The article by Fletcher and Frith explores the positive symptoms of schizophrenia, such as hallucinations and delusions, through a Bayesian framework. They argue that these symptoms are not distinct processes but are part of a core abnormality in error-dependent updating of inferences and beliefs about the world. The authors suggest that these symptoms can be understood within a disturbed hierarchical Bayesian framework, where a disturbance in the prediction-error signal underlies both abnormal perceptions and beliefs. They propose that abnormal dopamine neurotransmission disrupts the precision of prediction errors, leading to false inferences and beliefs. This disruption can manifest at various levels of the hierarchy, from low-level sensory processing to higher-level inferential processes, causing patients to experience strange and compelling sensations and beliefs. The article also discusses the social and environmental factors that contribute to the severity of these symptoms and the potential for cognitive behavioral therapy to reduce suffering.The article by Fletcher and Frith explores the positive symptoms of schizophrenia, such as hallucinations and delusions, through a Bayesian framework. They argue that these symptoms are not distinct processes but are part of a core abnormality in error-dependent updating of inferences and beliefs about the world. The authors suggest that these symptoms can be understood within a disturbed hierarchical Bayesian framework, where a disturbance in the prediction-error signal underlies both abnormal perceptions and beliefs. They propose that abnormal dopamine neurotransmission disrupts the precision of prediction errors, leading to false inferences and beliefs. This disruption can manifest at various levels of the hierarchy, from low-level sensory processing to higher-level inferential processes, causing patients to experience strange and compelling sensations and beliefs. The article also discusses the social and environmental factors that contribute to the severity of these symptoms and the potential for cognitive behavioral therapy to reduce suffering.