Each personality type has four Cognitive Functions. Functions put language to the way they process information and make decisions, and their order is based on personal preferences. Thinking and Feeling are used to make decisions, while iNtuition and Sensing are used to process information. Each type is referred to by their top two functions. Internal functions are the ones you use in your head, and external functions are the ones you use to interact with the world around you.
1st Function: Fi - Introverted Feeling
Fi-doms live in a world of internal feelings and thoughts. They take time to develop their values and opinions, which are quite firm once decided. Some Fi’s can be a bit squishy, but they're also quite serious.
While Fe is focused out toward people, Fi is focused inwardly. Fi’s are constantly conscious of their heart, regularly retreating inward and asking, “What do I feel about this?” or “What do I believe about this?”
They are quite mindful of others’ hearts. Fi’s subconsciously assume that most people have an internal world like theirs, even if it’s buried deep inside. Fi’s will choose their words and actions intentionally to protect and validate the other’s heart.
Fi’s are naturally bent to assume that everything is personal. (Of course, not everything should be taken personally. With Fi always being paired with Te, they may find clarity through external processing.) They usually have an innate sense of how individuals probably feel, and can easily picture themselves in another’s shoes. Fi is, in essence, empathy.
An Fi may or may not consider themselves a very emotional person. The essence of Fi is not necessarily feelings, but values. F in it’s purest form could be described as “making decisions based on what they find to be agreeable, rather than what they find to be logical (T)”.
To the Fi, emotions are experienced deeply. They are usually better than they think at keeping their emotions inside.
2nd Function: Se - Extraverted Sensing
Se’s live in a concrete world. They see things as tangible and real. With a solid understanding of how things are, they desire to experience all of it in it’s fullness.
How do they do this? They go on mountain hikes. They take bubble baths. They paint or photograph to capture the beauty that just “is”.
An Se-dom once said, “My goal in life is to live inspired, and create beauty from that place.”
Se’s live in the moment. They thrive on impulsiveness, and actually need it to feel alive. Freedom is of the utmost importance, and they might even enjoy breaking the rules.
Se’s have a hard time taking in any information that isn’t concrete. They may “make it” concrete as they take it in, or just not receive it at all. An Se could listen to an Ni-dom ramble for ten minutes and not have a clue what they said.
They may forget the context of a conversation half-way through. They’re unable to jump to conclusions in the same way that N’s can, and might get lost in a conversation that’s too random.
Dominant Se kids are likely to change their clothes multiple times a day (or simply go naked) because they “feel like it”. They want to do what they want to do, exactly when they think of doing it. Their parents might have planned an elaborate day at the beach, but the Se kid may decide on the way that they’d rather watch their favorite movie again, right now.
Se will seek out external stimulation -- sunsets, books, people, mountain hikes, good movies, etc. If the Se function isn’t “fed” properly, someone with Se may find themselves trying to meet this need in a not-so-healthy way, such as binge eating, mindlessly scrolling through random people’s photos on Facebook, or watching too much TV. None of these things actually “feed” the Se, so the person tends to feel more horrible than before.
3rd Function: Ni - Introverted iNtuition
Sensing and Intuition are so close with this type, that they tend to be pretty balanced between the two.
Ni lives in a land of mysterious connections. In this reality, everything is linked and everything has an impact on all other things.
Many times, if not most of the time, connections happen in their head so fast that the Ni isn’t aware of the process, they simply see the result. Sometimes these thoughts even feel like psychic premonitions.
To Se-doms, Ni can often feel like “permission to believe even when you don’t understand”. It provides peace in light of questions their Se cannot seem to answer.
People usually “store” their memories with their internal perceiving function. If Si would be the harddrive of a computer, Ni would be like the RAM (Random Access Memory.) Things are stored in a less organized fashion, making it harder at times to pull up the specific memory they want exactly when they want it. They are also more likely than Si’s to have memories come up randomly for no reason. Ni tends to make dreams more vague, whereas Si tends to make them more concrete.
Ni’s are the kings and queens of the “gut feeling”. They are the ones who say, “I have a bad feeling about this,” but might not be able to tell you why.
4th Function: Te - Extraverted Thinking
A person’s fourth function is often considered their achilles heel, but can also be one of their greatest hidden strengths.
Te’s are always looking for ways things could be better. Anything could be made more efficient, intelligent, and excellent, whether its architecture, a complex system, the company project, or their four-year-old’s picture of daisies.
“What you did was great, but if you had done this it would have been much better.”
Te’s are kings and queens of maximization. Whether or not they’re able to brainstorm new concepts on their own, Te’s can work wonders with a concept that’s already out there. Te’s are excellent people to run a plan by, get constructive criticism from, or have lead an important project. They can be very good entrepreneurs and make excellent technicians or business consultants, counselors, or personal coaches.
Fourth functions are often more “simple” versions of their dominant counterparts. With Te being fourth, The FiSe may find it fun or even relaxing to do simple Te things, such as scheduling, organizing, planning, coaching, or critiquing.
A person’s last function tends to come out negatively when they’re stressed, tired, hungry, etc. Te could come out as rants about how “people are illogical and dumb”, heartless critiques, or misapplied objective logic. Te serves as a way to see the world logically and objectively, as well as making decisions and taking action from that standpoint, but too much time spent in that world can be terrible. Fi-doms would be wise to watch out for these things, and find ways to get out of these cycles when they start.