Psychotyp — Psychological personality typing: the 16 | psychotyp.com
Eight functions — four introverted, four extraverted — fill the four positions of every type's stack, and the top two positions fix the type's letters.
The eight functions are the four processes in two attitudes each: introverted sensing (Si) and extraverted sensing (Se), introverted intuition (Ni) and extraverted intuition (Ne), introverted thinking (Ti) and extraverted thinking (Te), introverted feeling (Fi) and extraverted feeling (Fe). Every type draws its stack from this set of eight.
A stack has four positions: dominant, auxiliary, tertiary and inferior. The dominant is the most practised process, the one you reach for without deciding to; the auxiliary supports it; the tertiary works but tires quickly; the inferior is the least practised and the first to wobble under pressure.
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One rule makes the whole system checkable: the dominant and auxiliary always sit in opposite attitudes. An introverted dominant forces an extraverted auxiliary, and the reverse. Any claimed stack whose top two functions share an attitude is mis-assembled, and the letters should be re-scored.
The letters and the stack decode each other. The first letter (E or I) is the attitude of the dominant; the middle letters say which processes lead; and J/P names which kind of function is extraverted — the dominant for extraverts, the auxiliary for introverts. That last twist is why introverts are so often mis-typed by letter alone.
A worked example: INTJ unpacks to Ni–Te–Fi–Se — introverted intuition dominant, extraverted thinking auxiliary, introverted feeling tertiary, extraverted sensing inferior, attitudes alternating down the stack. To find your own letters first, use the five-pass method on the find-your-type page, then look up the matching stack among the sixteen types.
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