The Capgras delusion: an integrated approach

Delusions are studied in two different philosophical traditions: the continental or phenomenological tradition and the Anglo-American or analytic tradition. This thesis argues that the most plausible account of monothematic delusions ultimately incorporates valuable insights from both. It offers a new two-factor account of the Capgras delusion in which the characterisation of each factor reflects insights from the two traditions. I argue that the first factor is a delay in face encoding, which causes the face to be classified 'unknown', thus creating a conflict when the person's identity is accessed. I argue that this conflict is resolved by an application of the 'impostor' concept, which is an interpretation of the face in context, and further, that this concept is primarily developed through acquaintance with fiction. Applying a concept from fiction to reality creates cross-world conflict that cannot be resolved in the normal way. Consequently, the system that monitors conflicts is decoupled from executive control to allow the impostor attribution to pass unchallenged. The decoupling constitutes the second factor. I argue that the decoupling, which is a normal process that allows engagement with imaginative worlds, is brought to bear on an abnormal situation. This two-factor account is supported by neuroimaging data from investigations into conflict monitoring and executive control, and investigation of the hypnotic condition. In conclusion, I will suggest how the model presented could be applied to several other monothematic delusions.