"ARE YOU LEFT-BRAINED OR RIGHT-BRAINED?"
“Are you left-brained or right-brained?” Often times, we hear people asking us this question whenever they see the hand we use for writing; or sometimes, we sit around and wonder on what side of the brain do we use more frequently. Relatively, they said that the dominant hand we use to write is the opposite side of the brain that majorly functions. Hence, people claim that if you are right-handed, then you are probably using the left side of your brain; contrariwise, if you are left-handed, perhaps you are using the right side of your brain.
The idea of being a “left-brained” or a “right-brained” has been one of the most popular theory in the field of psychology. As what other people mostly assert, logical and methodological thinkers dominantly use the left side of their brain, while creative or artistic thinkers highly use the right side of their brain.
Has this concept been proven to be true or just a myth? Let’s figure it out!
Behold the human brain, its lumpy landscape visibly split into a left and right side. It is true that the brain has a right and a left side. Waters (2019) explained that this is most apparent with the outer layer, the cerebral cortex. Internal regions like the striatum, hypothalamus, thalamus, and brain stem appear to be made from continuous tissue, but in fact, they are also organized with left and right sides. The left and the right sides of the brain do control different body functions, such as movement and sight. The brain’s right side controls the motion of the left arm and leg and vice versa. The visual system is even more complex. Each eye has a left and right visual field. Both left visual fields are sent to the right side of the brain, whereas both right fields are sent to the left side. Hence, the brain uses both sides to make a complete image of the world. Scientists have no idea how that crossing over has been possible. One theory is it began soon after animals developed more complex nervous systems because it gave the survival advantage of quicker reflexes. If an animal sees a predator coming from its left side, it is best if it escapes to the right. Thus, we can say that vision and movement control are two systems that rely on this left-right structure.
This theory of the two brain hemispheres has evolved since 1960 and was popularized by a famous research psychologist and a Nobel Prize winner, Roger W. Sperry (Pietrangelo, 2019). In Sperry’s notable split-brain experiment, he discovered that this theory is based on the lateralization of the brain function (Cherry, 2020). Sperry conducted his research in attempt to treat refractory epilepsy. Thereby, he studied epileptic patients who had their corpus callosum (structure that connects the two brain hemispheres) surgically severed. As a result, Sperry discovered that both hemispheres maintain to be capable of learning after the split-brain operation, although, one hemisphere is insensible on what the other hemisphere has learned or experienced. This symptom appeared onto the patients by finding themselves unable to name the objects that were processed by the right side of the brain, in contrast to the left side of the brain. Accordingly, Sperry concluded that both hemispheres have different specialized roles. He suggested that the left side of the brain is normally used in tasks that involve analysis and language, while the right half shelters the tasks that involve space perception and music. For example, when people remember or teach directions, their right brain is definitely the one that is majorly functioning as of the moment. However, it is important to note that the right hemisphere can only produce basic words and phrases, since it is responsible in adding emotional context to language (Nobel Prize Outreach AB, 2021). All things considered, both brain hemispheres are important. Without the help of left hemisphere, you will only be able to visually recall that object and will not be able to recall it by its name.
In a study conducted by Nielsen, Zielinski, Ferguson, Lainhart, & Anderson (2013), they evaluated the lateralized brain connections in the brain through the use of Restating State Functional Connectivity Magnetic Resonance Imaging (rs-fcMRI). The study’s findings were consistent with the previous studies’ stating that the lateralized brain regions are responsible in controlling language and visuospatial processing. This can be explained why right-handed individuals direct their focus more on stimuli that involve language, while left-handed individuals direct their focus more on stimuli that involve visuospatial processing. With the help of rs-fcMRI techniques, it has become possible to characterize whole-brain lateralization using a data-driven approach. To define which network of an individual’s brain is dominant, Nielsen et al. demonstrated that we could view the consistent lateralization connections between the left and right hemispheres through discrete hubs. Overall, the study exhibited that an individual’s brain cannot be labeled as “left-brained” or “right-brained” as a whole-brain property, instead, there is only an asymmetric lateralization property where only a specific area of connection of interest is strongly lateralized. Thus, the relation on the lateralization degree for the other connections throughout the brain happens only if there is a shared common hub with the connection of interest, but it does not necessarily mean that one network favors over the other (i.e., left-brained or right-brained).
Problems arise when we over-extend that idea to logic and creativity. This concept began in the mid-1800s when two neurologists, Broca and Wernicke, examined patients who had problems communicating due to injuries. The researchers found damage to the patients’ left temporal lobes, so they suggested that language is controlled by the left side of the brain. That captured the popular imagination of left-brained and right-brained. Later research showed that one side of the brain is more active than the other for some functions. Language is more localized to the left, and attention to the right. As a result, one side of the brain may do more work, but this varies by system rather than by person. There is no evidence to suggest that individuals have dominant sides of the brain, or to support the idea of a left-right split between logic and creativity. Some people may be particularly logical or creative, but that has nothing to do with the sides of their brains. And even the idea of logic and creativity being at odds with each other does not hold up well. Solving complex math problems requires inspired creativity, and many vibrant works of art have intricated logical frameworks. Almost every feat of creativity and logic carries the mark of the whole brain functioning as one.
Therefore, the concept about an individual being identified as left-brained or right-brained is a BIG MYTH!
PRIMARY SOURCE:
Cherry, K. (2020, April 10). Left Brain vs. Right Brain Dominance: Is the analytical-creative separation true or false? Retrieved from VeryWell Mind: https://www.verywellmind.com/left-brain-vs-right-brain-2795005#citation-3
Pietrangelo, A. (2019, March 7). Left Brain vs. Right Brain: What Does This Mean for Me? Retrieved from Healthline: https://www.healthline.com/health/left-brain-vs-right-brain#takeaway
The Split Brain Experiments. (2022, May 6). Retrieved from Nobelprize.org (Nobel Prize Outreach AB 2021): https://educationalgames.nobelprize.org/educational/medicine/split-brain/background.html
Waters, E. (2019). The left brain vs. right brain myth. TED-Ed.
SECONDARY SOURCE:
Sperry, R.W. (1961). Cerebral Organization and Behavior. Science 133: 1749–57. http://people.uncw.edu/puente/sperry/sperrypapers/60s/85-1961.pdf
Goldie J. (2016). The Implications of Brain Lateralisation for Modern General Practice. Br J Gen Pract, 66(642):44-5. doi: 10.3399/bjgp16X683341
Stephan, K.E., Marshall, J.C., Friston, K.J., Rowe, J.B., & Ritzl A. (2003) Lateralized cognitive processes and lateralized task control in the human brain. Science 301: 384–386.
