The other day, while working with some high school students, one of them turned to me and started a question, "You know how we only use 10% of our brains...?" I cut her off right there. If the assumption that we only use a small portion of our brains was a premise for her question, then the question couldn't possibly be valid.
The 10% myth is incredible pervasive, considering how silly it is upon further inspection. Have you ever heard a neurosurgeon say something like, "Oh, well, the tumor's in your inactive brain area, so we're not going to worry about it?" Of course not, because that's not how the brain works.
First of all, in proportion to body size, humans have the largest brains of any animal, with a 1-to-50 brain weight to body weight proportion. As with all physical characteristics, this was shaped by natural selection. We adapted to have higher intelligence, by having larger and larger cerebral cortexes, the region of the mind used for problem solving, language, and abstract thinking. The cost of this is that it uses a lot of energy. Humans have to eat a lot in order to power our big brains, or we'll die. If we only used 10% of this grey matter, natural selection would quickly get rid of it.
- Brain Scans: ADHD Brain on Left, Normal on Right
We can also see how much of the brain gets used (source). Using PET or fMRI scans, we can watch a brain work. While not all of the brain is active all of the time, it's fairly active even doing the most simple tasks, like eating or sleeping. Even if all the neurons aren't firing, the glial and other support cells are active, and they make up a large percentage of the brain as well... far more than 10%. On top of that, damage to far less than 90% of the brain is incapacitating or fatal. Some proponents of the myth suggest that this is because only 10% of the brain is used for conscious functions, while the rest is subconscious. This isn't really supported by the data either, however; those same scans show that more of the brain "lights up" the more complex a task is occurring. Also, the idea that only 10% is conscious or active assumes the brain is very compartmentalized, that chunk of gray matter A does task A and only task A, and chunk B does something different. This isn't really accurate either. While some brain function is more or less focused in specific spots (the language center or vision center in the brain), it is not so black-and-white.
Besides simply being a major piece of misinformation, the 10% myth is important because it's a main argument of psychics and mediums. They flaunt this idea that the brain has huge untapped potential, and that scientists don't know how it works. Obviously, if you can just learn to turn on that unused portion, you too can have psychic abilities or superpowers. It's a comforting idea, to think that you can have more brainpower, in case of emergency. But from a scientific perspective, that's just not going to happen. The brain evolved to be used, not to sit dormant until magically being unlocked. The 10% claim is 100% myth.
Image from Wikimedia Commons
