Two points of view, no wrongs here, just a different direction taken from the starting point. Are we talking of the machine, or of its' purpose?

I chose the machine:

An instrument for making electroencephalograms

ELECTROENCEPHALOGRAPH definition and meaning | Collins English Dictionary

Yesterday I would have liked to have posted "that uncharacteristically @Myr keeps posting long words" but I am obviously wrong. My mind is addled and I need an electroencephalograph to identify the problem.

Interesting factoid

penguin brains don’t need encephalographs or grams

9 minutes ago, drpaladin said:

How small is a pebble?

they’re very popular, pretty little garden decorations this size

penguin brains? not so popular… 

Okay, the bell has rung, the round is over. Everyone back to their corners and let us use this timeout to look at things from a different perspective.

Rocks and pebbles have been mentioned, but have you considered, Pea Brained. I will leave you with two points/thoughts on this:

1- Just a simple fact of life.

2- Who says it ?

When I was eight-years-old, I had a convulsion due to high fever.  Before I was released from the hospital, and even after, I was given electroencephalographs to determine if there was any lingering problems/abnormalities.  A unusual and interesting side effect of the electroencephalographs was that I couldn't feel electrical shocks for several years afterward.  

Since we lived in the country, it meant I could grab ahold of my neighbors electric fence and step over it, but when anyone was with me, they would get a shock and unusually jump back and start swearing.  They would also want to know why I didn't warn them about being shocked, and I'd have to tell them I didn't feel a thing.  Of course, most wouldn't believe me and thought I'd set them up on purpose, which sometimes I had, but not feeling it myself it wouldn't dawn on me what would happen to them, and this was all do to the electroencephalographs I'd had.  

4 hours ago, drpaladin said:

How small is a pebble?

Pebbles can range from the size of a marble to the size of a golf ball.  David would have used one about the size of a golf ball when he slew Goliath.