Despite philosophical & conventional wisdom dating back to the ancients, researchers have only recently begun to uncover evidence that extreme standing on “normal” or “desirable” personality traits might be maladaptive

Extreme Personalities at Work and in Life. Nathan T. Carter, Joshua D. Miller, Thomas A. Widiger. Current Directions in Psychological Science, https://doi.org/10.1177/0963721418793134

Abstract: Contemporary personality taxonomies cast personality traits as ranging from the maladaptive (e.g., low conscientiousness) to adaptive (e.g., high conscientiousness) levels. Despite philosophical and conventional wisdom dating back to the ancients, researchers have only recently begun to uncover evidence that extreme standing on “normal” or “desirable” personality traits might be maladaptive. Here, we present an emerging perspective on why and how extreme standing on “desirable” trait continua translates into maladaptive behavior and undesirable outcomes at work and in life. An overview of the literature on the topic is presented for each trait within the five-factor model. We suggest two reasons for the lack of clarity in the empirical literature: (a) problems with statistical tests resulting from measurement error and (b) lack of breadth in the conceptualization and measurement of personality traits. We suggest that a solution to this problem is to extend trait continua to reflect maladaptive levels at both ends. We close by pointing out that a major implication of this emerging perspective indicates that many more people possess optimal personality-trait levels than previously thought and that future research needs to examine whether the question is consistent with evolutionary and neurophysiological accounts of personality science.

Keywords: personality, curvilinearity, inverted U, nonlinearity, personality disorders