In this blog post, we explore the origins of the myth that we only use 10% of our brain and examine the scientific facts to determine its truth in an easy and interesting way.
“Most people use only 5 to 6% of their brain. But I use 7%.” This is often attributed to the famous scientist Albert Einstein, but in fact, he never said this during his lifetime. Nevertheless, it has become a phrase frequently quoted by many people and has influenced as many people as Albert Einstein’s theory of relativity. The idea that humans use only 10% of their brain during their lifetime has spread as if it were established fact. So, do humans really only use 10% of their brain during their lifetime?
To get straight to the point, this rumor has no basis. Even scholars who study the metabolic activity of brain cells unanimously state that there are no non-functional areas in the brain. Fundamentally, nearly all of the brain’s neurons are utilized. The 100 billion brain cells in the human brain are each connected to at least 10,000 other cells and are busily performing their roles. However, not all areas of the brain are activated simultaneously. Barry Gordon, a neurologist at Johns Hopkins University School of Medicine, explains, “Humans actually use all parts of the brain, and most areas are almost always active. But at specific moments in a person’s life, such as when we are simply resting, we might be using only about 10% of our brain.” In other words, while humans use the entire brain throughout their lives, the whole brain is not used at every moment; specific brain regions activate according to the needs of the moment.
Brain imaging data also provides solid evidence that humans use the entire brain. Studies using imaging devices like PET (positron emission tomography), CAT, and fMRI show that there are no dormant areas in the brain. It is said that even when examining individual neurons (nerve cells) or cells within the brain, no inactive ones can be found. John Henry, a neurologist at the Mayo Clinic (Rochester, Minn), presented research findings using imaging devices and stated, “These imaging data show that humans use 100% of their brain even in a single day.” Even while a person sleeps, the prefrontal cortex, responsible for higher-order thinking and self-awareness, and the somatosensory system, which enables humans to perceive their surroundings, remain active.
In fact, brain activity does not decrease significantly during sleep. While dreaming, the brain plays a crucial role in processing sensory information and organizing memories. During this process, multiple brain regions become active, particularly those involved in visual experiences and emotional processing. Therefore, the fact that humans use a significant portion of their brain even during sleep provides further evidence refuting the myth that we only use 10% of our brain.
The myth that humans only utilize 10% of their brain can also be refuted from the following developmental perspective. When the nervous system first forms, the brain develops numerous synapses—the junctions connecting neurons. However, after a baby is born, many of these synapses are eliminated. The synapses that are eliminated are those that are not used due to a lack of consistent stimulation. In fact, the human brain is designed to eliminate synapses if appropriate stimulation is not continuously applied to them. The developmental principle that unused organs are eliminated and lost applies equally to the nervous system. This was proven experimentally by Nobel laureates David H. Hubel and Torsten N. Wiesel. Their experiments demonstrated that if visual information (appropriate stimulation) is blocked during the early developmental stages of the nervous system, the visual ability itself is permanently lost. Therefore, from a developmental perspective, if 90% of the brain were unused, the neural synapses in that portion should have disappeared. However, since synapses are actually distributed throughout the entire brain, the common misconception that humans use only 10% of their brain is untenable.
That said, it is true that the brain is not yet operating at 100% of its capacity. According to theoretical neuroscientist Dr. Dmitri Chklovskii, the number of synapses in the cerebrum is less than 30% of the maximum allowable capacity. Theoretically, the cerebrum still has about 70% unused synaptic capacity. To summarize, while nearly all brain cells are active, the connections between them are not yet saturated. This leaves room for human learning and adaptability, meaning humans can still expand brain function through new experiences and learning. Thus, the brain possesses the potential for continuous development through experience and learning.
The common misconception that humans use only 10% of their brain stems from a statement by 19th-century psychologist William James: “The average person uses 10% of their brain, while a genius uses 15-20%.” This was misinterpreted during subsequent explanations. Later, in the early 20th century, self-improvement lecturers frequently cited this theory to preach to audiences about the infinite potential of human beings. This led to the claim spreading widely among the public as if it were truth. However, humans use their entire brain and, furthermore, possess the ability to utilize various brain regions appropriately and effectively.
In fact, when discussing brain usage and potential, what matters is not merely the quantitative aspect but the qualitative one. That is, how efficiently specific parts of the brain are activated is the more crucial issue. For instance, during complex mathematical calculations or learning a new language, particular brain regions become highly active. At such times, specific neural circuits are intensively engaged, while other parts may be relatively less active. These brain regions, activated differently depending on the situation, are what enable humans to demonstrate superior concentration and creativity in specific activities.
Ultimately, the fact that humans use the entire brain is not a limiting factor on human potential. Rather, it is the driving force that has enabled human progress thus far and will serve as a pivotal stepping stone for future leaps. Furthermore, the human brain possesses the capacity for continuous change and growth. This potential suggests infinite possibilities for how much more potential we can unlock in the future. Scientists are still in the process of unraveling the brain’s mysteries, and as we learn more about the brain, its potential applications will continue to expand.
