I was actually doing some searching on here about this topic, and I was surprised by the lack of intelligent answers on the discussion, ranging from quoting socionics, basic cardboard s/n divide descriptions, to overlapping of other functions. So I want to give the subject life again, and see what comes up.
Some things for responders to note before answering, I've read countless descriptions so unless you believe the description is phenomenal and unavoidable, best to add something a little more critical to the subject.
Anyways, here is a brief on how I define the operations of Si and Ni
Si- In a seemly chaotic stream of information (theories, emotions, senses, boundaries), Si works to develop patterns and connections through hindsight. This basis then serves as a sifter from which to isolate and examine new information.
(Studying up on Ni has been a humorous journey as the definition seems to have been whored out more so than other functions, I also see people blend Ni with Ne)
Ni- If you actually look and it, it’s described more as an ability more so than a function (magical insight), but the best way to operationalize it would be a desire to discover the underlying principles behind a particular situation (inward/understanding vs connections between trends/concepts (Ne)), and with conceptual understanding one can construct and apply long range plans and visions.
I find this subject interesting because I have always scored high on both Si and Ni, and after quite a bit of reading, I actually don't see how a Ni user can operate without a strong Si function without a threat of Ni becoming irrelevant or why a Si user wouldn't use Ni (as one of the top four functions), simply due to the fact it would take less mental work to use the Si base to work Ni versus branching out into a new function which would take more work. In short I don’t see why the theories have them shadow each other.
Interesting enough, my investigation on the topic has brought me to several other theorists who have pondering the issue and have created different function orders. Lenore Thomson’s version caught my eye at any rate, still need to do more research on her theories though, the left/right brain dynamics she presents are very interesting to me especially after my last few years working on brain mapping.
Anyways, what are your thoughts? Have I presented any errors? What is your take on Si and Ni?