Islands of Inference: A Neurodevelopmental Architecture for Fixed Delusions.
Psychopathology May 4, 2026 Paul Goldsmith
Delusions can be highly selective, affecting only one domain while other thinking remains intact. Existing models that focus on dopamine or general belief-updating problems explain why delusions are intense and persistent but not why they are circumscribed. This paper proposes that subtle, naturally occurring variations in brain structure can create small cortical regions with unusually deep internal representations. When such a region supports advanced theory of mind, it can generate internally coherent social narratives that the surrounding brain network cannot adequately integrate or challenge, causing those beliefs to become fixed. This 'Islands of Inference' model explains why delusions often involve social content, emerge in late adolescence, resist counter-evidence, and worsen over time, and it clarifies how dopamine and cannabis amplify the influence of these islands without determining their content.