The authors declare no competing interests.Acknowledgments: NF has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement No. 803122). We thank Mathieu Roger for his help at the beginning of this project. We thank Samuele Cortese and Clément Dondé for their valuable advice.

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BackgroundMetacognitive deficits are well documented in schizophrenia spectrum disorders as a decreased capacity to adjust confidence to first-order performance in a cognitive task. Because metacognitive ability directly depends on first-order performance, observed metacognitive deficits might be driven by lower first-order performance. We aimed to determine the extent to which individuals with schizophrenia experience specific deficits when producing confidence judgments and examined whether studies controlling for first-order performance found metacognitive deficits of smaller magnitude.MethodElectronic databases were searched for studies published until April 24th 2020. We conducted a Bayesian meta-analysis of 43 studies comparing the calibration of confidence in 1458 individuals with schizophrenia compared to 1337 matched controls. Group analyses and meta-regressions quantified how metacognitive deficits depended on task performance, cognitive domains, clinical severity, and antipsychotic dosage.OutcomesWe found a global metacognitive deficit in schizophrenia (g = -0.57, 95% CrI [-0.71, -0.43]), which was driven by studies which did not equate first-order performance between groups (g = -0.64, 95% CrI [-0.77, -0.51]), and inconclusive among controlled-studies (g = -0.28, 95% CrI [-0.63, 0.07], BF01 = 1.3). Plus, the metacognitive deficit in non-controlled studies was correlated with first-order performance. No correlation was found between metacognitive deficit and clinical features of schizophrenia.InterpretationWe provide evidence for the existence of a deficit in the calibration of confidence judgments in schizophrenia, which is inflated due to non-equated first-order performance. Thus, efforts should be made to develop experimental protocols accounting for lower first-order performance in schizophrenia.