By way of introduction, many people first learn about their Myers-Briggs "type indicator" (MBTI) through taking a 'personality assessment' and getting a code: example, my MBTI is INTP.
There is a "boxy" way of understanding this. Psychological type defines a four-dimensional personality space and each type is a vector within it. If you proceed in this manner you get a good correlation with academic psychology's "Big-5" five-factor model (FFM) and it's common to hear that the MBTI is the FFM without the "Emotional-Stability -- Neuroticism" dimension.
But to view psychological type like this is to take the snapshot when you could be getting the movie. In the Jungian view, personality is about the active interplay of psychological functions or processes. Jung and Myers talked about the Dominant, Auxiliary, Tertiary and Inferior hierarchy of processes (each of which could appear as introverted or extraverted).
Subsequently Beebe, and later Berens, proposed extending the model with explicit consideration of subconscious processes (itemised as 5th, 6th, 7th and 8th). The priority-ranking of the processes for an INTP are shown below: only the 1st to the 4th are conscious.
The eight functions for an INTP
So what does this mean? My dominant function is Ti which means an orientation to theorising, modelling, looking for patterns, spotting inconsistencies. You don't see this because it's interiorised, introverted, but ask yourself: why else am I writing this stuff?
The Ne is extraverted iNtuition which you do see ... as the generation of creative new ideas in response to here-and-now stuff: present situation, conversation etc.
The tertiary Si is introverted Sensation, corresponding to memories, past experiences and stored knowledge. This is less central in driving my interior life but forms a backcloth to the Thinking function. Again, you don't see it directly.
The Fe is extraverted Feeling which you do see: a kind of rather unsophisticated cameraderie used in engaging with others. Let's not short-change myself here: there is a certain amount of warmth but it's subservient to stronger internal masters.
So what this amounts to is that the interior Ti provides the hidden core of my personality-processes, backed up with Si, while the external public form or wrapping is provided by an ideas-oriented, affable persona NeFe.
There, that wasn't so hard, was it?
The functions 5-8, my conscious orientations operating in their non-preferred way, are both weak in influence and unconscious.They are collectively called "the Shadow" and might manifest themselves in my behaviour if I lost control of myself. People might say things like "He behaved totally out of character," and it's a possible defence in a court of law (let's hope it never comes to that).
The prioritised functions for the 16 types
If you know your own Myers-Briggs type you can read your process hierarchy above (click on the image to make it larger). If you don't know it yet, discover your type by taking the assessment here.
Description of the Perceiving processes
Here is a more structured description of what the process-letters mean, first for Perceiving functions ...
Description of the Judging processes
... and here for Judging functions.
INTP talks to INTP
Now Beren's analysis starts to get really interesting as she considers communication and relationships between types. When any type meets their type-counterpart - someone else of the same type - then all their cognitive preferences are aligned. They often become friends because communication seems so natural.
So for example, in the diagram above, when an INTP meets another INTP they have a shared interior life of systems building and theorising. They both delight in the generation of ideas and the exploration of consequences, and they both share a general affability. The arrows go across horizontally.
They may enjoy a chat but do they care much about each other as people? No, not much. That Fe function is the inferior function and is not much of a driver in the psyche.
INTP talks to INFP
INTP with INFP: these two types are close to my heart as Clare is INFP. Her dominant process is Fi which in plain English describes a drive for positive ethical outcomes, harmony and spirituality.
Note where that is in my list! And note where Ti is in hers!
So the model predicts that we have common ground in ideas, concepts and shared experiences. But if my logical analysis and her moral values come into conflict we're never going to resolve things. And neither of us is much driven by Se which you can read as either a lack of concern for the minutiae of the world around us, or as no common sense whatsoever. In the conversational domain, Se equates to smalltalk and we both conspicuously lack that.
INTP talks to ISFP (or not)
Here's a relationship where meaningful communication is "interesting". I mention this because my mother is ISFP. The combination of SeFi, the latter dominant and introverted can be glossed as a strong orientation to moral values wrapped up in a common-sense reference system, robustly delivered (inferior Te): not however very susceptible to analytic disputation.
ISTJ talks to ISFP
Of course, with Linda Berens' instruction you can do this with your own relationships and those of others. Above is my diagram for ISTJ - ISFP, only showing those interactions where both parties are using their conscious processes (there are some more lines you can draw but if an arrow lands on one party's subconscious process communication is very difficult). My late father was ISTJ so it's an interesting exercise to translate this diagram into plain English.
To read more about Myers-Briggs Type Theory and brain architecture click here.