Tue, 20 May 2025 14:41:20 -0700WeeblyMon, 22 Apr 2013 15:35:54 GMThttps://www.neuropsyfi.com/frequently-asked-questions/the-10-use-of-the-brain-mythWritten by Tim Daly

The idea that  humans only use 10% of their brains has been around for more than half a century.  Believing that we all have a hidden reserve of intelligence and ability waiting to be unlocked is an appealing idea, and was depicted in the movie Limitless (201), but unfortunately evidence suggests otherwise. The origin of this myth can be traced back to a statement given by psychologist Williams James in the early 1900s.  James commented on the common problem of people achieving far less than that of which they are potentially capable (Della Sala, 2007).  Years later, in the preface to Dale Carnegie’s How to Win Friends and Influence People, Lowell Thomas reported on James’ statement, saying:

“Professor William James of Harvard used to say that the average person develops only 10 percent of his latent mental ability. Dale Carnegie, by helping business men and women to develop their latent possibilities, created one of the most significant movements in adult education.” (1936)

Carnegie’s book went on to become a best seller, and Lowell Thomas’s interpretation lives on today.

It is true that an overwhelming portion of the brain is made up of glial cells, rather than neurons.  Glial cells outnumber neurons 10:1, and are vital to maintaining a healthy environment in which neurons can function.  There are different types of glial cells, each with its own specialized function.  Some of these functions include providing physical structure for surrounding neurons, delivering nutrients, and creating the myelin sheath around neuronal axons to speed up signals (Zillmer, Spiers, & Culbertson, 2008).  Glial cells were previously thought only to act as a support system for neurons; however, as techniques for studying the functions of glial cells advance, researchers are finding evidence suggesting that glial cells can actively communicate with each other, communicate with neurons, and modify neuronal signaling (Nedergaard, 1994; Araque, Carmignoto, & Haydon, 2001). 

Neuropsychologists have long relied on brain injuries to help contribute to their knowledge of the brain, and the functions of its many parts.  If most people only used 10% of their brain, one could reason that damage to much of the brain would result in no effect.  This is certainly not the case as seen in people injured as a result of stroke and traumatic brain injuries.  Even the slightest damage can cause dramatic effects.

 Today, modern imaging techniques, such as fMRI, allow researchers to see the brain working in real time.  Functional Magnetic Resonance Imaging detects changes in blood oxygenation throughout the brain, showing which areas are activated at a given time.  Using this technique, researchers haven’t found any parts of the brain that remain inactive (Lilienfeld, Lynn, Ruscio, & Beyerstein, 2011).  

References

Araque, A., Carmignoto, G., & Haydon, P. G. (2001). Dynamic signaling between

astrocytes and neurons. Annual Review of Physiology, 63(1), 795-813.

Carnegie, D. (1936). How To Win Friends And Influence People.

Della Sala, S. (Ed.). (2007). Tall tales about the mind and brain: Separating fact from

fiction. Oxford University Press, USA.

Lilienfeld, S. O., Lynn, S. J., Ruscio, J., & Beyerstein, B. L. (2011). 50 great myths of

popular psychology: shattering widespread misconceptions about human behavior. Wiley-Blackwell.

Nedergaard, M. (1994). Direct signaling from astrocytes to neurons in cultures of

mammalian brain cells. Science, 263(5154), 1768-1771.

Thomas, L. (1936).  A Shortcut to Distinction. In D. Carnegie, How to Win Friends and

Influence People.

Zillmer, E., Spiers, M., & Culbertson, W. C. (2008). Principles of neuropsychology.

Wadsworth Publishing Company.



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