The “10% brain” Myth

Let me state this very clearly:

There is no scientific evidence to suggest that we use only 10% of our brains.

It is quite remarkable that a handful of ideas from the field of neuroscience spread like wildfire through the popular media, thereby becoming part of our culture and worldview, while other ideas remain neglected, known only to a small group of experts. Since I was little, I always heard that humans use only 10% of their brains. To me, this idea agreed with the age-old notion that we as humans have great potential. Years later, I learned the 10% myth most likely arose from a misunderstanding (or misrepresentation) of neurological research in the late 19th century or early 20th century.

The popular notion that large parts of the brain remain unused, and could subsequently be “activated”, is not based on scientific theory. Several books, films, and short stories have been written closely related to this myth. They include the novel “The Dark Fields”, and its film adaptation “Limitless” (claiming 20% rather than the typical 10%), as well as the 2014 film “Lucy”, all of which operate under the notion that the rest of the brain could be accessed through use of a drug. Lucy, in particular, depicts a character who gains increasingly godlike abilities once she surpasses 10%.

A possible origin is the reserve energy theories by Harvard psychologists William James and Boris Sidis in the 1890s that theorized that people only meet a fraction of their full mental potential. In 1936, American writer Lowell Thomas summarized this idea (in a foreword to Dale Carnegie’s How to Win Friends and Influence People) by adding a falsely precise percentage: “Professor William James of Harvard used to say that the average man develops only ten percent of his latent mental ability.” In the 1970s, psychologist and educator Georgi Lozanov, proposed the teaching method of suggestopedia believing “that we might be using only five to ten percent of our mental capacity.” And it goes downhill from there. Another possible origin comes from misinterpretation of the classic research by the great Wilder Penfield (1891-1976), an American born neurosurgeon who was the first director of the world-famous Montreal Neurological Institute of McGill University.

Neurologist Barry Gordon describes the myth as laughably false, adding, “we use virtually every part of the brain, and that [most of] the brain is active almost all the time.” Neuroscientist Barry Beyerstein sets out seven kinds of evidence refuting the ten percent myth:

• Studies of brain damage: If 90% of the brain is normally unused, then damage to these areas should not impair performance. Instead, there is almost no area of the brain that can be damaged without loss of abilities. Even slight damage to small areas of the brain can have profound effects.
• Brain scans have shown that no matter what one is doing, brains are always active. Some areas are more active at any one time than others, but barring brain damage, there is no part of the brain that is absolutely not functioning.
• The brain is enormously costly to the rest of the body, in terms of oxygen and nutrient consumption. It can require up to 20% of the body’s energy—more than any other organ—despite making up only 2% of the human body by weight. If 90% of it were unnecessary, there would be a large survival advantage to humans with smaller, more efficient brains. If this were true, the process of natural selection would have eliminated the inefficient brains. It is also highly unlikely that a brain with so much redundant matter would have evolved in the first place.
• Brain imaging (neuroimaging): Technologies such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) allow the activity of the living brain to be monitored. They reveal that even during sleep, all parts of the brain show some level of activity. Only in the case of serious damage does a brain have “silent” areas.
• Localization of function: Rather than acting as a single mass, the brain has distinct regions for different kinds of information processing. Decades of research have gone into mapping functions onto areas of the brain, and no function-less areas have been found.
• Microstructural analysis: In the single-unit recording technique, researchers insert a tiny electrode into the brain to monitor the activity of a single cell. If 90% of cells were unused, then this technique would have revealed that.
• Neural disease: Brain cells that are not used have a tendency to degenerate. Hence if 90% of the brain were inactive, autopsy of adult brains would reveal large-scale degeneration.

 

Further reading for those who may be interested –

http://www.scientificamerican.com/article/do-people-only-use-10-percent-of-their-brains/

http://www.sciencedaily.com/releases/2009/10/091016114055.htm

http://web.archive.org/web/20060402235936/http://brainconnection.com/topics/?main=fa/brain-myth

http://www.psychologytoday.com/blog/consciousness-and-the-brain/201106/do-we-use-only-10-percent-our-brain

http://www.scientificamerican.com/article/why-does-the-brain-need-s/

http://web.archive.org/web/20081027004544/http://faculty.washington.edu/chudler/tenper.html