Insight in nonverbal correlates of paranoid ideation can potentially help improve diagnostic procedures and guide interventions. The aim was to systematically evaluate the scientific evidence investigating nonverbal correlates of paranoid ideation.

The review follows the PRISMA guidelines. Databases PsycINFO, PubMed, Web of Science, and Cinahl were searched for studies concerning the use of standardized instruments for both verbal and nonverbal measurements of paranoid ideation in adult participants. Quality of studies was evaluated using the Effective Public Health Practice Project tool. Data were systematically extracted and summarized thematically and narratively. This review was registered with PROSPERO (CRD42022288001).

The search strategy yielded 3962 results of which 22 papers met inclusion criteria. Half (n = 11) of the included articles included patients with a diagnosis on the psychosis spectrum, the other articles (n = 11) studied healthy populations. Identified nonverbal categories were spatial behavior (n = 6), brain region activity (n = 5), visual perception (n = 5), stress physiology (n = 4), information processing (n = 3), and aggression (n = 1). Some studies investigated multiple nonverbal categories.

Evidence was strongest for spatial behavior and brain region activity as nonverbal correlates of paranoid ideation. Evidence for stress physiology, information processing, and aggression as potential nonverbal correlates was less robust, due to inconsistent findings and small numbers of publications. Using nonverbal methods to assess paranoid ideation requires more investigation and evaluation. The integration of nonverbal assessments might offer new diagnostic possibilities that move beyond traditional verbal methods.

Trait impulsivity is thought to play a key role in predicting behaviors on the externalizing spectrum, such as drug and alcohol use and aggression. Research suggests that impulsivity may not be a unitary construct, but rather multidimensional in nature with dimensions varying across self-report assessments and laboratory behavioral tasks. Few studies with large samples have included a range of impulsivity-related measures and assessed several externalizing behaviors to clarify the predictive validity of these assessments on important life outcomes.

Community adults (N = 1295) between the ages of 30 and 54 completed a multidimensional assessment of impulsivity-related traits (including 54 self-report scales of personality traits implicated in impulsive behaviors, and four behavioral tasks purporting to assess a construct similar to impulsivity) and reported on five externalizing behavioral outcomes (i.e. drug, alcohol, and cigarette use, and physical and verbal aggression). We ran an exploratory factor analysis on the trait scales, and then a structural equation model predicting the externalizing behaviors from the three higher-order personality factors (i.e. Disinhibition v. Constraint/Conscientiousness, Neuroticism/Negative Emotionality, and Extraversion/Positive Emotionality) and the four behavioral tasks.

Relations between the self-report factors and behavioral tasks were small or nonexistent. Associations between the self-report factors and the externalizing outcomes were generally medium to large, but relationships between the behavioral tasks and externalizing outcomes were either nonexistent or small.

These results partially replicate and extend recent meta-analytic findings reported by Sharma et al. (2014) to further clarify the predictive validity of impulsivity-related trait scales and laboratory behavioral tasks on externalizing behaviors.