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 TeNi’s functions are:
1. Te – extroverted Thinking
Te is the primary way TeNi’s interact with the world around them. Te is all about efficiency and getting things done. It is the TeNi’s primary decision-making process, which means that if a decision is needed in the moment, they will rely on what makes the most sense logically. They are primarily concerned with moving forward and are not interested in wasting time and energy nitpicking a solution to death before applying it. Their solution is the "perfect" solution in the moment. The best, most effective solution is often obvious to them, and they are masters of maximization and efficiency.

2. Ni – introverted Intuition
Ni is the way that a TeNi perceives their inner world, it dictates the way they store information and how they perceive that information. It also heavily dictates the path that their train of thought will take. Ni tends to store information in a spread out way with all the pieces of data having connections of various strengths to multiple additional pieces of data. This creates a dense web-like mass of information that is too large to be viewed in detail as a whole, but can be zoomed in on to show intricate clusters and threads of thoughts.

This network of data rests slightly outside of the conscious mind, giving Ni a dreamlike quality that is equally likely to be experienced in images and impressions as it is to produce concrete facts. Because the focus of the Ni perception is constantly scanning the whole but also frequently zooming in on various thoughts and feelings and changing angles on a subject, they tend to experience their inner world as constantly fluctuating.


3. Se – extroverted Sensing
Se helps the TeNi use their senses to understand the world around them. They enjoy living in the moment and are capable when it comes to dealing with things that they can experience and touch in addition the purely hypothetical. This is because their Ni and Se fall in the middle as far as preferences go, so they’re able to flip back and forth to use each one as it’s needed. Se is also what drives them to search out playful new sensory experiences.

4. Fi – introverted Feeling
Fi is their last function. Fi helps them to assess situations to see how things match up to their values and beliefs. They may think of their Fi as their “gut instinct”. It helps them learn to be sensitive to the values and feelings of those around them. It can act as a warning system when they think a decision makes sense logically, but somewhere inside, Fi is the alarm saying it’s a bad idea. However, because Fi is the TeNi’s weakest function, they will often act with the swift decisiveness of Te first, before considering how their actions might affect the feelings of others or taking time to think about whether their decision lines up with their values.


Dominant Function and Core of the External World:

Extraverted Thinking
TeNi’s flip between two modes - one in which they are constantly aware of their environment, actively making decisions and taking action, the other in which they are honed in on an interesting problem or question and get into a pattern-seeking, problem-solving mode. They use Te in the former. They are very efficient problem-solvers, naturally seeing the best course of action for the best outcome. They are highly logical and are natural-born leaders, easily seeing what everyone should be doing to accomplish the task at hand. 

While introverted Thinking (Ti) dominant people want to spend lots of time refining and perfecting their solutions, a healthy TeNi is confident in their in-the-moment problem solving ability. They don’t need to spend lots of time refining and reevaluating things, because they know they will be able to shift quickly and do spur-of-the-moment analyzations if their ‘Plan A’ somehow falls through.

TeNi’s are often very driven individuals. They value autonomy and doing things for themselves. They are the sort of person who is likely to get a job at 14-16 years old (as soon as they’re able), who works hard, and makes a name for themselves in whatever industry they’re in. TeNi’s can be good at almost any type of work, but they tend to be in sales, tech, law, or government. They are often C-level executives, managers, or entrepreneurs. While they may start at the bottom like everyone else, TeNi’s can be so driven and commanding that they are able to rise through the ranks with ease and grace if they put their mind to it.

Neuroscientist Dario Nardi noted that types like the TeNi “often show efficient use of mental energy as they rely on evidence-based decision making.” Not only do they value efficiency in their day-to-day decisions, their brain has actually learned how to function with less effort than most. This evidence-based decision making relies on sensory information in particular - what they see and hear, in addition to what they remember experiencing. They also tend to “focus on goals and are stimulated by task completion and error correction.”

They are able to “note errors in their environments and filter out unwanted information, including negative feedback from others.” This lets them focus on the task at hand despite naysayers, and also leads them to show others what they’re doing wrong quite often. However, they show high activity in the region that handles their own deeply felt values, which are often expressed in negative ways. Essentially “they are acutely aware of failures to live up to standards, moral or otherwise.” and tend to be quite hard on themselves and those around them as a result.

TeNi’s are very goal-oriented and results-driven. When they’re at their best, you aren’t likely to see them continue with an inefficient method for long. They tend to dislike getting into the dirty details of implementation and are likely to delegate as much as possible to others. It’s very obvious to a TeNi what is or isn’t going to work, and it can be frustrating when others don’t see solutions as obviously as they do. TeNi’s may be accused of being bossy or critical at times, but it’s important to note that they typically won’t bother correcting someone unless they value that person and/or their work. Although people might complain about the bossiness of a TeNi, the truth is that those around them would be usually be lost without their effective leadership.

TeNi’s thrive in systems of hierarchy, whether they are able to lead or take instruction from those in charge (provided those in charge are competent and effective leaders). If no leader is apparent, the TeNi will usually step up to unite the group and see that things get done. TeNi’s work most effectively when they know what boundaries and expectations they can operate within, although they may disregard those boundaries if they get in the way of achieving a goal. If they are under an ineffective leader, they will become very frustrated and will probably do everything they can to either have the leader replaced by someone competent, or help them overcome whatever hindrances they face.

Although TeNi’s are very social people, they are not afraid of being disliked in most cases. They don’t shy from necessary confrontation and when it comes to interpersonal conflict, they are apt to want to resolve issues in a quick, efficient manner and then move on with life. Only when they feel someone has wronged them or wounded them very deeply will they feel the need to cut people out of their life. In most instances, they prefer to resolve an issue and move on, without lingering too much in any emotional aspects of conflict. 

TeNi’s are very opinionated people, and are not shy about expressing their opinions in mixed company. They find debate stimulating and are won over by people who can hold their own in verbal sparring matches, as they don’t come across people like this often. If the other person becomes overly emotional with their arguments, or cannot articulate their points accurately and concisely, the TeNi will likely feel good in their "win" because they were able to keep their composure while explaining their side. They tend to get frustrated if someone does not understand where they’re coming from or tries to steamroll them with their own position without hearing the TeNi’s perspective.

TeNi’s don’t typically play ‘by the book’, and they thrive on calculated risks. Anything too safe is usually boring to them because of their ability to conceptualize the logistics of the way their plans will work out and think 10 steps ahead of most people. They are very innovative and idea-oriented, and generally aren’t afraid of trying new ideas or gambling on something if they have a really good idea.

TeNi’s are very all or nothing. They tend to be very deliberate about the choices they make and they like to do things with excellence when they’re working on something they care about. This means that doing the right work, they are extremely responsible and determined. With the wrong work, they may get irritable and apathetic about the way the job is done, or may focus too much on little details without being able to see what’s most important in the context of the big picture. 

They may also simply hate the work if they feel that they’re being led by an incompetent leader. Over time TeNi’s learn how to tell when it’s actually just a difference from their own leadership style, which they can respect, versus a real problem that is going to have significant negative consequences. Generally they’re able to start seeing this difference in their 20’s, but it can take a long time to give the benefit of the doubt to the person in charge.

Second Function and the Core of the Internal World:

Introverted Intuition
TeNi’s have a deep internal world that is often hard for them to put into words or share with others. Ni is their main source of creativity. They are very intuitive and can often see all the possibilities for how a particular situation will play out. They are then able to analyze all the options and refine them down until they arrive at what they feel is the most likely one. Their inner world is constantly shifting and changing and analyzing different aspects of things. When they make plans or have a goal in mind, they are naturally able to skip ten steps ahead to see how it might turn out.

When a TeNi is in analyzing mode, it often feels like their whole brain is working at once. On good days, it feels like smooth and cohesive movements of data headed to a single point on a horizon of discovery, but in times of stress, it seems more like a chaotic whirlwind of thoughts and emotions. For the younger TeNi’s, they may feel like spectators of this process rather than active participants, however as they mature, they will be able to exert more control and direction over this process.

According to work of Nardi, they tend to access their brain in a holistic way, engaging multiple areas of their brain and synchronizing those regions in a rhythmic, and tranquil pattern that is usually associated with the brain activity one would expect to see from an individual who is thinking in their area of expertise, however, for the TeNi, this is what happens to their brain when they encounter a new problem or concept. Because of this, they need to take on new challenges to their thinking regularly. They also have the ability to enter a creative mode in which their cortical circuits link key brain regions for hyper-fast thinking

Ni is primarily concerned with analysis and thought more for the experience of stretching its own perspectives and predicting possibilities rather than forming firm conclusions. While they like to know where they stand on particular issues, they tend to be comfortable with paradoxes and the unknowable more than other types. Ni is mainly focused either on the future, or things in the present that remain unknown or un-provable (for example: other people’s motives, the true origin of the universe, how will that cliffhanger on their favorite show be resolved). 

Some TeNi’s internal worlds differs from what most people would define as reality. They may end up accomplishing things others would deem impossible because of this difference in perspective. Although this makes them unique problem-solvers, they typically benefit from the feedback of trusted advisors to help determine when their ideas are genius, and when they are just a little too far out there.

TeNi’s thrive on improving things, or taking an idea and making it a masterful plan, and then executing it. They tend to enjoy work where they get to combine their ability to see ten steps ahead with their drive to make things better and more efficient. They may be interested in industries such as engineering, product design, architecture, or the sciences.

Given the nature of Ni, TeNi’s can sometimes approach detail overload. When this happens, it helps to externally record thoughts (in a journal, planner, to do list, or by talking with another person). Externally recording thoughts allows them to release the thought into long term storage, knowing that they are more likely to be able to recall it later. Or, if they feel they have adequately addressed the matter, it allows them to “delete” the info completely.

Ni also tends to bring up needed insight and stored information at exactly the right time, without much effort to consciously recall what is needed. Unfortunately, this automatic drive to bring relevant information into the forefront of consciousness can result in negative patterns, like over analyzing problems that have no immediate solution to the point that they can become fixated or obsessively worried. Ni makes it very difficult to put a problem “out of their mind” or compartmentalize their thoughts. They will often find themselves pulled back to the unresolved issue until they can solve it. Coping techniques include designating a later time to process, reaching out for support as soon as possible, distraction, and meditation/prayer. 

Third Function and Supporting Role in the External World:

Extroverted Sensing
While TeNi’s are great with abstract ideas, concepts, and conversations, they will see even more value for ideas when they can find a way to bring it out into the world and make it a tangible reality. While endless speculation about every possibility under the sun is fun, TeNi’s are very action-oriented people and they will be itching to do something to see all their ideas play out in the real world. Because their inner world is more abstract, they seek their stability in the world around them. 

TeNi’s need a certain level of impulsiveness in life to be happy. Being too tied to a schedule can feel like torture for them and planning too much takes the spontaneity out of life. They enjoy breaking rules from time to time, especially if they feel that others are trying to impose too much unwanted structure on them. They want to do what they want when they want, and rules often seem very arbitrary and illogical to them.

When it comes to getting to know people, TeNi’s often prefer doing things with people to spending hours talking as a means of getting acquainted. They crave thrill and adventure. They enjoy being engaged with the world around them. Exploring nature, getting involved in physical sports, or getting their hands dirty and doing things in the physical world is very cathartic for them. Their surroundings have a strong influence on them, and they can be very aware of their physical environment.

When a TeNi does something to engage their senses, this can be a source of energy. Without risky, fun, ‘5 senses’ types of experiences, their energy and creativity flatlines and they may turn to unhealthy vices like binging on food, alcohol, television, or video games to try to fill this need for physical engagement. This need is better filled with exercise, exploration, and play.

Their internal world has a certain intensity to it that they may feel is lost once it’s brought out through verbal communication. They tend to be more at ease communicating through images, sound, written word, or some other form of expression where they are able to explore the full depth of an idea and expand on it before presenting it to public scrutiny. They are also usually more interested in finding the meaning behind things than taking them at face value, which means they may take some time to process new opportunities or unusual circumstances they find themselves in.

Last Function and the Supporting Role of the Internal World:

Introverted Feeling
Introverted Feeling (Fi) is a slower decision-making process than their preferred Te method. Fi is the morals and values-based decision making process they use. Healthy TeNi’s typically operate by the “golden rule” of treating others how they would like to be treated. Because they put more emphasis on the the logical, blunt, take-charge side of themselves, they may view extremely soft-hearted people as being too sensitive.

For example, when someone reacts poorly to a great critique that they give because they know it could help that person improve immensely, they might think, “If I wasn’t being effective in that area and didn’t know it, I would want someone to point that out to me!” They might not know or take into account that others don’t operate like they do. Others may view the TeNi’s version of helpfulness as hurtful. 

They can unintentionally hurt people they care about in the moment while trying to help, but upon reflection they’re likely to realize that they hurt the person. It can take a few tries for the TeNi to know how to rectify such situations. Because their main method of operation is quick, decisive efficiency, they aren’t as inclined to ruminate at length over what should be done, or to spend a lot of time thinking through how their words and actions will affect others.

Fi is the small part of the TeNi that is quite vulnerable and sensitive. While others might view them as very blunt, outspoken people, inside they do have a soft heart. Their emotions, while perhaps uncomplicated, are felt very deep down. They don’t have very many emotional buttons, but when pushed, those they do have can bring them to their knees. Talking about their emotions - their innermost fears, their hopes, their love - may be quite difficult for the TeNi. 

If they are uncomfortable with this softer side of themselves, they will probably ignore it, which can lead to ruthless and cold behavior towards even those they care about. TeNi’s should be wary if they have a tendency to ignore their morality and emotions.
Their morals are decided without too much influence from others, although they will take their experiences with others into account. The more experience they have with a person, the more they are able to understand how to interact with them in an effective and caring manner. Their morals are most likely going to consist of what is effective, and they aren’t likely to adopt others “rules” unless those rules make sense to them.

Ultimately, they value their own opinion the most. If they believe they are doing the right thing, they will be able to rationalize almost anything. This aspect of a TeNi’s personality can actually be a hidden strength. They can make advancements in areas that others might be afraid to venture into, because they aren’t worried about what others think of them. Their own interests and values can keep them going on the path towards their goal, even in the face of disapproval from those around them.