I think there is a misconception of a good memory being attributed to an Introverted Sensing type. The Introverted Sensing type is said to be past oriented.
But now I'm discovering that an Introverted Intuitive type is also good at remembering and is also very past oriented. I think the Introverted Intuitive could be just as good at remembering facts.
But my thought about the difference is that the Si type will be better at remembering facts no matter what, while the Ni type will remember facts about things that are meaningful to them -- such as facts related to their interests, because those facts are focused on information that is meaningful, and so the facts aren't facts speaking for themselves, but for a purpose.
My mind is a storehouse for data, but only the data related to my interests. I'm very good at memorizing things about roller coasters and movies and such, and I do extensive research on these things. On the other hand, I have trouble collecting data that isn't meaningful to me. I have trouble remembering smaller things like what I had for dinner last night, remembering dates which are unimportant to me, and so forth.
I have trouble remembering the answers to questions on a test even when I study if the subject isn't related to my interests.
So having said this, is this sort of data collection Ni functioning since it's primarily collecting meaningful and relational data rather than data in of itself?