Neurobiological Functioning and the Personality-Trait Hierarchy: Central Serotonergic Responsivity and the Stability Metatrait.

Trait domains of the five-factor model are not orthogonal, and two metatraits have often been estimated from their covariation. Here, we focus on the stability metatrait, which reflects shared variance in conscientiousness, agreeableness, and (inversely) neuroticism. It has been hypothesized that stability manifests, in part, because of individual differences in central serotonergic functioning. We explored this possibility in a community sample (N = 441) using a multiverse analysis of (a) multi-informant five-factor-model traits and (b) stability as a predictor of individual differences in central serotonergic functioning. Differences in serotonergic functioning were assessed by indexing change in serum prolactin concentration following intravenous infusion of citalopram, a selective serotonin reuptake inhibitor. Results were mixed, showing that trait neuroticism, agreeableness, and conscientiousness, as well as the stability metatrait, were significantly associated with prolactin response but that these findings were contingent on a number of modeling decisions. Specifically, these effects were nonlinear, emerging most strongly for participants with the highest levels (or lowest, for neuroticism) of the component traits.