Wednesday, November 11, 2009

More on the Big 5 Personality Model

This morning I posted an article from World of Psychology on the Big 5 Personality Model. My friend John, over at Facebook, commented on its lack of multiperspectival validation. He's right, of course. Most typologies are not very accurate, often even in the 3rd person perspective.

Here is what my abnormal psych textbook says on the subject (not at all integral, but interesting). This is a slightly different and more reliable model than the one presented this morning. First a table giving the five factors, which are also different from this morning's model.

Table 12.4 Sample Items from the Revised NEO Personality Inventory Assessing the Five-Factor Model Personality Trait Sample Items

Neuroticism: I often feel tense or jittery
Extraversion/introversion: I really like most people I meet
Openness to experience: I have a very active imagination
Agreeableness/antagonism: I tend to be cynical and skeptical of others’ intentions (reverse scored)
Conscientiousness: I often come into situations without being prepared (reverse scored)

[Reproduced by special permission of the Publisher, Psychological Assessment Resources, Inc., 16204 North Florida Avenue, Lutz, FL 33549, from the NEO Personality Inventory-Revised by Paul Costa and Robert McCrae, Copyright 1978, 1985, 1989, 1991, 1992 by Psychological Assessment Resources, Inc. (PAR). Further reproduction is prohibited without permission of PAR.]

In contemporary research, a major focus is on the five-factor model (McCrae & Costa, 1990), in which the five factors, or major dimensions, of personality are neuroticism, extraversion/introversion, openness to experience, agreeableness/antagonism, and conscientiousness. Table 12.4 presents questionnaire items that assess each of these dimensions; by reading the items, you can get a sense of what each dimension means. One interesting set of findings has shown that these dimensions of personality are moderately heritable ( Jang et al., 2002).

Researchers have summarized the results of several studies linking these personality traits to schizoid, borderline, and avoidant personality disorders (Widiger & Costa, 1994). For example, people with schizoid personality disorder and those with avoidant personality disorder (two disorders that involve social aloofness) tend to be high in introversion but to differ in neuroticism—people with avoidant personality disorder tend to be higher in neuroticism than those with schizoid personality disorder. Rather than forcing each person into a discrete diagnostic category and then struggling with how to distinguish between the two disorders, the dimensional approach would simply describe each person’s levels of neuroticism and introversion.

A recent meta-analysis shows that findings are fairly consistent across a range of studies that have mapped personality disorder diagnoses onto the dimensions of the five-factor model. Most personality disorders are characterized by high neuroticism and antagonism. High extraversion was tied to histrionic and narcissistic disorders (two disorders that involve dramatic behavior), whereas low extraversion was tied to schizoid, schizotypal, and avoidant disorders (Saulsman & Page, 2004).

The five-factor model is not without its critics, however. In a study in which people with personality disorders completed a questionnaire assessing them on the basis of the five factors, the profiles of the various personality disorders turned out to be rather similar to one another (Morey et al., 2000). Some might say this is fine, and that fewer dimensions would simplify things. But proponents of the need to be more specific have responded to this difficulty by claiming that differentiating among the different personality disorders requires breaking down the five factors into their “facets” (Lynam & Widiger, 2001). Each of the five factors has six facets, or components; for example, the extraversion factor includes the facets of warmth, gregariousness, assertiveness, activity, excitement seeking, and positive emotionality. Differentiating among the personality disorders might require a more detailed assessment that includes these specific personality facets. Beyond the need to consider facets, it appears that some disorders, such as schizotypal personality disorder, are more distinct than being just extreme points along a dimension; statistical analyses suggest that people with these disorders tend to be qualitatively different from other people. For example, people with schizotypal personality disorder tend to experience perceptual oddities that others don’t experience even in mild degrees (Haslam & Kim, 2002).

The five-factor model is certainly not a total solution to the problem of classifying personality disorders, but the important point is that a dimensional model has several distinct advantages. Most importantly, it handles the comorbidity problem, because comorbidity is a difficulty only in a categorical classification system like the one used in DSM-IV-TR. A dimensional system also links normal and abnormal personality, so findings on personality development in general become relevant to the personality disorders.

Problems with classifying personality disorders should not lead us to underestimate the importance of being able to identify them. Personality disorders are prevalent, and they cause severe impairments. Some of the problems with classification and diagnosis stem from the fact that these disorders have been the subject of serious research for less time than have most of the other disorders considered in this book. As research continues, the diagnostic categories will most likely be refined, and many of these problems might be solved. Bear these issues in mind, though, as we now turn to a review of the clinical description and etiology of the personality disorders in cluster A, cluster B, and cluster C. (pg. 390-391)
Kring, Davison, Neale, Johnson. (2007). Abnormal Psychology. 10th Edition. NY: Wiley & Sons.

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