Psychoanalyzing a person's dominant function

Determining a person's type is hard, so let's start with what should be the easiest question: how do you figure out what a person's dominant function is? The question is much harder to analyze than at first glance. First, you need to understand what each information element looks like. Second, there is huge variety among people, even among people within the same type.

It would be easier to start with what not to look at. A fairly common mistake many people make is a face-value judgment simply from meeting a person. The reason why this is a mistake is that most people don't show you who they really are when you first meet them. An ENTp/ESTp may come off as warm and friendly, but the reality is that most ENTps and ESTps are extremely calculating individuals. An INFp may come across as an ISFp when she invites you for dinner, cooks you food, but then turns out to hold her time very tight-fistedly. The point is, people are hardly what they seem.

Another fairly common mistake is to stereotype a person based on his profession. Simply because a person is religious does not mean he's a "Feeler" or "Thinker." It hardly means that. I have known both ESTps and INFps to be extremely religious. I have met INTps who have defended their faith to the death (figuratively). Additionally, just having a job in the tech industry does not make you a Thinker in any way. But I digress.

The real interesting question to discuss is the actual process of finding out who a person is. Here's what you should: catch them trying to solve a problem, or watch how they discuss topics. In the process, they almost always bring out their dominant function. The property is the following: "The influence of the base function on perception and core values is so strong that people tend to project these values onto other people: everyone else surely must want the same things that your base function strives for" (Wikisocion).

As with anything, the concept is made clearest through examples. The first example I'll bring up is my close friend, an INTj. Whenever I banter with him about issues, he often brings up a "rule" in the form of "It's a general principle of humans to..." or "In general, people dont'...". He analyzes issues starting from rules, which ties in very well to his dominant function of Ti.

The second example will be about someone I used to know well, an INFp. The dominant function is Ni, which is about time. When I'd discuss with her about doing something, she would very frequently use directives like "Wait until I've done so and so and so", or "When do you want to do something?" "Now?" "Maybe later!" or "I had such a goood time", or "Let's just have a good time." As an aside, I had mistyped her as an ISFp for the longest time ever (1.5 years?). Had I been armed with the skill to analyze dominant function, her Ni would've been as clear as day.

Anyway, that's all I have for today. I've got to get back to work, but if there's any questions or comments, please do let me know.