Are You More ‘Left-Brained’ or‘Right-Brained’?

Learn the truth about the left and right sides of the brain.

The left brain and right brain refer to each of the two halves of the brain, also known as hemispheres. The two hemispheres are connected by a structure called the corpus callosum, which allows them to communicate with one another. While each hemisphere is nearly a mirror image of the other, they aren’t exactly the same. This is called hemispheric asymmetry. Part of hemispheric asymmetry includes different functions. That is, there are some functions that one hemisphere specializes in more than the other hemisphere.

While it is true that the two hemispheres of the brain do have some specialized functions, there is little evidence to support the popular understanding of hemispheric specialization. In reality, both hemispheres are highly interconnected, with different regions constantly communicating with one another and working together to carry out most cognitive tasks.

“I like nonsense, it wakes up the brain cells. Fantasy is a necessary ingredient in living.”
― Dr. Seuss

Left Brain vs Right Brain Theory

The theory of hemispheric specialization – or the idea that the left and right side of the brain performs different functions – has been around for a long time. The observation that most humans prefer to use their right over their left hand was one of the first clues.

In the 1800’s a French physician named Pierre Paul Broca made a discovery that provided evidence that some brain functions are localized to distinct brain areas. Specifically, he found that people with damage to a particular region in the lower frontal cortex on the left side of the brain struggled to produce speech (Broca, 1863).

In the following century, substantial evidence supporting the localization of brain function has been accumulated. Some of the most compelling evidence came from studies involving patients who had their corpus callosum (the structure that connects the two hemispheres) severed. This aptly-named split-brain procedure was a clinical method for controlling epilepsy but also had the result of allowing researchers to study the functions of each hemisphere independently. We’ll get into more details about split-brain studies a little later on, but for now, it is just important to know that this research provided evidence supporting the theory that the left hemisphere was important for language and the right hemisphere was important for emotional and non-verbal functions (Corballis, 2014).

These and similar findings led to the extrapolation that the left hemisphere was responsible for logic and critical thinking and the right hemisphere was responsible for emotion and creativity (Corballis, 2014).

Is Left Brain vs Right Brain a Myth?

As we now know, the idea that each hemisphere has specialized functions is valid. Interestingly, hemispheric functional asymmetry is something that is seen in all vertebrate species (Herve, et al., 2013). For example, about two-thirds of chimpanzees appear to be right-handed (Meguerditchian et al., 2010). However, the way that left-brain and right-brain behaviors are typically described in popular media tends to be oversimplified and exaggerated (Corballis, 2014).

Differences Between Left Brain and Right

Brain

As mentioned earlier, the two hemispheres are nearly mirror images of each other, but there are some structural differences that are typically found. Below are a few examples of anatomical asymmetries in the brain (Kang, et al., 2015).

● Hippocampus: The hippocampus, a subcortical structure that is critical for memory formation, is commonly larger on the left.

● Heschl’s gyrus: Heschl’s gyrus, which is a region of the brain involved in processing auditory information, is larger in the left hemisphere in most people.

● Anterior Cingulate Cortex: The anterior cingulate cortex is thought to be involved in a number of processes including pain perception, emotion regulation, and cognitive control. This region is commonly larger in the right hemisphere.

● Planum temporale: The planum temporale, which is a region of the brain involved in processing language, is also larger in the left hemisphere in most people.

In addition to the anatomical differences between the left and right sides of the brain, there is also evidence that supports functional differences including language, visuospatial skills, and attention.

In Sum

The distinction between left brain functions and right brain functions isn’t necessarily wrong. There are some functions, such as language and visual-spatial processing, that tend to be predominantly produced by one hemisphere or the other. However, the common understanding of the left brain vs right brain is an exaggeration and oversimplification of hemispheric asymmetry. Nevertheless, thinking of yourself as left-brained or right-brained, or categorizing activities as engaging your left brain or your right brain may still be useful as a descriptive tool, regardless of its literal accuracy.

References

● Broca, P. (1863). Localisations des fonctions cérébrales. Siège de la faculté du language articulé. Bulletin de la Société d’Anthropo- logie, 4, 200–208.

● Corballis, M. C. (2014). Left brain, right brain: facts and fantasies. PLoS biology, 12(1), e1001767.

● Kang, X., Herron, T. J., Ettlinger, M., & Woods, D. L. (2015). Hemispheric asymmetries in cortical and subcortical anatomy. Laterality: Asymmetries of Body, Brain and Cognition, 20(6), 658-684.

● Meguerditchian A, Vauclair J, Hopkins WD., (2010) Captive chimpanzees use their right hand to communicate with each other: implications for the origin of the cerebral substrate for language. Cortex 46: 40–48