The standard definitions of (i.e., sense of finding the right time for opportunities, fortune-telling, etc.) tend to be a bit mystifying, even to people who might be Ni-dominant.
Here's an alternative definition.
See if this sounds like to you. It's certainly different from in some versions of Socionics, but perhaps more compatible with other versions (?).
is the skill of imagining a complete entity, with complete flexibility over the parameters. People with dominant are good at creating an imaginary model of reality, which they tend to flesh out in greater detail than is typical in imagination.
Another difference between and is that tends to focus on things that have no relevance to the individual. Hence, whereas an -dominant person may be better at thinking up possibilities that can be implemented to start entrepreneurial projects, -dominant people will tend to think about things that don't concern them at all (e.g., what they'd do if they were president, what various countries should do, what's going to happen to the world, and what it would be like to give someone from 200 years ago of tour of modern life).
(Note...I'm aware that some of what I said in the last paragraph is exactly the opposite of some other descriptions of vs. . However, the view presented here is consistent with leading toward solitary imagination, and leading toward greater social interaction, and consistent with most views of introversion and extraversion. Feel free to comment. :-))
-dominant people are often good at writing stories, and are sometimes drawn to the arts. However, if is the second function, they may be more inclined to use their imagination to create mental models for use in scientific investigation.
Using their imagination, INTps are often particularly good at imagining structures; by picturing things in their imagination, they're able to solve logical problems. This ability to picture things may be visual, but it can also involve other senses such as auditory imagination. Because of the ability to imagine structures and solve logical problems, often appears equivalent to some definitions of .
INTps, using their , are often very able to separate reality from fantasy; hence, they're not tied to any imagination, so they can fantasize as much as they want knowing that they can easily come out of it. However, some INFps or INTps who are suffering from depression may have a harder time exiting a fantasy-view of the world, and may be trapped in their own conception, sometimes limiting their activities.