I do think that "marketing" presentations of functions are mostly for selling MBTI product and so on. They are like astrology in a way.
Why do I say so ? Because COGNITION and BEHAVIOUR are correlated but not essentially the same. We cannot say they intersect because they define different spaces.
What is Ni ? I think it is quite easy to explain while coming back to their essential essence.
A function is conceptually a "streaming" box transforming input A into input B. Its persona also includes nature of input and output, like :
f : x from set S1 -> Q(x) in set S2
S1 and S2 are basically data. S1 and S2 can belong to either I or E. Let's use the MBTI symbolic : i(ntroverted) and e(extroverted). Q is the concept of function (N, T, S, F).
If S1 is E, then Q persona is Qi (ok bad choice of letter...), else it is Qe extroversion means direction toward self...).
But wait...! Can data comes from the VOID ? No. That means that Qe either requires a Z function so that QoZ is defined from E to E or E to I or to be "volatile" (coming inside but quitting immediately).
The first case is Q as a JUDGING function. A judging function is always FED by data (no decision comes from void, it is against common sense).
The second case is Q as a PERCEIVING function. A perceiving function cannot be composed because by nature it uses raw external data. An EXTROVERTED perception is looping from exterior to exterior, it is a "volatile" thing. (Se is about living the moment then discard it, same stands for Ne : exhibits potentiality of bounds or directions contextually at a moment t).
On the other hand, an INTROVERTED perception is directed toward INNER STORAGE. It requires an INTERPRETATION to fit self. That is why Ni and Si are SLOWER, because they need to translate external things to inner things (like a compiler will turn Java user code to Java bytecode).
So why this disgression ? To understand that Ni is not a "magical thing" which works from the void. It actually STORES data before participating to whole functional stack.
I would say that Ni is very passive and discrete in this process, it is more like casual state of mind. It is not related to complicated things and it might be better triggered while WATCHING or READING FIGURATIVE or SURREALIST (depending on personnal big type) stuff (like refined tales and so on). I, as a Ni-dom (I am know sure of it) tend to watch figurative (with a convergent strong sense of DIRECTION and MEANING) very passively and tries to capture the whole point of it (by point, I mean its kind of color). This capture seems to resonnate in me in a very self-centered way.
After this, Ni is used internally to exhibit potential edge to a JUDGING function. A introverted, Ni has one reference point and tends to produce only one internal hint. Because this is the role of Ni : giving a hint. I see it trough classical logic : a hint is an overview on the result but a judging function must figure it out.
Ni might be wrong in fact as self-centered hint provider. It is silent because intuition deals with unconscious. Unconsious is in fact process that has been acquired so that it does not need to be called on a conscious level to be. Like when you are driving a car, you end up not looking brakes because it has been stored as a process by your body (it is not Ni here but a more raw body accustom).
Because I am like you, I hate when people give conceptual stuff and does not illustrate, I will just tell you how I come to this text. In fact : I do not really know HOW but I know what triggered it. I was taking a lot and lot of data, reading forums quite passively, jumping from post to another. I discarded very fast pieces of data which I did not find relevant and kept only I valued (in fact, this sorting part is also unconscious, I do not really know what I keep. You know why ? Because I use mainly Te to sort it. Come back to my model : here, Te process data from exterior to exterior so it is VOLATILE ==> I do not remember it at all in this context).
Then, I found myself somewhat overwhelmed with a huge headache, figuring out meaning was my main goal. But I failed because I would say that saturating an external perceiveing function is the best way to halt introverted perceiving process.
I therefore go to a rollecoster twice and BAM it pops out of my head. It was more a conclusion, at the same time a STRONG one (strong in meaning for me) and a WEAK one (in term of judging evaluation). I am just using my Te to give you all this and in fact all the analogies I tell here are very fast. I do not know where they come from but probably from my values.
You want me go to the point ? Ok, here it is :
Ni is like Ne in the internal sphere. It is in fact its mirrored image (reversed) because it is convergent. Why convergent ? Because SELF is ONE and EXTERNAL is MULTIPLE/CONTEXTUAL. Ni sees stored DATA (again, data is in a translated form, the one understood by our brain faster than words which are an attempt to singularize multiplicity of life) and infer a connexion our conscious brain may need. Ne in contrast exhibits the process hidden in Ni applied to external world.
What kind of data does Ni provide ? Intuition provides a VECTOR while Sensing provides a POINT (or a DISC if you want). A vector can materialize as a cause/effect link, etc.
When you ask an "absurd" question to a Ne dom, he will answer immediately, going with the flow of absurdity.
The Ni dom will ask: "What do you mean? What is the point?" and be stuck without an answer until it all make enough sense to elaborate one.
That represents well my point.
Ne points out candidate vectors from external world (world is the set of ALL minus SELF) while using it as a reference. I therefore flourish from external data like this.
Ni will require translation to call inner self (which is a costly operation) and refers to INNER SET OF MEANING like judging functions. I filters out ideas before taking it in the MEANING framework. While some people can mistake "it makes no sense" as manifestation of Ti, I will say it depends of the inner essence of rejection. Logical or "meaning" ?
When I ask my girlfriend (I love ask things like that I don't know why and I don't know what I do from answer in fact, it certainly goes internally to Ni) "do you prefer John of teddy bear ?", she tells me "it is not comparable" in terms of logic quickly. If someone tells "science proves religion wrong", I tend to be triggered in my deeper life painting (because I value science but hate people proclaming it holds truth as a a kind of totalyutary system of thinking). The first time I encoutered this, again it took me time but I had a Ni in action giving me this : religion and science are not same objects in their essence, the first is directed toward meaning of causes and the second to consequences. It is here a refined version of it but it ame first as a comprehensive language to me, like "religion is directed toward left, against cause/effect process and science towards right). You might say it is Ti product but I will argue to the contrary :
- first, I did not really think about that BEFORE in that fashion at all, I just had QUALITY data for the two topics I like, especially from an astrophysicist and I did not come to this conclusion after a conscious thinking
- secondly, the incompatibility lies more iin meaning than logic, here Ni gave me FUNDAMENTAL distinction between essences (or persona of the objects, not directly objects), it was not a judgement as first but it became because my Te was very excited to put it into common vocabulary
So here is my insight, does not know if I have clarified in a proper wording. Actually I am French.