Kernberg's Dimensional Approach: An Alternative Classification System
As discussed in the previous section, the current DSM diagnostic system (DSM-IV-TR)1 relies upon a categorical classification system and suffers from the usual problems inherent in categorical classification systems. Many clinicians and researchers believe the personality traits associated with a particular personality disorder are best understood as extreme variants of ordinary personality traits that differ from what is considered average or ordinary, by degree, rather than a difference in type. This alternative way of viewing personality disorders is called a dimensional or continuous approach2. In contrast to the categorical diagnostic system, a dimensional system views various personality features along a continuum. One such dimensional model, and an alternative to the DSM-IV-TR (APA, 2000) classification system, 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, particulary with respect to the 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. Similarly, "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.
1 At the time of publication (January 2011) DSM-IV-TR is the most recent version of the DSM. The next version, DSM-V, is expected in a few more years. Kernberg's model will remain relevant to understanding and categorizing personality disorders regardless of the final outcome of DSM-V. Further information about DSM-V is available at http://www.dsm5.org/pages/default.aspx and http://en.wikipedia.org/wiki/DSM-V.
2 Some form of this "alternative" dimensional diagnostic approach is expected to be adopted in the upcoming DSM-V. Further information about DSM-V is available at http://www.dsm5.org/pages/default.aspx and http://en.wikipedia.org/wiki/DSM-V.