Early and late signals of unexpected reward contribute to low extraversion and high disinhibition, respectively

Examining the Criterion and Incremental Validity of the MMPI-3 Impulsivity Scale

The Minnesota Multiphasic Personality Inventory-3 (MMPI-3) includes a new Impulsivity (IMP) scale designed to assess for poor impulse-control and non-planful behavior, which was added to broaden the utility of the instrument. The current study aimed to examine the criterion and incremental validity of the IMP scale. A university student sample (n = 1,440) and a community sample oversampled for externalizing tendencies (n = 231) were used for this purpose, and IMP scores were compared to scores on various well-validated criterion measures of impulsivity and externalizing psychopathology. To examine the scale's incremental validity, hierarchical multiple regression analyses were conducted to determine whether IMP adds to other MMPI-3 Specific Problem (SP) scales in the prediction of relevant criteria. The IMP scale primarily showed meaningful correlations with the Negative Urgency and Positive Urgency on the UPPS-P. Significant correlations were also observed with the cognitive, behavioral, disinhibition, and lifestyle domains of various psychopathy measures, as well as measures of antisocial personality disorder and substance use. The IMP scale scores accounted for incremental variance in most of the directly relevant criterion measures above and beyond scores of other MMPI-3 SP scales. Several important caveats, limitations, and future directions are discussed.

MMPI-3 Assessment of Externalizing Psychopathology in Targeted Community and University Samples

The Minnesota Multiphasic Personality Inventory-3 (MMPI-3) scales that are designed to assess various forms of externalizing psychopathology have received relatively little research attention to date. The goal of this investigation was therefore to examine the validity of these MMPI-3 scales in the measurement of the externalizing spectrum. A community sample (n = 206) with high levels of externalizing psychopathology and a university sample (n = 645) were used. The former sample was administered structured clinical interviews for various forms of externalizing psychopathology, whereas the student sample completed the Externalizing Spectrum Inventory-160. Confirmatory factor analysis was used to operationalize the externalizing spectrum using each set of measures. The results indicated that the externalizing MMPI-3 scales were associated with a general externalizing factor and an expected pattern of associations, while systematic residuals of individual disorder symptoms also emerged. Moreover, in the university sample, specific MMPI-3 scales hypothesized to assess antagonistic-externalizing (Aggressiveness, Aggression, and Cynicism) emerged as key predictors of a callous-aggression residual group factor. The Substance Abuse scale was unsurprisingly the best predictor of such dysfunction. These findings provide guidance for mental health practitioners who use the MMPI-3 for the assessment of externalizing psychopathology symptoms.

Examination of associations between psychopathy and neural reinforcement sensitivity theory constructs

We investigated psychopathy from the neurobiological perspective of reinforcement sensitivity theory (RST). In contrast to previous semantically derived self-report scales, we operationalised RST systems neurally with evoked electroencephalography (EEG). Participants were from a community sample weighted towards externalising psychopathology. We compared the Carver & White Behavioural Inhibition System (BIS)/Behavioural Approach System (BAS) scales with EEG responses associated with RST's systems of goal conflict (aka 'behavioural inhibition'), repulsion/outcome conflict (aka 'fight/flight/freeze') and attraction (aka 'approach'). Bivariate correlations and multiple regression analysis yielded results generally consistent with past literature for associations between psychopathy and the self-report BIS/BAS scales. There were some differences from self-report associations with neural measures of RST. With EEG measures, (1) no meaningful associations were observed between any psychopathy scales and the attraction system; (2) affective-interpersonal traits of psychopathy were negatively associated with goal conflict; (3) disinhibition-behavioural traits of psychopathy were negatively associated with goal conflict but, unexpectedly, positively associated with outcome conflict. These results indicate frontal-temporal-limbic circuit dysfunction in psychopathy as specific domains were linked to neural deficits in goal conflict processing, but there was no evidence for deficits in attraction-related processes.

Midfrontal theta reactivity to conflict and error are linked to externalizing and internalizing respectively

Dimensional psychopathology scores measure symptom severity; cutting across disorder categories. Their clinical utility is high given comorbidity, but their neural basis is unclear. We used scalp electroencephalography (EEG) to concurrently assess neural activity across internalizing and externalizing traits. "Theta rhythm" (4-7 Hz) spectral power at the frontal midline site Fz in specific goal conflict and action error phases within a trial of a Stop-Signal Task was extracted using process-specific contrasts. A final sample of 146 community participants (63 males, 83 females; mean age = 36; SD = 9; range = 18 - 56), oversampled for externalizing disorder (49% diagnosed with a DSM-5 externalizing disorder), also supplied psychopathology and personality data. We used the Minnesota Multiphasic Personality Inventory-3 (MMPI-3) to measure symptoms and traits of psychopathology. An MMPI-3 measure of the higher-order internalizing psychopathology spectrum was positively correlated with action error theta. An MMPI-3 measure of the higher-order spectrum of externalizing psychopathology was negatively correlated with goal-conflict theta. We showed that goal-conflict and error theta activity are higher-order processes that index psychopathology severity. The associations extend into the nominally healthy range, and so reflect theta-related factors that apply to the general population as well as patients with sub-threshold diagnoses.

Midfrontal conflict theta and parietal P300 are linked to a latent factor of DSM externalising disorders

Psychiatric illnesses form spectra rather than categories, with symptoms varying continuously across individuals, i.e., there is no clear break between health and disorder. Dimensional measures of behaviour and brain activity are promising targets for studying biological mechanisms that are common across disorders. Here, we assessed the extent to which neural measures of the sensitivity of the three biological systems in the reinforcement sensitivity theory (RST) could account for individual differences in a latent general factor estimated from symptom counts across externalising disorders (EXTs). RST explanatory power was pitted against reduced P300, a reliable indicator of externalising per previous research. We assessed 206 participants for DSM-5 EXTs (antisocial personality disorder, conduct disorder, attention-deficit/hyperactivity disorder, intermittent explosive disorder symptoms, alcohol use disorder, and cannabis use disorder). Of the final sample, 49% met diagnostic criteria for at least one of the EXTs. Electroencephalographic measures of the sensitivities of the behavioural activation system (BAS), the fight/flight/freeze system, and the behavioural inhibition system (BIS), as well as P300 were extracted from the gold bar-lemon and stop-signal tasks. As predicted, we found that low neural BIS sensitivity and low P300 were uniquely and negatively associated with our latent factor of externalising. Contrary to prediction, neural BAS/"dopamine" sensitivity was not associated with externalising. Our results provide empirical support for low BIS sensitivity and P300 as neural mechanisms common to disorders within the externalising spectrum; but, given the low N involved, future studies should seek to assess the replicability of our findings and, in particular, the differential involvement of the three RST systems.

Examining the Psychometric Properties of the Expanded Levenson Self-Report Psychopathy Scale in Community and University Samples

The aim of the current study was to further examine the psychometric properties of the Expanded Levenson Self-Report Psychopathy Scale (E-LSRP; Christian & Sellbom, 2016). Specifically, its reliability, internal structure, and convergent and discriminant validity were evaluated using university (N = 367) and community samples (N = 205) from Aotearoa New Zealand. The results provided support for the reliability and validity of the E-LSRP in both samples. More specifically, the internal consistency estimates of the E-LSRP were above the meaningful threshold, indicating good reliability. Furthermore, using confirmatory factor analysis, the hypothesized three-factor structure was supported and conceptually consistent with Cooke and Michie's (2001) Psychopathy Checklist-Revised (PCL-R) three-factor model. Lastly, the results generally provided support for the convergent and discriminant validity of the E-LSRP subscales; the E-LSRP Egocentricity was associated with criteria relevant to interpersonal impairment, the Callous scale with criteria relevant to the affective psychopathy domain, and the Antisocial scale with criteria representing behavioral dysfunction. Overall, the E-LSRP is a promising tool for assessing psychopathy in nonincarcerated populations.