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Myers Briggs - the dynamic model

This article describes the Myers Briggs dynamic model of personality. It also introduces a diagrammatic representation of the dynamic model called the 'Mental Muscle Diagram(TM)'.  Source:

The Myers Briggs model of personality is most often considered as consisting of four separate preferences:

This is the simple model. In fact, the Myers Briggs model is much more complicated than this - it is a dynamic model: Does this seem confusing? Is so, this article will explain.

Mental Muscles - S, N, T and F

The middle preferences - Sensing, iNtuition, Thinking and Feeling - are called 'Functions'. We prefer to call them mental muscles, because there are some analogies between the Myers Briggs functions and physical muscles. In considering the dynamic model, the middle preferences are the ones to concentrate on - the E/I and J/P preferences simply provide information about the middle preferences, or mental muscles. The meaning and purpose of the first and last preferences will be discussed later.

Order of preference

The dynamic model focuses on the four mental muscles (Sensing, iNtuition, Thinking and Feeling), their interaction and how they are used. The dynamic model states that we exercise an overall preference when using these four mental muscles. For example, an INFP prefers Feeling first, then iNtuition, then Sensing, then Thinking.

Usually, where one mental muscle is most preferred, the direct opposite of that preference is the least preferred. For example, if the most preferred function is iNtuition, then the least preferred function is Sensing, and Thinking and Feeling make up the second and third preferences. The following table shows the order of preferences for each Myers Briggs type:

Myers Briggs type 1st 2nd 3rd 4th

This order of functions is reflected in your approach to problem solving. An ENFP is likely to start to solve a problem by using the iNtuition function. That is, he is likely to ask: What are the possibilities in this situation? What is the vision? Where is this leading to? Is there anything that can be changed? Or perhaps the ENFP might experiment - changing something to see if it will solve the problem.

Diagram - Intuition - Feeling - Thinking - Sensing The most likely second step in the process is to use the Feeling function, considering the impact on people and other personal values. The ENFP will choose a possibility that fits in with what he wants to do, has a positive impact on people who are important to him, and does not violate any of his values. The next most likely step (if it gets this far) is to use the Thinking function, and reject any solution that is too costly or does not provide the appropriate benefits. Finally, the ENFP may investigate the facts, to see if they are consistent with the chosen solution.

This order of processing for an ENFP is demonstrated by the diagram.

Use and growth

Because we have an order of preference for the mental muscles, we tend to use the preferred muscles much more frequently than the lesser preferred ones. As with physical muscles, the mental muscles can grow in strength with use. As we become more practised with certain mental muscles, we tend to use them even more and eventually they may become dominant in our personality. An analogy of this process can be seen, physically, in our choice of hand for writing: we perhaps initially choose our 'natural handedness', but this choice becomes reinforced with practice over time.

In the following diagram, the sizes of the ellipses demonstrate how much each mental muscle is used (staying with the example of an ENFP). The most preferred mental muscle is called the dominant - because it dominates the personality.

Diagram - large intuition down to small sensing

Interactions between mental muscles

Whilst the dominant strongly influences personality, it does not operate in isolation from the other mental muscles. The way in which the dominant expresses itself is influenced by the mental muscle chosen as second preference (normally called the auxiliary).

For example, the ENFP's dominant is iNtuition, which perceives information in the form of patterns and possibilities. The way that this preference for insight is expressed is influenced by the Feeling function, which has an interest in people, and things of importance to the individual. The ENFP, therefore, prefers perceiving patterns and possibilities in people and other things that have meaning.

By contrast, an ENTP has a dominant function of iNtuition, and an auxiliary function of Thinking. Thinking is interested in logic, and principles. Thinking will therefore influence the iNtuitive function to perceive patterns and possibilities that help understand the theoretical basis of how and why things work. The ENTP's interest is therefore more likely to be in the sciences than in people, though people can sometimes be interesting subjects for scientific study.

Introversion and Extroversion

It is possible to use mental muscles either in the inner world (of thoughts, reflections and emotions) or the outer world (of actions and words). What these mental muscles do therefore depends on where they are applied - in the inner or outer world.

Consider iNtuition, for example. One feature of this particular mental muscle is a preference for 'change'. If this mental muscle is applied in the outer world, the individual will DO something, or SAY something to create change. The mental muscle is immediately applied to actions or words. The application of the iNtuition mental muscle to the outer world is sometimes called extraverted iNtuition.

If the mental muscle of iNtuition is applied in the inner world, the individual will change to his thoughts - ie he will THINK differently. The application of the iNtuition mental muscle to the inner world is sometimes called introverted iNtuition.

So, extraverted iNtuition means that the individual is likely to do and say things to change the world about him. He will therefore be quite active and creative. Meanwhile the introverted iNtuitive is likely to think differently - that is, be more thoughtful and gain deeper understanding of the world about him.

Some examples of the differences between the introverted and extraverted forms of the functions are given in the following table:

Introverted extraverted
Sensing Enjoy thinking - eg: crosswords Enjoy doing - eg: sports
iNtuition Creative thought (eg: ideas) Creative expression (eg painting)
Thinking Logically organise thoughts Logically organise people/situations
Feeling Feel appreciation for others Express appreciation for others

The dominant and auxiliary in opposite worlds

Each of the mental muscles is used, to some degree, in both the inner and outer world. However, the dynamic model states that each mental muscle is usually used predominantly in one domain or the other. The model also states that your preference for perceiving (which is Sensing or iNtuition) is usually used in the OPPOSITE world to your preference for judging (which is Thinking or Feeling). For example, in an ENFP, iNtuition is used primarily in the outer world of actions and words. Consequently, Feeling is used primarily in the inner world of thoughts and emotions.

So, for every Myers Briggs type, the model states that one of the middle two letters operates in the outer world, and the other in the inner world. But for each Myers Briggs type, how can you tell which is which?

The fourth preference

If you have read about the simple model of Myers Briggs, you have already had a hint of the 'dynamic' model, when considering the fourth preference - an organised or flexible lifestyle. You may recall the terms 'Judgement' and 'Perception' and wonder why they were used to describe organised and flexible lifestyles.

There is actually a very good reason! You may have noticed that these words - Perception and Judgement - are similar to the second and third preferences. The second preference is concerned with how you acquire information (Perception), and the third is concerned with how you make decisions (Judgement). If you use your preferred mode of Judgement in the outer world, your actions and words tend to be decisive, and as a consequence your life appears organised. If you use your preferred mode of Perception in the outer world, your lifestyle tends to be more inquisitive and therefore appears flexible.

The fourth preference is therefore an answer to the question: Which of your preferred Perceiving and Judging mental muscles is used in the outer world? If the last letter is a J, then the judging preference operates in the outer world. Diagram - P points to 2nd letter, J to 3rd If the last letter is a P, then the perceiving preference operates in the outer world. In other words, a P always points to the second letter in your Myers Briggs type and says 'this is used in the outer world'. A J always points to the third letter in your Myers Briggs type and says 'that is used in the outer world'. Whether your life is organised or flexible is simply a corollary of whichever function is used in the outer world.

Consider the example of an INFP. The INFP's preferred mode of Perception is N, and preferred mode of judging is F. For an INFP, which function is used in the outer world? The answer is 'P' - the preferred Perception function, which is N. An alternative way of working this out is to say that P points to the second letter of the Myers Briggs type, which is N. So the INFP uses iNtuition in the outer world. By deduction, this means that Feeling (usually) operates in the inner world.

By contrast, for an ESTJ, the J points to the third letter. So an ESTJ uses the Thinking function primarily in the outer world.

The first preference

The first preference (Extroversion vs. Introversion) states in which world the dominant function operates. Extroversion means that the dominant operates mainly in the outer world, whilst Introversion means that the dominant operates mainly in the inner world. Therefore, it is possible to deduce, from the 1st and 4th preferences, which is the dominant, and whether it is applied in the inner or outer world. This is done by using the following formula (again, the example of an ENFP is used for illustration). Intuition - extraverted, Feeling - introverted, Thinking - extraverted, Sensing - smallest and introverted How would this diagram differ for an INFP? Have a go at drawing it, and then compare your answer with the diagram at the bottom of this page.

The Great Tertiary Debate?

You may have wondered why, in the diagram for an ENFP, Thinking has been shown in the outer world, and Sensing in the inner world. In the Myers Briggs model, the least preferred mental muscle (called the inferior - in this case, Sensing) is believed to operate mainly in the world opposite to the dominant. There is some controversy as to the normal pattern for extroverting or introverting the third preferred (called the tertiary - in this case, Thinking). Some people believe that the tertiary operates in the same world as the dominant, others believe it operates in the opposite world, and yet more others believe it can operate in either. In my view, this is a dynamic model, where each function operates to some degree in both the outer and inner worlds. Also, individuals do not conform to a set pattern, and everyone introverts and extroverts the mental muscles according to their own unique pattern. Surely this means that it is not too important to resolve the issue of whether the tertiary is introverted or extraverted.

Having said that, the extroversion of Thinking in this case can explain some potential anomalies and misunderstandings. Whilst the ENFP is primarily a Feeling person, others may perceive him or her as being logical first. Suppose there is a significant cultural pressure, within the business environment, to operate in a logical fashion. As other people's views affect the individual's view of himself, he may come to believe that he is more logical, and lose touch with the inner Feeling side. (This issue might be raised during the 'mid-life transition', when individuals often seek to understand themselves better, and pay more attention to their own needs rather than accommodating the cultural pressure on them to conform. For further discussion of this subject, see 'Navigating Mid-life', a book published by Consulting Psychologists Press.)

Our convention is to draw the Mental Muscle Diagrams(TM) are usually drawn to show the tertiary function as in the same world as the dominant - but you should remember that it could be either. In fact, any function could be in either the outer or inner world, depending on the individual. The Mental Muscle Diagram(TM) simply shows the more 'typical' configuration.

Note: this mental muscle diagram accurately reflects all that is contained within the Myers Briggs dynamic model, and enables a complicated subject to be simplified in an easy to understand visual form. However, it is a new way of representing the Myers Briggs functions, so you may not come across it anywhere else.

The Mental Muscle Diagrams(TM)

Finally, here are the typical mental muscle diagrams for each of the 16 types.
Mental Muscles for the 16 types

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