I’ve never understood this question, and it’s one I do get asked from time to time. When it’s put to me what I always say is, ‘Is it true that you only use 10 per cent of the volume of your house?’ If you think about the volume of your house, you don’t occupy the top half of a room as much as the bottom half - unless you’ve got a bunk bed or something. And actually you don’t really occupy the space behind your sofa or whatever. Does that mean you don’t need that space?
"All the neurons in your brain fire all the time, so in that sense one could say you’re using all your brain"
I’ve never found any sensible definition of using brain power in any kind of technical sense that works. I think it’s a nonsense statement. All the neurons in your brain fire all the time, so in that sense one could say you’re using all your brain.
"You can’t have disc full for the brain"
Things are not stored in sectors in your brain, like they are on a hard disc. You can’t have disc full for the brain and that’s because all the representations are stored in a distributed way. So it doesn’t make any sense for the brain to be full because everything is stored on top of everything else anyway. The brain seems to get tired, but not full.
Representations and memories are distributed - they’re not laid out in a formal fashion - so you can’t always point generally to a single bit of the brain doing a single thing. Given that, doing more things doesn’t necessarily need more brain.