“Humans only use 10% of their brains”

The enduring notion that humans access only a small fraction of their brainpower, often cited as ten percent, likely originated from misinterpretations of early psychological theories. Harvard psychologists William James and Boris Sidis, in the late 19th and early 20th centuries, explored the concept of "reserve energy," suggesting that individuals only tap into a portion of their full mental potential. This idea, which is a plausible claim about cognitive efficiency, was then sensationalized and distorted, leading to the precise but inaccurate "ten percent" figure. Popularized by the self-help movement and figures like Lowell Thomas in the foreword to Dale Carnegie's book, the myth became widely accepted.

Modern neuroscience, however, offers a clear refutation. Advanced brain imaging techniques, such as fMRI and PET scans, demonstrate that virtually all parts of the brain are active, even during seemingly simple tasks and during sleep. There is no area of the brain that can be damaged without some functional consequence; even minor injuries can lead to significant impairments, which would not be the case if ninety percent of the brain were unused. Furthermore, from an evolutionary perspective, it would be highly inefficient for an organ that consumes about twenty percent of the body's energy to remain largely dormant.

The allure of this myth lies in its inspirational message: the exciting prospect of unlocking vast, untapped intellectual abilities. This idea fuels fantasies of heightened intelligence or extraordinary powers, as seen in various popular culture depictions. The desire for self-improvement and the belief in hidden potential contribute to the myth's persistence, making it a compelling, albeit incorrect, notion about human capacity.