7 Myths About the Brain

Separating Fact From Fiction

Brain and calculations (drawing)
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The human brain is amazing and sometimes mysterious. While researchers are still uncovering the secrets of how the brain works, they have discovered plenty of information about what goes on inside your noggin. Unfortunately, there are still a lot of brain myths out there.

The following are just a few of the many myths about the brain.

Myth 1: You only use 10 percent of your brain.

You've probably heard this oft-cited bit of information several times, but constant repetition does not make it any more accurate.

People often use this popular urban legend to imply that the mind is capable of much greater things, such as dramatically increased intelligence, psychic abilities, or even telekinesis. After all, if we can do all the things we do using only 10 percent of our brains, just imagine what we could accomplish if we used the remaining 90 percent.

Reality check: Research suggests that all areas of the brain perform some type of function. If the 10 percent myth were true, brain damage would be far less likely – after all, we would really only have to worry about that tiny 10 percent of our brains being injured. The fact is that damage to even a small area of the brain can result in profound consequences to both cognition and functioning. Brain imaging technologies have also demonstrated that the entire brain shows levels of activity, even during sleep.

"It turns out though, that we use virtually every part of the brain, and that [most of] the brain is active almost all the time. Let's put it this way: the brain represents three percent of the body's weight and uses 20 percent of the body's energy." - Neurologist Barry Gordon of Johns Hopkins School of Medicine, Scientific American

Myth 2: Brain damage is permanent.

The brain is fragile and can be damaged by things such as injury, stroke, or disease. This damage can result in a range of consequences, from mild disruptions in cognitive abilities to complete impairment. Brain damage can be devastating, but is it always permanent?

Reality check: While we often tend to think of brain injuries as lasting, a person's ability to recover from such damage depends upon the severity and the location of the injury. For example, a blow to the head during a football game might lead to a concussion. While this can be quite serious, most people are able to recover when given time to heal. A severe stroke, on the other hand, can result in dire consequences to the brain that can very well be permanent.

However, it is important to remember that the human brain has an impressive amount of plasticity. Even following a serious brain event, such as a stroke, the brain can often heal itself over time and form new connections.

"Even after more serious brain injury, such as stroke, research indicates that — especially with the help of therapy — the brain may be capable of developing new connections and “reroute” function through healthy areas." – BrainFacts.org

Myth 3: People are either "right-brained" or "left-brained."

Have you ever heard someone describe themselves as either left-brained or right-brained?

This stems from the popular notion that people are either dominated by their right or left brain hemispheres. According to this idea, people who are "right-brained" tend to be more creative and expressive, while those who are "left-brained" tend to be more analytical and logical.

Reality Check: While experts do recognize that there is lateralization of brain function (that is, certain types of tasks and thinking tend to be more associated with a particular region of the brain), no one is fully right-brained or left-brained. In fact, we tend to do better at tasks when the entire brain is utilized, even for things that are typically associated with a certain area of the brain.

"No matter how lateralized the brain can get, though, the two sides still work together. The pop psychology notion of a left brain and a right brain doesn’t capture their intimate working relationship. The left hemisphere specializes in picking out the sounds that form words and working out the syntax of the words, for example, but it does not have a monopoly on language processing. The right hemisphere is actually more sensitive to the emotional features of language, tuning in to the slow rhythms of speech that carry intonation and stress." – Carl Zimmer, Discover

Myth 4: Humans have the biggest brains.

The human brain is quite large in proportion to body size, but another common misconception is that humans have the largest brains of any organism. How big is the human brain? How does it compare to other species?

Reality Check: The average adult has a brain weighing in at about three pounds and measuring up to about 15 centimeters in length. The largest animal brain belongs to that of a sperm whale, weighing in at a whopping 18 pounds! Another large-brained animal is the elephant, with an average brain size of around 11 pounds.

But what about relative brain size in proportion to body size? Humans must certainly have the largest brains in comparison to their body size, right? Once again, this notion is also a myth. Surprisingly, one animal that holds the largest body-size to brain ratios is the shrew, with a brain making up about 10 percent of its body mass.

"Our primate lineage had a head start in evolving large brains, however, because most primates have brains that are larger than expected for their body size. The Encephalization Quotient is a measure of brain size relative to body size. The cat has an EQ of about 1, which is what is expected for its body size, while chimps have an EQ of 2.5 and humans nearly 7.5. Dolphins, no slouches when it comes to cognitive powers and complex social groups, have an EQ of more than 5, but rats and rabbits are way down on the scale at below 0.4." – Michael Balter, Slate.com

Myth 5: We are born with all the brain cells we ever have, and once they die, these cells are gone forever.

Traditional wisdom has long suggested that adults only have so many brain cells and that we never form new ones. Once these cells are lost, are they really gone for good?

Reality Check: In recent years, experts have discovered evidence that the human adult brain does indeed form new cells throughout life, even during old age. The process of forming new brain cells is known as neurogenesis and researchers have found that it happens in at least one important region of the brain called the hippocampus.

"Above-ground nuclear bomb tests carried out more than 50 years ago resulted in elevated atmospheric levels of the radioactive carbon-14 isotope (14C), which steadily declined over time. In a study published yesterday (June 7) in Cell, researchers used measurements of 14C concentration in the DNA of brain cells from deceased patients to determine the neurons’ age, and demonstrated that there is substantial adult neurogenesis in the human hippocampus." – Dan Cossins, The Scientist

Myth 6: Drinking alcohol kills brain cells.

Partly related to the myth that we never grow new neurons is the idea that drinking alcohol can lead to cell death in the brain. Drink too much or too often, some people might warn, and you'll lose precious brain cells that you can never get back. We've already learned that adults do indeed get new brain cells throughout life, but could drinking alcohol really kill brain cells?

Reality Check: While excessive or chronic alcohol abuse can certainly have dire health consequences, experts do not believe that drinking causes neurons to die. In fact, research has shown that even binge drinking doesn't actually kill neurons.

"Scientific medical research has actually demonstrated that the moderate consumption of alcohol is associated with better cognitive (thinking and reasoning) skills and memory than is abstaining from alcohol. Moderate drinking doesn’t kill brain cells but helps the brain function better into old age. Studies around the world involving many thousands of people report this finding." – PsychCentral.com

Myth 7: There are 100 billion neurons in the human brain.

If you've ever thumbed through a psychology or neuroscience textbook, you have probably read that the human brain contains approximately 100 billion neurons. How accurate is this oft-repeated figure? Just how many neurons are in the brain?

Reality Check: The estimate of 100 billion neurons has been repeated so often and so long that no one is completely sure where it originated. In 2009, however, one researcher decided to actually count neurons in adult brains and found that the number was just a bit off the mark. Based upon this research, it appears that the human brain contains closer to 85 billion neurons. So while the often-cited number is a few billion too high, 85 billion is still nothing to sneeze at.

"We found that on average the human brain has 86bn neurons. And not one [of the brains] that we looked at so far has the 100bn. Even though it may sound like a small difference the 14bn neurons amount to pretty much the number of neurons that a baboon brain has or almost half the number of neurons in the gorilla brain. So that's a pretty large difference actually." – Dr. Suzana Herculano-Houzel

More Psychology Facts and Myths:


Balter, M. (2012, Oct. 26). Why are our brains so ridiculously big? Slate. Retrieved from http://www.slate.com/articles/health_and_science/human_evolution/2012/10/human_brain_size_social_groups_led_to_the_evolution_of_large_brains.html

Boyd, R. (2008, Feb 7). Do people only use 10 percent of their brains? Scientific American. Retrieved from http://www.scientificamerican.com/article.cfm?id=people-only-use-10-percent-of-brain

BrainFacts.org. (2012). Myth: Brain damage is always permanent. Retrieved from http://www.brainfacts.org/diseases-disorders/injury/articles/2011/brain-damage-is-always-permanent

Cossins, D. (2013, June 7). Human adult neurogenesis revealed. The Scientist. Retrieved from http://www.the-scientist.com/?articles.view/articleNo/35902/title/Human-Adult-Neurogenesis-Revealed/

Hanson, D. J. (n.d.). Does drinking alcohol kill brain cells? PsychCentral.com. Retrieved from http://www2.potsdam.edu/hansondj/HealthIssues/1103162109.html

Herculano-Houzel S (2009). The human brain in numbers: A linearly scaled-up primate brain. Frontiers in Human Neuroscience, 3(31). doi:10.3389/neuro.09.031.2009

Randerson, J. (2012, Feb 28). How many neurons make a human brain? Billions fewer than we thought. The Guardian. Retrieved from http://www.guardian.co.uk/science/blog/2012/feb/28/how-many-neurons-human-brain

The Technium. (2004). Brains of white matter. http://www.kk.org/thetechnium/archives/2004/11/brains_of_white.php

Zimmer, C. (2009, April 15). The Big Similarities & Quirky Differences Between Our Left and Right Brains. Discover Magazine. Retrieved from http://discovermagazine.com/2009/may/15-big-similarities-and-quirky-differences-between-our-left-and-right-brains

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