I honestly don't remember exactly where, but I was reading a wiki for psychonauts once and it provided a scale for the potency of a dose (e.g. No effect, thresh

I honestly don't remember exactly where, but I was reading a wiki for psychonauts once and it provided a scale for the potency of a dose (e.g. No effect, threshold, etc) and the metric they used was the observer's ability to consciously resist the effects of the drug - kind of like when you're drunk or stoned and try to "force" yourself to sober up.