If we didn't use most of our brain, we wouldn't have it. It is a very expensive organ in terms of it's energy use, nutrition needs, and the many years it adds to our maturing to devlop it. If we didn't need it, evolution would have got rid of it.

I think it is sort of like the engine of your car. You don't drive around at flat-out, maximum power, with your engine redlined all the time. But if your car didn't need the extra power that it takes to accellerate and to drive fast when necessary, the engineers would not put it in. Why pay for the extra power and fuel consumption if it's not needed?

Also, like an engine, your brain is not capable of maintaining its maximum capacity all the time. Have you ever had to do long stretches of intense brain wrok? It is exhausting.

And I'd like to know how these scientists come up with the idea that you only use some small percentage of your brain. Do they mean you only use that much for conscious thought? Do they mean when you are just sitting around doing nothing except breathing and digesting or when you are doing calculus? How do they determine what the maximum capacity is, and how do they determine how much you are using? Say I am doing something that uses all the brain power I am able to muster, like an intense calculation of some kind, is that what they call the maximum? Or do they still call that only 15% because not every single neuron lights up on the CAT scan?

I have a feeling this statistic is something that a scientist used to describe one specific kind of measurable brain phenomenon, and people have taken it out of context to suggest that we aren't developing our minds the way we should.