The cognitive neuropsychiatry of delusional belief

According to the 'two-factor' cognitive-neuropsychiatric approach to delusional belief, two factors, in combination, explain the generation and maintenance of monothematic delusions. The first factor varies from delusion to delusion and explains why a patient generates a particular implausible thought in the first place. The second factor explains why a patient fails to reject the implausible thought as belief. This two-factor approach began with a 'two-deficit' account of bizarre monothematic delusions, according to which bizarre delusions are generated when a (first-factor) deficit of basic sensory/affective processing fundamentally distorts perceived reality. Deficits of this type are discussed and contrasted with motivated attentional biases in more mundane delusions. To better specify the second factor, I contrast 'explanationist' and 'endorsement' approaches to the role of aberrant experience in delusion formation and propose a 'received-reflective' spectrum. At one pole of this spectrum are purely received delusions, which arise fully formed and fully (mis)believed in consciousness as the (mis)perceived reality. At the other pole are purely reflective delusions, which arise after reflection upon a vague and disquieting experience, and for which the crystallization of delusional conviction is more gradual. Most delusions lie in between, a mix of received 'delusional seed' and reflective elaboration. Underpinning all monothematic delusions, wherever they might lie on this spectrum may be a form of 'doxastic inhibitory failure'-a difficulty with inhibiting a belief to reason about it as if it might not be true. I conclude by considering how this account might apply to polythematic delusions. WIREs Cogni Sci 2011 2 449-460 DOI: 10.1002/wcs.121 For further resources related to this article, please visit the WIREs website.