we just use 10%-15% of our brain capacity everyone knows this but who said it first and when?

Answer 1

This was first said in the early 1800's, but it isn't actually accurate. Actually, you use your entire brain, and unused parts of your brain actually get usurped by adjacent parts. This is the case when people lose limbs - the adjacent areas of the motor cortex "take over" the area formly allocated to detecting sensation of the missing limb.

Answer 2

My understanding is that no one knows where this idea came from; it cannot be attributed to a specific source. It probably does go back to a time when scientists did not *know* what most of the brain did. And as the first answer says, it isn't true. We use the whole darn thing.

Answer 3

We say it to lie to ourselves to make us feel better when we wish we were smarter. I think the first answer is right on target.

Answer 4

einstein in the 50's