Delusions (fixed, false beliefs that are not amenable to change in light of conflicting evidence) typically occur in the context of mental disorders and are the most prominent symptom of psychosis. They are accompanied by severe distress both for the person who holds them and for other people involved.

In recent years, interest in psychological models and interventions has started to grow. Cognitive behavioral interventions, in particular, have shown promise in reducing delusional conviction and distress, however, the effect sizes leave room for improvement. A step towards improved interventions would be to arrive at a better understanding of the mechanisms that contribute to the formation and maintenance of delusions. Building on research pointing to the relevance of several psychological mechanisms, such as emotion regulation, reasoning biases, and processing of self-relevant information, interventions that focus more explicitly on these mechanisms might be beneficial.

This collection of research from around the world focuses both on the challenge of improving our understanding of the psychological mechanisms that underlie delusions and on psychological therapy approaches that can be derived from this knowledge.