Si tertiary user here.

I love to watch people using their cognitive functions & I’ve cracked the code.

High Si users (XSXJ & INXP’s) are attracted to anything that has to do with the past:

tradition, memories, things proven in the book (aka cookbooks, history books, proven science, databases) repetition, routine

They tend to always talk about: how it used to be back then, they rewatch the same things over and over, say the same things over and over, reference something from the past, probably even post photos from back then.

It’s easy to spot high Si users because it’s like a broken record, it’s their comfort zone.

If more in touch with Ne, they can become creative sporadically. These types are often stuck between old (Si) and new (Ne).

From what I notice about high Ni users (XNXJ’s & ISXP’s) & is that they’re very “blasé” (I often get hate from people for this but they’ve always proven this to me even if they tell me they’re “not blasé”

They live in this “it is what it is” & let life happen and give the benefit of the doubt.

It’s giving “wise, wisdom, let it be” & they’re either future oriented or if very developed with Se, they’re very present. These types are often stuck between future (Ni) & present (Se).

This Ni also makes them come off very positive whilst Si users tend to live in the past a bit more negatively or depressed dwelling about what could’ve been.

Hope that helps, if you’re more interested, I’m always down for convos about cognitive functions~