I think this is important, considering the compound fiasco that just erupted into the "second date" thread. is a fairly straightforward function to understand and see in action, especially in the dominant position (though it looks a little different in creative position).
Dominant is centrally about forming abstract, general ideas. While this is a generic human skill, :ne: does it in a unique way. The images it forms can be verbal, visual, mathematical; whatever. I use "images" in a generic sense. When a type is talking to you about their ideas, they will use analogies and metaphor to paint a picture in your head, and emotive language to convey their sense of fascination. Being an Irrational function, it's all about impressing their imagery and level of interest on you. When you're talking to someone with and you're receptive to it, you find yourself mentally activated and very, very curious as the groundwork of ideas is built up and then resolved.
In the semantics study, one recurrent theme is "insight". likes to think of the world in terms of simple, highly abstracted ideas, which might be referred to as "essential ideas". The more specifics and facts are shedded, the more generalised the idea can become, and highly abstract, broadly applicable ideas are what moves toward. These ideas then tend to be communicated to others. This also falls under the topic of "understanding the main point". This tendency to look for "key", abstract ideas also produce's 's attitude to time: that it can be catabolised into critical points when various things were set in motion or determined.
In the creative position, is delivered as a final product, rather than a public process. creatives will deliver packages of polished insight, as opposed to the dominant presentation of a stream of things the speaker has found really interesting. When an XII delivers you and you're receptive to it, you'll think something like "Huh, that's interesting! You're quite right!"
Of course, dominants ar EP temperament. Their level of interestingness is proportional to their level of interestedness. A mentally activated dominant is fascinated and fascinating, but these states come suddenly an burn out quickly (on a micro scale, for perhaps tens of minutes; on a macro scale perhps for around a week). The rest of the time, you'd be looking for someone who openly shares their volumes of ideas and knowledge on a wide variety of things, and tends to draw lots of superfluous analogies (on this forum, hkkmr's connecting Socionics information processing to SVDs is an example).
Cognitive styles are also useful in distinguishing ILEs and IEEs. ILEs have a much clearer internal sense of reasoning, and will tend to produce clearly constructed ideas (I believe Y because of P, Q and R reasons): Gulenko likens this to formal logic, as thoughts have clear components and sources. IEEs will tend more to speaking in facts and general ideas, associating things with other things they know: Gulenko compares this to a fractal, as component parts are likened to other component parts within the overall idea, or to other ideas, without any catabolism into discrete logical parts (also consider that a fractal can be zoomed in on indefinitely: an IEEs ideas often reduce to larger "atoms" than an ILEs--in my own mind I've likened it to juggling onions, where an ILE is more like synthesising new molecules out of readily apparent atoms).
To flesh the cognitive styles out more, considering the rambling communication styles of users like Traveler and Anndelise, which explicitly reduce to fairly large concepts, or implicit refer to them, versus users like hkkmr and ephemeros whose ideas can be traced back to very simple ideas. From the outside in, you could say that IEEs produce "facts and connections" while ILEs produce "reasoning and arguments". Of course, argumentation is a skill and NTR, but this is looking at how thoughts are presented outside of a defensive position or a debate.