Introverted Sensing (Si) is the dominant cognitive function for the way certain personality types absorb and understand the world around them. All types utilize some variation of the Sensing function and roughly half of the population functions as an Si user. You will be able to identify them once you are familiar with their processing techniques.

Let’s assume that you are already familiar with the four letters of your Myers and Briggs personality type profile and know whether you function as Sensing, or prefer to use iNtuition. This dimension of your personality type tells you how your brain processes incoming information. All Sensors prefer using their senses (smell, touch, sight, taste, sound) in a very physical, hands-on way of learning.

Don’t know your personality type? Take the Typefinder test here

However, regardless of whether you are a Sensor or an Intuitive, you will use Sensing to a greater or lesser degree. For example, an ESTP has Sensing as their preferred function. An ENTP, on the other hand, will not pay as much attention to information coming in through their senses, but they can still tap into these skills when they need them. All aspects of personality exist on a spectrum – they are not absolute.  

So now we’ve explained the ‘S’ part of Si. Where does the ‘i’ part of the symbol come from? This letter tells you how you use your Sensing – whether it is processed internally (Introverted Sensing or Si) or whether it is proudly outward for the world to see (Extraverted Sensing or Se). More on this below.

The last piece of the puzzle decides whether your personality uses Si as a dominant function or an auxiliary, secondary or supporting, function. ISJ’s have Si as their dominant cognitive function and ESJ’s have Si as their auxiliary cognitive function.

For comparison, these personality types use the Si or Se function:

(Si) Introverted Sensing as a Dominant Function: ISFJ, ISTJ

(Si) Introverted Sensing as an Auxiliary Function: ESFJ, ESTJ

(Se) Extraverted Sensing as a Dominant Function: ESTP, ESFP

(Se) Extraverted Sensing as an Auxiliary Function: ISTP, ISFP

Other types have Si as their third or fourth function. This means they can call on it in times of need, but it doesn't feature in their day-to-day processes very much at all. 

Read more: Beginners Guide to Understanding the Cognitive Function

An Si and an Se walk into a bar

Sensors use the five senses as a frame of reference to absorb incoming information, but not all Sensors process it the same. This is where Extraverted Sensing and Introverted Sensing differ.  

Extraverted Sensors experience data through concrete physicality and external facts. You need the facts that your senses present to you in order to understand what you’re looking at and it reshapes somewhat faster into decisions. The Se user’s direct relationship with the senses allows them to react quicker and direct more energy to the task at hand and provide real-time feedback.

Introverted Sensors filter data and experiences through a pre-arranged set of inner memories and sensations such as pain or hunger, comparing and contrasting what is happening to anything that we’ve experienced before. This allows us to form subjective opinions and make decisions, but takes a little longer to arrive at them.

Another way to see these differences is to note that Se users work predominantly with short-term memory. Si users work with long-term memory. Se users will take in information and push older memories out of the way to make room for it. Si users will take in the information and mull it over. Ponder it. Dwell on it.

A good way to think of this is like a memory box.

We need to make sure the new data goes into the right box and is properly connected to everything we already know. That is a lot of little adjustments. But as a result, we are committing it to long-term memory and the older memories now support it. All of our memories remain based on the connections we made between them.

Si users contain their data in the boxes and stack them deep and wide. You will know them by what they tend to talk about. If someone is recounting a story from 20 years ago (and you’ve heard it before!), they are likely an Si. If someone prefers to chat about the here and now, they are likely an Se.

Working outside of the box

The way we handle the unknown is by comparing, contrasting, and extrapolating it with something already familiar to us. How else are we going to put it in the right box? As incoming data presents itself, we are reaching backwards for a link to tie it to. Everything connects, everything is a pattern, and we order our world accordingly.

You will find me at a new job position huddled over my desk, simply feasting on all the incoming data. Letting it digest. Rearranging the pieces over and over until a pattern forms, a routine blooms, and a sudden harmony comes from the chaos. I’ve found the right boxes, lined them up with the new system, and now we can go out and dominate at work.

Introverts refer to their inner world as they go about experiencing life. Constantly collecting and arranging new data in the current set of boxes, we will expand and sometimes reorganize the boxes as we learn new things. The sky is not always blue. We add each new color as we experience it and the box on skies rearranges and labels its files accordingly.

If we know for a fact, however, because our box says so, that there is only ever one sun in the sky, and we wake up to a double sunrise, our foundational box cracks. We are basically immobilized until this new data can be either aligned with a box or we build a brand-new box to hold it.

Benefit package

Si is a patient and generous function. Si personalities are skilled at recognizing inconsistencies or change. As previously mentioned, internal processing creates long-term and accurate memories in the Si user. This means they learn from their mistakes and rarely repeat them.

Si users are loyal, responsible, and traditional. They have a high regard for authority and prefer value systems that uphold it. Si users can be materially frugal and maintain that “if it ain’t broke, don’t fix it.” They are generally low maintenance people who avoid drama.

Healthy Si users can tap deliberately into their happier memories when deciding what new information might mean. They are better at creating and adapting new traditions and experiences when supportive environments are stable and predictable. Their skills with planning and organizing, combined with minimalist attitudes, result in welcome open space for new data and prevents them from becoming overwhelmed.

Once Si users have their boxes tidied, they can achieve a state of flow easily, putting them “in the zone” in real time. This looks like a deeply content Christmas morning or apparently seamless execution of a task at work.

Understanding the way our personalities function and the wiring that supports and directs our perception of the world lends itself to many ‘aha’ moments. If your dominant cognitive function is Si, you age with grace, pulling from history to make the future a better place.

Jolie Tunnell
Jolie Tunnell is an author, freelance writer and blogger with a background in administration and education. Raising a Variety Pack of kids with her husband, she serves up hard-won wisdom with humor, compassion and insight. Jolie is an ISTJ and lives in San Diego, California where she writes historical mysteries. Visit her at jolietunnell.com