Humans only use 10% of their brains.
A widely repeated claim — used in self-help books, films like Lucy and Limitless, and casual conversation — suggests that the brain has vast untapped capacity and that humans use only a small fraction of it.
The evidence
Functional brain imaging shows activity throughout virtually all of the brain across a 24-hour period. Different regions specialize in different tasks, and even during sleep most regions remain active.
Neurologist Barry Gordon has called the 10% claim "so wrong it is almost laughable." Damage to almost any part of the brain produces measurable deficits, which would not be the case if 90% were unused.
The origin of the myth is unclear but it has been traced variously to misquoted remarks by William James and to early 20th-century self-improvement marketing.
Sources
- Do People Only Use 10 Percent of Their Brains? — Scientific American
“Evidence would show over a day you use 100 percent of the brain.”