In considering the contribution of cognitive neuropsychology to the understanding of persecutory delusions, we shall proceed in this chapter as follows: First, we shall consider the contribution of the more conventional clinical neuropsychological approach to the study of delusions. After all, cognitive neuropsychology developed as a hybrid of clinical neuropsychology (the psychological study of brain-injured people) and cognitive psychology (the study of the mental information-processing procedures that people use to perform such activities as speaking and understanding speech, and recognizing objects). Second, we shall outline the cognitive neuropsychological approach with brief reference to its history. Third, we shall describe how this approach has been applied to the study of delusions with reference
to our two-deficit cognitive neuropsychological model of monothematic delusions. Finally we shall evaluate the applicability of this model to the explanation of other delusions that are not so obviously neuropsychological; here we shall focus on persecutory delusions.