10% of my brain?

I’m not sure if there is a definite answer to this, so it may be a GD (mods please move it if you think it’s appropriate), but here goes.

We got in a discussion in class today about computers that can think, and somehow that led into a tangent about humans using only 10% of their brain. So, here are my GQs.

1: Is this true?
-Is that 10% total, throughout our life, or 10% at any given moment? Example. If I am reading something, I am using 10%, but if I am writing something, I am still using 10%, only a different 10%.
-Does this add up to 100% over our life time, or is it still <100%?

2: If not true, then how much do we use?
-any given time?
I accidentally volunteered myself to find an answer to this from a reliable source, so any cites you have on the subject would be very helpful. Thanks a bunch!

Not true.



Uncle Cecil says it aint so

And if that ain’t enough…
Innumerable PET scans, often cited on TV (try the Discovery Health Channel) show electrical activity in the brain. Much of it is in action detectably most of the time.

Consider those who suffer physical damage to their brains; the famous case of Phineas Gage (iron tamping rod through the eye socket and frontal lobe), or former Press Secretary James Brady. If they only need 10 percent of their brains, then the damage shouldn’t have impared them at all.

It’s as meaningless a statement as it would be to look at a computer’s memory and say “hey, it’s a mixture of 1s and 0s; if we fill it entirely with 1s, it will work twice as well”

I think that’s the first Snopes article I’ve ever been disappointed in. While debunking the notion that the other 90% of our brains is a basis to support the idea of psychic abilities it doesn’t really say much about the 10% figure being correct.

Cecil does a better job in this respect but I find even his explanation a bit wanting.

Certainly PET scans and the like show activity all over the brain and someone with brain damage to even a relatively minor portion of the brain might show significant impairment.

However, I don’t believe anyone has addressed overall cognitive potential and if we truly live up to our full capacity. Some people are smarter than others. Did they just study harder in school or are they wired to make better use of their mind? Studying alone can’t account for all of it. Some people are downright naturally more intellectually capable than others. Doesn’t this argue that there is some spare, untapped capacity in the brain? While I’ll agree we have no objective way to know if this is true and just how far our untapped potential could go I still believe it is there.

Still not convinced? Try these links for a boy who had half his brain removed (literally half was completely removed). Today the boy shows very minor impairment (he has a slight limp) and is described as fairly bright. Being a child his remaining half a brain was able to takeover all the necessary functions of his missing half (an adult wouldn’t fare nearly as well with this procedure). If 1/2 the brain can effectively manage intellect, locomotion and all other brain functions I think it is safe to suppose that we don’t really use our brains to full capacity when we have both halves.

Half a Brain is Enough

A slightly better treatment of the boy with half a brain can be found at Cambridge Studies in Cognitive Perceptual Development (NOTE: This is a PDF file that requires Acrobat Reader to view)

I’m not sure that it follows that greater thinking capacity naturally follows as a simple result of increased brain activity (if we found some way to make that happen); the result could just as easily be hallucination or psychosis.

I would think the scientists were using 10% per cent of their brain when they came to that conclusion.

I’m not quite sure what you’re getting at with the hallucination part but I’ll posit two possibilities I see.
Assumption: George is a math whiz from age 3 and has been doing Tensors in his head since age 5. Doofy has trouble multiplying anything over the number 10 together in his head despite a college education.

  1. George is just ‘wired’ better for doing math. In effect George makes better use of the part of the brain that does math. It happens faster and more accurately than Doofy can manage. George effectively has greater capacity than Doofy. He can do more work in less time more accurately.

  2. George uses more of his brain while doing math. A PET scan reveals 20% of the mass of George’s brain lighting up when while he is thinking (don’t bother telling me George just had a seizure…it’s merely an illustration). Doofy’s PET scan shows us about 2% lighting up while thinking. George is thus putting more of his brain to use when tackling a problem hence his brain has a greater capacity for problem solving.

Certainly education can mitigate some of this but I’m sure we’ve all been around people who just seem to ‘get it’ much faster and more easily than almost everyone around them and even seem to study less. I think it is safe to say that person’s intellectual capacity is greater than those around him or her.

“Next up, Doofy and George show you the wrong way and the right way to clean out the milkshake machine!”

How about “Only using 10% of peak human mental ability”?

Idiot-savants prove that humans are capable of wonders, yet the majority of us never display them. And people have been researching the brains of prodigies and geniuses for centuries, but with no results.

The thing that makes me different than Feynman or Einstein is “mental ability”, not “percentage of brain used.”

So, are all of us born Einsteins, but we never teach ourselves how to use the equipment properly? Doubtful. What about 10yr old violin masters, why aren’t we all like that? Why aren’t all of us the same as the best of us?

One interesting thing I saw mentioned in an Oliver Sacks book: when Idiot Savants are given successful partial cures, not only do they gain some ability to take care of themselves, they also lose their amazing mental powers.

There is an interesting book called The Einstein Factor whose premise is, genius is made, not born. He spends most of the book giving exercises that he claims will boost your IQ. I never practiced any, mostly because they seemed rather silly and a lot like work.

The better scientific statement of the 10% use (and I’m not saying this is accurate, but it’s a lot closer) is that only 10% of the brain is irreplaceable. This is something noticed by the scientisits who did the first studies of people who had brain injuries – people who lost different parts of their brain eventually recovered much of their function, leading scientists to theorize that most parts of the brain are not irreplaceable. This has a lot of truth to it, though any hard and fast statement is way too simple to cover the complexity of the human brain.

But replaceable is much different from unused. Think of an office with 10 people. If one is gone, the office still goes on, as the remaining people take on a little bit of the missing person’s work. (Although if the head of the office was gone, it may well not be able to do anything.) This doesn’t mean the missing person never did any work. Just that the others can learn to cover, possibly at the expense of not doing their original work so well.

From a biological point of view, what would be the benefit of evolving a brain with such excess and wasted capacity?

My guess is that we all use 100% of our brains in one way or another or at some time or another in much the same way we use 100% of our muscles. Some of us are born with better physical abilities and some work hard at developing what they have, but over the course of our lives I suspect most of us tap into the maximum capacity of every single muscle we have.

It may offer a form of redundancy. Per the link to Cecil’s article we naturally lose maybe as many as 100,000 brain cells per day once past a certain age. If we fully used 100% of our brain I would expect we’d see diminished capcaity pretty quickly from people over the age of 30 something.

This also allows for a certain amount of brain damage to occur and yet recovery still be possible. Some stroke victims, after a good deal of time and a lot of work, are sometimes able to ‘retrain’ themselves to recover lost abilities due to the stroke. Apparently some of the rest fo the brain is making up for the now missing part. If 100% were truly used there’d be no room for the rest fot he brain to take on additional duties.

For another example of the brain not necessarily fully using all its capacity consider dogs. Take a Dachsund vs. a St. Bernard. The Dachsund’s brain is a fraction of the size of a St. Bernard’s brain yet both are (within minor variations) as intellectually capable as the other. What is the St. Bernard doing with all the extra millions of brain cells? If the St. Bernard used 100% of its mind shouldn’t it be a genius in comparison to the Dachsund?

I’d also still like to hear Doper’s thoughts on the boy with half-a-brain (literally) that I linked to above still being nearly as capable as a ‘full brained’ person.

It kills me. Some guy makes a strictly non-scientific, off-the-cuff remark about how lazy people are, and how little of their potential they achieve, and decades later, idiots are still debating about it as if it were a testable claim.

It’s editorial fluff, guys; polemic posturing, and nothing more. Intellectual capacity is not correlated to number of brain cells, and there’s no reason to expect that it is. Even the PET scans are only scratching the surface of brain function.

Further to Nametag’s cogent remarks, the tack I always take when debunking anyone I know who makes the usual 10% remark (and this happens fairly regularly) is to remind them that because the human brain takes up a large amount of the energy use of the body, and also because the large size of the head causes difficulties in labour, (with child and mother mortality consequences) there have to be some pretty strong evolutionary benefits to us having, and using all that we have.

If we really only needed 10% of the capacity we have, our heads would have ample reason to have shrunk over the last few hundred thousand years, not grown. Even as a metaphor for us not living up to our potential, it’s pretty weak.

I may be moving into GD territory here (if I haven’t already) but while this thread is here I will continue.

I am not arguing that only 10% (or any particular number for that matter) of our brain is active. Tests have shown over and over again that activity shows up all over the brain. Nor am I suggesting that what is being talked about here is necessarily testable. However, ‘off-the-cuff’ remarks such as the one above dodge what to me is at least anecdotal evidence to suggest that perhaps humans don’t use their brains to their fullest potential.

How can the boy with half-a-brain function nearly as well as a person with a complete brain if we need all of our brain to function?

How do you explain dogs with vastly differing brain sizes having very similar intellects? Wouldn’t that suggest that a St. Bernard somehow isn’t using a theoretical potential of its brain given that it has millions or billions more neurons to work with than a Dachsund does?

How do you explain prodigies and geniuses? I don’t believe genuises are only made and not born. I think it is evident* that some people are born with an innate intellect greater than that of the average population. Certainly this intellect must be trained and schooled but those people will have an easier time and will likely be able to push overall human knowledge further along than your average Joe no matter how hard your average Joe worked at learning.

Does anyone really suppose that the human race has reached the end of its intellectual capacity? Certainly we will cotinue to learn new things but our overall ability to think has hit an evolutionary dead end? Per rubberdemon’s post humans don’t have much room left for overal cranial capacity and expect natural childbirth to continue working.

You don’t need to expand the size of the brain to improve intellect. More efficient use of what you have can do the trick. Consider a computer program that needs all the available resources of a given PC to run. Now imagine a clever programmer comes along and tightens-up the code such that the computer can do the same job with only half the computer’s resources. The capacity of the computer has just increased without changing any of the hardware. The computer can now perform more work with the same hardware since the program has left more space available for other work to be done.

[sub]*-- Consider the case of Shrinivasa Ramanujan. Born in India and lacking access to what the West would consider a good education Ramanujan practically taught himself mathematics. Not only did he (from his perspective since he had never been taught otherwise) ‘invent’ math that already existed he moved the entire field of mathematics forward singlehandedly. I believe he is still considered today to have been one of the finest mathematicians who ever existed and he was that way despite a lack of a formal education.[/sub]