Its hard to see which function is your first function, which is why its so hard to figure out what type you are by trying to figure out what is your dominant function and your 2nd function: because the functions work together and never alone. Its especially hard to try and isolate the functions from each other and see which one is dominant and which one is second. Its a bit easier to see how two functions work in combination and see if that particlar combination of functions describe your thought patterns. But its still confusing, because the second function works for the first function, in other words the second function may actually seem as if it were the first. No wonder so many people have trouble figuring out their J//P prefernce by analyzing themselves through model A.
I know this proabably sounds redundant, as Ive already made a post about this. Im not preaching or anything, just trying to give my though on the subject, as I dont feel its been heard the first time. Or maybe it has, Im not sure. Basically what Im saying is that you can never be as sure of your base function as you can be of the Judging or perceiving criteria layed out in tests and in explantions of rationals vs irrationals. If you aerent even sure which criteria in the judging vs perceiving description describes you, you probably wont be sure which is your base function simply by analyzing your thought patterns, because this is more fuzzy and abstract information to deal with.
I know that one of the ways socionics distinguishes itself from MBTI is by the Model A. But try to see that not everything formulated by MBTI instructors is crap, and that setting apart specific criteria for describing rational types and irrational types is not a bad idea, and its something that is much easier to use for determining your base function than directly trying to determine your base function.
To me it makes sense that if your base function is thinking or feeling(introverted or extraverted) than youre a judging type(you prefer closure in MBTI terms), because more information is being judged than is going in. And if your base function is intuition or sensing(extraverted or intraverted) than you are perceiving(you prefer openness), because more information is going in than is going out. Its just alot easier to see if you prefer closure in general or openness in general than it is to see what your base function is, as it never appears alone and works too fast for you to seize its operations most of the time.