How the myth is born that there is a dominant hemisphere of the brain and that determines whether we are more rational or creative – Checked

February 28, 2022 08:00 a.m. | Reading time: 5 minutes
February 28, 2022 08:00 a.m.
| Reading time: 5 minutes

If you only have a few seconds, read these lines:

  • A frequently repeated misconception is that people have one hemisphere of the brain that they use more than the other and that this dominance determines characteristics of their cognition and abilities.
  • However, it is a myth. The fact that each hemisphere of the brain is specialized in some functions does not imply that people use predominantly one of them and less than that determines our abilities and cognitive abilities.
  • We tell you where this myth comes from and its negative impact on educational practices.

There are many myths about how the brain works (generally encompassed by the term “neuromyths”). One that is particularly repeated -and that, as we will see, has relevant impacts on educational practices- is that of the cerebral hemispheres that plainly and simply maintains that everyone has a dominant hemisphere of the brain (one “side” that they use more than the other) and that dominance determines characteristics of their cognition and abilities.

Thus, in cases where the left hemisphere is dominant, people are supposedly logical and do well with math and language, while in cases where the right side is supposed to be dominant, people are more creative. and artistic.

split brain

In 1865, at a meeting of the Anthropological Society of Paris, the physician and surgeon Paul Broca, after a series of investigations, made a famous statement: “We speak with the left hemisphere“. Almost a decade later, in 1874, the neurologist John Hughlings-Jackson proposed a complementary role for the right hemisphere: its specialization in the “recognition of objects, places and people.”, what today we would call visuo-spatial functions.

At that time, it was known that a brain injury, even small, if it was located in a particular region of the left hemisphere selectively disabled a person to read and the same happened with the understanding of spoken words when other areas were damaged.

The accumulation of many such observations – in which localized damage to the left hemisphere, but not the right, influenced the expression and understanding of language – forged the so-called classical view of a dominant hemisphere of language, the leftand a subordinate hemisphere, the right, non-linguistic that, in addition to not being linked to speech and writing, -it was deduced by extrapolation that- also lacked the higher cognitive faculties associated with language and symbolic processing.

This classical view of brain dominance was reinforced by concurrent findings on the apraxia, that is, the difficulty to make voluntary coordinated movements – even when a person understands orders and wants to carry them out – because the brain cannot generate or send the adequate “movement instructions”.

This meant that the left hemisphere also came to be considered primarily responsible for the direction and control of higher voluntary movements. Later, tests of left dominance were also extended to calculation and arithmetic reasoning.

Nearly a hundred years later, in the 1960s, Roger Sperry was the first to show that some brain functions are more “lateralized” or controlled primarily by brain regions of one hemisphere. This research was worth half of the 1981 Nobel Prize in Medicine. His work, together with Michael Gazzaniga, focused mainly on the treatment of patients with schizophrenia through the “split brain” technique, that is, cutting the corpus callosum, the main nerve fiber bundle responsible for communication between the two hemispheres of the brain. By that time, it was already known that this loss did not cause serious disabilities in people.

Experimenting with these patients, they found that each hemisphere functioned as a separate entity, with different reasoning processes. On the left were the functions of language, mathematics, and logic; in the right, spatial perception, face recognition and music. They also found that the right hemisphere seemed more emotional than the left.

So why is it a myth?

The fact that each hemisphere of the brain is specialized in some functions does not imply that people predominantly use one of them and less than less than that determines our abilities, emotionality and cognitive abilities.

In 2003, a meta-analysis Quantitative study of 65 neuroimaging studies with special emphasis on the lateralization of brain function in emotions. The researchers found no evidence to support the hypothesis. On the other hand, regarding the supposed differences between the brains of men and women, an analysis of the available evidence indicates that “the brain has no more gender than the liver, kidneys or heart”.

In 2013 a published study of two years in which the brains of more than a thousand people between the ages of 7 and 29 were scanned and specific mental processes that take place in each hemisphere were measured. The researchers divided the brain into 7,000 regions, and while they confirmed that certain functions are more lateralized, they found no evidence that participants had a stronger brain network on one side.

Furthermore, in 2017, a consortium of neuroscientists from the European Multilateral Project studied the asymmetry of a cortical region called the planum temporale, typically taken as a marker of language lateralization in the left cerebral hemisphere.

The first studies carried out in the mid-twentieth century revealed that the planum temporale (located in Wernicke’s area, considered the “processing center” of language in the brain) was one of the most asymmetrical regions: up to 10 times larger in the hemisphere left brain. But despite this notable difference, the main conclusion of this new study is that the size of a person’s planum temporale is not directly correlated with the side of the brain used dominantly to process language.

So, are there individual differences in people’s hemispheric specialization? Yes. Are they the same for all people? No. Can we speak of people with “left brains” and “right brains” as a generality and extrapolate their abilities from there? No.

Since the hemispheres operate somewhat independently, the question of how they are Combine your processing independent and/or which hemisphere “takes control” of the processing for a particular task is something that we are just beginning to understand. For example, there are different types of math skills and the research show that, in general, they arise from processing that takes place in both hemispheres.

As he points out in this extensive interview Dr. Kara Federmeier, director of the Brain and Cognition Laboratory at the University of Illinois, in the United States, “Most of us use both hemispheres of the brain almost all the time” and something not minor is that “the lateralization of the function changes with aging. Types of lateralized patterns of brain activity (…) are more common in young adults. Across many types of tasks and many brain areas, these lateralized patterns tend to change to bilateral patterns in healthy older adults.”

Why is it important to dispel this myth?

Although it may seem harmless, the false belief that there are people who use one of the hemispheres of the brain more and therefore have certain characteristics is not.

In 2007, the Organization for Economic Cooperation and Development (OECD) warned about the impact of this myth on education and this Article 2019 raises the importance of advising educators and families on how to avoid programs and interventions based on this myth.

Without going any further, this systematic review of 2021 shows that the growing interest in “neuroeducation” does not correspond to the proper use of the results of scientific research. This is worrying because many false beliefs can influence the way teachers teach. I know has seen that teachers enthusiastic about the possible application of neuroscience findings in the classroom show difficulties in distinguishing pseudoscience from scientific fact.

In this document of UNESCO, it is indicated that sustaining the myth of the cerebral hemispheres can limit “all students’ opportunities for learning and growth. By falsely believing that there are “left brain” or “right brain” students, we put students in boxes that can artificially narrow their interests or prevent them from trying new things.”

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How the myth is born that there is a dominant hemisphere of the brain and that determines whether we are more rational or creative – Checked