Comments on the content of persecutory delusions: does the definition need clarification?

Diagnostic criteria for subtypes of delusional beliefs based upon content have rarely been the subject of comment. In this article, several influential accounts of persecutory delusions are reviewed; differences and difficulties are noted, and their potential effect on cognitive psychological investigations discussed. One method of ensuring that researchers study similar phenomena is to use a more detailed definition than currently available, and therefore a new set of criteria is offered. Finally, related methodological problems in this emerging research area are highlighted. The issues discussed may stimulate further research on the content of delusional beliefs.