Fifteen Eighty Four

Academic perspectives from Cambridge University Press


Common Misconceptions About the Human Brain

Jeanne Ellis Ormrod


In my 40-plus years of teaching cognitive psychology, reading professional literature, and casually talking with friends and acquaintances, I’ve encountered many misconceptions about how the human brain and mind work. Here I’ll address three common misconceptions about the brain that have been discredited time and time again by neuroscientific and psychological researchers.

 Misconception #1:  Most of us don’t use more than 10% of our brain capacity.

A typical human brain has several trillion cells. Among those cells are perhaps 100 billion brownish-grayish neurons – cells that send messages to one another through both electrical impulses (within neurons themselves) and chemical substances known as neurotransmitters (across tiny gaps, or synapses, between neurons). Vastly outnumbering neurons are whitish-colored glial cells, which support and protect the neurons. At least a billion of those glial cells are star-shaped astrocytes, which appear to be just as important as neurons in encoding and retaining information in our brains.

Any single neuron might have hundreds or even thousands of synaptic connections with other neurons. And astrocytes are chemically interconnected with their neighbors and with nearby neurons. All told, our brain cells have countless interconnections with one another – I’m guessing that these interconnections number in the quadrillions or maybe even the quintillions. Thus, it shouldn’t surprise you to learn that the process of learning or thinking about virtually any tiny thing in our lives — even a single word — is spread out, or distributed, across many parts of the brain.1 Given the brain’s mind-boggling interconnectedness, it’s inconceivable that 90% of anyone’s brain – or even a small fraction of it – is sitting idly by with nothing to do.


Misconception #2:  Parents, teachers, and other adults need to do everything they can to minimize the loss of brain synapses in young children.

Beginning quite early in the prenatal period, an infant-to-be generates neurons at an astounding rate; for example, approximately 50,000 to 100,000 new neurons form per second between the 5th and 20th weeks after conception. Many of these neurons migrate to various locations in the slowly-emerging brain and elsewhere, and they reach out in an effort to form synapses with one another. Then, with the birth of the full-term infant comes a virtual explosion of new astrocytes, followed soon thereafter by the rapid formation of many additional new synapses.2 Thanks to the process of genetically driven synapse creation, called synaptogenesis, 2- and 3-year-olds have many more synapses than adults do. As growing children experience new and recurring events in their daily lives, some of their synapses come in quite handy and are used repeatedly. Those that aren’t terribly relevant or helpful gradually fade away in a process known as synaptic pruning. In some areas of the brain, much of this pruning occurs fairly early — for instance, in the preschool or early elementary years. In other areas, it begins later and continues until well into adolescence.3 Ultimately, some pruning of useless synapses probably occurs throughout the lifespan.

The universal tendency for the brain to eliminate unused synapses in the early years has been translated into many efforts to inundate babies, toddlers, and preschoolers with as much stimulation as possible in order to “save” some of those synapses. Parents enroll their young children in academically oriented daycare programs, sign them up for weekly violin lessons, and engage them in computer games that give them practice in eye-hand coordination, focusing attention, and basic reading and counting skills. In moderation, such interventions can be beneficial.4 But parents’ attempts to make their offspring as intelligent as possible sometimes get pretty ridiculous. And please don’t fall for all those ads declaring that certain software or Internet-based programs can “train the brain” and significantly “enhance IQ,” possibly turning a typical young child into a “genius.” There’s little evidence to back up their claims.

Not only are some synapses pretty useless, but others can actually be counterproductive. What Mother Nature seems to have done here is to program us to create many more synapses than we’ll every need; she then lets us discover on our own (a) which ones can best help us adapt to the particular circumstances we find in our physical and social environments and (b) which ones we should toss aside. Synaptic pruning, then, may be Mother Nature’s way of enhancing our brains’ efficiency and effectiveness.5


Misconception #3: The brain’s left and right hemispheres have very different functions and can be independently trained and nurtured.

The brain is divided into two major hemispheres, which are connected by a massive bundle of neural fibers known as the corpus callosum. On superficial examination, the two hemispheres appear to be mirror images of each other, but researchers have found some differences in what the left and right hemispheres do. Contrary to what might seem logical, the left hemisphere controls the right side of the body, whereas the right hemisphere controls the left side. In addition, the two hemispheres seem to specialize a bit in different aspects of human cognition.6 For most people, the left hemisphere is in charge of both language skills and detail-oriented, breaking-things-down-into-their-constituent-parts analyses; for instance, the left hemisphere tends to dominate in mathematical calculation skills and in analyzing music. Meanwhile, the right hemisphere takes the lead role in processing visual and spatial information, and it’s also much better than the left side at synthesizing information into multifaceted, meaningful wholes. In other words, the right hemisphere is better at seeing the big picture – it’s more likely to see the overall forest in situations in which the left hemisphere is being distracted by some of the trees.

However, thanks to the corpus callosum that connects them, the two hemispheres constantly collaborate in even the simplest of daily activities. It is virtually impossible to identify someone as being “right-brained” or “left-brained or to focus education and training on a particular hemisphere. Unless we’ve had significant brain injuries or surgical interventions (perhaps to control for severe epileptic seizures), we humans are whole-brain thinkers and learners.

In your readings of books, magazine articles, or Internet posts written by self-proclaimed experts, you might have seen discussions of “right-brain thinking,” “left-brain thinking,” or “teaching to the right [or left] brain.” Please don’t believe anything these so-called “experts” say. Their assertions and recommendations fly in the face of neuroscientific findings and thus are completely bogus.


1 For example, see Pereira, F., Detre, G., & Botvinick, M. (2011). Generating text from functional brain images. Frontiers in Human Neuroscience, 5(72). doi: 10.3389/fnhum.2011.00072.

2 For example, see Koob, A. (2009). The root of thought. Hoboken, NJ: Pearson.

3 For example, see Posner, M. I., & Rothbart, M. K. (2007). Educating the human brain. Washington, DC: American Psychological Association.

4 For example, see Neville, H. J., Stevens, C., Pakulak, E., Bell, T A., Fanning, J., Klein, S., & Isbell, E. (2013). Family-based training program improves brain function, cognition, and behavior in lower socioeconomic status preschoolers. PNAS, U.S.A., 110, 12138–12143.

5 For example, see Bryck, R. L., & Fisher, P. A. (2012). Training the brain: Practical applications of neural plasticity from the intersection of cognitive neuroscience, developmental psychology, and prevention science. American Psychologist, 67, 87–100.

6 For example, see Byrnes, J. P. (2001). Minds, brains, and learning: Understanding the psychological and educational relevance of neuroscientific research. New York, NY: Guilford.

About The Author

Jeanne Ellis Ormrod

Jeanne Ellis is Professor Emerita in UNC's School of Psychological Sciences & author of 'How We Think and Learn' ...

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