Psychological typology is a system for classifying people into psychological types on the basis of stable differences in the structure, organization, or functioning of the psyche.
A psychological type is a class of people who share stable features of the structure, organization, or functioning of the psyche that are adopted as the basis of classification within a given typology.
Jung’s psychological typology is a theory of individual differences that describes characteristic modes of psychological orientation by means of two attitudes — extraversion and introversion — and four psychological functions — thinking, feeling, sensation, and intuition — taking into account their different degrees of consciousness and the relations between the conscious and the unconscious.
In Jung’s typology, 16 psychological types are divided into extraverted and introverted types, as well as rational and irrational types.
In the present typology, Jung’s distinction between four psychological functions is retained, but the content of the functions of sensation and intuition is defined differently. Sensation (S) is understood as the perception of invariants, and intuition (N) as the perception of changes.
A three-letter notation, not used by Jung, is used to designate the psychological types. The first letter denotes the attitude of the dominant function: E — extraverted, I — introverted; the second denotes the dominant function; the third denotes the auxiliary function. Function symbols: S — perception of invariants, N — perception of changes, F — feeling, T — thinking.
Extraverted types: EFS, ETS, EFN, ETN, ESF, EST, ENF, ENT.
Introverted types: IFS, ITS, IFN, ITN, ISF, IST, INF, INT.
Rational types: EFS, ETS, EFN, ETN, IFS, ITS, IFN, ITN.
Irrational types: ESF, EST, ENF, ENT, ISF, IST, INF, INT.