The idea that only a small portion of our brains, like say, 10%, is actually used, can be found throughout our culture, and the idea implies that most of it goes unused, allegedly about 90%.
It’s difficult to pin down the exactly whence this comes, with many possibilities to consider. It may be from misquotes of Einstein, perhaps even statements by William James, or any number of other well-known authoritative figures. As may be expected, alleged psychics sometimes claim that psi-abilities come from the remaining 90% and this maintains the general public’s continued belief in psi.
The idea’s been kept going over the years by advertisers, credulous journalists, self-help gurus, a lot of popular fiction.
In actual brain-scans using the most recent techniques, it’s obvious that ALL of the brain is in use, with to each region its own uses, like unconscious activity crucially needed just to maintain life, thought, perception, and memory among many other important functions.
Removing parts of the brain inevitably disables function. The entire thing has some use, with some regions less active than others at any given moment. The brain is a ravenous organ, taking about 20% of the body’s energy usage, tremendous resources for a single organ allegedly mostly unused.
If the other 90% weren’t used at some time, then it just wouldn’t grow. That’s because the brain grows according to how it’s used, and such a brain would be a mere 10% of what it really is. Bodily use maps upon the growth and plasticity of the brain.
Brain regions never used, like the visual cortex for those blind throughout life, never get the opportunity to grow. Even with the functioning of the eyes, such brains don’t have the processing power to let them use what the eyes ‘see.’
The brain is an absolutely amazing organ; it’s a three pound mass of jelly that lets us ponder the nature of the universe, contemplate meaning and infinity, and can even think about itself thinking. So it’s a myth that only about 10% – 12% is ever used, no matter how popular that myth may be.
Source: The Skeptics’ Guide 5×5 | The 10% of the Brain Myth