There is growing interest in understanding the fluctuations in grandiose and vulnerable narcissistic states over time. Momentary data collection is vital in facilitating this new area of inquiry. Two narcissism adjective scales, the Narcissistic Grandiosity Scale and the Narcissistic Vulnerability Scale, have recently been developed for this purpose. In the present study, the validity of these 2 scales was examined across 3 different samples. Results indicate that these measures perform well psychometrically at both the momentary-and trait-level. Multilevel exploratory factor analyses reveal a clear 2-factor structure at both the within-and between-person level. Within-person correlations between these scales and other momentary scales (e.g., the Positive and Negative Affect Schedule) are consistent with theoretical expectations. Finally, individual differences in endorsement of both of these scales correlated with other dispositional measures, including existing narcissism measures (e.g., The Pathological Narcissism Inventory and The Five Factor Narcissism Inventory), at the between-person level in the expected manner. We conclude these scales are well-suited for momentary narcissism assessment in studies wishing to examine fluctuations in grandiosity and vulnerability. Public Significance StatementThis study demonstrates the validity of scales that were developed to assess momentary narcissism states. These scales provide researchers and clinicians with the tools needed to reliably and validly assess fluctuations in grandiosity and vulnerability in day-to-day life.

Using multilevel structural equation modeling, the authors examined within− and between-person predictors of daily impulsivity, with a particular focus on testing a cascade model of affect and daily stress in a 100-day daily diary study of 101 psychiatric patients with personality disorder diagnoses. On average (i.e., fixed effect), within-person increases in daily stress were associated with increased daily impulsivity, both independently and as accounted for by positive associations with increased negative and positive affect. Higher Personality Inventory for DSM-5 (PID-5) Impulsivity scores were associated with amplified within-person links between impulsivity and daily stress and negative affect, but not the links between daily stress and either positive or negative affect. The results of this cascade model are consistent with the hypothesized links between daily affect and stress and daily impulsivity while providing further evidence for the validity of the PID-5 Impulsivity scale and its ability to predict daily impulsivity above and beyond fluctuations in affect and stress.

Recent personality neuroscience research in large samples suggests that personality traits tend to bear nullto-small relations to morphometric (i.e., brain structure) regions of interest (ROIs). In this preregistered, two-part study using Human Connectome Project data (N = 1,105), we address the possibility that these null-to-small relations are due, in part, to the "level" (i.e., hierarchical placement) of personality and/or morphometry examined. We used a Five-Factor Model framework and operationalized personality in terms of meta-traits, domains, facets, and items; we operationalized morphometry in terms of omnibus measures (e.g., total brain volume), and cortical thickness and area in the ROIs of the Desikan and Destrieux atlases. First, we compared the patterns of effect sizes observed between these levels using mixed effects modeling. Second, we used a machine learning framework for estimating out-of-sample predictability. Results highlight that personality-morphometry relations are generally null-to-small no matter how they are operationalized. Relatively, the largest mean effect sizes were observed at the domain level of personality, but the largest individual effect sizes were observed at the facet and item level, particularly for the Ideas facet of Openness and its constituent items. The largest effect sizes observed were at the omnibus level of morphometry, and predictive models containing only omnibus variables were comparably predictive to models including both omnibus variable and ROIs. We conclude by encouraging researchers to search across levels of analysis when investigating relations between personality and morphometry and consider prioritizing omnibus measures, which appear to yield the largest and most consistent effects.

Personality researchers have posited multiple ways in which the relations between personality traits and life outcomes may be moderated by other traits, but there are well-known difficulties in reliable detection of such trait-by-trait interaction effects. Estimating the prevalence and magnitude base rates of trait-by-trait interactions would help to assess whether a given study is suited to detect interaction effects. We used the Life Outcomes of Personality Replication Project dataset to estimate the prevalence, nature, and magnitude of trait-by-trait interactions across 81 self-reported life outcomes ( n ≥ 1350 per outcome). Outcome samples were divided into two halves to examine the replicability of observed interaction effects using both traditional and machine learning indices. The study was adequately powered (1 − β ≥ .80) to detect the smallest interaction effects of interest (interactions accounting for a Δ R2 of approximately .01) for 78 of the 81 (96%) outcomes in each of the partitioned samples. Results showed that only 40 interactions (5.33% of the original 750 tests) showed evidence of strong replicability through robustness checks (i.e., demographic covariates, Tobit regression, and ordinal regression). Interactions were also uniformly small in magnitude. Future directions for research on trait-by-trait interactions are discussed.