29 November 2017: Beliefs and the Brain: Computational Mechanisms of Hallucinations and Delusions

Phil Corlett
Department of Psychiatry
Yale University

Psychosis is generally defined in terms experiences that deviate appreciably from consensual reality. I will discuss two of its component symptoms; anomalous perceptions (“hallucinations”) and bizarre and inexplicable beliefs (“delusions”). A major challenge in developing a coherent understanding of psychosis is to characterize the disturbances that may give rise both to profoundly altered experiences and to impairments in belief. I will explore the degree to which understanding the brain as a predictive inference device may help us explain psychotic symptoms. I will argue that hallucinations and delusions may arise and be maintained as a result of aberrant prediction errors which garner strong top-down priors as palliative explanatory responses. By refining our understanding of how these disturbances may occur, we gain valuable insights to how the brain generates our experiences more generally.