The idea is, that each Jungian type can possess a Subtype, which can “boost” the Strength (Dimensionality) of specific functions, while it “diminishes” (weakens) the Strength of others.

It appears as if the majority of people possesses “no subtype”, where none of the functions are boosted or diminished, so the standard functional distribution applies to the majority of people.

However, there is also a substantial amount of people who favor either their first or second function, which is a sign that they are the first (function) subtype or second (function) subtype. This has a considerable impact on the strengths and weaknesses of their functions.

For this overview, it is assumed for simplicity’s sake that the functional strength of the 4-Dimensions is being “boosted” by +0.5, and “diminished” by -0.5 respectively. In the case of a weak subtype, the change may rather revolve around 0.3 at most.

This has an impact on the functional strengths in the following manner (from strongest to weakest):

First (function) subtype

1. Lead (4.5 D)
2. Ignoring (3.5 D) / Demonstrative (3.5 D)
3. Creative (2.5 D) / Activating (2.5 D)
4. Role (1.5 D) / PoLR (1.5 D)
5. Suggestive (0.5 D)

See Model A 

Second (function) subtype

1. Demonstrative (4.5 D)
2. Lead (3.5 D) / Creative (3.5 D)
3. Role (2.5 D) / Ignoring (2.5 D)
4. Activating (1.5 D) / Suggestive (1.5 D)
5. PoLR (0.5 D)

It can be said that the Dimensionality of the functions expresses itself in this manner in the individual (who doesn’t know about the functional strengths of their type):

(Greater than) 4 D: “I know my sh*t.”
(Greater than) 3 D: “I am rather good at this.”
Greater than 2 D: ”I can handle this.”
Less than 2 D: “I think I need help.”
(Less than) 1D: “I don’t know I need (a lot of) help.”

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Let’s take ISFP/ESI as an example:

Fi subtype

1. Fi (“I know my sh*t”)
2. Fe / Si (“I am rather good at this.”)
3. Se / Ni (“I can handle this.”)
4. Ti / Ne (“I think I need help.”)
5. Te (“I don’t know I need (a lot of) help.”)

Se subtype

1. Si (“I know my sh*t”)
2. Fi / Se (“I am rather good at this.”)
3. Ti / Fe (“I can handle this.”)
4. Ni / Te (“I think I need help.”)
5. Ne (“I don’t know I need (a lot of) help.”)

As can be seen above, the subtype can have quite a significant effect on the Dimensionality of the functions, and how the individual both expresses and experiences them.

In this light, mistypings can be understood and analyzed more easily, for instance how ISFP-Fi/ ESI-Fi is often mistyped as INFx, for they experience/express both Se and Ni around the same strength – and if the ESI is focusing on their Ni, it might more easily appear as if they are Ni lead, or at least not merely 2D Ni as it is usually said to be the case for ESI.

Furthermore, attraction to one’s Dual (or not) can also be more varied, based on subtype. The (strong) Inert subtype will always have “a thing” for their Dual-Seeking function primarily, though the Contact subtype might develop a “secondary” Dual-seeking function in the form of their Mobilizing function. In real life, the common scenario of this playing out, is SEE-Fi people often marrying Delta STs, who provide them (at least) with their “secondary” Dual-seeking function.

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Functional Strengths of each of the 16 Types

… from the strongest (4.5 D) to the weakest (0.5 D)

SF & NT:

SEI-Fe / ESI-Fi

1. Fi
2. Fe / Si
3. Se / Ni
4. Ti / Ne
5. Te

SEI-Si / ESI-Se

1. Si
2. Fi / Se
3. Ti / Fe
4. Ni / Te
5. Ne

ESE-Si / SEE-Se

1. Se
2. Si / Fe
3. Fi / Te
4. Ne / Ti
5. Ni

ESE-Fe / SEE-Fi

1. Fe
2. Se / Fi
3. Ne / Si
4. Te / Ni
5. Ti

LII-Ti / ILI-Te

1. Ti
2. Te / Ni
3. Ne / Si
4. Fi / Se
5. Fe

LII-Ne / ILI-Ni

1. Ni
2. Ti / Ne
3. Fi / Te
4. Si / Fe
5. Se

ILE-Ne / LIE-Ni

1. Ne
2. Ni / Te
3. Ti / Fe
4. Se / Fi
5. Si

ILE-Ti / LIE-Te

1. Te
2. Ne / Ti
3. Se / Ni
4. Fe / Si
5. Fi

NF & ST:

IEI-Ni / EII-Ne

1. Ni
2. Ne / Fi
3. Fe / Ti
4. Si / Te
5. Se

IEI-Fe / EII-Fi

1. Fi
2. Ni / Fe
3. Si / Ne
4. Ti / Se
5. Te

LSI-Ti / SLI-Te

1. Ti
2. Te / Si
3. Se / Ni
4. Fi / Ne
5. Fe

LSI-Se / SLI-Si

1. Si
2. Ti / Se
3. Fi / Te
4. Ni / Fe
5. Ne

EIE-Fe / IEE-Fi

1. Fe
2. Ne / Fi
3. Se / Ni
4. Te / Si
5. Ti

EIE-Ni / IEE-Ne

1. Ne
2. Fe / Ni
3. Te / Fi
4. Se / Ti
5. Si

SLE-Se / LSE-Si

1. Se
2. Si / Te
3. Ti / Fe
4. Ne / Fi
5. Ni

SLE-Ti / LSE-Te

1. Te
2. Ti / Se
3. Si / Ne
4. Fe / Ni
5. Fi