Curvilinear associations between neuroticism and dyadic adjustment in treatment-seeking couples

Among personality traits, neuroticism has been shown to be the most significant predictor of dyadic adjustment. Despite some propositions arguing that low, as well as high levels of personality traits are maladaptive tendencies, only the negative linear relationship between neuroticism and couple satisfaction has been addressed in past research. The aim of this study was to examine the nonlinear association between neuroticism and dyadic adjustment for both partners of a clinically distressed sample of couples. The sample included 472 couples seeking couple therapy who completed the NEO-FFI (P. T. Costa & R. R. McCrae, 1992, NEO PI-R professional manual, Odessa, FL, Psychological Assessment Resources) and the Dyadic Adjustment Scale (G. B. Spanier, 1976, Measuring dyadic adjustment: New scales for assessing the quality of marriage and similar dyads, Journal of Marriage and the Family, 38, pp. 15-28). Results showed, for actor and partner effects, a significant nonlinear, inverted U-shaped relationship between neuroticism and dyadic adjustment. In particular, both very low levels and high levels of neuroticism were associated with lower dyadic adjustment for both the individual and his or her partner. This finding is in contrast with the traditional negative linear association between neuroticism and dyadic adjustment observed in previous research. Openness and agreeableness also positively predicted self and partner dyadic adjustment. Findings bear important clinical implications for therapists assessing and working with distressed couples.