In 1848, the foreman of a railway construction crew in Vermont suffered a serious accident that sent a 3½-foot metal rod through his head. It destroyed a large part of his brain's frontal lobe. Despite this terrible injury, the man, Phineas Gage, survived. In fact, he reportedly stood up just after it happened and talked with those trying to help him.

If a person has a significant brain injury and is still able to function, how important could that injured area be? Could that part of the brain be unused? Does this anecdote lend credence to the claim that the average person uses just 10 percent of the brain?

Actually, the brain is a rather unforgiving organ. Gage’s story is a fluke. That’s probably why it’s told so often--there are few such stories to report. And serious disability after suffering significant brain trauma is not nearly as fascinating, though much more common.

The brain doesn't tolerate injury well and doesn't heal nearly as well or as quickly as other body parts. Although the Gage story shows that remarkably large portions of the brain can be damaged with relatively little immediate effect and that a person may return to a normal life, this is rare. Typically, personality changes, behavioral problems and other, more serious neurological damage occurs with brain damage, tumors, surgery, stroke or other brain disease. Gage was just lucky, it seems.

And it’s not as if the injury didn’t affect Gage at all. Before the accident, he was described as highly competent, efficient and shrewd. After his recovery, he was reportedly impatient, indecisive, inconsiderate and even anti-social. He soon developed seizures, and died 12 years after the accident at age 37.

The 10 percent myth

It is true that many organs have more capacity than we actually need on a day-to-day basis. You can have an entire lung or kidney removed and get along fine without them. You can do without your appendix, your thymus and your spleen. There's skin, intestines and bone marrow to spare, as well.

But that's not true of the brain. Brain scans, such as magnetic resonance imaging (MRI) or positron emission tomography (PET) show that humans regularly use all of the brain. Some parts may be more active at any given time or during a particular activity. Some parts of the brain may be less critical than others for vital functions, such as breathing, speaking, understanding or walking. But no part of the brain is known to be completely unused or unnecessary.

I’m not sure where the “10 percent myth” came from, but I do know that when the myth first began, doctors and scientists had no reliable way to measure how much of the brain was used. Even now, MRI and PET scans don't provide a perfect estimate of how much of the brain is being used at any one time. After all, it's not as if we can count brain cells and measure their activity like we can count hits on a Web site. Plus, when an area of the brain is active during a particular activity, not every cell in that area is being used. But that’s not the same as saying that those cells are never used.

Brain size: Does it matter?

You might think that the bigger the brain, the smarter the person. After all, humans are smarter than squirrels, and our brains are much larger than theirs. Alas, the comparison of size and smarts does not hold up when comparing one human to another.

Rumor has it that Albert Einstein's brain was remarkable for its unremarkable size and shape. It looked much like every other human brain.

However, as language and complex reasoning skills evolved in humans over time, brain size increased dramatically. This is a strong argument against the 10 percent myth. It defies logic and well-accepted scientific principles for an organ to increase in size over thousands of years if 90 percent of it was going unused—especially considering that the brain requires a good deal of blood flow and energy to keep running.

The reality

It might be true that the brain has underutilized parts, but it's unlikely that 90 percent is useless. If we had that much unused brain capacity, we should be able to withstand brain disease or damage pretty well. But we can't. So not only do we use all (or nearly all) of the brain, we don’t tolerate losing brain tissue very well.

I’ve heard psychics and fortune tellers use this 10 percent myth to explain their “powers” to predict the future, read minds or bend spoons without touching them. They say that they have tapped into this 90 percent of the brain that you or I can’t get to. As someone who doesn’t believe in psychics, I think this is just another of the many myths told as “facts everyone knows” to attract a bigger audience.

Even if small parts of the brain go unused, it's unlikely that anyone can enlist these unused areas to bend spoons or predict the future. That said, I have no proof that every brain cell is vital or what underutilized parts of the brain might be called on to do.  So if you want to spend your time trying to bend spoons with your mind, I can’t offer you scientific data proving that it’s a waste of your time and energy. I would just hope that the parts of your brain that you are using would help you find something more useful to do

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