For clarity, this is the scenario my husband (INFP) and I (INFJ, natch!) discussed. You reach into your pocket where you think your keys are, and they aren't there. In my case, my mind immediately, without any conscious input, jumps to what if I don't have my keys, who I'd have to call, what I'd do in the meantime, and it goes through all these possibilities and settles on how to handle them in the instant it takes to check my other pocket to see that my keys are there. He says that his first thought is "Okay, I have to find my keys" and the other stuff does not flash through his mind.
I think there is some Ni/Ne thing in play here, but maybe it's just me? I'm struggling to understand what Ni actually *is*, because all of the descriptions sound like gobbletygook but I'm fairly certain I do use and prefer this function. I'm trying to identify the ways in which I use it because they aren't immediately obvious to me.