.
You might be tempted to take one of these tests in the hope of learning more about yourself.
But, as you now know, they are based a faulty premise and do you a disservice by strengthening self-limiting beliefs.
But what you may not know is that they can be used against you in unscrupulous ways.
Left-Brain Right-Brain Tests Exist to Make Money Off You
When websites offer free services like online psychology or personality tests or quizzes, you’d like to think they are a genuine service.
While some online tests are created by reputable organizations or educational institutions, that will not be the case with left-brain right-brain tests since there is no scientific merit to the underlying theory.
So these quizzes are designed for one purpose — profit.
While some sites lure you with a test to sell their products or services, the “product” is just as likely to be your personal information.
This information is sold to advertisers, marketers and researchers, or, all too commonly, to criminals.
The most innocuous test can gather more data about you than you might suspect, even if you reveal no personal details.
Organizations that mine data can easily tell what type of computer you use, your IP address, your location, and the sites you visited before and after you arrived at their site. (15)
From there it’s not hard to find your name, address, and a lot more about you.
So before you take a brain dominance test (or any online test, quiz, or survey), browse around the site.
Is there a reputable organization behind it?
Someone spent time and money creating this test.
What do you think their motivation is?
Pay attention to the answers and listen to your feelings (now there’s non-dominance in action for you!).
If the situation does not feel trustworthy to you, my advice is to avoid it.
A Review of Online Left-Brain Right-Brain Tests
If you do an online search for left-brain right-brain tests, you’ll see a variety of options — tests and quizzes, books, apps, and more.
I took an in-depth look at Google’s top search results for “left-brain right-brain test.” Here’s what I found.
Most websites offer a free left-brain right-brain test as a draw to sell a range of products and services including:
- graphic design and advertising services
- brain training app
- biofeedback equipment
- brainwave entrainment sound files
- office supplies
In many cases, the connection between test and product is not obvious, but if you take a moment you can find it.
But some sites use a brain dominance test as a lead-in for more tests and quizzes such as:
- tests used in screening potential job candidates
- quizzes “just for fun”
- quizzes about health
These sites offer no obvious way of making money from their free test.
That’s a red flag.
Sites like this exist only to gather your information and sell it.
Beware of sites that do not have an “about us” page, contact information, disclaimers, or privacy notices.
About half of these suspicious sites are based in non-English speaking countries including China.
Left-brain right-brain test questions may ask whether you are orderly, a risk taker, impulsive, punctual, good in math, or have good communication skills.
Can you see why this information might be interesting to others — like a potential employer?
Left-Brain Right-Brain Myth: The Bottom Line
The left-brain right-brain dominance theory is a myth, albeit persistent, that science has now debunked.
The consequence of continued belief in this myth is the perpetuation of social prejudices and limiting beliefs.
It is also used to exploit people via bogus online left-brain right-brain tests.
Your takeaway from this article should be that all parts of your brain work together.
Don’t let yourself or anyone else compromise your potential or privacy to the outmoded concept of left-brain right-brain dominance.