Reduced Neural Convergence and Reorganized Paranoia-Related Representations During Ambiguous Social Narrative Processing in Schizophrenia

Schizophrenia may involve a fundamental disruption in the ability to construct a shared understanding of social reality, yet conventional neuroimaging studies have largely examined social cognition using simplified and highly structured paradigms that may not capture how individuals interpret complex and ambiguous interpersonal events in everyday life. Using an ecologically valid naturalistic fMRI paradigm, we examined shared and paranoia-related neural representations during ambiguous social narrative processing in 38 patients with schizophrenia and 46 healthy controls. Intersubject correlation was used to quantify neural convergence across individuals, whereas intersubject representational similarity analysis was used to examine how individual differences in paranoid ideation were reflected in neural representations. Compared with healthy controls, patients with schizophrenia showed reduced neural convergence within distributed systems supporting social inference, contextual integration, and salience attribution, including temporoparietal, temporal, insular, and inferior frontal regions. Furthermore, paranoid ideation was associated with altered neural representational structure. In healthy controls, higher paranoia was linked to reduced neural similarity across social-cognitive and affective regions, suggesting reduced convergence toward shared interpretations of ambiguous social information. In schizophrenia, paranoia-related representations showed sparse within-group associations but elevated patient-control differences across a distributed social-affective circuit, indicating a reorganization rather than a simple amplification of paranoia-related processing. Together, these findings demonstrate that schizophrenia involves both impaired alignment of neural responses during shared social meaning construction and organization of paranoia-related representations, providing an ecologically grounded framework for understanding abnormal social inference in psychosis.