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Deficits in sleep spindle activity in individuals with psychotic disorders could represent a neurobiological marker of (premorbid) attentional deficits and perceptual distortions that ultimately add to psychotic symptom formation. We analysed the links between sleep spindle activity and psychotic experiences and probed for the mediating roles of attentional performance and self-reported perceptual distortions in a community sample (N=70; mean age 26.33 (SD = 4.84)). Polysomnography was recorded during a 90-minute daytime nap and sleep spindle activity was detected using an automated algorithm. Duration, amplitude, and density from slow (10-13 Hz) and fast (13-16 Hz) sleep spindles were extracted. Attentional performance was assessed via subtests of the Test of Attentional Performance (TAP) and with an antisaccadic eye movement task. Psychotic experiences (i.e., paranoid thoughts; hallucinatory experiences) and perceptual distortions (i.e., anomalous perceptions; sensory gating deficits) were assessed via self-report questionnaires. We conducted sequential mediation analyses with sleep spindle activity as predictor, psychotic experiences as dependent variable, and attentional performance and perceptual distortions as mediators. We found reduced right central slow and fast sleep spindle amplitude to be associated with paranoid thoughts. Increased antisaccadic error rate was associated with anomalous perceptions and perceptual distortions were associated with psychotic experiences. We did not find significant mediation effects. The findings support the notion that reduced sleep spindle activity is involved in psychotic symptom formation and that decreased antisaccadic performance is indicative of perceptual distortions as potential precursors for psychotic experiences. However, further research is needed to corroborate the here proposed mediation hypothesis.

Manuscript accepted for publication in Personality and Social Psychology Bulletin

BackgroundDifficulties in the ability to adapt beliefs in the face of new information are associated with psychosis and its central symptom – paranoia. As cognitive processes and psychotic symptoms are both known to be sensitive to stress, the present study investigated the exact associations between stress, adapting of beliefs [reversal learning (RL), bias against disconfirmatory evidence (BADE), and jumping to conclusions (JTC)] and paranoia. We hypothesized that paranoia would increase under stress and that difficulties in adapting of beliefs would mediate or moderate the link between stress and paranoia. Furthermore, we hypothesized that the investigated effects would be strongest in the group of individuals diagnosed with a psychotic disorder.MethodsWe exposed 155 participants (38 diagnosed with a psychotic disorder, 40 individuals with attenuated psychotic symptoms, 39 clinical controls diagnosed with an obsessive-compulsive disorder, and 38 healthy controls) to a control condition and a stress condition, in which we assessed their levels of paranoia and their ability to adapt beliefs. We applied multilevel models to analyze the data.ResultsParanoia was higher in the stress condition than in the control condition, b = 1.142, s.e. = 0.338, t(150) = 3.381, p < 0.001. RL, BADE, and JTC did not differ between conditions and did not mediate or moderate the association between stress and paranoia (all ps > 0.05).ConclusionsThe results support the assumption that stress triggers paranoia. However, the link between stress and paranoia does not seem to be affected by the ability to adapt beliefs.

Research suggests that people spontaneously infer traits from behavioral information, thus forming impressions of actors’ personalities. Such spontaneous trait inferences (STI) have been examined in a wide range of studies in the last four decades. Here, we provide the first systematic meta-analysis of this vast literature. We included data from k = 86 publications, with overall N = 13,630 participants. The average STI effect was moderate to large ( dz = 0.59) and showed substantial heterogeneity. The type of experimental paradigm significantly moderated the STI effect size, with larger effects in long-term memory–based paradigms compared with working memory–based paradigms. Generally, STI effects were robust to various methodological variations and also to potential concerns of publication bias. Contrary to expectations, cultural background (independent vs. interdependent) did not emerge as a significant moderator of STI effects. We discuss these findings with respect to their theoretical relevance and derive implications for future research and theorizing.

Individual differences in trait levels of openness to experience and creativity have been theoretically linked to dopamine function. However, empirical evidence for this assumption is scarce, especially for causal connections. The present study aims to directly assess the influence of dopamine activity on the established association between openness to experience and divergent thinking (i.e., an index of creativity). We hypothesized that manipulating dopamine activity alters the relationship between self-reported openness to experience and ideational fluency and flexibility. In a placebo-controlled between-subjects design, 193 healthy male volunteers completed four divergent thinking tasks after they received either the dopamine-receptor blocker sulpiride (200 mg) or a placebo. The data revealed an interaction such that openness to experience was more positively associated with divergent thinking in the dopamine blocker group (r = 0.304) than in the placebo group (r = −0.002). Specifically, highly open individuals in the dopamine blocker group reached the highest divergent thinking scores. Thus, sulpiride administration selectively affected divergent thinking as a function of trait levels of openness to experience. Although somewhat limited by the unexpected absence of the association between openness to experience and divergent thinking in the placebo group, the present study provides novel evidence for an association between dopamine activity and both openness to experience and divergent thinking.