jung's psychological types - principal and auxiliary functions

Jung's eight main psychological types are in themselves an over-simplification. This is borne out by Jung himself in his 1921 book Psychological Types following his presentation of each of the eight main types:

"...In the foregoing descriptions I have no desire to give my readers the impression that such pure types occur at all frequently in actual practice. They are, as it were, only Galtonesque family-portraits, which sum up in a cumulative image the common and therefore typical characters....... Accurate investigation of the individual case consistently reveals the fact that, in conjunction with the most differentiated function, another function of secondary importance, and therefore of inferior differentiation in consciousness, is constantly present, and is a relatively determining factor..." (Psychological Types, Chapter 10, General Description of the Types, point 11: The Principal and Auxiliary Functions)

(Incidentally, the word 'Galtonesque' is a reference to Sir Francis Galton (1822-1911), an eminent English scientist, cousin of Charles Darwin, who asserted that personality and other traits and abilities are hereditary (inherited or genetic) factors. Interestingly Galton also devised the finger-printing identification system which he first published in his book Finger Prints in 1892. Jung's use of the word Galtonesque intends to convey a general 'broad brush' meaning - the main family groups of personality - as if 'inherited' - not detailed personality types which implictly within Jung's concepts are subject to much influence and change after a person's conception, and therefore outside Galton's ideas of inherited 'genetic' traits.)

Jung's theory does not aim to 'pigeon-hole' all people into one of eight personality types. The eight Psychological Types are simply the eight main groupings represented by Extraversion or Introversion and one 'Four Functional Types' (the superior or principal function). In reality each of these eight type-combinations (represented by E or I plus one Function) is augmented by one or other 'auxiliary' function according to the Jungian theory whereby conscious personality is represented by a dominant function from each of the 'Rational' and 'Irrational' (judging and perceiving) functional pairs of opposites.

So, for example, an 'Extraverted Thinking' main psychological type would be augmented by a preferred auxiliary function from the 'Irrational' (or perceiving) Sensing-Intuition pairing, on the basis that Thinking is the preferred 'Rational' (or judging) Function.

And also for example an 'Introverted Intuition' main psychological type would be augmented by a preferred auxiliary function from the 'Rational' Thinking-Feeling pairing, on the basis that Intuition is the preferred 'Irrational' (or perceiving) Function.

jung's sixteen personality types

These types are automatically and unavoidably implied by Jung's theory, although Jung himself never made a big song and dance about them. They do however help to build up a fuller picture of Jung's theory, and they also relate directly to Myers Briggs'® interpretation and equivalents of these types (for which Myers Briggs® used their additional Judging-Perceiving dimension to determine dominance between the two preferred functional types after the Jungian Introverted or Extraverted 'attitudes').

Logically, adding an auxiliary function to each of Jung's main eight Psychological Types now produces sixteen types, which (subsequent to Jung's Psychological Types book), might be shown as follows, and in each case the first 'Function' (the middle word) is the most dominant. Remember that Introversion and Extraversion are not 'Functions', they are Jungian 'Attitudes':

1. Extraverted Thinking Sensation - ET(S)
2. Extraverted Thinking Intuition - ET(N)
3. Extraverted Feeling Sensation - EF(S)
4. Extraverted Feeling Intuition - EF(N)
5. Extraverted Sensation Thinking - ES(T)
6. Extraverted Sensation Feeling - ES(F)
7. Extraverted Intuition Thinking - EN(T)
8. Extraverted Intuition Feeling - EN(F)
9. Introverted Thinking Sensation - IT(S)
10. Introverted Thinking Intuition - IT(N)
11. Introverted Feeling Sensation - IF(S)
12. Introverted Feeling Intuition - IF(N)
13. Introverted Sensation Thinking - IS(T)
14. Introverted Sensation Feeling - IS(F)
15. Introverted Intuition Thinking - IN(T)
16. Introverted Intuition Feeling - IN(F)

Using what you know about each of these attitudes and functional types you might now be able to begin to identify and understand your own Jungian type.

(How each of these Jungian types including auxiliaries relate to the Myers Briggs® interpretation and system is explained in the Myers Briggs® section. As you will see when you come to it, the Myers Briggs® system uses the additional dimension or pairing of Judging-Perceiving, not only as a type indicator in its own right based on Jungian ideas, but also as a means of determining functional dominance among the two preferred functions, whose methodology depends also on whether the dominance is directed via Introversion or Extraversion.)

While Jung's theories are used widely in psychometrics and personality testing, his original purpose and focus was clinical, in pursuit of better understanding and treatment of mental illness, and improving the quality of human existence. As such Jung placed greater emphasis on the unconscious than is represented within modern psychometrics and 'commercialised' personality theories.

On which point there is great value for us all in Carl Jung's thinking about the deeper workings of the mind, especially the unconscious, beyond simply seeing Jung's ideas as a model for categorising personality.

Significantly Jung for instance observed that improving our awareness and acceptance of the four functions within ourselves - whether as conscious or unconscious elements - is important for developing a healthy existence, and 'life-balance', as we might say today.

Conversely, repression of any of the functions, by oneself or by another person or pressure, is unhelpful and unhealthy, and leads to problems surfacing sooner or later, one way or another.

We see evidence of this when parents condition or force certain behaviour on their children, or when adults inhibit their feelings, or deny themselves sensation of reality. We also see evidence of people's unconscious mind reverting from unconscious to conscious behaviour when they are under the influence of alcohol or significant stress. And we also see the unconscious mind as a chief element within the theories of Transactional Analysis, which when studied alongside Jung's ideas, together provide a powerful perspective of personality and behaviour. It's all mighty powerful and thoroughly fascinating stuff.

The aim of studying and learning about these ideas brings us back to Jung's own purposes and the fact that Jungian theory recommends that all people should strive to develop any neglected or suppressed functions, and to embrace all four functions as being part of the whole person.

myers briggs® type indicator (MBTI®)

The Myers Briggs® Type Indicator (MBTI®) is a widely used and highly regarded system for understanding and interpreting personality, and derives most of its underpinning theory from Carl Jung's Psychological Types ideas and to a lesser extent the Four Temperaments (or Four Humours).

Myers Briggs® (in fact Isabel Briggs Myers working with her mother Katharine Briggs) essentially developed Carl Jung's theories into a usable methodology and system for understanding and assessing personality (more easily and accessibly than by becoming an expert on Jung and his theories).

The owners of the system, the Myers Briggs® Foundation, explain that the purpose of their MBTI® 'personal inventory' system is to "make the theory of psychological types described by Carl G Jung understandable and useful in people's lives...", and that, "..The essence of the theory is that much seemingly random variation in the behavior is actually quite orderly and consistent, being due to basic difference in the way individual prefer to use their perception and judgment...."

(This last sentence is interesting because it highlights Myers Briggs'® emphasis on and interpretation of their Judging-Perceiving dimension - basically Jung's Rational/Irrational definitions - as a means of clarifying function dominance within each whole MBTI® personality type.)

The MBTI® model and test instrument was developed by Katharine Briggs and her daughter Isabel Briggs Myers in 1942 after their studies particularly of Carl Jung, whose basic concepts relating to this aspect of personality and behaviour are described above.

Myers Briggs'® MBTI® concept is featured in Katharine Briggs and Isabel Briggs Myers' key book 'MBTI® Manual: A Guide to the Development and Use of the Myers-Briggs Type Indicator®' which was first published in 1962, some years after the tests had been in use. Isabel Briggs Myers later extended and built on these ideas in her 1980 book 'Gifts Differing'.

The Myers Briggs Foundation explains also that "...The theory of psychological type was introduced in the 1920s by Carl G. Jung. The MBTI® tool was developed in the 1940s by Isabel Briggs Myers and the original research was done in the 1940s and 50s. This research is ongoing, providing users with updated and new information about psychological type and its applications..."

According to the Myers Briggs Foundation more than two million people are assessed using the MBTI® personal inventory instrument around the world every year. It's a big business...

The MBTI® model (along with other personality theories and psychometrics models) is particularly useful for:

• understanding and developing yourself
• understanding and developing others
• understanding what motivates others
• understanding others' strengths and weaknesses
• working in teams - by ensuring that all relevant necessary capabilities are represented in the team
• allocating and agreeing tasks and project responsibilities
• agreeing roles and development with others and for oneself

Myers Briggs® theory and the MBTI® model is a method for understanding personality and preferred modes of behaving. It is not a measurement of intelligence or competence, emotional state or mental stability, 'grown-upness' or maturity, and must be used with great care in assessing aptitude for jobs or careers: people can do most jobs in a variety of ways, and the MBTI® gives little or no indication of commitment, determination, passion, experience, ambition etc., nor 'falsification of type', all of which can have a far greater influence on personal success than a single personality test.

In most respects psychometrics tests and personality models are aids to personal development and to helping people understand more about themselves. They are not to be used a single basis for recruitment or career decisions.

myers briggs® theory and the MBTI® model

The Myers Briggs® MBTI® system uses a four-scale structure for identifying and categorising an individual's behavioural preferences, based almost entirely on Carl Jung's theories and his (translated) descriptive words.

Each of the four MBTI® scales represents two opposing 'preferences' (in other words, preferred styles or capabilities). All abbreviations are obvious first letters, other than N for Intuition, which causes the word to be shown sometimes as iNtuition - just in case you were wondering. The Myers Briggs® Judging-Perceiving dimension basically equates to Jung's Rational/Irrational categories of the two pairs of Jungian Functional types. The colour coding is consistent with the colours used in the Jung section - it was not part of Jung's or Myers Briggs'® theory, but hopefully the colours help explain the pattern and connections.

Myers Briggs® (Isabel Briggs Myers and Katharine Briggs) added a fourth dimension to the three Jung dimensions (Introvert-Extravert, Thinking-Feeling, Sensation-Intuition), namely Judging-Perceiving, which is related to a personality's approach to decision-making, and particularly how the personality deals with the outer world (Extraverted) as distinct from the inner world (Introverted). The Myers Briggs® Judging-Perceiving dimension can also be used to determine functional dominance among the two preferred functional types (aside from Introvert-Extravert, which are not functions but 'Attitudes', or orientations). This can be a tricky little aspect of the Myers Briggs® theory and is explained at the end of this Myers Briggs® section. Happily it's not crucial to deriving value and benefit from Myers Briggs'® ideas, so don't agonise over it if you don't understand it straight away.

Aside from determining functional dominance, irrespective of the way decisions are made (by Thinking or Feeling) the Judging type makes decisions sooner than the Perceiving type. As such the Myers Briggs'® Judging-Perceiving dimension is not found (as a functional dimension) in the Jung model, although Judging and Perceiving most certainly relate to the Jungian descriptions respectively of Rational and Irrational, which Jung uses to categorise the two pairs of Functional Types (the Rational 'judging' Thinking and Feeling, and the Irrational 'perceiving' Sensing and Intuition - refer to the Jung explanation).

Moving on, David Keirsey, in his book Please Understand Me II, provides some additional helpful explanation of how Isabel Myers attached her own meanings to these Jungian words, he said, "putting her own spin on them". Keirsey interestingly also points out that Myers differed markedly from Jung's use of the words Sensation and Perception, which Jung considered held the same meaning, but to which you can see here and elsewhere that the Myers Briggs® system attached different meanings. For this reason if you want to avoid doubt and any confusion in the minds of Jungian purists then it's safest to use the words 'Rational' and 'Irrational' when correlating these Jung terms to the Myers Briggs'® 'Judging' and 'Perceiving'. The right-side column is simply a translation, using more recognisable modern words, for showing the four MBTI® dimensions.

It is interesting to note that many of these words above appear commonly in different personality testing systems, for example DISC systems, which again demonstrates the closely connected nature of many psychometrics models and products.

Most people, to varying degrees at different times depending on circumstances, use both preferences within each of the four scales, but each of us tends to have (and therefore will indicate via testing) a certain preference for one style or another in each of the four scales.

There are no 'right' or 'wrong' or 'good' or 'bad' preferences, and there are no good or bad or right or wrong 'types' although obviously certain 'preference' behaviours and personality 'types' can be more or less appropriate or effective in given situations. Within personal limits, adaptability, as ever, is a valuable attribute. Self-awareness enables adaptability. If you seek confirmation of the value of adaptability look at the Cybernetics page (later best, not right now).

Here are descriptions of each of the MBTI® preferences in slightly more detail.

According to the Myers Briggs® (MBTI®) system each of us is represented by four preferences, one from each of the four scales. Can you begin to identify yourself, and others around you?

By measuring or categorising a person's overall personality or behavioural style according to four preferences - one from each of the four scales (E-I, S-N, T-F, J-P), the MBTI® system logically contains sixteen main 'types', each represented by four-letter code, for example: ESFJ or INFP or ESTJ, etc.

The sequence of the four-letter preferences within the Myers Briggs® code, whatever the combination, does not change:

The 1st letter denotes the Jungian 'Attitude' or orientation; the direction or focus of the personality - Introvert or Extravert

The middle two letters denote the Jungian 'Functional Type' preferences, namely:

The 2nd letter is the preferred Jungian 'Irrational' function (Myers Briggs® 'perceiving') - Sensing or Intuition

The 3rd letter is the preferred Jungian 'Rational' function (Myers Briggs® 'judging') - Thinking or Feeling

The 4th letter is Myers Briggs'® added dimension to indicate the preferred way of dealing with the outer world; to evaluate and decide or to continue gathering information - Judging or Perceiving - equating to Jung's 'Irrational' and 'Rational' functional type categories, and thereby enabling functional dominance to be determined.

All sixteen different Myers Briggs® MBTI® personality type combinations, each being a four-letter code, are commonly presented in an MBTI® 'Type Table'.

In the 'Type Table' example below the groupings correlate (according particularly to Keirsey) to the Four Temperaments, which for interest is reflected by the colour coding in the table below to to aid comparisons when you look again at the Four Temperaments types. However this is merely an interesting point of note, and is not significant in the workings of the Myers Briggs® theory or its application. The Four Temperaments correlations are more significant in the Keirsey model.

The MBTI® 'Type Table' is typically shown elsewhere in other resources without these headings, and can be shown using other groupings, depending on the views of the theorist or interpreter.

the MBTI® 'type table' related to Four Temperaments Keirsey groupings

I repeat that you will see these MBTI® types shown in different groupings than the Keirsey/Four Temperaments structure shown above. This is by no means the definitive arrangement of the MBTI® personality types. There are others. I place no particular significance on the structure of these groupings and perhaps neither should you since many great minds disagree about it.

For example Myers Briggs® themselves prefer to show the types in no particular stated grouping, but which are actually grouped in four columns ST, SF, NF and NT, which are the four logical groupings when combining pairs of Jung's four functional types. This is close to Keirsey's presentation of them, but not the same.

And highly the regarded MBTI® Jungian neurologist, psychiatrist, psychopharmacologist, and psychotherapist Robert I. Winer, M.D., prefers the following four-way grouping on the basis that he considers these types to be the four most distinguishable through observation of people's behaviour: TJ, ('Thinker-Judgers') FJ ('Feeler-Judgers'), SP ('Sensor-Perceiver') and NP ('Intuitive-Perceiver'). You pays yer money and takes yer choice as they say. Incidentally Winer's 'Winer Foundation' website (www.gesher.org) is one of the most impressive and wonderous on the web dedicated to MBTI®/Jungian theory, full of useful profiles and guidance for self-awareness and development. He seems a lovely fellow.

Other interesting groupings of the sixteen MBTI® types are shown in matrix presentations in each of the Benziger and DISC sections. These different groupings attempt to correlate the personality types (and traits implied) between the different systems and as such can be very helpful in trying to understand it all.

The Myers Briggs® organisation is at pains to point out, rightly, that all (MBTI®) types are equal. As with the individual 'preferences', there are no 'right' or 'wrong' or 'good' or 'bad' types, although again obviously, certain 'type' behaviours can be more or less appropriate in different given situations.

Indeed most people will display type-behaviours resembling many of the sixteen types in any one day, depending on the circumstances. It is however the case that most of us will have a certain preferred type with which we are most comfortable, and which is held to be, according to the MBTI® model, our 'personality'.

In terms of understanding what personality characteristics each of these sixteen various 'MBTI®' types represent, at a very basic level you can simply combine the type descriptions, for example:

An ISTJ is someone who is on balance focused inwardly (Introvert - I) who tends to or prefers to gather information by concentrating on facts (Sensing - S), makes decisions by logic and process (Thinking - T), and whose approach and response to the world is based on order, control, and firm decisions (Judging - J).

And for a contrasting example, an ENFP is someone who is on balance focused on external things and people (Extravert - E) who tends to or prefers to gather information by interpreting patterns, possibilities and meaning (Intuitive - N), makes decisions according to personal values and what matters to self or others (Feeling - F), and whose approach and response to the world is flexible, adaptable and understanding (Perceiving - P).

At a more detailed level it's useful to consider 'functional dominance', specifically relating to the original four Jungian functions (the middle two letters of the four-letter Myers Briggs® MBTI® code). The methodology for identifying dominant and auxiliary functions, and thereafter 3rd and 4th functions (which do not appear in each four-letter type code), is explained below in the MBTI® function dominance sub-section. While a little tricky for some people to grasp quickly, anyone can understand this if they put their mind to it, and it's well worth the effort because identifying functional dominance does provide an excellent and rapid way to define each and any of the sixteen main personality types from their four-letter codes without the need for reams of supporting notes.

At a more complex and fully detailed level there are various resources which give detailed descriptions of the MBTI® personality types, including myersbriggs.org, and in my opinion far more fully and clearly at the excellent www.gesher.org. The Jungian psychologist Michael Daniels' website at www.mdani.demon.co.uk is also an excellent resource for learning about Myers Briggs® types and Jungian theory.

MBTI® function dominance

Acknowledgments to Simon Pusey for the in MBTI® Function Dominance diagram (Powerpoint slide) and a PDF diagram; also to Andrew Roughton for the alternative explanation of MBTI® dominance; to Ian Mitchell for correcting an error in the the ISTJ example below (previously wrongly shown as ISTJ), and to José María Ribal for correcting an error in two paragraphs which wrongly referred to the 2nd letter being 'Thinking or Feeling' instead of 'Sensing or iNtuition'.

For a quick explanation see the in MBTI® Function Dominance diagram in Powerpoint slide format or as a PDF. For a more detailed explanation of function dominance read on.

It's not vital to understand function dominance in order to benefit from the Myers Briggs® theory, but it does help explain how to identify the dominant function (of the middle two letters - the Jungian Functional Types) within any MBTI® four-letter type code, and logically from this the auxiliary function (and then also the 3rd and 4th functions). The methodology therefore enables rapid description and understanding of any four-letter MBTI® type code without supporting notes. It's a neat technique. An additional alternative explanation of MBTI® dominance using different examples and perspective follows this one. Feel free to skip ahead to it if the first explanation is not to your liking. In any event having two different perspectives of a complex theory is often helpful towards gaining best possible understanding.

Remember that the first letter is the Introvert-Extravert 'Attitude' or orientation - it's not a 'function', and the fourth letter is the Myers Briggs® additional Judging-Perceiving dimension, it's not a Jungian 'Function', and was largely introduced by Myers Briggs® in order to determine dominance between the preferred Jungian Functions (second and third letters).

Understanding Myers Briggs'® functional dominance methodology also helps explain how the Myers Briggs'® four-dimension model (four letters) relates to Jung's three-dimension model (main Jungian 'Psychological Type' plus auxiliary function - three letters), at least in the way that the Myers Briggs® interpretation implies and considers it to do so. (Just to repeat once more, Jung didn't use the Judging-Perceiving dimension as such, he stuck with three dimensions: Introvert-Extravert; Sensing-Intuition, and Thinking-Feeling.)

This explanation necessarily repeats the essential structure already explained in order to stand alone as a useful item in its own right.

Here goes. Hold on to your hats.

The Myers Briggs® MBTI® personality type is always presented as a four-letter code, in which the letters take the same positions in the code regardless of dominance. This is to say: function dominance is not indicated by the sequence of the letters.

Again, here is the sequence of the MBTI® letters and descriptions of what they denote. View this table as columns, not rows:

These four preferences produce a four-letter code, for example ENFP or ISTJ.

It is very useful if we can determine within the personality which is the dominant Function of the essential Jungian 'Four Functional Types'. In other words is it the 2nd or 3rd letter that is most dominant within the whole type?

If we know the dominant superior function then obviously we can determine the auxiliary, because it will be the other middle letter in the code. (Incidentally when we've sorted out the superior and auxiliary functions, we can also then determine the 3rd and 4th functions, which is explained after we sort out the superior and auxiliary).

So, for the examples above:

Within the ENFP personality type is Intuition (N) or Feeling (F) dominant?

And within the ISTJ personality type is Sensing (S) or Thinking (T) dominant?

In fact the dominant function within the ENFP personality type is N (Intuition), which for the sake of this exercise we will show as ENFP. This means that F (Feeling) is the auxiliary function.

And the dominant function within the ISTJ personality type is S (Sensing), which for the sake of this exercise we show as ISTJ. This means that T (Thinking) is the auxiliary function.

But why?

Here's my best explanation of the Myers Briggs® methodology for determining dominant function, which they based on their interpretation of Jung's theory, and it is quite logical when you think about it. The methodology operates by using different points of reference - it's like a formula or a process:

First,

• Extraverts direct their dominant function outwardly, towards the outer world, and their auxiliary function inwardly.
• Introverts direct their dominant function inwardly, towards their inner world, and their auxiliary function outwardly.
• So whether the personality is Extravert or Introvert (1st letter E or I) is a factor in determining functional dominance (between the 2nd and 3rd letters).

Second,

Remember Jung categorised the two pairs of opposite functions as Irrational and Rational, which correlate to Myers Briggs® Judging and Perceiving:

• Myers Briggs® 'Perceiving' refers to Jung's 'Irrational' functions (2nd letter) - Sensing or Intuition.
• Myers Briggs® 'Judging' refers to Jung's 'Rational' functions (3rd letter) - Thinking or Feeling.

Third,

• A Judging preference (4th letter J) indicates that the personality prefers to use the Judging function (3rd letter Thinking or Feeling) to deal with the outer world.
• A Perceiving preference (4th letter P) indicates that the personality prefers to use the Perceiving function (2nd letter Sensing or Intuition) to deal with the outer world.

Fourth, therefore,

If the personality is Extravert (1st letter E) and is also Judging (4th letter J) then the Judging Function (3rd letter Thinking or Feeling) will be the dominant function (since this is the function used chiefly to deal with the outside world, and Extroverts use their dominant function chiefly to deal with the outside world). For example in the ENFJ type, Feeling is the dominant function, which is mainly directed outwardly. The auxiliary function Intuition which tends to be directed inwardly.

If the personality is Extravert (1st letter E) and is also Perceiving (4th letter P) then the Perceiving Function (2nd letter Sensing or iNtuition) will be the dominant function (again this is the function used to deal with the outside world, and Extroverts use their dominant function to deal with the outside world). For example in the ESTP type, Sensing is the dominant function, which is mainly directed outwardly. The auxiliary function is Thinking, which is mainly directed inwardly.

Fifth, (on the other hand),

Remember that an Introvert's dominant function is mainly directed inwardly, towards their inner world, therefore an Introvert's Judging-Perceiving preference (4th letter J or P) which represents how they approach the outer world will indicate their less dominant function, which means that for Introvert types, the letter other than the one indicated by the 4th letter J or P will be their dominant function.

So it follows, if the personality is Introvert (1st letter I) and is also Judging (4th letter J) then the Judging Function (3rd letter Thinking or Feeling) will be the auxiliary function, since this is the function used to deal with the outside world. Remember, Introverts use their dominant function chiefly to deal with their inner world, not the outside world. An Introvert uses their auxiliary function chiefly to deal with the outside world. For example, in the INTP type, Intuition is used mainly to deal with the outside world, but since the priority focus of the Introvert is their inner world, so Thinking is their dominant function.

Similarly if the personality is Introvert (1st letter I) and is also Perceiving (4th letter P) then the Perceiving Function (2nd letter Sensing or iNtuition) will be the auxiliary function since this is the function used to deal with the outside world. The dominant function will be the other function, which the Introvert focuses on their inner world. For example, in the ISFJ type, the outside world approach indicated by the Judging preference (4th letter J) is Feeling, which because it is focused on the outside world in an Introvert is the auxiliary function. Therefore the other function, Sensing, is the dominant one focused on the Introvert's priority inner world.

There. That's the difficult bit. You may now take a break.

Here is additional explanation of MBTI® dominant functions. Having a second perspective can assist overall appreciation of any complex matter.

additional explanation of MBTI® function dominance

This additional explanation is kindly provided by Andrew Roughton, which is gratefully acknowledged. (I'm also grateful to Ian Mitchell for correcting an error in the ISTJ example above which was wrongly shown as ISTJ, and to Pierre Lemasson for correcting an error in 3b below - probably my typo, not Andrew's - which stated that the the remaining letter will be your auxiliary instead of dominant function.)

1) Your dominant function is found in either the 2nd or 3rd letter in your code. You also have an auxiliary (second) function.

a) If the 2nd letter is your dominant function then the 3rd is your auxiliary function and vice versa.

b) If the 3rd letter is your dominant function then the 2nd is your auxiliary function.

Remember the 2nd letter in your code relates to your Perceiving function. Do you perceive information through your senses (S) or through intuition (N)?

The 3rd letter in your code relates to your Judging function. Do you make judgements (decisions) through Thinking (T) or through Feeling (F)?

2) The 4th letter describes how you relate to the outside world. Do you prefer to deal with the world through your Judging function or through your Perceiving function?

a) If your 4th letter is J then we first look to the Judging functions - Thinking or Feeling.

i) If your code is ISFJ then we first look to the judging functions.

b) If your 4th letter is P then we first look to the Perceiving functions - Sensing or Intuition.

i) If your code is ENFP then we first look to the Perceiving functions.

3) The 1st letter in your code (E or I) tells you whether you will first find your dominant or your auxiliary function.

a) If your 1st letter is E (Extravert) then you will first identify your dominant function letter and the remaining letter will be your auxiliary function.

i) If your code is ENFP then you will find your dominant function. Because the 4th letter is P we look to the perceiving function letter in your code which in this case is N for Intuition. So your dominant function is Intuition. Your auxiliary function is represented by the remaining letter F for Feeling.

b) If your 1st letter is I (Introvert) then you will first identify your auxiliary code and the remaining letter will be your dominant function.

i) If your code is ISFJ you will first identify your auxiliary function. Because the 4th letter is J we look to the judging function letter in your code which in this case is F for Feeling. So your auxiliary function is Feeling. Your dominant function is represented by the remaining letter S for Sensing.

4) The reason for the different treatment for Extravert and Introvert is to do with the preference for the outer (E) or inner (I) world, and the 4th letter only identifies how they relate to the outer world. For the Introvert this will always be their auxiliary function because their dominant function must relate to their inner world.

a) Logically if the introvert relates to their outer world through, for example, their judging functions (thinking or feeling) then their remaining letter tells you which function they use in their inner world. This, for them, is their dominant function.

i) The ISFJ relates to the outer world through their Judging function (represented by the J) which in this case is Feeling (represented by the F). By elimination they must relate to their inner world through the Sensing function (represented by the S). Thus Sensing is the ISFJ's dominant function and Feeling is their auxiliary function.

b) Extraverts on the other hand use their dominant function to relate to the outer world and so the 4th letter identifies how you relate to the outer world.

i) The ENFP relates to the outer world through their Perceiving function (represented by the P) which is Intuition (represented by the N). Thus Intuition is the ENFP's dominant function and Feeling is their auxiliary function. 

Andrew Roughton, July 2006.
National Principal
Vision College New Zealand