In the previous section we discussed a dimensional model for diagnosing personality disorders listed in the DSM-5 (APA, 2013) chapter called Emerging Measures and Models. Although it is not the current "official" diagnostic method, it offers an alternative to the categorical model. The categorical model and dimensional models have been compared in a prior section. However, long before the DSM-5 was published, other dimensional models were in use. One such model is offered by the psychoanalyst and theorist Otto Kernberg. Dr. Kernberg is a highly regarded expert on personality disorders and has written extensively on this subject. He is particularly well known for his work with Borderline and Narcissistic Personality Disorders.
Instead of viewing personality traits and disorders in terms of distinct and separate categories, Kernberg understands personalities along two continuous dimensions: 1) a dimension called personality organization that describes the severity of a disorder and 2) a dimension of introversion and extroversion.
Thus, Kernberg's dimensional model looks like a grid with two intersecting (orthogonal) lines representing two dimensions: From top to bottom, on the Y-axis, is the degree of personality organization (ranging in severity from neurotic to borderline to psychotic). From left to right, on the X-axis, he plots the dimension of introversion to extroversion. Thus, using Kernberg' s model it becomes possible to chart the position of different personality types based on the severity of personality organization on the Y axis (neurotic, borderline, psychotic), and the degree of extraversion or introversion on the X axis.
Let's examine these personality dimensions in greater detail:
The dimension of introversion and extroversion
The first personality dimension refers to a well-established dimension of human personality: introversion and extroversion. When used to describe personality traits, these two words have meanings that are somewhat different from their usual everyday usage. In everyday language, we tend to think of "introverted" people as painfully shy, reserved, and socially inept. But in psychological terminology, introversion more broadly describes people who derive much of their energy from time spent alone, and who tend to direct their attention inwardly, toward themselves. Likewise, "extroverts" call to mind the gregarious, bubbly "life of the party." But as a personality trait, extroversion describes people who derive much of their energy from interactions with others and who tend to direct their attention outwardly, toward others. These two terms also describe the characteristic ways that people process their thoughts and understand their internal experiences: Introverts tend to process and understand their thoughts and experiences without an audience, while extroverts typically benefit from an audience to facilitate this same process. Furthermore, in Kernberg's model, introversion is associated with low degree of emotional expression, while extroversion is associated with a high degree of emotional expression.
Thus when considered as a single, continuous dimension, in the moderate, healthy range of this dimension we might find people who tilt toward the introversion side of the continuum but who can certainly enjoy interactions with others, and are quite socially competent. However, social interactions may deplete them and they may require some time alone afterward to recover. Similarly, in the moderate, healthy range we may find people who lean toward the extroverted side but who can certainly be introspective, insightful, and enjoy some solitude. But too much time alone does not provide them enough stimulation and they can become fatigued and restless. Once again, it becomes a matter of the degree of expression that distinguishes more healthy personalities from less healthy ones.