The point is, referring to the process of thinking logically as a "logic center," and referring to lucidity as the "turning on" of that center is just shorthand. It is much easier to talk about the process of thinking as something concrete, and by monitoring (experimentally defined) logical thinking, MRIs have found that certain parts of the brain have more blood flow, which is an indicator of more activity. Does that prove that the increased activity is what produces the logic? No. The increased activity is only correlated, and one cannot base conclusions off of correlations (because some third party could be causing both events to occur).

That being said, in the case of non-WILD techniques, we don't know if the initial realization causes the "logic center activity" to increase, or if the "logic center" must be active before the realization. There is only a correlation. Based on my personal experiences in DILD, however, I think both outcomes are equally likely (depending on your effort in lucid dreaming at the time). Sometimes, first will come the initial spark in the dream that "turns on the logic center." I will become lucid based on a reality check. Once I become lucid, I suddenly notice all the other signs that it is a dream (I will notice that the text on the "Doomsday Billboard" is unreadable. I become lucid, and realize that there is no such thing as a "Doomsday Billboard" in real life.). Other times, I will be aware of the finer nonsense-details from the start of the dream (this seems to infer that my "logic center" remained active). I prepare for these dreams beforehand (WBTB/WILD). Both types of lucidity can attain the same quality once you get into good practice.