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.

The FeSi’s functions are:
1. Fe – extroverted Feeling
Fe is the FeSi’s primary function and is what they use to communicate with the world. It is also how the world communicates back to them. Fe is not about emotions, but the "gut instincts" they might have about a person or situation. This function is focused outwardly and is primarily motivated and energized by the presence of other awesome people. Because Fe is first, all the other functions “serve” it.

2. Si – introverted Sensing
While Fe gathers information about people, Si is running internally in the background to keep track of this information in an organized fashion—like a filing cabinet or a very organized library. Si helps FeSi’s remember data that is important to them and helps them to determine if things are "right" or "wrong" based on the data that is collected by Fe.

3. Ne – extroverted iNtuition
Ne supports Fe as it helps fuel the FeSi’s instincts about the world around them. It helps them navigate unfamiliar situations and see potential in people. Ne also helps keep their Si in check, so that when they use Si they don’t become too set in their ways, which can isolate some people.

4. Ti – introverted Thinking
Ti is the FeSi’s last function, so it can be their Achilles heel. Their Ti, in tandem with Si, helps them examine and analyze information that Fe collects. Ti helps them determine if their ideas and opinions stand up to scrutiny. However, because Ti is their weakest link, they might have trouble when asked to analyze complex theoretical problems in their head—i.e. intricate math equations.


Dominant Function and Core of the External World:

Extraverted Feeling
Extraverted Feeling is best described as a verb. It is not one process or method that can be summed up neatly and efficiently, because it is many processes and methods constantly in motion. One way it is is used is for quick, in-the-moment decision making. An FeSi uses Fe to “read” the vibes of everyone in the room and is constantly keeping tabs on what everyone seems to be thinking and feeling. They subconsciously take in all this information, and make most of their choices based on this info, which essentially boils down to, “What can I do that will benefit the most people?” At the same time, the FeSi also uses their own mannerisms, expressions, emotions, and capabilities to influence and help others around them. When the FeSi gets good vibes, feelings, or a sense of something that sparks their interest from another person or group of people, they build on that expression and mirror it back to the person or group.

Because FeSi’s are so in tune with people around them and aware of their external world, they can easily be distracted from a solo activity by the smallest interaction with others in their near vicinity. A person passing by their room in the hall, strangers sitting near them in a restaurant, a friend watching TV next to them; FeSi’s are hyper aware of these people. They naturally and unconsciously acknowledge the presence of people around them, without any effort. When an FeSi hears someone talking, their ears naturally perk up to listen. When they’re with another person, they’re constantly aware of the other person’s position, body language, tone of voice, choice of words, and facial expressions.

They have this hyper awareness of people without meaning to. Saying that an FeSi is energized by “social interaction” is too simple - it is making a deep, meaningful connection with a friend, helping those closest to them, and making a practical difference in people’s lives that gives life to an FeSi. When they are able to make a meaningful difference in the life of a person they love, they get a surge of adrenalin and feel like they can conquer the world. Without meaningful relationships to pour themselves into, an FeSi would consider their life truly bleak.

Thankfully, the FeSi is an expert relationship builder. Through Fe they can sense and assess where someone else is at in life or a certain situation. This may allow them to “share” in part of a friend’s feelings as their friend describes a situation they feel particularly strongly about. An FeSi will feel true indignation, joy, anger, etc. on behalf of others, making them master empathizers. Those around them typically describe them as warm, caring people and great friends.
Fe can be described as the ultimate “mothering” function. People with strong Fe are driven to care for those around them. They have a strong instinct to take care of others’ needs, even above their own needs. For example, even at a friend’s house, when offered a beverage, they may feel a little guilty letting another person get the drink themselves and might be the one to say, “No, no, I’ll get it! You stay there. Also, would you like anything while I’m up?” FeSi’s feel most themselves when they are taking care of others and not expecting anything in return. They usually help others simply because they can’t help it.
Fe differs from Fi (introverted Feeling), because Fi is focused internally and is constantly asking, “How do I feel about this?”, while Fe is focused externally and is constantly asking, “How does the group feel about this?” The main difference between Fe and Fi is that those with Fi can naturally qualify and quantify their own picture of themselves as if they are looking directly into a mirror. For those with Fe, their metaphorical mirror is pointed outward. This means they may know how they feel inside, but they can’t get a clear sense of what that actually means/looks like until they get feedback from others. 

To outsiders or those who don’t understand Fe, this may look like insecurity. However, the healthy FeSi’s have a strong a sense of themselves, thinking “I am me.” Fe is an information-gathering function, but those with Fe cannot objectively gather information about themselves, like people with Fi can. Fe is focused on the external world, so FeSi’s are stuck relying on information others give them about themselves.

Fe acts a bit like a vacuum without a filter when it comes to the information in the world around them. If the FeSi perceives their environment to be off balance, their mind won’t be at peace until balance has been restored, because the external clutter creates a sort of mental clutter. Once they are able to restore balance (however they define it) to their surroundings, they are able to focus better on tasks that require the use of their internal functions. 

Because they are very in touch with the external world, and they have a good instinct for how they want something to feel, FeSi’s might be good at channeling this instinct into brilliant artistic expression. Their “gut instinct” approach to the world allows them to express themselves without over-analyzing how each brush stroke is laid, or which note should come next in their song. Because they are very in tune with other people’s thought, feelings, and needs, they may also make great social workers. Their value for the opinions of a group and interpersonal skills may also make them beloved managers and excellent leaders in the workplace. Or, because they are in tune with the needs of others, they may also make very natural assistants or child care workers. But, of course, a well-rounded FeSi with enough ambition can excell in any position, in any industry they have a passion for.

FeSi’s have an extremely high value for harmony in their relationships. This can make it very difficult for an FeSi to be around or involved with interpersonal conflict. Although it might be tempting for some, avoiding the conflict and pretending it doesn’t exist in order to create a ‘false harmony’ is a bad coping mechanism that might signal a deeper feeling of being unable to control themselves. When conflict arises for FeSi’s at their best, they want to face it head on as soon as possible in order to resolve it. Although conflict is difficult on them, suppressing or avoiding the conflict feels even worse. They will ruminate on the unresolved conflict over and over in their minds, possibly losing sleep over it and imagining things are even worse than they really are. FeSi’s tend to be passionate people, and although they can be aggressive in the heat of an argument, their temper is likely to be short-lived. It’s common for people with Fe to need to express their emotions in order to get over them. Once conflict has been resolved, an FeSi will be able and willing to move forward in harmony.

When it comes to conflict that the FeSi isn’t directly involved in, they might show an interest, or want to get involved in the situation. Typically, this is done out of true concern and desire to help others, and not because they revel in drama-- in fact, most people of this type hate drama for it’s own sake. But because FeSi’s are often very good at understanding people and helping them understand each other, and they get a lot out of helping people, they might offer to involve themselves. When conflict has no direct effect on the FeSi personally, they are able to think clearly and objectively, and often give very good advice. A mature FeSi will be able to tell when their input is wanted and refrain from giving their advice or opinion to those who aren’t likely to be receptive.
FeSi’s may also use Fe to persuade people to do something they might not normally do. When a healthy FeSi persuades people, the other person probably won’t know they are being persuaded unless they know the FeSi very well, because the healthy FeSi knows when to back off. While the less mature FeSi might be more driven to change the other person or make them do things rather than just making a suggestion, the healthy FeSi can put the brakes on when they can see that they’re not motivating the other person in a positive way.

Second Function and the Core of the Internal World:

Introverted Sensing
Si is the second function of the FeSi. This process is all about real-world experiences, and how 5-senses (seeing, hearing, tasting, seeing, smelling) affect the person. FeSi’s value their own experiences very highly, and typically have a very good memory or catalogue of details about them.

People with strong Si naturally become ritualistic in their everyday behavior, because they find positive experiences that work for them and want to continue having those experiences. They also might highly value “traditions” in the personal sense. Perhaps they like having a certain kind of cake on their birthday every year, or they prefer going on vacations to the places they always visited as a kid. However, Si is very subjective, which means each person who uses Si might value vastly different “traditions” or rituals from the next person. 

FeSi’s will relate to the description of having an internal mental filing cabinet that can store information in an organized fashion. They take in information about the world and process it in a concrete way internally. Their ‘filing cabinet’ stores info primarily gleaned from real-world experience (rather than imaginary possibilities), so FeSi’s are typically more comfortable doing things in a way that has produced desired results in the past.
High-Fe types in general might describe “picking up”, “sensing”, or “feeling” the moods or emotions of other people. For the FeSi in particular, they might be able to look at a person and ‘know’ they are feeling a certain emotion or thinking about a certain thing. An FeSi mind in particular is equipped uniquely to be able to gather the information they receive about a group’s feelings and then process them separately in a linear, step-by-step way. This process may sound tedious for those whose minds work differently, but it is subconscious and is usually done in seconds, without effort. If an FeSi sits in a coffee shop and observes people, they can naturally and easily know the general mood of everyone they observe.
For example, FeSi’s tend to be especially intelligent when it comes to reading facial expressions and body language. When they scan the room, they subconsciously take in the “aura” or “feeling” that radiates from each individual person. In the mind of an FeSi, this process categorizes the “feeling” gleaned from each person and notes the person’s facial expression, gesticulations, body placement, etc. and stores them away to be accessed and pulled from later. An FeSi might make remarks like, “This lady at the gym was staring me down. I have no idea what I did, but she definitely hated me for some reason!” Although this might seem silly or improbable to people who are less focused on (or oblivious to) this people-data gathering and sorting process, FeSi’s have a highly detailed catalogue of facial expressions and body-language filed away in their minds, and their observations tend to be very insightful.

When it comes to observing close friends and family, their accuracy is heightened because they know these people well and have had more experiences observing them. FeSi’s who are aware of and have finely honed this skill can tell when a friend looks glum but doesn’t want to talk out their feelings. In these cases, the FeSi knows to give them space, because although their own instinct is to do something for their friend, they also understand that that isn’t what the person wants at that time.
FeSi’s are famous for knowing how to act in social situations, and while some of that ability does come from their catalogue of what experience tells them is most likely to be acceptable, they can also read the room and determine how each individual wants to be interacted with based on the vibes they emit. FeSi’s typically want other’s interactions with them to be pleasant and enjoyable experiences, so they’re likely to remember little details about people in order to show their care and interest in the conversation, especially if they like someone a great deal.
FeSi’s are very concrete inside—they have a sense internally that their world is very black and white; ‘right’, and ‘wrong’. Because of this, FeSi’s can be incredibly hard on themselves. They tend to set very high standards for themselves, because they believe that anything less is unacceptable. FeSi’s can use this to their advantage to create things with excellence, but they should be careful not to get so caught up in it that they don’t actually put anything out there because they feel it isn’t good enough, or become so focused on making things perfect that they lose sight of what actually matters.

This ‘inner critic’ side of an FeSi can make it extremely difficult for them to be around blunt people, and they might be labeled ‘sensitive’ because of it. FeSi’s tend to be very aware of their own shortcomings and might have trouble listing their own good qualities. Even if an FeSi knows their blunt friend is trying to help them by pointing out their faults, it usually just makes them feel even worse. 
Because Si is internal, and FeSi’s are extraverted, they might keep this ‘inner critic’ side of themselves fairly private. Because their main focus is on reading people and helping them or caring for their needs accordingly, the FeSi might feel that their own drive to attain perfection for themselves should not be allowed to burden others. In fact, this might drive them to work even harder to make sure those around them have their needs met, because their perception of themselves is gauged by others’ perceptions of them. FeSi individuals should be careful to surround themselves with good-willed, honest people to make it easier not to “give” themselves to death.

An FeSi spends a good deal of their internal thought life thinking about relational issues—how their actions affect others, how they feel about what others said to them, and often realizing after the fact that something they said could have been taken in a way they did not intend, which causes them to worry that they might have unintentionally hurt or offended someone. Their thoughts are linear and often focused on practical issues. Many FeSi’s describe having a constant ‘to-do’ list that they keep track of mentally, and they might even have several mental to-do lists that pertain to different aspects of their lives-- work, personal physical needs, practical needs of those around them, etc. However, when the FeSi has a special project that they are truly excited about, they may have trouble focusing on other tasks until their project has been completed. 
FeSi’s with more of a balance between their inner world and the external world might be very private with their own opinions and feelings. When faced with opposing beliefs, their tendency is likely to find 1 or 2 points that they can agree with from the other person’s presentation and use those to drive their side of the conversation instead of voicing what they truly think. They don’t see the need to turn everything into a debate, and they don’t enjoy pitting one person against the other. FeSi’s are likely to express their unpopular opinions only with someone they trust who won’t see disagreement as an attack, and who will allow the discussion to remain fairly neutral. If an FeSi hasn’t developed their internal world much yet, they might venture into debate type situations and be so overcome with passion for defending what they believe to be true that they have trouble making their point in a clear, concise way.


Third Function and Supporting Role in the External World:

Extroverted iNtuition
Ne is the process of exploring many abstract possibilities and ideas, often jumping from one to the other without much concern for resolution. This makes an FeSi great at taking something—an idea, a person, etc.—and seeing beyond what it currently is to what it could possibly become. For an FeSi, well developed Ne keeps Si in check-- this external process helps them to not get too bogged down in their set-in-stone, black-and-white perspectives. While FeSi’s can be slow to change their mind once it’s made, a good conversation with different perspectives can open their eyes to a whole new world of possibilities. Because this type is very relationally driven, they are likely to be very open-minded when someone they admire presents them with a new concept. 

While they are not the starry-eyed idealists of the world, FeSi’s are often optimistic in a pragmatic way. For example, they might look at a person they really like in an ugly situation and see all sorts of different positive outcomes for them, but they also know a good outcome is only possible if the person will take X, Y, and Z steps. Their Ne side tends to look on the bright side of things and enjoy unrealized possibilities, while their Si side keeps them grounded.

It can be hard for an FeSi to get really theoretical in their own head, because they’re so focused on the external world, and their minds are so pragmatic. FeSi’s prefer to talk to people about complex, theoretical ideas because in that context they can ask questions, use analogies, and build on what the other person says. Conversations about theoretical possibilities with an FeSi tend to bring out their wacky, random, abstract side.

Their Ne process may be apparent when the FeSi is explaining something, or theorizing about their own ideas. They might be able to see the outcome they want for the conversation—their complete thought—but have trouble finding the right language to express themselves. The FeSi will often repeat themselves several times with slightly varying vernacular, as they mentally hone and refine their ideas. Through this process of verbal refinement and explanation, the FeSi might also come to realize new facets of their own point. They often have ‘ah-ha!’ moments about things as they are speaking, making verbal processing a very important exercise for this type.

It’s almost as if their ideas are downloaded straight to their mouth—they are not necessarily aware of the new ideas being formed before they say them, and are fully realizing their point as they talk. FeSi’s can use this to their advantage when they have a problem. Talking it out with a trusted advisor may help them realize new things about a situation which helps solve their issue. However, FeSi’s who haven’t fully developed their filter should be aware of their tendency to verbally process in this way, and be careful with what they talk about and to whom. Journaling or blogging can be used in a similar way that verbal processing can be used to express their  ideas, and may be a safer option to process their more personal issues.

FeSi’s may have trouble when trying to make big life decisions. They can see lots of good options available to them, but feel that choosing just one means closing themselves off to all the other options. Because what they could potentially accomplish in their life is automatically laid out step-by-step in their minds, they see all the steps necessary to take before their dreams are realized, which may be overwhelming. The FeSi should be aware of this and make a conscious decision not to become paralyzed by all the options and the steps required to actually accomplish them, in order to avoid never doing anything they really want in life.

An area a lot of FeSi’s have trouble with is getting out of their comfort zone. Because of their high preference for rituals and returning to the same sensory comforts, doing new things and taking risks may be uncomfortable for them. It is easy for this type to stagnate themselves by getting too comfortable in a routine.  Their preference for Si makes them creatures of habit-- when they find something that pleases their 5 senses, they want to return to it over and over again. When they get comfortable, the idea of uprooting their comfort can sometimes be daunting, even when they know it’s necessary. Routines are easy for FeSi’s, and breaking out of them can be a scary thing to do. FeSi’s in a rut must learn to embrace newness in order to get out of the rut, or prevent being stuck in one. They must learn consciously to adventure, and find ways of being comfortable in new situations. Slowly transitioning into new situations and bringing small comforts into adventures may help to ease the anxiety of the unknown.


Last Function and the Supporting Role of the Internal World:

Introverted Thinking
Ti is the FeSi’s last function. Because FeSi’s are so focused on relationships and connecting with people, their mental threshold for complex logic analyzations is comparably lower. They may have trouble thinking about complex, theoretical ideas on their own for extended periods, unless they are presented with a practical application for those types of concepts.

It might be presumed that FeSi’s aren't the best with logic, especially by those who have a higher Thinking preference. FeSi’s can use their dominant Fe in very logical ways, but they have a tendency to overcomplicate things. They are very concerned with the domino effect of all their choices - “How will this affect this person, that person, my career, my spouse's career, etc.?” They go over and over what they think the “right choice” will be based on how things will affect people they care about, and what will be the best outcome relationally for everyone.

How do they themselves feel about it, and how are they going to feel about certain people's reactions? How are they going to deal with this person or that person having feelings about this choice or that choice? To an FeSi, it makes complete sense to go with whatever path has the least relational resistance, and they can often back up their choice with very logical reasons. But this is subjective logic, i.e. "What makes sense to me."

In order to succeed in life, and to become healthy, well-rounded individuals, FeSi’s must also accept objective logic, i.e. "What is true based on undisputed facts." They will become stronger when they can accept and learn to properly wield this objective version of logic, where appropriate and necessary. Sometimes subjective logic will do quite well, but there are other times that it cannot be substituted for objective logic. Wise FeSi’s will learn the difference and understand which is called for in various situations.
When it comes to making decisions, FeSi’s process might look very emotional or illogical to other types. Although they are often led by their gut feelings, this process can still be subjectively logical. Other people may mistake an emotional response to a problem or conclusion for a conclusion without a good reason, but this isn’t likely to be the case. An FeSi is taking into account lots of data points that might be disregarded by other types—such as the well being of those around them, the well being of humanity, their own peace of mind, the social consequences of their actions, etc. This is why FeSi’s subjective logic is easily misunderstood by those who are not considering the same data points.

Of course, healthy FeSi’s can and will use objective logic, but this generally takes much more time than their preferred method of decision making - Fe gut instincts. They are generally so focused on other things, that they are more likely to go with their in-the-moment Fe “gut instinct” about something, instead of stopping to analyze every situation objectively for hours on end. An FeSi may not be able to backtrack and explain the path of logic for their decision-making in the moment, because their gut inherently makes sense to them without necessarily putting language to their entire thought process. This can be frustrating for those who want a logical explanation for every action.

If someone needs to make a decision in partnership with an FeSi, it’s best to talk it over in advance when possible, so the FeSi has time to use their more time-consuming Ti objective logic process. If a decision is left up to an FeSi in the moment, they are most likely to go with their gut, because they trust it, and because subjective logic is a good, quick solution for a lot of their problems. If objective logic is not imperative to a situation, those around an FeSi should be able to trust that they have their own way of coming to good, reasonable conclusions. 
Some FeSi’s may not value their Ti analyzation and decision making process. It takes more effort and is longer and more thorough than their gut instincts. If they have always gotten by successfully with their “what’s best for the group” quick, in-the-moment gut reaction, the in-depth, detailed, perfectionist, truth seeking process might seem tedious and unnecessary. These FeSi’s are likely to follow the group’s morals and opinions instead of ruminating on their own beliefs and seeking out the truth for themselves. Smart, self-aware FeSi’s should do research on big decisions and beliefs as well as talk to other people. And they should make sure the people they do talk to are smart and good-willed.

When an FeSi does value this longer, more in-depth, objective Ti process, they are able to come to conclusions that are indisputably true and right based on the information they’ve internalized by observing and talking to trusted advisors, as well as doing their own research. Once they have enough information, having time alone to think through these things in depth will help them gain clarity and form their own solid opinions on things. For FeSi’s with the majority of their focus on their external world, it can be difficult to break away for the alone time needed to immerse themselves in this process, but it is a necessary part of being a well-rounded and capable individual.

It is the Ti process that says, "This is what X means". Because Ti is less emphasized in this type, it doesn’t “drive the car” of their thought process, so to speak. It's more like the backseat driver who thinks it knows where to go, but is really only making suggestions. When Ti is given a map (Fe conversation and research) however, it is able to make much better suggestions. 

Dominant Ti types often get lost in their own thoughts of “Why?” and “What if?” and “How?” and endless mental speculation and analyzation about everything under the sun. FeSi’s, however, prefer to take in complex, theoretical, and philosophical questions via conversation and research. When FeSi’s are able to talk out the “Why’s?” and “What if’s?” and “How’s?” with someone, they engage their preferred process of connecting with others, and are better able to analyze things within this context.

FeSi’s might not ask themselves these kinds of questions on their own for amusement, for example: “Is there a higher purpose to DNA replication?”, but they are typically interested in these things in the context of conversation with others. They tend to use their Ti when they've been prompted to because of a personal/relational connection to the topic. While Ti-doms are driven to learn about anything and everything, FeSi’s are more likely to learn things as needed, or as they come up in conversation. It is infinitely more interesting for FeSi’s to explore deep philosophical questions in a conversation with someone knowledgeable, whom they enjoy talking to, than to ponder it completely on their own.

Because the thought-life of FeSi’s is quite relationally driven, they will replay particularly interesting conversations over and over in their minds. They will analyze exactly what was said, which will enable them to deepen their understanding of the topic and try to determine the objective truth, if, in fact, there is one. During this further reflection, they will often be driven to do research on the topic on their own as well. When an FeSi latches onto a topic that interests them, they will research it and analyze it for days, weeks, or even months, until they have satisfied their curiosity and learned all there is to know about it. 

During times of heightened stress or when they are tired, FeSi’s might find themselves bombarded with a string of analytical thoughts. This can be annoying, but potentially advantageous if they have been stewing on an issue all day. They may find that they are clearly able to solve their own issues once their head hits the pillow. It’s a good idea for FeSi’s to keep a pen and notebook by their bed in case they need to write down their conclusions or solutions in order to fall asleep.