Psychology Myths 3 of 5

Myth #3 People are either left-brained or right-brained

"I'm not good at Math. It's 'cause I'm right-brained."     "I can't draw. Because, you know, I'm left-brained."

Have you heard these excuses before? They are excuses and not reasons because they are false. But first let's look at the real differences in each hemisphere.

(If you would like to learn more about this and other myths check out 50 Great Myths of Popular Psychology by clicking this link)

Split Brain Procedure

What is the main difference between hemispheres? Functions (Springer & Deutsch, 1997). How do we know that? Well, there are many ways to study the brain, some of them include the electroencephalogram (EEG), computerized axial tomography (CAT), positron emission tomography (PET), and functional Magnetic Resonance Imaging (fMRI). However, two of the first methods used to investigate the brain were accidents and injuries. Of course, psychologists didn't go to the streets with a bat knocking people out in order to learn more about the brain.

They studied brains after lesions or operations. One of these operations is split brain procedure.

This consists of surgeons cutting the corpus callosum, which is a tract of fibers that connects the hemispheres. According to The Epilepsy Foundation of America, split brain procedure is used to stop severe epilepsy from spreading from one hemisphere to the other. 

In 1981, Roger Sperry, David H. Hubel, and Torsten N. Wiesel shared the Nobel Prize in Physiology or Medicine for studying patients who had undergone this surgery (Gazzaniga, 1998). At first, patients didn't show any effects from the procedure, their behavior appeared to be the same as before the operation. However, Sperry created experiments that demonstrated that when the corpus callosum was cut, it seemed as the hemispheres worked independently from each other.

The researchers found that the hemispheres were not communicating with each other by conducting several different experiments. In one of them, patients had to look at the center of a screen while words or pictures flashed in front of them. Since the information seen from the left eye goes to the right hemisphere, the experiment consisted of showing words in the left visual field in order to learn about the right hemisphere and vice versa. Moreover, the majority of people that have their right hand as the dominant one, as well as lefties, have the primary area responsible for the production of speech in the left hemisphere. So, in the experiment, they showed a nude picture of a woman in the left visual field of participants. They discovered that the participants presented physical reactions to the photo such as giggling and blushing. But because the right hemisphere, which is where the information about the picture was processed, could not communicate to the left one, which is where speech production is handled, what it saw, the patients had to create a motivation for why they were blushing. One of those excuses was "Oh doctor, you have some machine. (Gabrieli, 2011)"

In another version of the same experiment, patients were shown a picture of a spoon on the left visual field and a cup on the right visual field. When they were asked what did they saw, they would only say a cup (Gabrieli, 2011). This happened because the  left hemisphere, which is mostly responsible for the production of speech, only saw the cup, and the right hemisphere, which saw the spoon, was not able to pass that information onto the other hemisphere because the corpus callosum was cut. 

The next thing researchers tried to do was to compare verbal and written responses. So, in the same type of experiment, patients were shown a rectangle in their left visual field and a triangle in their right visual field. When asked what they saw, patients responded by saying a triangle, but when asked to draw what they saw they drew a rectangle (Gabrieli, 2011). This happens because the left visual field that saw the rectangles is connected to the right side hemisphere, which would correspond to the left hand drawing the figure. Another version of this experiment was when the instructions of "Walk across the room" were presented on the left visual field. Thus, when the patients were asked why did they do that, they did not know. This happened because the right hemisphere was responsible for receiving the information but could not pass it onto the left hemisphere.

The last version of this experiment tested patients by showing them the word "key" in the left visual field and "ring" in the right visual field. The patient would answer ring if asked what he/she saw, but if asked to pick up what he saw, he would raise a key instead.  

The differences of each hemisphere

Now, that it has been established that hemispheres process some information independently from each other some question arise. What are the differences between them? Is one analytical and the other creative? Well, the answer is no. The main difference of each hemisphere is seen in the way they process tasks instead of what kind of things they process (McCrone, 1999). One example of this is language. The right hemisphere handles better the patterns of speech made when words are pronounced. However, the left is better at tasks such as grammar and word generation. Nevertheless, both hemispheres participate in both tasks, thus, both contribute to language. Another task in which it is evident that both hemispheres work together is visual processes. In this example, the right hemisphere is better at handling a sense of space and the left one at locating objects in specific places.


People are not left-brained or right brained as a lot of people think (Aamodt & Wang, 2008; Corballis, 1999, 2007; Della Sala, 1999). In fact, brain imaging results show that each side of the brain is constantly communicating with each other on most tasks (Mercer, 2010) (unless the person has undergone split-brain procedure). In addition, research shows that when compared to functions they share more similarities than differences (Geake, 2008). This myth has expanded thanks to the media and to books such as "The Right Mind: Making Sense of the Hemispheres" by Robert Ornstein, who promotes the concept of tapping into our creative right hemisphere.
As well as "Drawing on the Right Side of the Brain" by Betty Edwards. This book encourages people to suppress their rational left part of the brain.

Additionally, there are programs that assert that they can unleash the untapped potential of a particular hemisphere, such as the "Applied Creative Thinking Workshop (Hermann, 1996). Nevertheless, the U.S. National Academy of Sciences found that there was not evidence that the differences between hemispheres could be trained (Druckman & Swets, 1988).

In the Journal Plos One, Dr. Nielsen, a neuroscientist, stated after he conducted his experiment: "Yet our analyses suggest that an individual brain is not “left-brained” or “right-brained” as a global property" (Nielsen, 2013).

Let's work together like the hemispheres to fight other myths.

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