Human Intelligence

Do we really use only 10 percent of our brains?
Answered by Lu Fong and Discovery Channel
  • Lu Fong

    Lu Fong

  • Discovery Channel

    Discovery Channel

  1. The 10 percent myth is an amazingly attractive idea. It essentially makes each one of us untapped geniuses -- idiot savants who could compose complex symphonies or rattle off a thousand digits of pi if only we could access that unused treasure trove of grey matter. It’s the seductive concept that drove this summer’s hit film, "Limitless" -- a movie about a pill that unlocks that secret part of a person’s brain [source: Kaufman].

    Unfortunately, the movies are the only place that this myth is true. Traced back to psychologist William James who claimed that we’re only making use of “a small part of our mental and physical resources,” the assertion has been warped and bastardized to the point where most people wrongly consider it a hard fact of our neurology.

    Another culprit in this scientific tall tale could be an 18th-century neurosurgeon named Wilder Penfield who spearheaded a now famous series of experiments bent on curing epilepsy. His methods involved actually destroying the part of the brain he believed was causing the seizures. (Be grateful you weren’t sick in the 18th century.)  Penfield found that massaging parts of the brain with an electrode could elicit a rainbow of responses from involuntary muscle movement to vivid hallucinations. One patient claimed she was transported to a delightful concert in London. Yet, others would exhibit no obvious effect. So the assumption at the time was that these parts of the brain weren’t doing anything [source: Morsella].

    The fact is that our brains can’t afford to be that idle. Though it’s true that not all of our brain is completely active at every given moment, brain-imaging technology has proven that most of our brain’s neurons are functioning at a variety of levels, 24 hours a day [source: Boyd]. Doing what? Oh, just keeping us alive.

    Researchers at the National Academy of Sciences USA have found that two thirds of your brain’s energy is busy making sure that the brain itself can function. After all, neurons are energy-sucking little devils. Your brain alone accounts for 20 percent of where you expend your body’s energy -- making it the most energy-intensive organ of your body. But without neurons firing, the body wouldn’t be able to function, so the expense is worth it [source: Swaminathan].

    The most compelling arguments against this myth, though, are brain-injury patients themselves. Talk to someone who’s suffered damage to just one section of the cerebellum and you’ll quickly dispel any fable that we don’t desperately need every part of our brain. Minor brain damage to a minute portion of your brain can do anything from prevent smooth motor function to wiping out all short-term memory to drastically altering your artistic vision [sources: Wang and Dobbins]. In short, our brains are delicate creatures. The idea that any part of its carefully balanced infrastructure could be just “hanging out” is wishful thinking at best.



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  2. Sorry to disappoint you, but you don't have an unused 90 percent of your brain that you can tap into to become another Albert Einstein. You have to ask yourself: Why would you have 100 percent of a brain if you only can use 10 percent of it? It seems like such a waste. The 10 percent myth was originally attributed to an early 20th-century psychologist named William James, who was quoted as saying: "The average person rarely achieves but a small portion of his or her potential." Each of us has may have had a teacher tell our parents that we weren't "performing up to our potential." That might be so, but it wasn't because only 10 percent of our brain was in use at the time.

    Our brains are filled with individual nerve cells called neurons that are connected to one another by appendages called axons and dendrites. Every time you move, think or feel, the differences in electrical potential between ions on the surface membranes of these neurons generate electrical impulses that travel from neuron to neuron. Even when you sleep, some of the brain is at work, although the brain needs the downtime to rest up for more active work when the mind is alert and the body's moving around. Still, during sleep, areas such as the frontal cortex remain active. This area of the brain helps control higher-level thinking and how we sense our surroundings [source: Scientific American].

    There are about 100 billion neurons, or nerve cells, in the human brain that carry the messages to help the brain and body function. With so much going on, it's no wonder that brain scans have proven that the human brain is always working. That means all of it -- helping us to execute the many tasks we perform as we go about our days.

    Neuroscientists have begun to understand how the brain's neurons work, but as important as they are, they make up only about 10 percent of our brains. Glial cells make up the other 90 percent. All that's really known about glial cells is that they house and support neurons. So it's probably more accurate to say that we understand only 10 percent of our brains, even though we use the entire organ.

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