Myths and famous claims
Do we only use 10% of our brain?
What is documented
People use virtually all of their brain, not 10%. PET scans show the entire brain is constantly active, even during sleep, and a neurologist told Scientific American that over a full day a person uses 100 percent of it. The brain is about 3 percent of body weight but uses about 20 percent of the body’s energy.
Want your own number? The test is 25 visual puzzles, about 12 minutes, no sign-up.
The myth
The claim is that humans use only 10% of their brains, and that the other 90% is idle capacity that the right technique, pill or program could switch on.
The short verdict
It is false. Neurologist Barry Gordon of Johns Hopkins told Scientific American that the myth is "so wrong it is almost laughable" (Boyd, Scientific American 2008). The brain uses virtually all of its parts, and a Mayo Clinic neurologist said that over a full day a person uses 100 percent of the brain.
What the evidence shows
- Imaging. The Association for Psychological Science notes that PET scans show the entire brain is constantly active, even during sleep (Chew, 2018 (APS)). No large region sits unused.
- Energy. The brain is about 3 percent of body weight but uses about 20 percent of the body's energy (Boyd, Scientific American 2008). An organ that expensive is not 90% idle.
- Intelligence is spread out. Research on brain and intelligence points to distributed networks, not a hidden reserve. Jung and Haier's review of 37 imaging studies proposed a network linking frontal and parietal regions with parts of the temporal and occipital lobes (Jung & Haier, 2007).
Try one · Quantitative Reasoning
Which number comes next?
1, 5, 12, 22, 35, 51, ?
Tap the option you think is right, or show the answer.
Show the answer
The next number is 70 (option 6).
How to solve it
- Find the gaps between neighbors: 4, 7, 10, 13, 16.
- The gaps between the numbers grow by 3 each time.
- So the next gap is 19, and 51 + 19 = 70.
That was 1 puzzle. The full test has 25.
Where it came from
No one knows exactly who started it. It has been linked to psychologist William James and falsely attached to Einstein (Boyd, Scientific American 2008). The APS traces one version to a misreading of a 1907 essay by James that does not claim we use only a small part of the brain (Chew, 2018 (APS)). The Einstein connection is part of a wider pattern of made-up Einstein stories, like the claim that he failed math.
Why it persists
The myth is common even among people who care about the brain. In a survey of 242 UK and Dutch teachers interested in neuroscience, 48% of the UK teachers and 46% of the Dutch teachers endorsed the statement that we only use 10% of our brain (Dekker et al., 2012). On average the teachers believed 49% of the neuromyths in the survey, and those with more general knowledge about the brain were more likely, not less, to believe them. Knowing some brain facts, it seems, does not protect against appealing brain fiction.
What is actually true
The real relationship between brain and intelligence is modest and complicated. A meta-analysis of 88 studies with more than 8,000 people found a positive link between brain volume and IQ of r = .24, and its authors concluded that brain size should not be treated as a stand-in for intelligence differences (Pietschnig et al., 2015). There is no switch to flip. The page on brain and intelligence covers the research in more depth.
Related myths include left-brained and right-brained people and the promise that brain training games raise IQ. If you want to see how you reason on visual puzzles, try the free puzzles.
Sources
- Boyd, R. (2008, February 7). Do People Only Use 10 Percent of Their Brains? Scientific American www.scientificamerican.com/article/do-people-only-use-10-percent-of-their-brains/
- Chew, S. L. (2018, August 29). Myth: We only use 10% of our brains. Association for Psychological Science. www.psychologicalscience.org/uncategorized/myth-we-only-use-10-of-our-brains.html
- 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. doi.org/10.3389/fpsyg.2012.00429
- Pietschnig, J., Penke, L., Wicherts, J. M., Zeiler, M., & Voracek, M. (2015). Meta-analysis of associations between human brain volume and intelligence differences: How strong are they and what do they mean? Neuroscience & Biobehavioral Reviews, 57, 411-432. doi.org/10.1016/j.neubiorev.2015.09.017
- Jung, R. E., & Haier, R. J. (2007). The Parieto-Frontal Integration Theory (P-FIT) of intelligence: Converging neuroimaging evidence. Behavioral and Brain Sciences, 30(2), 135-154. doi.org/10.1017/S0140525X07001185