Follower, thank you, I think you've described pretty well what I was intending to point to.

Now, if you remember, if not... I will write it all. The most important experiment in proving lucidity, as far as I konw, was those in which the dreamer will learn a certain eye-movement pattern that will have to reproduce once being lucid. If in the REM state the dreamer would exactly reproduce the given pattern, the experimenter will conclude it was lucidity.

My question: wasn't it all just a common dream of doing that pattern, the necessary eye movements having derived from the hypothesis of acting out the dream at the possible active motor levels?
The eyeballs' muscles are the only one active during REM sleep. Some say their activity stands for visualy cheking out the visual dream imagery. So, if the common dream had those patterns incorporated, they would generate REM movements as well.

I also know that lucid dreams are accompanied by some specific brain waves (brain activity). But how do we know it isn't just a beginning of lucidity, the moment you realize you're dreaming, and then on is just a common dream, but a dream about lucidity, thing that might induce the different brain activity, due to high levels of metacognition, but not lucidity?

I know it's a complicated thing and this theory might not be welcomed in a lucid dream community. But I'm not 100% sure it might be true, that is why I want to test it. In the way described in the first post or by another means... I'm awaiting your proposals. If you think it's time wasting, no big deal, it is you freedom of choice, which I won't ignore.
All the good things.