So I ran into this nonsense again, someone saying that we only use 10% of our brain. *Sigh*.

To anybody who actually sits down and thinks about it for a while, it is obviously false. For example, how many times have you heard of somebody having a stroke, in the part of the brain they don't use and therefore being unaffected, or how many times have you heard of somebody having a brain injury, but being unaffected by it. If what they say is true, then we should hear of people stabbed in the head which caused severe damage to their brain but they suffer from no retardation. Of course in reality, typically such a wound is fatal, and even if it is not, it does cause some loss of brain function.

We use our entire brain, we can measure activity in the brain using tools like an MRI scanner, and the whole thing gets used at least some of the time.

The brain consists of about 2% of our body mass, yet it consumes, by various estimates from blood flow etc, about 20% of the body's energy. The brain is an extremely expensive organ and if 90% of it was unused, evolutionary pressures would trim it down to size.

Unfortunately over the years this has embedded itself in the public concious, I know the first time I ever heard of it was when I was a child watching the film Flight of the Navigator, every now and then I catch it said on the TV.

What really bugs me however is how it gets used by the woo woo crowd.

They use this 10% thing to support anything they want. For example...

We only 10% of our brains, therefore the other 90% is used for psychic power/talking to god/ESP/telekinesis/{insert personal belief here}

This doesn't work for two reasons.

1) Argument from ignorance, we don't know what this 90% is used for therefore it must be {insert personal belief}, without any evidence to support that position.

2) The argument is built upon a false premise, in that the 10% thing is actually false anyway.

I stumbled upon which seems to be a haven of nonsense over on Yahoo! Answers. Here we see somebody called Milly ask:

If we really do only use 10% of our brain, is it potentially possible that someone can be genuinely psychic?

Well to start off with, no we don't. You don't really need to go any further, but I will anyway.

Yes it is possible that somebody could be psychic.

So let's speculate on a method for this to work, I'll assume by psychic, one means being able to read other people's minds (ones who are alive) as the term psychic is very broad.

Nature gives us four forces to work with, we can dismiss the nuclear forces as they only apply at the atomic level, we can also dismiss gravity, which correlates with mass as our brain isn't that massive, and even if it were, there would be no way to reasonably alter the mass to be able to send data. That leaves us with the electro-magnetic force, specifically the EM spectrum.

Due to the size of our heads, one can rule out the longer radio wavelengths, to be realistic we'd have to start somewhere near the microwave area of the spectrum, once we get to the infra-red it becomes hard for us to control the signal without our body heat getting in the way, by the time we reach visible, it gets worse, can you imagine how bright a light you'd need to shine through your skull? You'd have to spend all day eating to stand a hope in hell of generating so much energy, by the time we're at these frequencies the brain would simply cook itself, touching your head would be like touching a 1000 watt light bulb, then of course if it were visible, we'd be able to see it with our eyes, I don't remember the last time I saw somebody with a glowing head.

So if we were to communicate using the EM spectrum, it would probably be around microwave wavelengths, this is the same frequencies that mobile phones, and 802.11 devices use.

As our brain does have an electrical current, it also generates an electro-magnetic field, however this is a by-product of the electrons whizzing around in our heads, and cannot encode any information. Also it is extremely weak, and we need sensors on the skull itself to stand much hope of even measuring it. So I believe we can rule this out going forward.

OK, so let's say we use microwaves, what we'd need is some form of transmitter in our brains, which can vary the microwave signal so we can encode our thoughts along with it. Also the psychics would need a receiver in their heads.

So yes Milly, it is possible. You don't have to break the laws of nature to do it.

However. From an evolutionary prospective it would be an expensive system to develop, the energy required to send out a constant stream of thoughts would drastically increase the amount of energy our brain uses. We also have ways to communicate which cost very little, we can send information through sound waves by banging things, or by changing the pitch of sounds using our vocal system.

Of course, these alone don't rule it out they just make it less likely to develop.

We could be generous and grant psychics the use of an undiscovered force, which costs very little energy and doesn't require much in the way of transmitters or receivers.

However still, they fall flat on their faces. We've been doing experiments with psychics for over a hundred years now, and nothing, nothing at all, negative, no effect.

Why? It's an easy experiment to do, it costs very little it is something that could be done in every secondary school in the world. We don't need to spend $8 billion building 20km particle accelerators to do it. It is cheap and easy to do.

I believe the reason they fall flat on their faces is because there is no effect going on.

However it seems some of the people answering Milly's question, seem to have an inability to think critically.

Personally, I am not ready or willing to write something completely off, like psychic abilities, because there is no definitive proof of it.

Right? So the fact that it is for starters implausible, and the fact they've failed every study done has no impact on you at all?

There is no way to prove psychic abilities without a doubt

Of course there is, do the studies and show there is an effect. If somebody could accurately read, for example images somebody else was being shown 70% or 80% of the time and if those studies were replicated in other centres, with everything doubled blinded and sound methodology. That would prove that person has the ability to see what somebody else is seeing, it would prove something is going on.

So don't give me that wishy washy nonsense.

but since it can't be disproved either, I think the only responsible thing is to be (at the very least) open to the possibility of it.

You cannot disprove a negative. That is unfairly placing the burden of evidence.

To illustrate my point. To prove Father Christmas exists, all one would need to do is grab the bugger as he's crawling down the chimney and see if there's a flying sleigh above your roof.

To disprove Father Christmas we could for example stay up Christmas Eve and see if he crawls down the chimney. If he doesn't does that disprove Father Christmas? No. Maybe he didn't visit our house this year because we were naughty. So then what would we need to do? Grab every person on the planet, lock them up, or put a camera monitoring them all to see if any of them is Father Christmas? No, maybe he's hiding, OK so we search every building, cave, swamp and igloo on the planet, does that disprove him? No. Maybe he's invisible, and so on.

You get my point, proving Father Christmas exists is relatively simple. Disproving him beyond all doubt is impossible, not only does it require a planetary study, heck even that isn't enough maybe he lives on the Moon, or Mars, and so on and so on. This is the same reason one cannot disprove a divine all-powerful being.

If psychics think there's a real effect going on PROVE IT, the burden of evidence is on YOU.

The default position any thinking person should take would be...

1) Implausible, therefore my position is doubtful.

Lots of studies get done and then...

2) No effect detected with plenty of good solid studies, therefore it doesn't exist.

You should be open to the possibility, but never so open minded that your brain falls out. If you base your opinions on the evidence then you have nothing to worry about, nobody will laugh at you and say you were wrong if new evidence comes in and you update your opinions. Because that is the rational, and intelligent thing to do, base your opinions on such matters on the data.

However if you stick to your guns and say hmm there's something going on, or maybe there's something going on, ignoring all the evidence you deserved to be laughed at. You'd be nothing but a crank, like so many so-called psychics...

Creeping around, spouting nonsense and woo woo thinking, avoiding scientists or rational people and making money off innocent people all at the same time. Can anybody say fraud and jail time?

To sum up...

1) We need and use all of our brain, the 10% thing is nonsense, spread by the likes of the media and psychics out to prove whatever nonsense they want.

2) Psychics = con artists.

3) I cannot disprove the existence of Father Christmas, that doesn't mean he exists.