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 NeTi’s functions are as follows:
1. Ne - extroverted iNtuition

Ne is the NeFi’s core function. They use it to find patterns and underlying principles, to see future possibilities, to construct theories and frameworks, and to form connections as they talk, write, or create. To others, Ne is what can make the NeFi seem like they have their head in the clouds, constantly having ideas, thoughts, and theories that might not seem like they’re totally in sync with reality. The rest of the functions below are said to "serve" the Ne. This means that the Ne way of doing things gets priority most of the time.

2. Fi - introverted Feeling
Although it’s referred to as “Feeling”, Fi is not internal emotions, but rather values that come from within. NeFi’s might experience a deep well of emotions, but this is not the root of Fi. It is a decision making-process that makes them very interested in determining their own moral code and what their gut instinct tells them is right, which is often based on how they would like to be treated themselves. They tend to be very considerate of others, and are likely to be highly aware of how they feel other people see them. It may take a long time to mull over their own beliefs to make sure they seem right. This values-refining process can take quite a bit of time and requires mental solitude, which can make the NeFi seem very introverted in these times. Fi generally puts authenticity in high esteem and is repulsed by anything that seems fabricated or shallow to them.

3. Te - extroverted Thinking
Te is the NeFi’s third function. Te is a very logic-oriented way of problem solving. It is the side of them that naturally looks to find a better solution to a problem, improve the efficiency of a process, or critique and refine what is already in place. NeFi’s tend to be balanced between this quick, decisive efficient way of making decisions and the pondering, value-driven decision making process of their Fi. While they prefer to take their time to make decisions, as long as it doesn’t go against their values they can use their Te to make sure they make a decision when necessary.

4. Si - internal Sensing
Si is the NeFi’s last function. Because of this, it is inherently not as strong as the other functions. It operates subconsciously for the most part, and allows them to store all the interesting knowledge and insights into people they gather in an organized way in their mind for future reference. People with Si first or second are really good at implementation, following detailed instructions, and keeping a system running smoothly over long periods of time. Because Si is not the main focus of an NeFi, they may struggle with being consistent, reliable, and actually implementing their ideas. However, as they grow and develop, they often learn to overcome these weaknesses.

Dominant Function and Core of the External World:

External Intuition

NeFi’s love thinking up new ideas and considering all the possibilities in any given situation. They learn about the world through observation and experimentation. According to Dario Nardi, Ph.D., they are masters of trans-contextual thinking. This means that they can easily think about things across contexts.

From his book, Neuroscience of Personality:
“Regardless of the kind of stimulus that enters the brain -- sights, sounds, smell, sensation, or so forth -- the brain responds by rapidly processing that stimulus in multiple regions, including regions seemingly not applicable to the stimulus. For example, for most people, hearing the words ‘dog’ and ‘cat’ will evoke auditory regions...and perhaps some visual or memory regions...Perhaps we recall a beloved childhood pet. However, the Ne types get busy using all regions to tap relationships across situations, perhaps suddenly imagining a story about two brothers, one of whom is faithful and sociable (like a dog) while the other is independent and quiet (like a cat). They might wonder about dog and cat writing styles too!”

This ability to think outside the box and context of the current topic is key to the NeFi’s creativity. Since Ne is their priority, their ideas are usually shared with the world first and then prioritized by Fi afterwards. As a result, some of their ideas can be very abstract and random and may not make sense if they haven’t been run through their internal filter yet. According to Nardi, NeFi’s are often very good at using their imaginations, especially to act and mimic others.

NeFi’s are constantly chasing new shiny ideas and studying fresh topics of interest. They derive satisfaction from learning about a huge variety of topics so they can use the information to fuel their ideas. The more diverse their learning and exploring is, the more likely it is that they can find a unique solution to a problem by pulling from their library of knowledge or understanding. 

NeFi’s naturally come up with new ideas, create hypotheses, and explore possibilities. Although their Ne side makes them excellent at coming up with new ideas, their Si is their last priority, which means that they can struggle to implement their ideas in a systematic way. Types with strong Si are often able to easily perform tasks that require learning a detailed system (like grammar, accounting, or legal rules) or ones that are simply repetitive, like brushing one’s teeth, with a high level of consistency. It’s not uncommon for strong Si types to have regular routines in their lives by choice. NeFi’s however, might resist performing these kinds of tasks in any sort of consistent manner. These systematic, routine tasks generally bore and irritate them because they don’t provide them with good ideas or fodder for their imaginations.

Their ideas are more likely to reach the implementation stage if they feel like the idea will benefit others in a meaningful way. They generally do better when they avoid most of the things that require high attention to detail, mindless repetition or action, or rote memorization. Of course there are things that are personally worth the potential frustration or boredom that can come with doing Si tasks, like practicing to become a better musician. There are also certain things that ideally should not be avoided, like showering. In these cases, they may be able to think of ways to at least make the task less dull. It’s likely that with tasks like this, they will not follow a regular pattern. While an Si dominant type might shower every day at 7 am for 20 years, NeFi’s might end up showering twice in a single day, avoid showering for the next two, then shower at 5 pm, and the next day at 2 pm.

Although NeFi’s primarily value competence over mastery, they aren’t incapable of becoming experts. They are great at adapting to their present circumstances and generally feel comfortable not really knowing what their life will look like ten years from the present day. Often they fall into mastery through their various intellectual pursuits and adaptations, rather than mapping out a path from childhood to achieve a specific expert status.

There are times when they have multiple interests they’re trying to feed at once. They generally enjoy having a lot of variety available to them, especially if they have the ability to switch between interests at their whim, but this can easily get out of hand if there are many plates being spun and no reliable system to make sure things actually get accomplished. If the goal is simply to try things out and learn, this might be acceptable, but if it involves responsibility to others like completing a project for work, it can cause problems. While variety is good for them, when they become more distracted than productive, they might find it helpful to surround themselves with people who can take over some of the less interesting or more menial tasks.

NeFi’s get their ideas from the world around them and their ideas usually flow best when they have someone to bounce ideas off of. This is the nature of Ne and other external functions (denoted by the lowercase “e”) - they need interaction with the world to function optimally. This is a double-edged sword, as the outside world can also be highly distracting. Because of this, they tend to need alternating stages of input and output.

Input can come from almost anywhere. It may come in the form of observations, conversations with weird and fascinating humans, good books and articles, traveling to new places, interesting assignments at work, or even simple things like enjoying nature. While some ideas may come when they’re alone, having others to share their ideas with can provide useful refinement as well as input on whether the idea will make sense in the real world or not. How much alone time an NeFi needs to have can be a delicate balance, but ultimately they are less likely to feel fulfilled and be their best self if they spend too much time isolated from others.

It’s not always easy for them to find the right people to share their ideas with. They can be extremely abstract and often seem to spring up from nothing to outside observers, so it’s not always easy for other people to comprehend what they’re saying. They also tend to be impatient to get started on their ideas immediately after conceiving them, and they might be disappointed when others don’t immediately jump in to help them implement it.

NeFi’s really like their autonomy. Although they like working with other people on interesting ideas, they despise being micromanaged by someone they don’t respect and trust. They usually prefer to take on a challenge their own way, without the steps being pre-defined for them.
An NeFi’s outside-the-box thinking can lead to what others may see as disruptive behaviour. Often, if someone tries to make them do something one way, they’ll look for a different way. This usually isn’t an intentional rebellion. They look for new ways to do things because it’s more exciting than following conventional routes or just doing what they’ve done before. Their other functions all serve their drive to find new solutions to problems. 

They thrive in “chaotic” environments as they find them fun. It gives their Ne driven mind more interesting input to play with for ideas. It also gives them more information to look for patterns in and is more likely to be a positive space for new ideas to come forth, as opposed to  environments that are more conventional and traditional. 


Second Function and the Core of the Internal World:

Internal Feeling
NeFi’s are very warm and caring to those they are close to, especially because they may subconsciously believe that everyone has an inner world similar to theirs. Like most people, they still tend to take a while to truly open up to people. However, they often find themselves way over sharing with people they hardly know at times - something they tend to feel embarrassed and uncomfortable with after the fact.

Once they let someone into their inner circle of true friends, they are likely to keep that connection open as long as harmony remains between the two. For example, if the other person shows themselves to be inauthentic or living out a strong opposition to a value the NeFi holds, the NeFi will most likely retreat from the relationship. As long as those principles aren’t violated, they will likely feel connected to that person for life, whether or not they see them regularly or keep in touch.

They are highly protective of their “inner circle”, feeling that those they share the intimate details of their persona with are in some ways part of themselves. They will not hesitate to defend themselves or those they are close to if they are attacked or threatened.

Strong Fi can often cause a person to have brief judgmental thoughts about people on a regular basis. NeFi’s are one of the types that struggle with this as it often goes against the way they would like to see and treat people, and yet it’s a sort of automatic response. This response comes from the way Fi tends to enjoy ranking and sorting things and people into “like” or “dislike”, or even ranking things from what they like the most to what they dislike the most. While this feels harmless when directed at inanimate objects, it can be frustrating to the NeFi and cause them to feel guilt or shame at times if it’s a common occurrence for them. This natural ranking or sorting habit may also cause them to feel deep attachments to particular objects or people - often as a mix of nostalgia and this invisible tie they feel that gives that object or person an especially high importance in their mind.

At their best, NeFi’s are really good at self-care and putting healthy boundaries in place. They are naturally empathetic people, so they see the needs of others and want to care for them. However, healthy NeFi’s learn over time that they cannot effectively care for others unless they first care for themselves. They know their limits and how to say “no” when they aren’t able to do something or fit something into their lives, even if it makes them uncomfortable because of the conflict it might create.

Fi differs from Fe (extroverted Feeling) because Fe is is focused externally and is constantly asking, “How does the group feel about this?”, whereas Fi is focused internally and is constantly asking, “How do I feel about this?” Once their own needs are met, NeFi’s tend to hone in on one or two significant relationships. They naturally take care of these people and treat them like family. These people could be a romantic partner, a best friend, etc.

NeFi’s are extremely self-aware and spend a good deal of time on self-reflection. They are very concerned with the depth and nuances of their values system and spend a large amount of their mental space clarifying, sifting, and refining their beliefs. This process can be very connected to deep emotions for NeFi’s. They might find themselves laughing or crying at the beauty of a seemingly random object that has meaning to them, while bystanders who notice their reaction might be quite confused at their sudden outburst. For some NeFi’s, their emotions run so deep that there have to have been a lot of feelings building under the surface for quite some time before they will burst forth. They tend to seek out things (movies, books, etc.) that will engage their emotions, because following characters they care about through an emotional journey can be very rewarding for them.

It’s worth noting that when we talking about Feeling (Fi or Fe) as a cognitive function, we do not necessarily refer to just emotions. Emotional experiences or expressions can be related to Feeling (Fe or Fi), but they are not the root cause of the cognitive Feeling. The root of Fi or Fe boils down to a person’s values, meaning what a person thinks is important based on their own conscience and the reasons they believe it’s important. An NeFi’s moral code is derived from what their conscience or "gut instinct" tells them is right, and they generally treat others the way they want to be treated. This Fi value is not based in emotions, but neither is it 100% logical. It is not overly concerned with the logic behind treating others fairly… It simply “feels” like the good and right thing to do because they themselves want to be treated fairly. 

The NeFi’s instinct is to achieve inner harmony by remaining true to themselves, their own values, and minimizing the influence that external factors (societal expectations, and maybe even the opinions of friends and family) have on their values. They may love discussing their values with others, as long as they are able to remain true to themselves while doing so. However, they can get very uncomfortable in debates if they feel they’re being personally attacked or that their own values are being questioned. After a lengthy discussion, NeFi’s need time by themselves to evaluate the conversation and consider what the other person said and how they might fit it into their value system.

NeFi’s find their own principles to be trustworthy and valuable, and are inherently skeptical of  others that try to impose on them. If something does not line up with their beliefs, they cannot act in accordance with it. To go against their own values is to cause inner discord, which NeFi’s can’t tolerate for long.

NeFi’s can get lost in their own world of trying to figure out what a stranger, who is sitting 20 feet away from them in a coffee shop, is thinking, how their day is going, what their life must be like, etc. They love people watching, and may even imagine a conversation with someone rather than actually speaking to them in real life, or as practice for how an actual conversation might play out.

NeFi’s tend to have an active imagination well into adulthood. Strong Fi types are very concerned with The Story of/behind various things. For example, they might see a large, sturdy tree and wonder how long it’s been there, and try to imagine the events it’s been around for, or who else sat in its shade, what wisdom might be attached to or inside of that tree, etc. They automatically look for meaning everywhere - in books, movies, a passing remark from a friend, a special cup they like to use, or even why a certain tree was planted in a certain place.

They tend to assign meaning to everything. Because they are so involved with and entangled in the depth and nuance of the meaning of everything, and how the meaning of something relates to everything else, it can become incredibly captivated by the right idea or story. When something sparks their imagination, or taps into an aspect of meaning that carries a lot of weight with an NeFi, they become entranced by the story or idea. The process of a story unfolding can be more meaningful to them than the sum of the story’s parts. 


Third Function and Supporting Role in the External World:

External Thinking
Te is the third function and the supporting role in the NeFi’s external world. Te is a process that allows them to take in information from the real world, make quick decisions on what the most effective solution is, and put that solution into play right away. Because of their awareness of the external world, and creative thinking, they can pull out their troubleshooting skills when necessary and get a job done effectively.

Because this side of them makes them value excellence and efficiency, they may have trouble getting started with new hobbies, career paths or other big life changes. Although they know it’s not really possible, they often feel that they should be masters of whatever they try when they do it the first time.

While they do prefer to take their time on decision making, it isn’t always possible or practical. In these situations, it’s useful to have Te so that they can make a quick, in-the-moment decision. Because they are able to rely on their Fi internal compass in the background to let them know when something feels off, they can feel comfortable with their decision even if they can’t articulate a solid reason for it at the time, as long as it passes their “gut check”. For example, if they have the sense that someone they see walking down the street could be harmful to them in some way, they don’t have time to untangle why they have that feeling. They just know they don’t feel safe next to this person, and the best solution is the cross the street or take a detour in order to avoid them.

Te is often the protector function of the NeFi. When used in a healthy way, if one of their values comes under attack they can rely on a direct, matter-of-fact Te communication style to defend it. When they feel so strongly about a subject that they know they must take action on it, they tap into this part of themselves that is powerful and commanding to take a stand for that what they believe is right. Te can also be the part of them that tells them to just pick something (a career, a hobby, an outfit, etc) and stick with it, at least for a short period of time. It’s the part of them that pushes them to come to a conclusion and be decisive. They know they can’t contemplate how they feel about everything forever, so this quick decisive process helps them make choices when quick action is necessary.

In general, NeFi’s dislike being harsh and judgemental. They aim to maintain peace and harmony as much as possible. They are aware that other people have their own thoughts and emotions, and try to approach people from a place of understanding. They might find themselves jumping into critique mode because their Te sees how something could be improved. Although they might find themselves being overly critical without meaning to be, they are likely to regret it if they come across in a way that they don’t feel reflects their true character. 

NeFi’s best use their Te when there is already a system in place, as it is easiest for them to use a simple version of Te - critiquing and refining. When something is already in place and needs improvement, it can be easier to analyze it and see the solution. When starting from scratch, they will have lots of ideas, but the act of putting systems and and structures of efficiency into place is harder for them.

Last Function and the Supporting Role of the Internal World:

Internal Sensing
The NeFi’s last function is Si (introverted Sensing). Si is all about how real world, 5-senses (seeing, hearing, tasting, touching, and smelling) experiences affect NeFi’s. They value their own experiences very highly, and typically have a good memory or catalogue of details about their experiences that they deem important stored away. While the external world is a constantly shifting realm of never-ending possibility to the NeFi, their internal world is more solid and set in stone. They generally relate to the sense of being grounded or anchored inside, although they might appear quite idealistic to others around them. They might relate to the idea that their internal world is like an organized library of information and values that they can pull from at a moment’s notice. However, because Si is their last function, the level to which their mind is organized might be fairly limited compared to someone with Si first.

NeFi’s tend to very nostalgic and sentimental about things that hold deep meaning for them. Perhaps they like having a certain kind of cake on their birthday every year because their mother made it for them growing up, or they might be very attached to certain objects that mean something to them. NeFi’s value vastly different traditions or rituals from most people, and demonstrate them in less obvious ways. To put it another way, their traditions are often not very traditional.

Because their internal world is more solid-feeling, a lot of their basic values have been decided fairly early on, and they fall back on these until new experiences, ideas, or realizations cause them to reevaluate certain values. They typically consider themselves to be pretty open-minded. However, when faced with a new principle that they have no experience with, they might need a lot of time to themselves to evaluate their stance on the subject. Once they have had adequate time to consider the matter, even if they don’t have it figured out 100%, they feel better knowing that they have reached some level of understanding within themselves.

Because Si is their last function, NeFi’s can have a hard time dealing with tons of minute details or implementing their ideas. They usually have a lot more fun generating ideas than carrying them out. When it comes to productivity, if they try to implement everything themselves they may feel disappointed in how little they do compared to the number of ideas they have.
It can also be easy for them to forget to have a specific end goal for their lives. They often have a wide range of things they could do, but it can be hard to nail down and commit to accomplishing one thing in particular.

When Si is not well developed yet, they may have a lot of trouble deciding that it’s worth it to commit to anything long-term. Their Ne side loves it when they keep all their options open and they hate to feel restricted. Once Si has been developed more, they can usually see that in certain circumstances, it’s beneficial or even necessary to make a long-term commitment in order for them to get what they want. They also may find that sometimes putting some restrictions around themselves in the right way can actually stimulate more creativity than having an endless amount of choices and options.

Because Si is last, in younger years when it’s not well developed it can cause some trouble for the NeFi. Although chores can be strongly disliked if someone else tries to put pressure on them to do them at a specific time, chores that they decides to complete on a whim can be relaxing because of their reliance on simple, known routines. They can get really frustrated with maintenance when it feels unnecessary, so they tend to prefer getting involved in things they can do really well in one go, rather than having to constantly come back and be nitpicky about fixing little pieces that don’t really improve that overall state of things.

They may also resort to wearing the same outfit or eating the same food over and over again so they can rely on a minimal amount of Si. This lets them revert to a routine that has been internalized, as opposed to having to make decisions about a huge number of details on a daily basis. It can also be comforting for them to go with what’s familiar and nostalgic in these situations. 

It’s common for NeFi’s to get so absorbed by something fascinating that rest or nutrition is unintentionally forgotten because they’ve temporarily lost awareness regarding their physical needs. This absorption can also lead to bumping into things or losing things (even things that might literally be in their pocket) because of a general forgetfulness regarding the presence of the physical world.

Some NeFi’s describe opening 10’s or even 100’s of tabs in their web browser and not reading the content in them, or having a hard time throwing things away because they think they might use it later. Ne likes keeping all the possibilities open and having weaker Si can mean that it’s hard to figure out which pieces are more useful than others.

NeFi’s generally don’t do well with a lot of detail. They prefer to look at big picture connections rather than single concrete details. This can cause them to get easily distracted or forget what they’re doing in the middle of a task if they go too far off the main path. This is why they thrive when they can be the ideas person and let other people handle the details of implementation.

Once Si becomes more developed, NeFi’s tend to become more productive and can be more satisfied with what they’ve done in their day. They can take an idea and immediately get to work on it instead of keeping it in the idea stage forever. They can also begin to find ways to relax through Si tasks like doing dishes or cooking. The predictability and physical aspect of the process is what their Si side especially appreciates. It can also assist them in realistically seeing the steps necessary to accomplish their ideas.