Ten percent of the brain myth

The 10 percent of the brain myth is a widely perpetuated urban legend that most or all humans only use 10 percent (or some other small percentage) of their brains. It has been misattributed to many people, including Albert Einstein. By extrapolation, it is suggested that a person may harness this unused potential and increase intelligence.

Changes in grey and white matter following new experiences and learning have been shown, but it has not yet been proven what the changes are. The popular notion that large parts of the brain remain unused, and could subsequently be "activated", rests in popular folklore and not science. Though mysteries regarding brain function remain—e.g. memory, consciousness—the physiology of brain mapping suggests that all areas of the brain have a function.

One possible origin is the reserve energy theories by Harvard psychologists William James and Boris Sidis in the 1890s who tested the theory in the accelerated raising of child prodigy William Sidis; thereafter, James told audiences that people only meet a fraction of their full mental potential, which is a plausible claim. 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". This book was not the first to use the 10 percent figure, which was already circulating within the self-help movement before then; for example, the book Mind Myths: Exploring Popular Assumptions About the Mind and Brain includes a chapter on the ten percent myth that shows a self-help advertisement from the 1929 World Almanac with the line "There is NO LIMIT to what the human brain can accomplish. Scientists and psychologists tell us we use only about TEN PERCENT of our brain power."

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". The origin of the myth has also been attributed to Wilder Penfield, the U.S.-born neurosurgeon who was the first director of Montreal Neurological Institute of McGill University.

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