Social priors and mentalizing connectivity across autistic and schizotypal traits.

Autism spectrum disorder (ASD) and schizophrenia spectrum disorder (SSD) both involve social-cognitive difficulties but may rely on opposite predictive mechanisms. Predictive-coding and diametrical accounts propose weak priors in ASD versus strong priors in SSD. We tested whether autistic and positive schizotypal traits differentially shape the use of social priors when interpreting ambiguous social cues. Two studies with non-clinical adults employed an adapted Animated Triangles Task (ATT) with three cueing conditions: Random-Uncued, Random-Cued, and ToM-Cued. Study 1 (n = 71) assessed behavior; Study 2 (n = 45) combined behavioral data with task-based functional magnetic resonance imaging (fMRI), including region-of-interest (ROI) and psychophysiological interaction (PPI) analyses of the temporoparietal junction (TPJ), medial prefrontal cortex (mPFC), and cerebellar Crus II. Social-attribution ratings increased across conditions, confirming the cueing manipulation. At the uncorrected level, higher positive schizotypal traits were associated with greater social attribution without cues, whereas higher autistic traits were associated with lower intention ratings despite strong cues. ToM-Cued trials activated the mentalizing network. Both trait dimensions showed exploratory associations with reduced mentalizing-network connectivity. These preliminary findings suggest potentially shared neural patterns coupled with divergent behavioral responses across the autism-psychosis trait continuum, pending further validation with larger sample sizes and adjusted statistical analyses.