This is arguably the most popular, persistent and preposterous neuroscience myth to rule them all. The myth proposes the truth to be that we go through life using a very small part of our brains, while the rest of it (around 90%) remains unused- that's 9/10 of the human brain just sitting there, full of unrealised potential, full of unexploited capabilities. Though the exact percentage ratio has fluctuated over the years, this 10:90 divide seems to be most popular.
However far-fetched the neuroscience myths may be, they always have some element of truth to them. It is because of this truthful component, however small, that the myths have become, to so many, truisms. If there was absolutely no truth to them or no reason for trusting them, they would not become truth, certainly not to significant portions of the population.
The '10% of your brain' myth may have roots in philosophy and early psychodynamic psychology. Firstly, in the early 20th century, philosopher and psychologist William James ruminated on the idea that we are in possession of 'latent metal energy'- he considered the potential for energy in the brain that may be unrealised but his ponderings had nothing to do with how much of the brain is used. This may demonstrate a reason why this myth has been so long-standing. The 'latent energy' vs. 'amount of brain in use' distinction is unclear, and these issues are understood differently by different people. Additionally, infamous psychologists such as Freud who were pioneers in their propositions regarding the unconscious mind. Though Freud and his peers have been written off by those in domains of neuroscientific study, no one can deny that Freud's original idea about the conscious vs. unconscious mind being almost like an iceberg- the tip residing above the surface demonstrating what we are conscious of, while below the surface there is an enormous amount that is inaccessible to us- still remains the theoretical root of even very contemporary and advanced practice in neuroscience. Contemporary neuroscientists can tell you that many of our neurological processes operate beneath our level of awareness. After all, if we were aware of everything the brain is doing as it is happening, the cognitive load would be too much for the brain to handle. Therefore, though this myth is a false belief, there is truth to the idea that there is a significant portion of our brain that we are not in control of or aware of. The difference is, we are using all of it, whether or not we know it.
Another root of this myth came from our own Albert Einstein who, for the most part, gets things so right, yet got this one so wrong. There is a quote that came from his conversation with a reporter which describes that the secret to his genius is using the full capacity of his brain instead of just the 10% used by everybody else. Nevertheless, the aforementioned conversation itself might be mythical too.
The way that research in the field of neuroscience is wrongfully interpreted may also explain why the myth has been allowed to go on for so long. One example comes from a study of epilepsy carried out in the 1930s by Wilder Penfield. He directly stimulated the surface of the brains among epilepsy patients and found that doing so provoked various sensations. When he stimulated some regions, however, there was no noticable effect. Findings such as this led to the false conclusion that large areas of our cortex is 'silent'. In fact, as more up-to-date findings have shown, the 'silent' areas belong to what we now know as the 'association cortex', which is far from silent. Its regions of tissue are actually implicated in higher-level cortical functioning. There was also, of course, the practice of lobotomy. The very idea that parts of the brain could be removed and not only would the patient be undamaged but actually benefit from such a treatment no doubt fuelled the false belief that there are parts of our brains we don't need or use and could just cut out and not know the difference.
The myth was popular enough of a concept to inspire blockbuster films such as the 2011 'Limitless' and 2014 'Lucy'. In 'Limitless', the protaconist says, 'we can only access 20% Of our brains', and the story follows his experiences after taking a magical drug that allows him to access the entirety of his brain. In this story, he manages to learn other languages and write a novel overnight. He even manages to make vast amounts of money through his sudden and advanced understanding of the stock market that, back when he only had access to this '20%" of his brain, was totally foreign to him. Moreover, the poster advertising the film 'Lucy' starring Scarlett Johansson boasted the phrase, 'The average person uses 10% of their brain capacity. Imagine what she could do with 100%.' In this film, while a neuroscientist played by Morgan Freeman states, 'I'm not sure that mankind is ready', Scarlett Johansson's character is able to throw a car with the power of her mind and completely master all knowledge.
There are a plethora of reasons why this myth is actually a little ridiculous. Firstly, if you really only used 10% of your brain, that would suggest that 90% of your brain matter is just sitting there within the confines of your skull, showing no activity or signs of life, whereas a small area, or collection of small areas comprising the 10%, is alive and kicking. There has never been a neuroimaging study that showed that any area of the brain being completely devoid of activity. Dependent on individual differences in neuroanatomy, some areas may not respond to specific processes, and some areas or networks of areas may show decreased or absent functioning, but all areas are used.
In truth, we use the whole thing. There is no residual brain matter just sitting there, unused and inactive. No parts of our brains are dressed up with nothing to do. Confirmation for this empirical conclusion comes from countless neuroimaging studies highlighting the activity occuring throughout the entirety of the brain. Even when we think of nothing, something is going on, everywhere. There is even a network of areas that becomes more active in those moments when we try to do nothing, when we clear our minds, called the 'default mode network'. Furthermore, as tiny lesions in the brain can have terrible outcomes, as seen in brain damaged patients, supports the truth behind the myth- we need it all, and it's all systems go.
Boyd, R. (2008). Do people only use 10 percent of their brains. Scientific American, 7.
Jarrett, C. (2014). Great myths of the brain. John Wiley & Sons.
Penfield, W., & Jasper, H. (1954). Epilepsy and the functional anatomy of the human brain.
Schenberg, E. (2014). The Mythical Brain: Is the Science of Movie Lucy Wrong?. Journal of Consciousness Exploration & Research, 5(11).
Stephenson, W. (1986). William James, Niels Bohr, and Complementarity: II—Pragmatics of a Thought. The Psychological Record, 36(4), 529-543.
2. Mental illness is caused by a chemical imbalance in the brain.
A recent survey conducted in order to gauge the public's general opinions about mental health showed that approximately 80% of people held the belief that mental illness is the result of a neurological chemical imbalance. This belief is as robust among the population as it is unfounded because nobody, not neuroscientists or psychiatrists or those moving in the circles of experts in the field of clinical psychology, could definitvely say what balance of chemicals in the brain is healthy or correct.
It's not difficult to see how this myth originated. Over the past few decades, as prescriptions of medication in the treatment of mental health conditions, particularly depression, has become more commonplace, people have learnt that anti-depression medication is affective through its alteration of levels of neurochemicals. But though adjusting chemical levels is how depression is often treated and one might assume therefore that depression is a problem with 'wrong' chemical levels, it doesn't logically follow, when you think about it, that the problems are caused themselves by problematic chemical levels- after all, one might take ibuprofen to help treat a headache, but nobody goes on to believe that an absence or 'wrong' amount of ibuprofen has caused the headache.
It's also simple to see why this myth has been so persistent and is so widely-held. Despite its inaccuracy, the idea that mental illness is caused by neurochemical imbalance has been promoted by both sufferers of mental disorders and campaigners for their cause, probably because a health problem seems to be more worthy of attention and treatment if it has a physical basis. The idea that those ways in which many people are suffering due to mental illness could be due to a problem over which they have and have never had any control, something irrefutably legitimate in any physician's eyes, something comparable to a tumor or broken bone because it resides within, resides somewhere inaccessible, resides in the concrete workings of our body and unrelated to psychological or subjective experience, emotion or cognition, which some may believe to be too abstract to consider as contributing factors to their un-abstract, disordered feelings and behaviours.
However, though the assumption may be that blaming it on the brain makes it easier to understand or more worthy of being seen as something to notice, worry about, invest in or treat, research has also demonstrated that the chemical imbalance theory and other biological accounts of mental illness actually may increase stigmatization of sufferers in society, potentially because such accounts endorse the belief that mental illness is permanent or some incurable condition you are born with or you aren't and have no control over.
It's important to understand that this myth is purely myth in order to help change widespread attitudes, because mental health conditions such as depression- the main focus of the chemical imbalance discussions- are treatable, are curable, and can be taken under control by the sufferer through seeking treatment. Someone with a mental illness does not have a naturally skewed brain, they may not be even remotely neurologically squiffy, and though the levels of neurochemicals can be the target of some medication treatments and are theorised to factor into why mental illness exists, there is no known correct balance of chemicals to promote perfect mental health anyway.
Lebowitz, M. S., & Ahn, W. K. (2014). Effects of biological explanations for mental disorders on clinicians’ empathy. Proceedings of the National Academy of Sciences, 111(50), 17786-17790.
Pescosolido, B. A., Martin, J. K., Long, J. S., Medina, T. R., Phelan, J. C., & Link, B. G. (2010). “A disease like any other”? A decade of change in public reactions to schizophrenia, depression, and alcohol dependence. American Journal of Psychiatry, 167(11), 1321-1330.
3. Some of us are right-brained, some of us are left-brained.
The right vs. left brain myth is almost ridiculously reductive. Like the brain, the myth comes in two halves, both popular very misguided conceptions- firstly, the conception that there is a difference in the types of thinking carried out by the opposing hemispheres, and secondly, the conception that there is a difference between individuals in how they favour either the right or left hemisphere.
Despite the broad body of research that has in recent years used advanced neuroimaging technology to explore and conclude which regions of the brain are implicated in a wide array of processes, and despite the many informative findings, people still seem to believe that the left hemisphere of the brain is responsible for analytical thought, logic and verbal reasoning, whereas the right hemisphere is responsible for emotion, creativity and visuo-spatial capability. And people also believe that individuals either have a dominant left side or a dominant right side, and depending on which is the dominant hemisphere, their disposition and cognitive styles will fall into a left (logical/analytical) or right (emotional/creative) category.
This myth is so incredibly far from what is true. The only way someone might have left or right-brained thinking is if they had some hemispatial neglect.
As with all the neuroscience myths, however, the myth wasn't plucked from nowhere and is not completely fantastical. There is an element of truth in it- there are two hemispheres that are joined by the corpus collosum, a tract of connective tissue; some processes are partially or completely located in one hemisphere or another, and most processes show some specialisation to the right or left. Meta-analyses has shed light on the concept of lateralisation- (hemispheric specialisation), first observed in the mid 19th century through the study of brain-damaged patients and their later autopsies, and still studied today, especially since the creation of transcranial doppler sonography (tcds), which uses sonographic technology to measure blood flow betwee hemispheres during various tasks. The meta-analytic research has shown that, indeed, language is, for the most part, lateralised (or specifically located) to the left, whereas visuo-spatial functioning is lateralised to the right. However, it also shows that language is not limited only to the left hemisphere- studies demonstrate how the left hemisphere is involved in phonological processing (the way that words sound) whereas the right hemisphere is also important, but for elements of language such as comprehension of meaning and context, lip-reading and intonation. Most of the time, the right and left sides of the brain work together, and it is this cohesiveness that gives rise to so many of our neurological, cognitive, emotional and behavioural processes. In recent years we have been able to gain an understanding of how the hemispheres are connected, how they interact, and how their interaction varies throughout one's life. It is therefore odd that, despite this improved understanding, so many people still see the brain as two halves that have different purposes and functions and are more interesting separately than working together as the amazing machine that is the brain.
With regards to the second part of the myth- the difference between individuals and their right or left hemisphere dominance- there is an iota of truth in this myth too. Lateralisation between the two hemispheres does vary between individuals. There are structural lateralisation differences- how different the actual tissue of the brain can be from person to person- and functional ones- how different the activity across hemispheres can be between people. Nevertheless, there is no overall dominance of one side of the brain above the other and this is not something that varies between people. Evidence corroborating this was found in a 2013 study, in which more than 1,000 brain scans were analysed. Though some evidence of lateralisation was discovered in the regions that have been associated with particular tasks- such as language-related tasks in the left hemisphere and attention-related tasks in the right- no evidence was ever found that could support the mythological belief that people have some inherent preference for right or left hemispheric processing as more pronounced, or that people are 'wired' to the right or to the left. There will never be any evidence of this because it is not grounded in truth.
Dassonville, P., Zhu, X-H., Ugurbil, K., Kim, S-G., & Ashe, J. (1997). Functional activation in motor cortex reflects the direction and the degree of handedness. PNAS 94 (25), 14015-14018.
Mihov, K. M., Denzler, M., & Förster, J. (2010). Hemispheric specialisation and creative thinking: A meta-analytic review of lateralisation of creativity. Brain and Cognition, 72, 442-448.
Nielsen, J. A., Zielinski, B. A., Ferguson, M. A., Lainhart, J. E., & Anderson, J. S. (2013). An evaluation of the left-brain vs. right-brain hypothesis with resting state functional connectivity magnetic resonance imaging. PloS one, 8(8), e71275.
Vigneau, M., Beaucousin, V., Herve, P. Y., Jobard, G., Petit, L., Crivello, F., Mellet, E., Zago, L., Mazoyer, B., & Tzourio-Mazoyer, N. (2011). What is right-hemisphere contribution to phonological, lexico-semantic, and sentence processing? Insights from a meta-analysis. Neuroimage, 54 (1), 577-593.
Warrier, C., Wong, P., Penhune, V., Zatorre, R., Parrish, T., Abrams, D., & Kraus, N. (2009). Relating structure to function: Heschl’s gyrus and acoustic processing. Journal of Neuroscience, 29 (1), 61-69.
4. There are fundamental gender differences in the brain.
Stereotypes will be stereotypes and they are, unfortunate and untrue as they are, always likely to be a part of how we understand society. It seems that some, especially the media but even scientists, are single-mindedly focusing on finding evidence from neuroscientific research that will support stereotypical beliefs about gender differences. They are so single-minded, perhaps, that all new evidence is interpreted through the skewed lens of bias, thus incorrectly reinforcing the stereotypes. An example of how this happened occured in 2013 when Verma et al. wrote that they had found fundamental differences in how male brains are wired compared to female ones, in the 'connectivity patterns in males and females.' They stated that male brains had more connectivity within each heisphere, while female brains had more connectivity between hemispheres. It was in the additional statements they made in the press and in their report that could not have been more wrong, yet seemed right enough to believe by so may people- they said that their findings of the differences between male and female brains can explain behavioural differences between the sexes; woman are better at multi-tasking and show better intuition than men, whereas men are better at sports and reading maps. Popular newspapers such as The Independent and Daily Mail picked up these findings and emblazoned them across the pages.
The problem with their findings, though the statistical difference was significant between males and females, the average differences had far too much overlap to ever be considered 'fundamental'. For instance, as a female, my brain might be wired more like an average male brain than one of my male friends' brain is wired, and his brain might be wired more like an average female brain. And as for the information about intuition and map-reading, those were only guesses, hypotheses conjured by the researchers to explain their statistical findings.
There have since been no studies to corroborate the theory that female brains are more efficient in multi-tasking or intuition, or that male brains are more efficient in map-reading and spatial-kinesthetic processing (as in sports capabilities. However, there are indeed little anatomical differences between male and female brains. In women, the hippocampus- implicated mostly in memory- is larger than in men. Conversely, the amygdala- implicated in social perception, emotion and response to environmental threat- is smaller in women than in men. When you think about it, this is the opposite of what the myth predicts. According to the myth, the memory-related region ought to be larger than the emotion-related one for men, and vice versa for women.
Arnal, L. H., Flinker, A., Kleinschmidt, A., Giraud, A. L., & Poeppel, D. (2015). Human screams occupy a privileged niche in the communication soundscape. Current Biology, 25(15), 2051-2056.
Fine, C. (2005). Delusions of gender: The real science behind sex differences. Icon Books Ltd.
Fine, C. (2013). New insights into gendered brain wiring, or a perfect case study in neurosexism?. The Conversation.