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 SiFe’s functions are:
1. Si - introverted Sensing
SiFe’s naturally use Si to catalogue experiences and information they deem important. In particular, they remember their impressions of experiences they’ve had. They have an organized internal world and their mind can easily put similar pieces of information into appropriate categories. They learn straightforward, practical systems, rules, and strategies with ease and grace. Si gives the sense of the SiFe being grounded and having a linear, black and white way of thinking about things.

2. Fe - extroverted Feeling
Fe is the primary way SiFe’s interact with and understand the people in the world around them. It is not emotions, but “gut instincts” they might have about a person or situation. This function is focused outwardly and reads or “takes in” information about other people. It picks up on their vibes and what their thoughts and feelings might be. Fe also helps SiFe’s relate back to and communicate with people in a way that people are comfortable with.

3. Ti - introverted Thinking
Ti analyzes information and seeks truthful answers to all of life’s questions. When Ti serves Si in an SiFe, it analyzes things in a categorical, organized manner, and seeks truth about experiences and situations. Because Ti is right after Fe in order of preference, SiFe’s can be very balanced between their stoic analytical side and the side of them that values people.

4. Ne - extroverted iNtuition
Ne is the SiFe’s last function. Ne is the small part of the SiFe that craves simple new experiences and ideas, but because it is their weakest function, it can only be used in simple ways or for short periods. For example, when coming up with an idea to execute a project, they can take a lot of details they’ve gathered from previous experience and put them together to form a really great concept, but coming up with an idea about a project when they have no relevant practical experience catalogued away can be very difficult. Ne can also fuel sudden “lightbulb” moments where an idea strikes them out of nowhere as they’re talking.


Dominant Function and Core of the Internal World:

Introverted Sensing

Si is internal or introverted Sensing. It’s all about real-world experiences, and how 5-senses (seeing, hearing, tasting, seeing, smelling) affect people with Si. SiFe’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 always go on vacation to the same place every summer. However, Si is very subjective, which means each person who uses Si might value vastly different “traditions” or rituals from the next person.

SiFe’s might have different reasons for valuing their own Si experiences than other types. They are very likely, for example, to value a certain kind of cake on their birthday because their mother always made it. They tend to be quite sentimental because their subjective experiences are made more meaningful by the people they're around. If someone that an SiFe cares deeply for creates any sort of ritual with them, that ritual will likely be all the more valuable to the them.

SiFe’s are generally pretty in touch with the world around them because of their high value for real-world, tangible experiences. They tend to take care of life’s daily needs very well through an organized schedule or a to-do list planned out in their heads. Because the to-do list in their head is being added to just as quickly as they check things off, they may feel that they haven’t accomplished much unless they are able to see tangible results from their efforts.

SiFe’s might relate to the idea of an internal filing cabinet that stores the information they gather from the world in an organized fashion. Once they learn the details of how a system works, they are unlikely to forget it quickly. They are also easily able to see the next steps in a process when they have experience with the underlying system because of their naturally linear thought patterns. They usually enjoy work where a key part of their role is to learn and become the expert in a set of procedures, a piece of software, a machine, or anything else that runs in a clear, linear, systematic way.

SiFe’s are often able to implement and maintain highly complex systems with incredible grace, whether it looks like creating a way to manage all of the orders and customers for a business, or keeping track of all their kids’ activities for the week and finding a way to make sure everyone gets where they need to go. They tend to live knee-deep in the details which helps with managing high levels of complexity, but they may struggle to zoom and give a big picture view of something.

People with strong Si like to know what to expect and to plan accordingly. Routine is one of the their best tools, and they wield it well. When they know what is expected of them, they can accomplish really great things. However, they may not do well with vague instructions or surprises that affect the task at hand. If they spend enough time with a particular person, whether it’s as a partner, parent, employee, boss, or child, they may be able to find ways to interpret a vague idea into the details they need, but they nearly always need a lot of detail and clarity in the beginning of a relationship.

SiFe’s can feel uncomfortable when faced with an entirely new situation where they have no past knowledge or experience to rely on. They greatly prefer having a set of criteria or a specific way to complete tasks that they know works for them. If they decide to take on something big and new, they usually feel a lot more comfortable taking it slowly and getting used to one element at a time, rather than jumping in head first and figuring out the details later.

SiFe’s are very reliable and dependable, and they expect the same from others. It can be frustrating for them when they can understand and see the steps needed to complete a project, but others around them can’t seem to see the work and details that will be necessary - especially when it’s the people who they need help from in order to accomplish their goal.

SiFe’s plan, organize, and execute their plans in a very linear fashion. When they put their all into a project and have all the proper resources, you can be sure it will be very well executed. It can be frustrating for SiFe’s who don’t realize that some people aren’t capable of being organized in the same way they are. Because they want to be helpful and useful to those around them, and highly detailed systems are very simple and easy to them, they may attempt to make others use their systems as well, thinking, “If this works for me, of course it should work for the person I’m helping!”

They may not have an easy time recognizing their own intelligence, because once they learn a complex, detailed system, it becomes simple to them. However, this is not a skill that most people possess.

SiFe’s also tend to have very high standards for themselves, which can cause them to focus on where they feel they’re falling short, even though those around them probably don’t demand the near-perfection they demand of themselves.

Second Function and the Core of the External World:

Extraverted Feeling

Fe is sometimes 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. Even at a friend’s house, the SiFe may feel a little guilty letting another person get a 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?” They feel most themselves when they are helping others and not expecting anything in return. They tend to help others simply because it’s hard not to.

Fe differs from Fi in that 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 I’m in feel about this?” For an SiFe, because Fe is second, they might be less concerned with how an entire group feels about something than what their closest friends or partner feels about it. SiFe’s are highly protective of those they have taken into their “inner circle” and will put themselves into a confrontational situation on behalf of someone close to them, although they would likely let the same situation slide if it only affected them.

People with Fi can naturally qualify and quantify their own picture of themselves as if they are looking directly into a mirror. For people with strong Fe, their metaphorical mirror is pointed outward. Fe is a data-gathering function, but it cannot objectively gather data about itself like Fi can. Fe relies on outside sources to gather data it deems accurate. Essentially, an SiFe constantly gathers information from their external world to find out if people think they are good or bad, and then they weigh this against their own internal Si values/opinions.

It’s worth noting that when we talking about Feeling (Fi or Fe) as a cognitive function, we do not necessarily refer to emotions. Emotional experiences or expressions can be related to Feeling, but they are not the root cause of the Feeling functions. The root of Fi or Fe boils down to a person’s values - what a person thinks is important based on their own conscience and why. The SiFe’s conscience or "gut instinct" is led by sympathy they have for others close to them, and their moral code is influenced by what those people need and value.

Their Fe values are not based directly in emotions, but neither are they 100% logical (They don’t necessarily need to know the REASON people want to be treated a certain way in order to respect it). SiFe’s observe those around them, and ask themselves "What do others want? How do others want to be spoken to? How would others like to be treated?"

SiFe’s strong internal sense of right and wrong can color their sense of themselves, as they naturally see all the things they aren’t perfect at (because their mental to-do list is never complete), and all the steps needed to obtain perfection, which overwhelms them. Because SiFe’s can naturally focus on what still needs to be done, using Fe feedback from other people to understand what they are really like in the world is a valuable process that can help the SiFe see the areas they are already excelling in.

Because Fe is serving Si in this type, SiFe’s are most comfortable around people they know well, and are likely to only share their true inner principals and opinions with people in their “inner circle” and/or those whom they know aren’t likely to turn an intelligent discussion into an debate. They don’t see the need to turn everything into a debate, and they don’t enjoy pitting one person against the other. If they determine that entering into a debate type discussion will directly benefit someone in their “inner circle”, however, they will probably not hesitate to engage. They value harmony very highly, until they feel that someone they love is being attacked/threatened, and then they quickly become very justice-oriented. SiFe’s are not afraid to stand their ground in defence of another.

SiFe’s tend to have at least a small handful of topics in which they see the issue as so clear cut that they will not hesitate to argue for their stance - even though debate/argument is typically offensive to their Fe. When these topics come up, they might have the sense that because the issue is so obviously clear cut in their mind, they are doing the other party a service by explaining why they are “right” or “wrong” in their belief.


Third Function and Supporting Role in the Internal World:

Introverted Thinking

Ti is a very analytical function that is primarily concerned with finding the absolute truth. It prides itself on logic and objectivity. SiFe’s are often very logical internally, but the subject matter they analyze is usually people-focused or people-related. People-focused subject matter is rarely, if ever, going to be completely objective and will almost always have a wide, multi-faceted scope. SiFe’s are certainly capable of thinking about complex analytical subject matter, but some of them may not be interested in complex analyzations simply for the sake of complex analyzations.  

Ti in general is a very focused process based on what the individual thinks about things. It processes information and asks, “Does this seem logical to me?” and “Is this factual?” SiFe’s often enjoy hobbies and pursuits that allow them to use their Ti analyzation skills in conjunction with their Si real-world organization skills. They might find things like sudoku or crosswords to be just the right amount of challenging and relaxing.

Some SiFe’s enjoy becoming experts in areas that require lots of analytical thought within a detailed system. This could mean things like data analysis or home organization. It all depends on where the person’s interest lies.

Many SiFe’s analyze primarily people-related, value-centric data with their Ti. Their analysis is led by their subconscious Si observations, which takes information from their real-world experiences and sorts it into preliminary default decisions based on previous experience. Because they store large amounts of information from their experiences with people, they find that people are fairly predictable. So for example, if someone they know is upset, they can tell because that person’s body language, tone of voice, etc. is generally the same from one emotionally tumultuous situation to another.

SiFe’s may have strong emotional reactions to situations at times. In these cases they’re likely to spend time analyzing why they had those feelings, where the emotion came from, how to avoid it in the future if it was negative, or how to reproduce it in the future if it was positive.

Ti also helps them define concepts (a = b, and b = c, so a = c), and sort through the information to determine whether they think those decisions are accurate. They try to determine what is true based on what is logical in combination with the information they’ve gathered from their other functions. It might look like a process of elimination based on what they’ve experienced in the past-- “My boss is giving me the cold shoulder today. Last time he acted this way, he was really stressed about a deadline. I bet he’s stressed again today.”

Because Ti is serving Si in the SiFe, they generally feel compelled to come to solid conclusions about things. Their opinions are often very quickly solidified, and they might not naturally look beyond what they have internalized as being right or good. Once they’ve put something into a “bad” or “good” category in their minds, they will move on to the next thing to analyze and come to a decision on. If a topic comes up again that the SiFe has already come to a conclusion about, their default is to recall and understand it the way they did the first time. Their opinions can certainly change, but when they do, it will likely happen very gradually over time.


Last Function and the Supporting Role of the Internal World:

Extraverted iNtuition

Ne is the SiFe’s last and weakest function. It is all about abstract ideas, endless possiblities new experiences, and hypothetical exploration. Because SiFe’s are so focused on their real-world, practical experiences, they may have trouble coming up with new ideas and concepts without a lot of real world data to refer to. However, they can come up with brilliant plans when they have the right kind and amount of data to prepare. Ne is the part of an SiFe that naturally looks at the  big picture. Because it’s last, SiFe’s can have a hard time tapping into it, and are generally knee deep in the details of life, using their Si to assess every little piece of things.

Ne is a thrill-chasing, idea-exploring, external stimulant-seeking function, but since it is serving all the other functions in the SiFe’s stack, it can be draining for them to do things outside of their comfort zone. They might like having an aspect of adventure within an already familiar experience; for example, coming up with a new exercise routine at home where they can be in control of all of the aspects of their experience, or the previous example of going on vacation, but going to the same destination every year (especially if it holds nostalgic value). However, when left to their own devices, an SiFe will typically be quite happy with the same routine.

It might be relaxing for SiFe’s to do small-scale Ne things that they can be in control of-- i.e. coming up with a new route home from work to get around traffic, figuring out a new strategy to clean their room faster, or cooking a familiar dish with strategic changes to make it something new and delicious.

This side of SiFe’s frequently comes out when they’re talking. They can easily lose their train of thought when they don’t have their thoughts outlined before they start talking. When this happens, they go on rabbit trails, and change topics randomly in the middle of rambling because they forget the point they originally wanted to make. When they forget their point, they might continue talking in hopes that it comes back to them as they go along - like an automatic "download" into their brain once they stumble back to the right track. They might be described as adorable or endearing by those around them because of this tendency.  

When an SiFe is forced to have a lot of new experiences at once or operate in areas that they have zero practice in, it can be extremely draining for them. They are pretty good at predicting what people around them are going to do, or how certain things they have a lot of experience in are going pan out. When this ability to predict what is going to come next fails them, they can become mentally drained as they continuously try subconsciously to figure out what to expect. Not knowing what comes next can feel like getting dragged down mentally and like the SiFe has to be on high alert for the next unexpected event, because they still want to be prepared… Somehow.

SiFe’s do best with new situations when they have time to plan and prepare. Those around the SiFe should understand this and find ways to work with the planning and preparing process. This is especially true with big risks, which tend to fall outside the SiFe’s comfort zone. Any type of high risk life decision is likely to be incredibly draining to an SiFe - quitting a steady job to start their own business, moving to an unfamiliar place where they don’t know anyone, etc. However, once an SiFe has researched and planned things to their level of comfort, they can be quite agreeable to new experiences and learn to enjoy their ‘new normal’.