Do we only use 10% of our brains?

If you’re feeling bored on a Friday night, a fun and entertaining way to spend your time would be to watch the movie “Lucy”. Starring Scarlett Johansson, the movie follows a young woman who unlocks 100% of her brain’s potential, allowing her to exhibit extraordinary mental and physical abilities. This movie is based off of the popular myth that humans only use 10% of their brain’s true capacity - and, while it makes for good movies, this statement is a laugh in the face of science.

There are multiple ways scientists have debunked this myth. To break it down, the claims that we only use 10% of our brains imply that the other 90% isn’t doing anything to aid the body’s functioning. This is a problem for 2 reasons. Firstly, and most obviously, if we only need 10% of our brains for basic functioning, that means that the majority of brain injuries, which would damage the other, “useless”, 90%, would have no actual consequences on our ability to function. However, perhaps an ever stronger argument lies in the fact that those propagating the myth are also claiming that 90% of a bodily organ is useless. This immediately reveals the flaw in their argument, as natural selection disallows the development of useless and futile anatomical components. Moreover, all humans have devoted large amounts of resources and nutrients to developing and maintaining the excessive amounts of brain tissue that comprise a massive 3% of the body’s weight. Why waste time building and fueling an organ that is never going to get used? Couldn’t our brains then be reduced to consist of only that 10%?

Another way scientists have proven this myth to be false is through PET (Positron Emission Tomography) and fMRI (functional Magnetic Resonance Imaging) scans. These tests have become more standardized in the last 3 decades, allowing researchers to track the functioning of the brain and revolutionizing our understanding of how this complex organ works. For example, PET scans have been used to detect the activity in different regions of the brain during different periods of use. For this to happen, a radioactive substance called a tracer is injected into the patient to show any chemical and functional changes in the brain. These changes cannot be seen through any other methods of scanning as PET scans provide an unparalleled level of detail in their imaging. As the brain works, and the tracer is metabolized, small particles called positrons are emitted. As the activity in one segment of the brain increases, so does the positron emission, allowing scientists to see spikes in different regions of the brain during functioning. Sensors in the PET scanners then detect the positrons and a computer works in tandem with the technology to produce a 3D model of the brain based on the concentration of positrons. If the 10% theory was true, most of the brain would constantly be dark, showing no positron emission as a result of the lack of activity. However, PET scans show all regions of the brain to be constantly active, even when the person is sleeping. This proves that the brain is constantly thinking, regulating, monitoring, sensing, interpreting and acting. 

Attributed roughly 20% of the body’s total energy, the brain allocates energy to its 3 main parts proportional to their jobs. The largest area of the brain, the cerebrum, performs higher cognitive functions, ranging from problem solving to decision making, language to memory. The cerebellum controls motor functions, encompassing more simplistic daily actions like buttoning a shirt or turning a doorknob. Finally, the brainstem controls involuntary functions, such as breathing and heart rate. Majority of the 20% of energy dedicated to the brain is divided across these 3 main verticals, and the remaining energy is used to control other activities - both conscious and unconscious. Hence, the entire brain is involved in the body’s functioning, and almost every part of the brain is constantly active and operational.

So where did this myth even originate? It is most commonly speculated that the myth stems from a statement made by 19th-century psychologist William James in an article - “We are making use of only a small part of our possible mental and physical resources”. Although people have made their own interpretations of this, James simply points out the untapped potential of humans, seemingly attributing it to the lack of stimulating social environments and interactions that do not fully engage people. James does, in no way, declare that a certain percentage of our brain is being dismissed and unutilized. Furthermore, barring popular culture and the media’s strong reinforcement of this myth, the misconception is mainly supported by people’s beliefs about their own brains. People tend to see their own mental “fogginess” or unclarity, coupled with other shortcomings, as proof of some unexplored potential of the brain. While that is an entirely inaccurate belief, it does carry a certain ring of truth. This is because, at certain moments in a person’s life, their brains will be at a stage of rest and contemplation, where all regions are not active and not needed for functioning. 

By Asha

Works Cited

“Brain PET/CT Scan | Boston Children’s Hospital.” Www.childrenshospital.org, www.childrenshospital.org/treatments/brain-pet#:~:text=Positron%20emission%20tomography%20(PET)%20is.

Chew, Stephen L. “Myth: We Only Use 10% of Our Brains.” Association for Psychological Science, 29 Aug. 2018, www.psychologicalscience.org/uncategorized/myth-we-only-use-10-of-our-brains.html.

The Editors of Encyclopaedia Britannica. “Do We Really Use Only 10 Percent of Our Brain?” Encyclopædia Britannica, 2019, www.britannica.com/story/do-we-really-use-only-10-percent-of-our-brain.