For me at least, I think of Ni as sort of like an inversion. Normally I just sort of nibble on various little musings I have grabbed from my environment or own thoughts, playing out little timelines based on small things that will probably never happen for my own amusement. If I actually get stimulated and highly interested in something that I'm thinking about, trying to solve, etc., I sort of completely detach from reality in an inverted manner, as if I'm drawing my entire focus inward to manipulate a problem, a thought, etc. When I'm engaged in this state, I literally have no connection to the external world; I just completely neglect all sensory input in favor for the imagery in my mind. The best way to describe the exact process would be ripping the thought/problem to shreds in my mind with such celerity that my own reasoning can't keep up with it to make sure it hasn't made an illogical tear at the stimuli. It sort of feels like sprinting in your own mind while cleaning up the footprints behind the sprinter at the exact same time. Sometimes I will reach a conclusion and have forgotten my entire process for arriving at the conclusion, meaning that I have to retrace my thoughts while already having the conclusion in my mind to double-check my own rapid, uncontrollable work. I stay completely drawn into my own mind while in this state, and the deeper the thoughts/problems go, the more internalized my focus becomes. Eventually, I get to the point where I completely assimilate an idea, a conclusion, a solution, etc., where it feels personalized, as if it is mine. Thus begins a wave of idiosyncratic associative weaving where I knit a visual perspective through information that had been drawn into the abyss that is me. I favored Chemistry much due to the fact that I would absorb the information, rip it apart, and weave it back together to form my own artistry of atoms colliding in clouds of gas, and electrons oscillating energy levels and orbital shells all while seeming to pop into existence and out of existence due to wave particle duality. It feels like the world itself has been ripped apart by my mind, and I get to see the beautiful mechanism that governs everything about it.