OBJECTIVES: The aim of the present study was to investigate the effects of comorbid obsessive-compulsive symptoms (OCS) on the perception of insincere speech (e.g., sarcasm and white lies) in patients with first-episode psychosis.DESIGN AND METHOD: Participants were 65 patients with nonaffective first-episode psychosis (FEP) and 47 healthy controls. The patient group was divided into two subgroups, those with (FEP+; n= 38) and those without OCS (FEP-; n = 27). The ability to process sarcasm and lie was assessed with the Perception of Social Inference Test (PESIT). Severity of psychotic symptoms and OCS was assessed with the Positive and Negative Syndrome Scale (PANSS) and the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), respectively.RESULTS: Deficits in the perception of sarcasm and lie were confirmed in patients with nonaffective first-episode psychosis compared to healthy controls. In patients, comorbidity with OCS was associated with worse performance on certain aspects of insincere speech (i.e., lie) compared to FEP- patients. Y-BOCS scores correlated significantly with the perception of lying. The cognitive factor of the PANSS predicted accuracy on the perception of sincere speech, paradoxical sarcasm, and white lies, while the presence of OCS predicted accuracy on the perception of sincere speech and white lies.CONCLUSIONS: Our finding of impaired counterfactual information processing in patients with first-episode psychosis suggests that these deficits are already present at illness onset. Presence of OCS appears to have additional deleterious effects on the successful interpretation of intentional lying, further supporting that these patients are characterized by more extensive cognitive impairment.