It is the summer of 2014 on Earth’s Northern hemisphere and the movie Lucy is hitting theatres. The official promotional posters and movie trailers contain the tagline “The average person uses 10% of their brain capacity. Imagine what she could do with 100%.” Lucy becomes the second most successful debut for a French action film, grossing worldwide at almost 460 million $ US, against a budget of 40 million $ US. As a French sci-fi action movie – not terrible, but as a neuromyth perpetuator – absolutely brilliant. The premise of the movie is centred around the idea that humans normally use 10% of their brains, and after Lucy (played by Scarlett Johansson) is subject to large amounts of an experimental synthetic drug, she breaks this barrier and reaches to a whole new level of human evolution. Lucy acquires increasingly enhanced physical, cognitive, and extrasensory capabilities, including telepathy, telekinesis, an ability not to feel pain, mental time travel, and grows emotionless and ruthless. Once she reaches 100% of her brain’s capacity she disappears, and becomes one with with the spacetime continuum.
While very intriguing, the 10% idea has unfortunately been thoroughly debunked. Despite our current understanding of full-brain utilization (discussed below), the 10% of the brain myth is still considered true by a significant proportion of people. Even The Hangover actor/comedian, and medical practitioner Ken Jeong in an episode of Hot Ones was asked if the myth “we use only 10% of the brain was true?” to which he replied “Yes that number does sound right 10-15%, it does sound right but I don’t know the exact percentage”. This is just one example of even medical professionals being prey to such popular myths. So where exactly did this neuromyth come from?
Neuromyth origin and persistence
The origin of some neuromyths is easier to trace than others, and this one lies on the harder side. Some neuromyths originate in distorted, outdated, or misinterpreted scientific results, but it is not precisely known where this neuromyth was born. Pasquinelli (2012) proposed that this neuromyth may stem from parapsychological beliefs and considerations of the untapped potential of the human psyche. It may also be inspired by work on glia-neuron rates, or research into differences between grey and white brain matter. It also seems as though this myth has been around since the early 1900s and was perhaps made popular by self-help books promoting ways to reach “your full potential”. Whatever the case may be, the birth of this neuromyth is not as scary as the fact that it still persists, even after a myriad of solid contradicting evidence. The OECD (2002) has described some common neuromyths with the 10% myth being named as the most prevalent misconception among the public. This myth is commonly taught in schools, and a frequent plot in popular media, including movies and TV shows. The 2011 movie Limitless and 2015 spin off TV show (both based on the novel The Dark Fields) for example, feature a writer who takes an experimental drug which allows him to access 100% of his brain’s power and become a high-powered business broker. Again, although an interesting fictional story, it’s far away from the truth about brain function. The interesting catch here is that through years of myth persistence, this popular neuromyth has morphed into several notions. One notion states that “we only use 10% of our brain’s POWER“, another states that “we use 10% of our brain’s CAPACITY“, and then there is the more general belief that “we use 10% of our brains“. Through various scientific misinterpretations, anecdotal reiterations, and popular media features, this myth has been contorted to mean “we do not use our entire brains“.
Have you heard about neuromyths before?
Click the button below to find out more about what neuromyths are and how they persist.
The truth about your brain
So how much of your brain do you actually use? It may be hard to believe to some extent, but we use all of it. The truth is that a typical brain uses 100% of its capacity.
Think about it for a minute, if you are sitting in front of your computer reading this article, you are required to use your senses (e.g. see), read text, decode and understand what you are reading, think, move (perhaps to shift your position or scroll through this page), remember what you have previously seen or read, and countless other tasks.
At any given time of the day, you are required to intake and decode information from various sources, speak, move, use your senses, pay attention to things, remember past events, feel emotions, learn new things, drive a vehicle etc. All of these activities, require your brain to be engaged across multiple modalities, and function seamlessly at 100% capacity. Not to mention, for functions such as breathing and the beating of your heart, your brain is always engaged. Your brain is active fairly constantly actually, even while sleeping. Although some areas of your brain may be more active at certain times than other parts, there are no areas that ever go completely dark without any activity.
Picture this scenario: Peter and Parker standing and facing each other while having a conversation. Peter is telling Parker a cool story about something that happened the day before, and Parker is listening. For Peter, brain areas that are involved in speech production, vision, and hearing among others, will be more metabolically active. These may include the left inferior frontal gyrus (Broca’s area), and some motor and subcortical areas (e.g. basal ganglia). Parker on the other hand is listening to Peter’s story and starts jumping with excitement. For him, regions involved with listening, language comprehension, and gross motor movements, will be slightly more metabolically active than others. These may include Heschl’s gyrus, the superior temporal cortex, ventral anterior temporal lobe, the motor cortex, and cerebellum, among others. While different brain regions will show varying activity, both Peter’s and Parker’s whole brains will be metabolically active at all times performing a plethora of tasks.
When Dr Rebecca Segrave, a clinical neuropsychologist and a senior research fellow at Monash University was asked about this topic, she said “the entire brain is active at all times- even when we’re asleep, we’re using our whole brain.” She also reiterated that even though our brain makes up 2-3% of our body weight, it uses up to 20% of our daily energy, but this is a topic for another time!
How do we measure brain activity?
As popular as the 10% myth is, nowadays the truth about brain activity is becoming common knowledge. Even prior to the release of Lucy many media sources featured the debunking of this neuromyth. So when Lucy came out, there were actually many fans who criticised the movie for perpetuating the myth even further. Nowadays, there are a plethora of online sources, articles, videos, and other materials addressing this neuromyth, mainly at the effort of neuroscientists. Since the 1880s brain imaging techniques have been in development, but it wasn’t until the 1980s and 1990s that we finally got the ability to directly observe brain activity with the most refined techniques. Two of the most commonly used techniques are functional Magnetic Resonance Imaging (fMRI) and Positron Emission Tomography (PET).
Functional Magnetic Resonance Imaging (fMRI)
fMRI is a special type of magnetic scan which measures brain activity by detecting changes in the amount of oxygen in the blood, and also the amount of blood flow that occurs with neural activity. This is also known as blood-oxygen-level-dependent activity (BOLD activity). In this sense, BOLD activity is a convenient stand-in for brain activity. Like other cellular processes in the body, neural activity requires energy, which is generated by using oxygen to break down sugar. Therefore, when neural activity is higher more energy is being used. When a certain brain region is active, hence using more energy, more oxygen-rich blood is transported to that brain region in order to meet the energy demand. Oxygen in the blood is being carried by a molecule called haemoglobin, which contains iron. Iron is a metal with magnetic properties, so the brain region to which oxygen-rich blood is being transported is going to be slightly more magnetic. fMRI enables us to create brain activation maps using the different patterns of electromagnetic waves, that help us visualise the activity of different brain regions during various mental processes. Here is a short video detailing how the machine exactly works.
Positron Emission Tomography (PET)
A Positron Emission Tomography (PET) scan is used to visualise the metabolic or biochemical function of tissues and organs, including the brain. A small amount of a radioactive compound or dye, called a tracer, is injected into the blood stream, which then binds with either oxygen or glucose in the blood, depending on what type of tracer is being used. The idea behind the PET scan is similar to that of the fMRI described above: more neural activity, more energy needed, more oxygen needed, more glucose being metabolised. Sensors in the PET scanner can detect the radioactive compound, as is being accumulated in different regions of the brain, depending on the energy demand for cell metabolism. The data is then used to create multicoloured two- or three-dimensional images depicting brain metabolism. Here is a short video explaining the process in more detail.
I found a great visual comparison addressing the 10% myth, on the Association for Psychological Science website. I took the images below from a lesson plan on several topics about the brain and behaviour, posted on their website. These images are of a PET scan, where warmer colours represent more activity, and the blue outline is the skull.
If you slide the slider completely to the left, you will see a scan depicting typical brain activity, or metabolism. You will notice that the entire brain is active, although some parts show more activity than others, as demonstrated by the different colours (more activity shown by warmer colours). If you slide the slider completely to the right, you will see what our brain activity would actually look like if we used only 10% of our brains. The majority of the organ would not show any metabolic activity and be completely dark, but this is not the case.
In a nutshell, next time you see certain drinks or products that claim they can unlock the full potential of your brain, you will know it’s a marketing scam, because as we have seen today, your brain is functionating at its full capacity.
Know a myth that needs busting?
If you know a neuromyth that we haven’t covered yet, or if you simply want to fact check your neuroscience knowledge, let us know via our socials, or leave us a message below.
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Amanamba, U., Sojka, A., Harris, S., Bucknam, M., & Hegdé, J. (2020). A Window Into Your Brain: How fMRI Helps Us Understand What Is Going on Inside Our Heads. Frontiers For Young Minds, 8. doi: 10.3389/frym.2020.484603
Dekker, S., Lee, N. C., Howard-Jones, P., & Jolles, J. (2012). Neuromyths in education: Prevalence and predictors of misconceptions among teachers. Frontiers in Psychology, 3(429), 1–8. doi:10.3389/fpsyg.2012.00429
Mayo Clinic. (2021). Positron emission tomography scan. Retrieved from https://www.mayoclinic.org/tests-procedures/pet-scan/about/pac-20385078#:~:text=A%20positron%20emission%20tomography%20(PET)%20scan%20is%20an%20imaging%20test,normal%20and%20abnormal%20metabolic%20activity.
NIDA. (1996). The Basics of Brain Imaging. Retrieved from https://archives.drugabuse.gov/news-events/nida-notes/1996/12/basics-brain-imaging
Organisation for Economic Co-operation and Development (OECD). (2002). Understanding the brain: Towards a new learning science. Paris, France
Pasquinelli, E. (2012). Neuromyths: Why Do They Exist and Persist?. Mind, Brain, And Education, 6(2), 89-96. https://doi.org/10.1111/j.1751-228x.2012.01141.x
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